// Frontend authentication module - connects to backend API
use serde::{Deserialize, Serialize};
use wasm_bindgen::JsCast;
use wasm_bindgen_futures::JsFuture;
use web_sys::{Request, RequestInit, RequestMode, Response};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct User {
    pub id: String,
    pub username: String,
    pub email: String,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct UserInfo {
    pub id: String,
    pub username: String,
    pub email: String,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct RegisterRequest {
    pub username: String,
    pub email: String,
    pub password: String,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct LoginRequest {
    pub username: String,
    pub password: String,
}

#[derive(Debug, Serialize, Deserialize)]
pub struct AuthResponse {
    pub token: String,
    pub user: UserInfo,
}

#[derive(Debug, Deserialize)]
pub struct ApiErrorResponse {
    pub error: String,
    pub status: u16,
}

// Frontend auth service - connects to backend API
pub struct AuthService {
    base_url: String,
}

impl AuthService {
    pub fn new() -> Self {
        // Default to localhost backend - could be configurable via env var in the future
        Self {
            base_url: "http://localhost:3000/api".to_string(),
        }
    }

    pub async fn register(&self, request: RegisterRequest) -> Result<AuthResponse, String> {
        self.post_json("/auth/register", &request).await
    }
    
    pub async fn login(&self, request: LoginRequest) -> Result<AuthResponse, String> {
        self.post_json("/auth/login", &request).await
    }
    
    pub async fn verify_token(&self, token: &str) -> Result<UserInfo, String> {
        let response = self.get_with_auth("/auth/verify", token).await?;
        let json_value: serde_json::Value = response;
        
        if let Some(user_obj) = json_value.get("user") {
            serde_json::from_value(user_obj.clone())
                .map_err(|e| format!("Failed to parse user info: {}", e))
        } else {
            Err("Invalid response format".to_string())
        }
    }

    // Helper method for POST requests with JSON body
    async fn post_json<T: Serialize, R: for<'de> Deserialize<'de>>(
        &self,
        endpoint: &str,
        body: &T,
    ) -> Result<R, String> {
        let window = web_sys::window().ok_or("No global window exists")?;
        
        let json_body = serde_json::to_string(body)
            .map_err(|e| format!("JSON serialization failed: {}", e))?;

        let opts = RequestInit::new();
        opts.set_method("POST");
        opts.set_mode(RequestMode::Cors);
        opts.set_body(&wasm_bindgen::JsValue::from_str(&json_body));

        let url = format!("{}{}", self.base_url, endpoint);
        let request = Request::new_with_str_and_init(&url, &opts)
            .map_err(|e| format!("Request creation failed: {:?}", e))?;

        request.headers().set("Content-Type", "application/json")
            .map_err(|e| format!("Header setting failed: {:?}", e))?;

        let resp_value = JsFuture::from(window.fetch_with_request(&request))
            .await
            .map_err(|e| format!("Network request failed: {:?}", e))?;

        let resp: Response = resp_value.dyn_into()
            .map_err(|e| format!("Response cast failed: {:?}", e))?;

        let text = JsFuture::from(resp.text()
            .map_err(|e| format!("Text extraction failed: {:?}", e))?)
            .await
            .map_err(|e| format!("Text promise failed: {:?}", e))?;

        let text_string = text.as_string()
            .ok_or("Response text is not a string")?;

        if resp.ok() {
            serde_json::from_str::<R>(&text_string)
                .map_err(|e| format!("JSON parsing failed: {}", e))
        } else {
            // Try to parse error response
            if let Ok(error_response) = serde_json::from_str::<ApiErrorResponse>(&text_string) {
                Err(error_response.error)
            } else {
                Err(format!("Request failed with status {}", resp.status()))
            }
        }
    }

    // Helper method for GET requests with Authorization header
    async fn get_with_auth(
        &self,
        endpoint: &str,
        token: &str,
    ) -> Result<serde_json::Value, String> {
        let window = web_sys::window().ok_or("No global window exists")?;
        
        let opts = RequestInit::new();
        opts.set_method("GET");
        opts.set_mode(RequestMode::Cors);

        let url = format!("{}{}", self.base_url, endpoint);
        let request = Request::new_with_str_and_init(&url, &opts)
            .map_err(|e| format!("Request creation failed: {:?}", e))?;

        request.headers().set("Authorization", &format!("Bearer {}", token))
            .map_err(|e| format!("Authorization header setting failed: {:?}", e))?;

        let resp_value = JsFuture::from(window.fetch_with_request(&request))
            .await
            .map_err(|e| format!("Network request failed: {:?}", e))?;

        let resp: Response = resp_value.dyn_into()
            .map_err(|e| format!("Response cast failed: {:?}", e))?;

        let text = JsFuture::from(resp.text()
            .map_err(|e| format!("Text extraction failed: {:?}", e))?)
            .await
            .map_err(|e| format!("Text promise failed: {:?}", e))?;

        let text_string = text.as_string()
            .ok_or("Response text is not a string")?;

        if resp.ok() {
            serde_json::from_str::<serde_json::Value>(&text_string)
                .map_err(|e| format!("JSON parsing failed: {}", e))
        } else {
            // Try to parse error response
            if let Ok(error_response) = serde_json::from_str::<ApiErrorResponse>(&text_string) {
                Err(error_response.error)
            } else {
                Err(format!("Request failed with status {}", resp.status()))
            }
        }
    }
}