#!/bin/sh
# Regenerates crates/resolved/src/solar_data.rs from LISIRD.
#
# The source is the TSIS-1 Hybrid Solar Reference Spectrum at 1 nm bandwidth,
# which LISIRD serves sampled every 0.1 nm. Keeping every 10th row (integer
# wavelengths) loses nothing: the spectrum is already smoothed to 1 nm.
# Values are written in SI units (meters, W/m^2 per meter) to 6 significant
# figures, well inside the data's 0.3 % uncertainty.

set -eu

url='https://lasp.colorado.edu/lisird/latis/dap/tsis1_hsrs_1nm.csv'
out="$(dirname "$0")/../crates/resolved/src/solar_data.rs"
tmp=$(mktemp)
trap 'command rm -f "$tmp"' EXIT

curl -fsS "$url" -o "$tmp"

# Integer-nanometer rows only, as "wavelength_m irradiance_per_m".
rows=$(awk -F, 'NR > 1 && $1 ~ /\.0$/ { printf "%.0fe-9 %.5e\n", $1, $2 * 1e9 }' "$tmp")
count=$(printf '%s\n' "$rows" | wc -l)

# One column of $rows as a Rust array body, six values per line.
emit() {
    printf '%s\n' "$rows" | awk -v col="$1" '
        { v[NR] = $col }
        END {
            for (i = 1; i <= NR; i++) {
                if ((i - 1) % 6 == 0) printf "    ";
                printf "%s,", v[i];
                if (i % 6 == 0 || i == NR) printf "\n"; else printf " ";
            }
        }'
}

{
    echo "//! The TSIS-1 Hybrid Solar Reference Spectrum: solar spectral irradiance at 1 AU."
    echo "//!"
    echo "//! @generated by scripts/fetch-solar-spectrum.sh on $(date -u +%Y-%m-%d) from"
    echo "//! <$url>. Do not edit by hand."
    echo "//!"
    echo "//! Coddington, O. M., et al. (2021). The TSIS-1 Hybrid Solar Reference Spectrum."
    echo "//! Geophysical Research Letters, 48, e2020GL091709."
    echo "//! <https://doi.org/10.1029/2020GL091709>"
    echo ""
    echo "/// Vacuum wavelength, in meters, every 1 nm from 202 to 2730 nm."
    echo "#[rustfmt::skip]"
    echo "pub(crate) static WAVELENGTH: [f64; $count] = ["
    emit 1
    echo "];"
    echo ""
    echo "/// Solar spectral irradiance at 1 AU over a 1 nm band, in W/m^2 per meter of wavelength."
    echo "#[rustfmt::skip]"
    echo "pub(crate) static IRRADIANCE: [f64; $count] = ["
    emit 2
    echo "];"
} > "$out"

echo "wrote $count samples to $out"