#!/bin/bash
# fetch-rpi-firmware.sh — Download Raspberry Pi firmware blobs for boot
#
# Downloads firmware from the official raspberrypi/firmware GitHub repository.
# Extracts only the boot files needed: start*.elf, fixup*.dat, DTBs, bootcode.bin.
#
# Output: build/cache/rpi-firmware/ containing all required boot files.
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
CACHE_DIR="${CACHE_DIR:-$PROJECT_ROOT/build/cache}"

# shellcheck source=../config/versions.env
. "$SCRIPT_DIR/../config/versions.env"

RPI_FW_DIR="$CACHE_DIR/rpi-firmware"
RPI_FW_ARCHIVE="$CACHE_DIR/rpi-firmware-${RPI_FIRMWARE_TAG}.tar.gz"

# --- Skip if already fetched ---
if [ -d "$RPI_FW_DIR" ] && [ -f "$RPI_FW_DIR/start4.elf" ]; then
    echo "==> RPi firmware already cached: $RPI_FW_DIR"
    echo "    Files: $(ls "$RPI_FW_DIR" | wc -l)"
    exit 0
fi

echo "==> Downloading Raspberry Pi firmware (tag: ${RPI_FIRMWARE_TAG})..."
mkdir -p "$CACHE_DIR" "$RPI_FW_DIR"

# --- Download firmware archive ---
if [ ! -f "$RPI_FW_ARCHIVE" ]; then
    echo "    URL: $RPI_FIRMWARE_URL"
    wget -q --show-progress -O "$RPI_FW_ARCHIVE" "$RPI_FIRMWARE_URL" 2>/dev/null || \
        curl -fSL "$RPI_FIRMWARE_URL" -o "$RPI_FW_ARCHIVE"
    echo "    Downloaded: $(du -h "$RPI_FW_ARCHIVE" | cut -f1)"
else
    echo "    Archive already cached: $(du -h "$RPI_FW_ARCHIVE" | cut -f1)"
fi

# --- Extract boot files only ---
echo "==> Extracting boot files..."
TEMP_DIR=$(mktemp -d)
trap "rm -rf '$TEMP_DIR'" EXIT

# Extract only the boot/ directory from the archive
# Archive structure: firmware-<tag>/boot/...
tar -xzf "$RPI_FW_ARCHIVE" -C "$TEMP_DIR" --strip-components=1 '*/boot/'

BOOT_SRC="$TEMP_DIR/boot"
if [ ! -d "$BOOT_SRC" ]; then
    echo "ERROR: boot/ directory not found in firmware archive"
    ls -la "$TEMP_DIR"/
    exit 1
fi

# Copy GPU firmware (required for boot)
for f in "$BOOT_SRC"/start*.elf "$BOOT_SRC"/fixup*.dat; do
    [ -f "$f" ] && cp "$f" "$RPI_FW_DIR/"
done

# Copy bootcode.bin (first-stage boot for Pi 3 and older)
[ -f "$BOOT_SRC/bootcode.bin" ] && cp "$BOOT_SRC/bootcode.bin" "$RPI_FW_DIR/"

# Copy Device Tree Blobs for Pi 4 + Pi 5
for dtb in bcm2711-rpi-4-b.dtb bcm2711-rpi-400.dtb bcm2711-rpi-cm4.dtb \
           bcm2712-rpi-5-b.dtb bcm2712d0-rpi-5-b.dtb; do
    [ -f "$BOOT_SRC/$dtb" ] && cp "$BOOT_SRC/$dtb" "$RPI_FW_DIR/"
done

# Copy overlays directory (needed for config.txt dtoverlay= directives)
if [ -d "$BOOT_SRC/overlays" ]; then
    mkdir -p "$RPI_FW_DIR/overlays"
    # Only copy overlays we actually use (disable-wifi, disable-bt)
    for overlay in disable-wifi.dtbo disable-bt.dtbo; do
        [ -f "$BOOT_SRC/overlays/$overlay" ] && \
            cp "$BOOT_SRC/overlays/$overlay" "$RPI_FW_DIR/overlays/"
    done
fi

trap - EXIT
rm -rf "$TEMP_DIR"

# --- Summary ---
echo ""
echo "==> RPi firmware extracted to: $RPI_FW_DIR"
echo "    Files:"
ls -1 "$RPI_FW_DIR" | head -20
echo "    Total size: $(du -sh "$RPI_FW_DIR" | cut -f1)"