Refactor handlers.rs into modular structure for better maintainability

- Split 1921-line handlers.rs into focused modules:
  - handlers/auth.rs: Authentication handlers (login, verify_token, get_user_info)
  - handlers/calendar.rs: Calendar management (create_calendar, delete_calendar)
  - handlers/events.rs: Event operations (CRUD operations, fetch events)
  - handlers/series.rs: Event series operations (recurring events management)
- Main handlers.rs now serves as clean re-export module
- All tests passing (14 integration + 7 unit + 3 doc tests)
- Maintains backward compatibility with existing API routes
- Improves code organization and separation of concerns

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/auth.rs

@@ -104,7 +104,7 @@ impl AuthService {
         Ok(())
     }
 
-    fn generate_token(&self, username: &str, server_url: &str) -> Result<String, ApiError> {
+    pub fn generate_token(&self, username: &str, server_url: &str) -> Result<String, ApiError> {
         let now = Utc::now();
         let expires_at = now + Duration::hours(24); // Token valid for 24 hours
 

backend/src/handlers/auth.rs

@@ -0,0 +1,159 @@
+use axum::{
+    extract::State,
+    http::HeaderMap,
+    response::Json,
+};
+use std::sync::Arc;
+
+use crate::{AppState, models::{CalDAVLoginRequest, AuthResponse, ApiError, UserInfo, CalendarInfo}};
+use crate::calendar::CalDAVClient;
+use crate::config::CalDAVConfig;
+
+pub fn extract_bearer_token(headers: &HeaderMap) -> Result<String, ApiError> {
+    let auth_header = headers.get("authorization")
+        .ok_or_else(|| ApiError::Unauthorized("Missing Authorization header".to_string()))?;
+    
+    let auth_str = auth_header.to_str()
+        .map_err(|_| ApiError::BadRequest("Invalid Authorization header".to_string()))?;
+    
+    if let Some(token) = auth_str.strip_prefix("Bearer ") {
+        Ok(token.to_string())
+    } else {
+        Err(ApiError::BadRequest("Authorization header must be Bearer token".to_string()))
+    }
+}
+
+pub fn extract_password_header(headers: &HeaderMap) -> Result<String, ApiError> {
+    let password_header = headers.get("x-caldav-password")
+        .ok_or_else(|| ApiError::BadRequest("Missing X-CalDAV-Password header".to_string()))?;
+    
+    password_header.to_str()
+        .map(|s| s.to_string())
+        .map_err(|_| ApiError::BadRequest("Invalid X-CalDAV-Password header".to_string()))
+}
+
+pub async fn login(
+    State(state): State<Arc<AppState>>,
+    Json(request): Json<CalDAVLoginRequest>,
+) -> Result<Json<AuthResponse>, ApiError> {
+    println!("🔐 Login attempt:");
+    println!("  Server URL: {}", request.server_url);
+    println!("  Username: {}", request.username);
+    println!("  Password length: {}", request.password.len());
+    
+    // Basic validation
+    if request.username.is_empty() || request.password.is_empty() || request.server_url.is_empty() {
+        return Err(ApiError::BadRequest("Username, password, and server URL are required".to_string()));
+    }
+    
+    println!("✅ Input validation passed");
+    
+    // Create a token using the auth service
+    println!("📝 Created CalDAV config");
+    
+    // First verify the credentials are valid by attempting to discover calendars
+    let config = CalDAVConfig {
+        server_url: request.server_url.clone(),
+        username: request.username.clone(),
+        password: request.password.clone(),
+        calendar_path: None,
+        tasks_path: None,
+    };
+    let client = CalDAVClient::new(config);
+    client.discover_calendars()
+        .await
+        .map_err(|e| ApiError::Unauthorized(format!("Authentication failed: {}", e)))?;
+    
+    let token = state.auth_service.generate_token(&request.username, &request.server_url)?;
+    
+    println!("🔗 Created CalDAV client, attempting to discover calendars...");
+    
+    Ok(Json(AuthResponse {
+        token,
+        username: request.username,
+        server_url: request.server_url,
+    }))
+}
+
+pub async fn verify_token(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+) -> Result<Json<serde_json::Value>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let is_valid = state.auth_service.verify_token(&token).is_ok();
+    
+    Ok(Json(serde_json::json!({ "valid": is_valid })))
+}
+
+pub async fn get_user_info(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+) -> Result<Json<UserInfo>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+    
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config.clone());
+    
+    // Discover calendars
+    let calendar_paths = client.discover_calendars()
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?;
+        
+    println!("✅ Authentication successful! Found {} calendars", calendar_paths.len());
+    
+    let calendars: Vec<CalendarInfo> = calendar_paths.iter().map(|path| {
+        CalendarInfo {
+            path: path.clone(),
+            display_name: extract_calendar_name(path),
+            color: generate_calendar_color(path),
+        }
+    }).collect();
+    
+    Ok(Json(UserInfo {
+        username: config.username,
+        server_url: config.server_url,
+        calendars,
+    }))
+}
+
+fn generate_calendar_color(path: &str) -> String {
+    // Generate a consistent color based on the calendar path
+    // This is a simple hash-based approach
+    let mut hash: u32 = 0;
+    for byte in path.bytes() {
+        hash = hash.wrapping_mul(31).wrapping_add(byte as u32);
+    }
+    
+    // Define a set of pleasant colors
+    let colors = [
+        "#3B82F6", "#10B981", "#F59E0B", "#EF4444", "#8B5CF6",
+        "#06B6D4", "#84CC16", "#F97316", "#EC4899", "#6366F1",
+        "#14B8A6", "#F3B806", "#8B5A2B", "#6B7280", "#DC2626",
+        "#7C3AED", "#059669", "#D97706", "#BE185D", "#4F46E5"
+    ];
+    
+    colors[(hash as usize) % colors.len()].to_string()
+}
+
+fn extract_calendar_name(path: &str) -> String {
+    // Extract calendar name from path
+    // E.g., "/calendars/user/calendar-name/" -> "Calendar Name"
+    path.split('/')
+        .filter(|s| !s.is_empty())
+        .last()
+        .unwrap_or("Calendar")
+        .replace('-', " ")
+        .replace('_', " ")
+        .split_whitespace()
+        .map(|word| {
+            let mut chars = word.chars();
+            match chars.next() {
+                None => String::new(),
+                Some(first) => first.to_uppercase().collect::<String>() + chars.as_str(),
+            }
+        })
+        .collect::<Vec<String>>()
+        .join(" ")
+}

backend/src/handlers/calendar.rs

@@ -0,0 +1,71 @@
+use axum::{
+    extract::State,
+    http::HeaderMap,
+    response::Json,
+};
+use std::sync::Arc;
+
+use crate::{AppState, models::{ApiError, CreateCalendarRequest, CreateCalendarResponse, DeleteCalendarRequest, DeleteCalendarResponse}};
+use crate::calendar::CalDAVClient;
+
+use super::auth::{extract_bearer_token, extract_password_header};
+
+pub async fn create_calendar(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<CreateCalendarRequest>,
+) -> Result<Json<CreateCalendarResponse>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.name.trim().is_empty() {
+        return Err(ApiError::BadRequest("Calendar name is required".to_string()));
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Create calendar on CalDAV server
+    match client.create_calendar(&request.name, request.description.as_deref(), request.color.as_deref()).await {
+        Ok(_) => Ok(Json(CreateCalendarResponse {
+            success: true,
+            message: "Calendar created successfully".to_string(),
+        })),
+        Err(e) => {
+            eprintln!("Failed to create calendar: {}", e);
+            Err(ApiError::Internal(format!("Failed to create calendar: {}", e)))
+        }
+    }
+}
+
+pub async fn delete_calendar(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<DeleteCalendarRequest>,
+) -> Result<Json<DeleteCalendarResponse>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.path.trim().is_empty() {
+        return Err(ApiError::BadRequest("Calendar path is required".to_string()));
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Delete calendar on CalDAV server
+    match client.delete_calendar(&request.path).await {
+        Ok(_) => Ok(Json(DeleteCalendarResponse {
+            success: true,
+            message: "Calendar deleted successfully".to_string(),
+        })),
+        Err(e) => {
+            eprintln!("Failed to delete calendar: {}", e);
+            Err(ApiError::Internal(format!("Failed to delete calendar: {}", e)))
+        }
+    }
+}

backend/src/handlers/events.rs

@@ -0,0 +1,580 @@
+use axum::{
+    extract::{State, Query, Path},
+    http::HeaderMap,
+    response::Json,
+};
+use serde::Deserialize;
+use std::sync::Arc;
+use chrono::Datelike;
+
+use calendar_models::{VEvent, EventStatus, EventClass, CalendarUser, Attendee, VAlarm, AlarmAction, AlarmTrigger};
+use crate::{AppState, models::{ApiError, DeleteEventRequest, DeleteEventResponse, CreateEventRequest, CreateEventResponse, UpdateEventRequest, UpdateEventResponse}};
+use crate::calendar::{CalDAVClient, CalendarEvent};
+
+use super::auth::{extract_bearer_token, extract_password_header};
+
+#[derive(Deserialize)]
+pub struct CalendarQuery {
+    pub year: Option<i32>,
+    pub month: Option<u32>,
+}
+
+pub async fn get_calendar_events(
+    State(state): State<Arc<AppState>>,
+    Query(params): Query<CalendarQuery>,
+    headers: HeaderMap,
+) -> Result<Json<Vec<CalendarEvent>>, ApiError> {
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+    println!("🔑 API call with password length: {}", password.len());
+    
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+    
+    // Discover calendars if needed
+    let calendar_paths = client.discover_calendars()
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?;
+    
+    if calendar_paths.is_empty() {
+        return Ok(Json(vec![])); // No calendars found
+    }
+    
+    // Fetch events from all calendars
+    let mut all_events = Vec::new();
+    for calendar_path in &calendar_paths {
+        match client.fetch_events(calendar_path).await {
+            Ok(mut events) => {
+                // Set calendar_path for each event to identify which calendar it belongs to
+                for event in &mut events {
+                    event.calendar_path = Some(calendar_path.clone());
+                }
+                all_events.extend(events);
+            }
+            Err(e) => {
+                eprintln!("Failed to fetch events from calendar {}: {}", calendar_path, e);
+                // Continue with other calendars instead of failing completely
+            }
+        }
+    }
+    
+    // If year and month are specified, filter events
+    if let (Some(year), Some(month)) = (params.year, params.month) {
+        all_events.retain(|event| {
+            let event_year = event.dtstart.year();
+            let event_month = event.dtstart.month();
+            event_year == year && event_month == month
+        });
+    }
+    
+    println!("📅 Returning {} events", all_events.len());
+    Ok(Json(all_events))
+}
+
+pub async fn refresh_event(
+    State(state): State<Arc<AppState>>,
+    Path(uid): Path<String>,
+    headers: HeaderMap,
+) -> Result<Json<Option<CalendarEvent>>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+    
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+    
+    // Discover calendars
+    let calendar_paths = client.discover_calendars()
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?;
+    
+    // Search for the event by UID across all calendars
+    for calendar_path in &calendar_paths {
+        if let Ok(Some(mut event)) = client.fetch_event_by_uid(calendar_path, &uid).await {
+            event.calendar_path = Some(calendar_path.clone());
+            return Ok(Json(Some(event)));
+        }
+    }
+    
+    Ok(Json(None))
+}
+
+async fn fetch_event_by_href(client: &CalDAVClient, calendar_path: &str, event_href: &str) -> Result<Option<CalendarEvent>, crate::calendar::CalDAVError> {
+    // This is a simplified implementation - in a real scenario, you'd want to fetch the specific event by href
+    // For now, we'll fetch all events and find the matching one by href (inefficient but functional)
+    let events = client.fetch_events(calendar_path).await?;
+    
+    // Try to match by UID extracted from href
+    let uid_from_href = event_href.trim_end_matches(".ics");
+    for event in events {
+        if event.uid == uid_from_href {
+            return Ok(Some(event));
+        }
+    }
+    
+    Ok(None)
+}
+
+pub async fn delete_event(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<DeleteEventRequest>,
+) -> Result<Json<DeleteEventResponse>, ApiError> {
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Handle different delete actions for recurring events
+    match request.delete_action.as_str() {
+        "delete_this" => {
+            // For single occurrence deletion, we need to:
+            // 1. Fetch the recurring event
+            // 2. Add an EXDATE for this occurrence
+            // 3. Update the event
+
+            if let Some(mut event) = fetch_event_by_href(&client, &request.calendar_path, &request.event_href).await
+                .map_err(|e| ApiError::Internal(format!("Failed to fetch event: {}", e)))? {
+                
+                if let Some(occurrence_date) = &request.occurrence_date {
+                    // Parse the occurrence date and add it to EXDATE
+                    if let Ok(date) = chrono::DateTime::parse_from_rfc3339(occurrence_date) {
+                        let exception_utc = date.with_timezone(&chrono::Utc);
+                        event.exdate.push(exception_utc);
+                        
+                        // Update the event with the new EXDATE
+                        client.update_event(&request.calendar_path, &event, &request.event_href)
+                            .await
+                            .map_err(|e| ApiError::Internal(format!("Failed to update event with EXDATE: {}", e)))?;
+                        
+                        Ok(Json(DeleteEventResponse {
+                            success: true,
+                            message: "Single occurrence deleted successfully".to_string(),
+                        }))
+                    } else {
+                        Err(ApiError::BadRequest("Invalid occurrence date format".to_string()))
+                    }
+                } else {
+                    Err(ApiError::BadRequest("Occurrence date is required for single occurrence deletion".to_string()))
+                }
+            } else {
+                Err(ApiError::NotFound("Event not found".to_string()))
+            }
+        },
+        "delete_following" => {
+            // For "this and following" deletion, we need to:
+            // 1. Fetch the recurring event
+            // 2. Modify the RRULE to end before this occurrence
+            // 3. Update the event
+
+            if let Some(mut event) = fetch_event_by_href(&client, &request.calendar_path, &request.event_href).await
+                .map_err(|e| ApiError::Internal(format!("Failed to fetch event: {}", e)))? {
+                
+                if let Some(occurrence_date) = &request.occurrence_date {
+                    if let Ok(date) = chrono::DateTime::parse_from_rfc3339(occurrence_date) {
+                        let until_date = date.with_timezone(&chrono::Utc);
+                        
+                        // Modify the RRULE to add an UNTIL clause
+                        if let Some(rrule) = &event.rrule {
+                            // Remove existing UNTIL if present and add new one
+                            let parts: Vec<&str> = rrule.split(';').filter(|part| {
+                                !part.starts_with("UNTIL=") && !part.starts_with("COUNT=")
+                            }).collect();
+                            
+                            let new_rrule = format!("{};UNTIL={}", parts.join(";"), until_date.format("%Y%m%dT%H%M%SZ"));
+                            event.rrule = Some(new_rrule);
+                            
+                            // Update the event with the modified RRULE
+                            client.update_event(&request.calendar_path, &event, &request.event_href)
+                                .await
+                                .map_err(|e| ApiError::Internal(format!("Failed to update event with modified RRULE: {}", e)))?;
+                            
+                            Ok(Json(DeleteEventResponse {
+                                success: true,
+                                message: "This and following occurrences deleted successfully".to_string(),
+                            }))
+                        } else {
+                            // No RRULE, just delete the single event
+                            client.delete_event(&request.calendar_path, &request.event_href)
+                                .await
+                                .map_err(|e| ApiError::Internal(format!("Failed to delete event: {}", e)))?;
+                            
+                            Ok(Json(DeleteEventResponse {
+                                success: true,
+                                message: "Event deleted successfully".to_string(),
+                            }))
+                        }
+                    } else {
+                        Err(ApiError::BadRequest("Invalid occurrence date format".to_string()))
+                    }
+                } else {
+                    Err(ApiError::BadRequest("Occurrence date is required for following deletion".to_string()))
+                }
+            } else {
+                Err(ApiError::NotFound("Event not found".to_string()))
+            }
+        },
+        "delete_series" | _ => {
+            // Delete the entire event/series
+            client.delete_event(&request.calendar_path, &request.event_href)
+                .await
+                .map_err(|e| ApiError::Internal(format!("Failed to delete event: {}", e)))?;
+            
+            Ok(Json(DeleteEventResponse {
+                success: true,
+                message: "Event deleted successfully".to_string(),
+            }))
+        }
+    }
+}
+
+pub async fn create_event(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<CreateEventRequest>,
+) -> Result<Json<CreateEventResponse>, ApiError> {
+    println!("📝 Create event request received: title='{}', all_day={}, calendar_path={:?}", 
+             request.title, request.all_day, request.calendar_path);
+    
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.title.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event title is required".to_string()));
+    }
+    
+    if request.title.len() > 200 {
+        return Err(ApiError::BadRequest("Event title too long (max 200 characters)".to_string()));
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Determine which calendar to use
+    let calendar_path = if let Some(path) = request.calendar_path {
+        path
+    } else {
+        // Use the first available calendar
+        let calendar_paths = client.discover_calendars()
+            .await
+            .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?;
+        
+        if calendar_paths.is_empty() {
+            return Err(ApiError::BadRequest("No calendars available for event creation".to_string()));
+        }
+        
+        calendar_paths[0].clone()
+    };
+
+    // Parse dates and times
+    let start_datetime = parse_event_datetime(&request.start_date, &request.start_time, request.all_day)
+        .map_err(|e| ApiError::BadRequest(format!("Invalid start date/time: {}", e)))?;
+    
+    let end_datetime = parse_event_datetime(&request.end_date, &request.end_time, request.all_day)
+        .map_err(|e| ApiError::BadRequest(format!("Invalid end date/time: {}", e)))?;
+
+    // Validate that end is after start
+    if end_datetime <= start_datetime {
+        return Err(ApiError::BadRequest("End date/time must be after start date/time".to_string()));
+    }
+
+    // Generate a unique UID for the event
+    let uid = format!("{}-{}", uuid::Uuid::new_v4(), chrono::Utc::now().timestamp());
+
+    // Parse status
+    let status = match request.status.to_lowercase().as_str() {
+        "tentative" => EventStatus::Tentative,
+        "cancelled" => EventStatus::Cancelled,
+        _ => EventStatus::Confirmed,
+    };
+
+    // Parse class
+    let class = match request.class.to_lowercase().as_str() {
+        "private" => EventClass::Private,
+        "confidential" => EventClass::Confidential,
+        _ => EventClass::Public,
+    };
+
+    // Parse attendees (comma-separated email list)
+    let attendees: Vec<String> = if request.attendees.trim().is_empty() {
+        Vec::new()
+    } else {
+        request.attendees
+            .split(',')
+            .map(|s| s.trim().to_string())
+            .filter(|s| !s.is_empty())
+            .collect()
+    };
+
+    // Parse categories (comma-separated list)
+    let categories: Vec<String> = if request.categories.trim().is_empty() {
+        Vec::new()
+    } else {
+        request.categories
+            .split(',')
+            .map(|s| s.trim().to_string())
+            .filter(|s| !s.is_empty())
+            .collect()
+    };
+
+    // Parse alarms - convert from minutes string to EventReminder structs
+    let alarms: Vec<crate::calendar::EventReminder> = if request.reminder.trim().is_empty() {
+        Vec::new()
+    } else {
+        match request.reminder.parse::<i32>() {
+            Ok(minutes) => vec![crate::calendar::EventReminder {
+                minutes_before: minutes,
+                action: crate::calendar::ReminderAction::Display,
+                description: None,
+            }],
+            Err(_) => Vec::new(),
+        }
+    };
+
+    // Parse recurrence with BYDAY support for weekly recurrence
+    let rrule = match request.recurrence.to_uppercase().as_str() {
+        "DAILY" => Some("FREQ=DAILY".to_string()),
+        "WEEKLY" => {
+            // Handle weekly recurrence with optional BYDAY parameter
+            let mut rrule = "FREQ=WEEKLY".to_string();
+            
+            // Check if specific days are selected (recurrence_days has 7 elements: [Sun, Mon, Tue, Wed, Thu, Fri, Sat])
+            if request.recurrence_days.len() == 7 {
+                let selected_days: Vec<&str> = request.recurrence_days
+                    .iter()
+                    .enumerate()
+                    .filter_map(|(i, &selected)| {
+                        if selected {
+                            Some(match i {
+                                0 => "SU", // Sunday
+                                1 => "MO", // Monday
+                                2 => "TU", // Tuesday
+                                3 => "WE", // Wednesday
+                                4 => "TH", // Thursday
+                                5 => "FR", // Friday
+                                6 => "SA", // Saturday
+                                _ => return None,
+                            })
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+
+                if !selected_days.is_empty() {
+                    rrule = format!("{};BYDAY={}", rrule, selected_days.join(","));
+                }
+            }
+            
+            Some(rrule)
+        },
+        "MONTHLY" => Some("FREQ=MONTHLY".to_string()),
+        "YEARLY" => Some("FREQ=YEARLY".to_string()),
+        _ => None,
+    };
+
+    // Create the VEvent struct (RFC 5545 compliant)
+    let mut event = VEvent::new(uid, start_datetime);
+    event.dtend = Some(end_datetime);
+    event.summary = if request.title.trim().is_empty() { None } else { Some(request.title.clone()) };
+    event.description = if request.description.trim().is_empty() { None } else { Some(request.description) };
+    event.location = if request.location.trim().is_empty() { None } else { Some(request.location) };
+    event.status = Some(status);
+    event.class = Some(class);
+    event.priority = request.priority;
+    event.organizer = if request.organizer.trim().is_empty() { 
+        None 
+    } else { 
+        Some(CalendarUser {
+            cal_address: request.organizer,
+            common_name: None,
+            dir_entry_ref: None,
+            sent_by: None,
+            language: None,
+        })
+    };
+    event.attendees = attendees.into_iter().map(|email| Attendee {
+        cal_address: email,
+        common_name: None,
+        role: None,
+        part_stat: None,
+        rsvp: None,
+        cu_type: None,
+        member: Vec::new(),
+        delegated_to: Vec::new(),
+        delegated_from: Vec::new(),
+        sent_by: None,
+        dir_entry_ref: None,
+        language: None,
+    }).collect();
+    event.categories = categories;
+    event.rrule = rrule;
+    event.all_day = request.all_day;
+    event.alarms = alarms.into_iter().map(|reminder| VAlarm {
+        action: AlarmAction::Display,
+        trigger: AlarmTrigger::Duration(chrono::Duration::minutes(-reminder.minutes_before as i64)),
+        duration: None,
+        repeat: None,
+        description: reminder.description,
+        summary: None,
+        attendees: Vec::new(),
+        attach: Vec::new(),
+    }).collect();
+    event.calendar_path = Some(calendar_path.clone());
+
+    // Create the event on the CalDAV server
+    let event_href = client.create_event(&calendar_path, &event)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to create event: {}", e)))?;
+
+    println!("✅ Event created successfully with UID: {} at href: {}", event.uid, event_href);
+
+    Ok(Json(CreateEventResponse {
+        success: true,
+        message: "Event created successfully".to_string(),
+        event_href: Some(event_href),
+    }))
+}
+
+pub async fn update_event(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<UpdateEventRequest>,
+) -> Result<Json<UpdateEventResponse>, ApiError> {
+    // Handle update request
+    
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.uid.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event UID is required".to_string()));
+    }
+    
+    if request.title.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event title is required".to_string()));
+    }
+    
+    if request.title.len() > 200 {
+        return Err(ApiError::BadRequest("Event title too long (max 200 characters)".to_string()));
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Find the event across all calendars (or in the specified calendar)
+    let calendar_paths = if let Some(path) = &request.calendar_path {
+        vec![path.clone()]
+    } else {
+        client.discover_calendars()
+            .await
+            .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?
+    };
+
+    let mut found_event: Option<(CalendarEvent, String, String)> = None; // (event, calendar_path, event_href)
+    
+    for calendar_path in &calendar_paths {
+        match client.fetch_events(calendar_path).await {
+            Ok(events) => {
+                for event in events {
+                    if event.uid == request.uid {
+                        // Generate event href from UID
+                        let event_href = format!("{}.ics", event.uid);
+                        found_event = Some((event, calendar_path.clone(), event_href));
+                        break;
+                    }
+                }
+                if found_event.is_some() {
+                    break;
+                }
+            },
+            Err(e) => {
+                eprintln!("Failed to fetch events from calendar {}: {}", calendar_path, e);
+                continue;
+            }
+        }
+    }
+
+    let (mut event, calendar_path, event_href) = found_event
+        .ok_or_else(|| ApiError::NotFound(format!("Event with UID '{}' not found", request.uid)))?;
+
+    // Parse dates and times
+    let start_datetime = parse_event_datetime(&request.start_date, &request.start_time, request.all_day)
+        .map_err(|e| ApiError::BadRequest(format!("Invalid start date/time: {}", e)))?;
+    
+    let end_datetime = parse_event_datetime(&request.end_date, &request.end_time, request.all_day)
+        .map_err(|e| ApiError::BadRequest(format!("Invalid end date/time: {}", e)))?;
+
+    // Validate that end is after start
+    if end_datetime <= start_datetime {
+        return Err(ApiError::BadRequest("End date/time must be after start date/time".to_string()));
+    }
+
+    // Update event properties
+    event.dtstart = start_datetime;
+    event.dtend = Some(end_datetime);
+    event.summary = if request.title.trim().is_empty() { None } else { Some(request.title) };
+    event.description = if request.description.trim().is_empty() { None } else { Some(request.description) };
+    event.location = if request.location.trim().is_empty() { None } else { Some(request.location) };
+    event.all_day = request.all_day;
+
+    // Parse and update status
+    event.status = Some(match request.status.to_lowercase().as_str() {
+        "tentative" => EventStatus::Tentative,
+        "cancelled" => EventStatus::Cancelled,
+        _ => EventStatus::Confirmed,
+    });
+
+    // Parse and update class
+    event.class = Some(match request.class.to_lowercase().as_str() {
+        "private" => EventClass::Private,
+        "confidential" => EventClass::Confidential,
+        _ => EventClass::Public,
+    });
+
+    event.priority = request.priority;
+
+    // Update the event on the CalDAV server
+    client.update_event(&calendar_path, &event, &event_href)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to update event: {}", e)))?;
+
+    Ok(Json(UpdateEventResponse {
+        success: true,
+        message: "Event updated successfully".to_string(),
+    }))
+}
+
+fn parse_event_datetime(date_str: &str, time_str: &str, all_day: bool) -> Result<chrono::DateTime<chrono::Utc>, String> {
+    use chrono::{NaiveDate, NaiveTime, NaiveDateTime, Utc, TimeZone};
+    
+    // Parse the date
+    let date = NaiveDate::parse_from_str(date_str, "%Y-%m-%d")
+        .map_err(|_| format!("Invalid date format: {}. Expected YYYY-MM-DD", date_str))?;
+    
+    if all_day {
+        // For all-day events, use midnight UTC
+        let datetime = date.and_hms_opt(0, 0, 0)
+            .ok_or_else(|| "Failed to create midnight datetime".to_string())?;
+        Ok(Utc.from_utc_datetime(&datetime))
+    } else {
+        // Parse the time
+        let time = NaiveTime::parse_from_str(time_str, "%H:%M")
+            .map_err(|_| format!("Invalid time format: {}. Expected HH:MM", time_str))?;
+        
+        // Combine date and time
+        let datetime = NaiveDateTime::new(date, time);
+        
+        // Assume local time and convert to UTC (in a real app, you'd want timezone support)
+        Ok(Utc.from_utc_datetime(&datetime))
+    }
+}

backend/src/handlers/series.rs

@@ -0,0 +1,694 @@
+use axum::{
+    extract::State,
+    http::HeaderMap,
+    response::Json,
+};
+use std::sync::Arc;
+use chrono::TimeZone;
+
+use crate::{AppState, models::{ApiError, CreateEventSeriesRequest, CreateEventSeriesResponse, UpdateEventSeriesRequest, UpdateEventSeriesResponse, DeleteEventSeriesRequest, DeleteEventSeriesResponse}};
+use crate::calendar::CalDAVClient;
+use calendar_models::{VEvent, EventStatus, EventClass};
+
+use super::auth::{extract_bearer_token, extract_password_header};
+
+/// Create a new recurring event series
+pub async fn create_event_series(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<CreateEventSeriesRequest>,
+) -> Result<Json<CreateEventSeriesResponse>, ApiError> {
+    println!("📝 Create event series request received: title='{}', recurrence='{}', all_day={}", 
+             request.title, request.recurrence, request.all_day);
+    
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.title.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event title is required".to_string()));
+    }
+    
+    if request.title.len() > 200 {
+        return Err(ApiError::BadRequest("Event title too long (max 200 characters)".to_string()));
+    }
+
+    if request.recurrence == "none" {
+        return Err(ApiError::BadRequest("Use regular create endpoint for non-recurring events".to_string()));
+    }
+
+    // Validate recurrence type
+    match request.recurrence.to_lowercase().as_str() {
+        "daily" | "weekly" | "monthly" | "yearly" => {},
+        _ => return Err(ApiError::BadRequest("Invalid recurrence type. Must be daily, weekly, monthly, or yearly".to_string())),
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Determine which calendar to use
+    let calendar_path = if let Some(ref path) = request.calendar_path {
+        path.clone()
+    } else {
+        // Use the first available calendar
+        let calendar_paths = client.discover_calendars()
+            .await
+            .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?;
+        
+        if calendar_paths.is_empty() {
+            return Err(ApiError::BadRequest("No calendars available for event creation".to_string()));
+        }
+        
+        calendar_paths[0].clone()
+    };
+
+    println!("📅 Using calendar path: {}", calendar_path);
+
+    // Parse datetime components
+    let start_date = chrono::NaiveDate::parse_from_str(&request.start_date, "%Y-%m-%d")
+        .map_err(|_| ApiError::BadRequest("Invalid start_date format. Expected YYYY-MM-DD".to_string()))?;
+
+    let (start_datetime, end_datetime) = if request.all_day {
+        // For all-day events, use the dates as-is
+        let start_dt = start_date.and_hms_opt(0, 0, 0)
+            .ok_or_else(|| ApiError::BadRequest("Invalid start date".to_string()))?;
+        
+        let end_date = if !request.end_date.is_empty() {
+            chrono::NaiveDate::parse_from_str(&request.end_date, "%Y-%m-%d")
+                .map_err(|_| ApiError::BadRequest("Invalid end_date format. Expected YYYY-MM-DD".to_string()))?
+        } else {
+            start_date
+        };
+        
+        let end_dt = end_date.and_hms_opt(23, 59, 59)
+            .ok_or_else(|| ApiError::BadRequest("Invalid end date".to_string()))?;
+
+        (chrono::Utc.from_utc_datetime(&start_dt), chrono::Utc.from_utc_datetime(&end_dt))
+    } else {
+        // Parse times for timed events
+        let start_time = if !request.start_time.is_empty() {
+            chrono::NaiveTime::parse_from_str(&request.start_time, "%H:%M")
+                .map_err(|_| ApiError::BadRequest("Invalid start_time format. Expected HH:MM".to_string()))?
+        } else {
+            chrono::NaiveTime::from_hms_opt(9, 0, 0).unwrap() // Default to 9 AM
+        };
+
+        let end_time = if !request.end_time.is_empty() {
+            chrono::NaiveTime::parse_from_str(&request.end_time, "%H:%M")
+                .map_err(|_| ApiError::BadRequest("Invalid end_time format. Expected HH:MM".to_string()))?
+        } else {
+            chrono::NaiveTime::from_hms_opt(10, 0, 0).unwrap() // Default to 1 hour duration
+        };
+
+        let start_dt = start_date.and_time(start_time);
+        let end_dt = if !request.end_date.is_empty() {
+            let end_date = chrono::NaiveDate::parse_from_str(&request.end_date, "%Y-%m-%d")
+                .map_err(|_| ApiError::BadRequest("Invalid end_date format. Expected YYYY-MM-DD".to_string()))?;
+            end_date.and_time(end_time)
+        } else {
+            start_date.and_time(end_time)
+        };
+
+        (chrono::Utc.from_utc_datetime(&start_dt), chrono::Utc.from_utc_datetime(&end_dt))
+    };
+
+    // Generate a unique UID for the series
+    let uid = format!("series-{}", uuid::Uuid::new_v4().to_string());
+
+    // Create the VEvent for the series
+    let mut event = VEvent::new(uid.clone(), start_datetime);
+    event.dtend = Some(end_datetime);
+    event.summary = if request.title.trim().is_empty() { None } else { Some(request.title.clone()) };
+    event.description = if request.description.trim().is_empty() { None } else { Some(request.description.clone()) };
+    event.location = if request.location.trim().is_empty() { None } else { Some(request.location.clone()) };
+    
+    // Set event status
+    event.status = Some(match request.status.to_lowercase().as_str() {
+        "tentative" => EventStatus::Tentative,
+        "cancelled" => EventStatus::Cancelled,
+        _ => EventStatus::Confirmed,
+    });
+    
+    // Set event class
+    event.class = Some(match request.class.to_lowercase().as_str() {
+        "private" => EventClass::Private,
+        "confidential" => EventClass::Confidential,
+        _ => EventClass::Public,
+    });
+    
+    // Set priority
+    event.priority = request.priority;
+
+    // Generate the RRULE for recurrence
+    let rrule = build_series_rrule(&request)?;
+    event.rrule = Some(rrule);
+
+    println!("🔁 Generated RRULE: {:?}", event.rrule);
+
+    // Create the event on the CalDAV server
+    let event_href = client.create_event(&calendar_path, &event)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to create event series: {}", e)))?;
+
+    println!("✅ Event series created successfully with UID: {}, href: {}", uid, event_href);
+
+    Ok(Json(CreateEventSeriesResponse {
+        success: true,
+        message: "Event series created successfully".to_string(),
+        series_uid: Some(uid),
+        occurrences_created: Some(1), // Series created as a single repeating event
+        event_href: Some(event_href),
+    }))
+}
+
+/// Update a recurring event series with different scope options
+pub async fn update_event_series(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<UpdateEventSeriesRequest>,
+) -> Result<Json<UpdateEventSeriesResponse>, ApiError> {
+    println!("🔄 Update event series request received: series_uid='{}', update_scope='{}'", 
+             request.series_uid, request.update_scope);
+    
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.series_uid.trim().is_empty() {
+        return Err(ApiError::BadRequest("Series UID is required".to_string()));
+    }
+    
+    if request.title.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event title is required".to_string()));
+    }
+    
+    if request.title.len() > 200 {
+        return Err(ApiError::BadRequest("Event title too long (max 200 characters)".to_string()));
+    }
+
+    // Validate update scope
+    match request.update_scope.as_str() {
+        "this_only" | "this_and_future" | "all_in_series" => {},
+        _ => return Err(ApiError::BadRequest("Invalid update_scope. Must be: this_only, this_and_future, or all_in_series".to_string())),
+    }
+
+    // Validate recurrence type
+    match request.recurrence.to_lowercase().as_str() {
+        "daily" | "weekly" | "monthly" | "yearly" => {},
+        _ => return Err(ApiError::BadRequest("Invalid recurrence type. Must be daily, weekly, monthly, or yearly".to_string())),
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Determine which calendar to search (or search all calendars)
+    let calendar_paths = if let Some(ref path) = request.calendar_path {
+        vec![path.clone()]
+    } else {
+        client.discover_calendars()
+            .await
+            .map_err(|e| ApiError::Internal(format!("Failed to discover calendars: {}", e)))?
+    };
+
+    if calendar_paths.is_empty() {
+        return Err(ApiError::BadRequest("No calendars available for event update".to_string()));
+    }
+
+    // Find the series event across all specified calendars
+    let mut existing_event = None;
+    let mut calendar_path = String::new();
+
+    for path in &calendar_paths {
+        if let Ok(Some(event)) = client.fetch_event_by_uid(path, &request.series_uid).await {
+            existing_event = Some(event);
+            calendar_path = path.clone();
+            break;
+        }
+    }
+
+    let mut existing_event = existing_event
+        .ok_or_else(|| ApiError::NotFound(format!("Event series with UID '{}' not found", request.series_uid)))?;
+
+    println!("📅 Found series event in calendar: {}", calendar_path);
+
+    // Parse datetime components for the update
+    let start_date = chrono::NaiveDate::parse_from_str(&request.start_date, "%Y-%m-%d")
+        .map_err(|_| ApiError::BadRequest("Invalid start_date format. Expected YYYY-MM-DD".to_string()))?;
+
+    let (start_datetime, end_datetime) = if request.all_day {
+        let start_dt = start_date.and_hms_opt(0, 0, 0)
+            .ok_or_else(|| ApiError::BadRequest("Invalid start date".to_string()))?;
+        
+        let end_date = if !request.end_date.is_empty() {
+            chrono::NaiveDate::parse_from_str(&request.end_date, "%Y-%m-%d")
+                .map_err(|_| ApiError::BadRequest("Invalid end_date format. Expected YYYY-MM-DD".to_string()))?
+        } else {
+            start_date
+        };
+        
+        let end_dt = end_date.and_hms_opt(23, 59, 59)
+            .ok_or_else(|| ApiError::BadRequest("Invalid end date".to_string()))?;
+
+        (chrono::Utc.from_utc_datetime(&start_dt), chrono::Utc.from_utc_datetime(&end_dt))
+    } else {
+        let start_time = if !request.start_time.is_empty() {
+            chrono::NaiveTime::parse_from_str(&request.start_time, "%H:%M")
+                .map_err(|_| ApiError::BadRequest("Invalid start_time format. Expected HH:MM".to_string()))?
+        } else {
+            existing_event.dtstart.time()
+        };
+
+        let end_time = if !request.end_time.is_empty() {
+            chrono::NaiveTime::parse_from_str(&request.end_time, "%H:%M")
+                .map_err(|_| ApiError::BadRequest("Invalid end_time format. Expected HH:MM".to_string()))?
+        } else {
+            existing_event.dtend.map(|dt| dt.time()).unwrap_or_else(|| {
+                existing_event.dtstart.time() + chrono::Duration::hours(1)
+            })
+        };
+
+        let start_dt = start_date.and_time(start_time);
+        let end_dt = if !request.end_date.is_empty() {
+            let end_date = chrono::NaiveDate::parse_from_str(&request.end_date, "%Y-%m-%d")
+                .map_err(|_| ApiError::BadRequest("Invalid end_date format. Expected YYYY-MM-DD".to_string()))?;
+            end_date.and_time(end_time)
+        } else {
+            start_date.and_time(end_time)
+        };
+
+        (chrono::Utc.from_utc_datetime(&start_dt), chrono::Utc.from_utc_datetime(&end_dt))
+    };
+
+    // Handle different update scopes
+    let (updated_event, occurrences_affected) = match request.update_scope.as_str() {
+        "all_in_series" => {
+            // Update the entire series - modify the master event
+            update_entire_series(&mut existing_event, &request, start_datetime, end_datetime)?
+        },
+        "this_and_future" => {
+            // Split the series: keep past occurrences, create new series from occurrence date
+            update_this_and_future(&mut existing_event, &request, start_datetime, end_datetime)?
+        },
+        "this_only" => {
+            // Create exception for single occurrence, keep original series
+            update_single_occurrence(&mut existing_event, &request, start_datetime, end_datetime)?
+        },
+        _ => unreachable!(), // Already validated above
+    };
+
+    // Update the event on the CalDAV server
+    // Generate event href from UID
+    let event_href = format!("{}.ics", request.series_uid);
+    client.update_event(&calendar_path, &updated_event, &event_href)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to update event series: {}", e)))?;
+
+    println!("✅ Event series updated successfully with UID: {}", request.series_uid);
+
+    Ok(Json(UpdateEventSeriesResponse {
+        success: true,
+        message: "Event series updated successfully".to_string(),
+        series_uid: Some(request.series_uid),
+        occurrences_affected: Some(occurrences_affected),
+    }))
+}
+
+/// Delete a recurring event series or specific occurrences
+pub async fn delete_event_series(
+    State(state): State<Arc<AppState>>,
+    headers: HeaderMap,
+    Json(request): Json<DeleteEventSeriesRequest>,
+) -> Result<Json<DeleteEventSeriesResponse>, ApiError> {
+    println!("🗑️ Delete event series request received: series_uid='{}', delete_scope='{}'", 
+             request.series_uid, request.delete_scope);
+    
+    // Extract and verify token
+    let token = extract_bearer_token(&headers)?;
+    let password = extract_password_header(&headers)?;
+
+    // Validate request
+    if request.series_uid.trim().is_empty() {
+        return Err(ApiError::BadRequest("Series UID is required".to_string()));
+    }
+    
+    if request.calendar_path.trim().is_empty() {
+        return Err(ApiError::BadRequest("Calendar path is required".to_string()));
+    }
+
+    if request.event_href.trim().is_empty() {
+        return Err(ApiError::BadRequest("Event href is required".to_string()));
+    }
+
+    // Validate delete scope
+    match request.delete_scope.as_str() {
+        "this_only" | "this_and_future" | "all_in_series" => {},
+        _ => return Err(ApiError::BadRequest("Invalid delete_scope. Must be: this_only, this_and_future, or all_in_series".to_string())),
+    }
+
+    // Create CalDAV config from token and password
+    let config = state.auth_service.caldav_config_from_token(&token, &password)?;
+    let client = CalDAVClient::new(config);
+
+    // Handle different deletion scopes
+    let occurrences_affected = match request.delete_scope.as_str() {
+        "all_in_series" => {
+            // Delete the entire series - simply delete the event
+            delete_entire_series(&client, &request).await?
+        },
+        "this_and_future" => {
+            // Modify RRULE to end before this occurrence
+            delete_this_and_future(&client, &request).await?
+        },
+        "this_only" => {
+            // Add EXDATE for single occurrence
+            delete_single_occurrence(&client, &request).await?
+        },
+        _ => unreachable!(), // Already validated above
+    };
+
+    println!("✅ Event series deletion completed with {} occurrences affected", occurrences_affected);
+
+    Ok(Json(DeleteEventSeriesResponse {
+        success: true,
+        message: "Event series deletion completed successfully".to_string(),
+        occurrences_affected: Some(occurrences_affected),
+    }))
+}
+
+// Helper functions
+
+fn build_series_rrule(request: &CreateEventSeriesRequest) -> Result<String, ApiError> {
+    let mut rrule_parts = Vec::new();
+    
+    // Add frequency
+    match request.recurrence.to_lowercase().as_str() {
+        "daily" => rrule_parts.push("FREQ=DAILY".to_string()),
+        "weekly" => rrule_parts.push("FREQ=WEEKLY".to_string()),
+        "monthly" => rrule_parts.push("FREQ=MONTHLY".to_string()),
+        "yearly" => rrule_parts.push("FREQ=YEARLY".to_string()),
+        _ => return Err(ApiError::BadRequest("Invalid recurrence type".to_string())),
+    }
+    
+    // Add interval if specified and greater than 1
+    if let Some(interval) = request.recurrence_interval {
+        if interval > 1 {
+            rrule_parts.push(format!("INTERVAL={}", interval));
+        }
+    }
+    
+    // Handle weekly recurrence with specific days (BYDAY)
+    if request.recurrence.to_lowercase() == "weekly" && request.recurrence_days.len() == 7 {
+        let selected_days: Vec<&str> = request.recurrence_days
+            .iter()
+            .enumerate()
+            .filter_map(|(i, &selected)| {
+                if selected {
+                    Some(match i {
+                        0 => "SU", // Sunday
+                        1 => "MO", // Monday
+                        2 => "TU", // Tuesday
+                        3 => "WE", // Wednesday
+                        4 => "TH", // Thursday
+                        5 => "FR", // Friday
+                        6 => "SA", // Saturday
+                        _ => return None,
+                    })
+                } else {
+                    None
+                }
+            })
+            .collect();
+
+        if !selected_days.is_empty() {
+            rrule_parts.push(format!("BYDAY={}", selected_days.join(",")));
+        }
+    }
+    
+    // Add end date if specified (UNTIL takes precedence over COUNT)
+    if let Some(end_date) = &request.recurrence_end_date {
+        // Parse the end date and convert to RRULE format (YYYYMMDDTHHMMSSZ)
+        match chrono::NaiveDate::parse_from_str(end_date, "%Y-%m-%d") {
+            Ok(date) => {
+                let end_datetime = date.and_hms_opt(23, 59, 59)
+                    .ok_or_else(|| ApiError::BadRequest("Invalid end date".to_string()))?;
+                let utc_end = chrono::Utc.from_utc_datetime(&end_datetime);
+                rrule_parts.push(format!("UNTIL={}", utc_end.format("%Y%m%dT%H%M%SZ")));
+            },
+            Err(_) => return Err(ApiError::BadRequest("Invalid recurrence_end_date format. Expected YYYY-MM-DD".to_string())),
+        }
+    } else if let Some(count) = request.recurrence_count {
+        if count > 0 {
+            rrule_parts.push(format!("COUNT={}", count));
+        }
+    }
+    
+    Ok(rrule_parts.join(";"))
+}
+
+/// Update the entire series - modify the master event
+fn update_entire_series(
+    existing_event: &mut VEvent,
+    request: &UpdateEventSeriesRequest,
+    start_datetime: chrono::DateTime<chrono::Utc>,
+    end_datetime: chrono::DateTime<chrono::Utc>,
+) -> Result<(VEvent, u32), ApiError> {
+    // Create a new series request for RRULE generation
+    let series_request = CreateEventSeriesRequest {
+        title: request.title.clone(),
+        description: request.description.clone(),
+        start_date: request.start_date.clone(),
+        start_time: request.start_time.clone(),
+        end_date: request.end_date.clone(),
+        end_time: request.end_time.clone(),
+        location: request.location.clone(),
+        all_day: request.all_day,
+        status: request.status.clone(),
+        class: request.class.clone(),
+        priority: request.priority,
+        organizer: request.organizer.clone(),
+        attendees: request.attendees.clone(),
+        categories: request.categories.clone(),
+        reminder: request.reminder.clone(),
+        recurrence: request.recurrence.clone(),
+        recurrence_days: request.recurrence_days.clone(),
+        recurrence_interval: request.recurrence_interval,
+        recurrence_end_date: request.recurrence_end_date.clone(),
+        recurrence_count: request.recurrence_count,
+        calendar_path: None, // Not needed for RRULE generation
+    };
+
+    // Update all fields of the existing event
+    existing_event.dtstart = start_datetime;
+    existing_event.dtend = Some(end_datetime);
+    existing_event.summary = if request.title.trim().is_empty() { None } else { Some(request.title.clone()) };
+    existing_event.description = if request.description.trim().is_empty() { None } else { Some(request.description.clone()) };
+    existing_event.location = if request.location.trim().is_empty() { None } else { Some(request.location.clone()) };
+    
+    existing_event.status = Some(match request.status.to_lowercase().as_str() {
+        "tentative" => EventStatus::Tentative,
+        "cancelled" => EventStatus::Cancelled,
+        _ => EventStatus::Confirmed,
+    });
+    
+    existing_event.class = Some(match request.class.to_lowercase().as_str() {
+        "private" => EventClass::Private,
+        "confidential" => EventClass::Confidential,
+        _ => EventClass::Public,
+    });
+    
+    existing_event.priority = request.priority;
+
+    // Update the RRULE
+    existing_event.rrule = Some(build_series_rrule(&series_request)?);
+
+    Ok((existing_event.clone(), 1)) // 1 series updated (affects all occurrences)
+}
+
+/// Update this occurrence and all future occurrences
+fn update_this_and_future(
+    existing_event: &mut VEvent,
+    request: &UpdateEventSeriesRequest,
+    start_datetime: chrono::DateTime<chrono::Utc>,
+    end_datetime: chrono::DateTime<chrono::Utc>,
+) -> Result<(VEvent, u32), ApiError> {
+    // For now, treat this the same as update_entire_series
+    // In a full implementation, this would:
+    // 1. Add UNTIL to the original series to stop at the occurrence date
+    // 2. Create a new series starting from the occurrence date with updated properties
+    
+    // For simplicity, we'll modify the original series with an UNTIL date if occurrence_date is provided
+    if let Some(occurrence_date) = &request.occurrence_date {
+        // Parse occurrence date and set as UNTIL for the original series
+        match chrono::NaiveDate::parse_from_str(occurrence_date, "%Y-%m-%d") {
+            Ok(date) => {
+                let until_datetime = date.and_hms_opt(0, 0, 0)
+                    .ok_or_else(|| ApiError::BadRequest("Invalid occurrence date".to_string()))?;
+                let utc_until = chrono::Utc.from_utc_datetime(&until_datetime);
+                
+                // Create modified RRULE with UNTIL clause
+                let mut rrule = existing_event.rrule.clone().unwrap_or_else(|| "FREQ=WEEKLY".to_string());
+                
+                // Remove existing UNTIL or COUNT if present
+                let parts: Vec<&str> = rrule.split(';').filter(|part| {
+                    !part.starts_with("UNTIL=") && !part.starts_with("COUNT=")
+                }).collect();
+                
+                rrule = format!("{};UNTIL={}", parts.join(";"), utc_until.format("%Y%m%dT%H%M%SZ"));
+                existing_event.rrule = Some(rrule);
+            },
+            Err(_) => return Err(ApiError::BadRequest("Invalid occurrence date format".to_string())),
+        }
+    }
+    
+    // Then apply the same updates as all_in_series for the rest of the properties
+    update_entire_series(existing_event, request, start_datetime, end_datetime)
+}
+
+/// Update only a single occurrence (create an exception)
+fn update_single_occurrence(
+    existing_event: &mut VEvent,
+    request: &UpdateEventSeriesRequest,
+    start_datetime: chrono::DateTime<chrono::Utc>,
+    end_datetime: chrono::DateTime<chrono::Utc>,
+) -> Result<(VEvent, u32), ApiError> {
+    // For single occurrence updates, we need to:
+    // 1. Keep the original series unchanged
+    // 2. Create a new single event (exception) with the same UID but different RECURRENCE-ID
+    
+    // Create a new event for the single occurrence
+    let occurrence_uid = if let Some(occurrence_date) = &request.occurrence_date {
+        format!("{}-exception-{}", existing_event.uid, occurrence_date)
+    } else {
+        format!("{}-exception", existing_event.uid)
+    };
+    
+    let mut exception_event = VEvent::new(occurrence_uid, start_datetime);
+    exception_event.dtend = Some(end_datetime);
+    exception_event.summary = if request.title.trim().is_empty() { None } else { Some(request.title.clone()) };
+    exception_event.description = if request.description.trim().is_empty() { None } else { Some(request.description.clone()) };
+    exception_event.location = if request.location.trim().is_empty() { None } else { Some(request.location.clone()) };
+    
+    exception_event.status = Some(match request.status.to_lowercase().as_str() {
+        "tentative" => EventStatus::Tentative,
+        "cancelled" => EventStatus::Cancelled,
+        _ => EventStatus::Confirmed,
+    });
+    
+    exception_event.class = Some(match request.class.to_lowercase().as_str() {
+        "private" => EventClass::Private,
+        "confidential" => EventClass::Confidential,
+        _ => EventClass::Public,
+    });
+    
+    exception_event.priority = request.priority;
+
+    // Note: This function returns the exception event, but in a full implementation,
+    // we would need to create this as a separate event and add an EXDATE to the original series
+    Ok((exception_event, 1)) // 1 occurrence updated
+}
+
+/// Delete the entire series
+async fn delete_entire_series(
+    client: &CalDAVClient,
+    request: &DeleteEventSeriesRequest,
+) -> Result<u32, ApiError> {
+    // Simply delete the entire event from the CalDAV server
+    client.delete_event(&request.calendar_path, &request.event_href)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to delete event series: {}", e)))?;
+    
+    println!("🗑️ Entire series deleted: {}", request.series_uid);
+    Ok(1) // 1 series deleted (affects all occurrences)
+}
+
+/// Delete this occurrence and all future occurrences (modify RRULE with UNTIL)
+async fn delete_this_and_future(
+    client: &CalDAVClient,
+    request: &DeleteEventSeriesRequest,
+) -> Result<u32, ApiError> {
+    // Fetch the existing event to modify its RRULE
+    let event_uid = request.series_uid.clone();
+    let existing_event = client.fetch_event_by_uid(&request.calendar_path, &event_uid)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to fetch event for modification: {}", e)))?
+        .ok_or_else(|| ApiError::NotFound(format!("Event series with UID '{}' not found", event_uid)))?;
+    
+    // If no occurrence_date is provided, delete the entire series
+    let Some(occurrence_date) = &request.occurrence_date else {
+        return delete_entire_series(client, request).await;
+    };
+    
+    // Parse occurrence date to set as UNTIL for the RRULE
+    let until_date = chrono::NaiveDate::parse_from_str(occurrence_date, "%Y-%m-%d")
+        .map_err(|_| ApiError::BadRequest("Invalid occurrence date format. Expected YYYY-MM-DD".to_string()))?;
+    
+    // Set UNTIL to the day before the occurrence to exclude it and all future occurrences
+    let until_datetime = until_date.pred_opt()
+        .ok_or_else(|| ApiError::BadRequest("Cannot delete from the first possible date".to_string()))?
+        .and_hms_opt(23, 59, 59)
+        .ok_or_else(|| ApiError::BadRequest("Invalid date calculation".to_string()))?;
+    let utc_until = chrono::Utc.from_utc_datetime(&until_datetime);
+    
+    // Modify the existing event's RRULE
+    let mut updated_event = existing_event;
+    if let Some(rrule) = &updated_event.rrule {
+        // Remove existing UNTIL or COUNT if present and add new UNTIL
+        let parts: Vec<&str> = rrule.split(';').filter(|part| {
+            !part.starts_with("UNTIL=") && !part.starts_with("COUNT=")
+        }).collect();
+        
+        updated_event.rrule = Some(format!("{};UNTIL={}", parts.join(";"), utc_until.format("%Y%m%dT%H%M%SZ")));
+    }
+    
+    // Update the event on the CalDAV server
+    client.update_event(&request.calendar_path, &updated_event, &request.event_href)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to update event series for deletion: {}", e)))?;
+    
+    println!("🗑️ Series modified with UNTIL for this_and_future deletion: {}", utc_until.format("%Y-%m-%d"));
+    Ok(1) // 1 series modified
+}
+
+/// Delete only a single occurrence (add EXDATE)
+async fn delete_single_occurrence(
+    client: &CalDAVClient,
+    request: &DeleteEventSeriesRequest,
+) -> Result<u32, ApiError> {
+    // Fetch the existing event to add EXDATE
+    let event_uid = request.series_uid.clone();
+    let existing_event = client.fetch_event_by_uid(&request.calendar_path, &event_uid)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to fetch event for modification: {}", e)))?
+        .ok_or_else(|| ApiError::NotFound(format!("Event series with UID '{}' not found", event_uid)))?;
+    
+    // If no occurrence_date is provided, cannot delete single occurrence
+    let Some(occurrence_date) = &request.occurrence_date else {
+        return Err(ApiError::BadRequest("occurrence_date is required for single occurrence deletion".to_string()));
+    };
+    
+    // Parse occurrence date
+    let exception_date = chrono::NaiveDate::parse_from_str(occurrence_date, "%Y-%m-%d")
+        .map_err(|_| ApiError::BadRequest("Invalid occurrence date format. Expected YYYY-MM-DD".to_string()))?;
+    
+    // Create the EXDATE datetime (use the same time as the original event)
+    let original_time = existing_event.dtstart.time();
+    let exception_datetime = exception_date.and_time(original_time);
+    let exception_utc = chrono::Utc.from_utc_datetime(&exception_datetime);
+    
+    // Add the exception date to the event's EXDATE list
+    let mut updated_event = existing_event;
+    updated_event.exdate.push(exception_utc);
+    
+    println!("🗑️ Added EXDATE for single occurrence deletion: {}", exception_utc.format("%Y%m%dT%H%M%SZ"));
+    
+    // Update the event on the CalDAV server
+    client.update_event(&request.calendar_path, &updated_event, &request.event_href)
+        .await
+        .map_err(|e| ApiError::Internal(format!("Failed to update event series for single deletion: {}", e)))?;
+    
+    Ok(1) // 1 occurrence excluded
+}