#!/usr/bin/env php
<?php

/**
 * generate-cover-webp.php — Backfill small WebP cover thumbnails.
 *
 * Covers are uploaded as full-resolution PNG/JPEG but rendered into a small
 * 4:3 card on the public home grid. Serving the original is wasteful — a single
 * cover can be ~15 MB. This scans every `*_COUVERTURE.*` file under the storage
 * root and, for any that lacks a `.webp` sibling, downscales + re-encodes it in
 * one `cwebp -resize` pass (typically ~95%+ smaller, to ~800px wide @ q80).
 *
 * Idempotent: skips covers that already have a `.webp` sibling. Safe to re-run.
 *
 * Usage:
 *   php scripts/generate-cover-webp.php              # dry-run (list pending)
 *   php scripts/generate-cover-webp.php --no-dry-run # actually generate
 *   COVER_WEBP_WIDTH=1000 COVER_WEBP_QUALITY=85 php scripts/generate-cover-webp.php --no-dry-run
 *
 * Requires `cwebp` on PATH (see docs/environment.md). Exit code 0 on success,
 * 1 on error.
 */

declare(strict_types=1);

// Resolve APP_ROOT robustly. In production the app code is deployed flat under
// /var/www/xamxam/ (src/, storage/, templates/ at the root, no app/ subdir).
$prodRoot = '/var/www/xamxam';
if (is_dir($prodRoot . '/src') && is_file($prodRoot . '/src/Database.php')) {
    define('APP_ROOT', $prodRoot);
    $storageRoot = $prodRoot . '/storage';
} else {
    define('APP_ROOT', dirname(__DIR__) . '/app');
    $storageRoot = APP_ROOT . '/storage';
}

$dryRun = !in_array('--no-dry-run', $argv, true);

// Tuning (mirrors ThesisFileHandler::generateCoverWebp defaults).
$maxWidth = (int) (getenv('COVER_WEBP_WIDTH') ?: 800);
$quality  = (int) (getenv('COVER_WEBP_QUALITY') ?: 80);
if ($maxWidth < 1) {
    $maxWidth = 800;
}
if ($quality < 0 || $quality > 100) {
    $quality = 80;
}

if (!is_dir($storageRoot) || !is_readable($storageRoot)) {
    fwrite(STDERR, "[generate-cover-webp] storage root not readable: $storageRoot\n");
    exit(1);
}

if (!function_exists('exec')) {
    fwrite(STDERR, "[generate-cover-webp] exec() is disabled; cannot run cwebp.\n");
    exit(1);
}

// Recursively collect cover files.
$covers = [];
$rii = new RecursiveIteratorIterator(
    new RecursiveDirectoryIterator($storageRoot, FilesystemIterator::SKIP_DOTS)
);
foreach ($rii as $entry) {
    if (!$entry->isFile()) {
        continue;
    }
    $name = $entry->getFilename();
    // Only source covers (original upload) count as inputs; the generated
    // `.webp` sidecars must NOT be re-scanned as sources.
    if (!preg_match('/_COUVERTURE\.[a-z0-9]+$/i', $name) || str_ends_with($name, '.webp')) {
        continue;
    }
    $covers[] = $entry->getPathname();
}
sort($covers);

$pending  = [];
$existing = 0;
foreach ($covers as $sourcePath) {
    $webpPath = preg_replace('/\.[a-z0-9]+$/i', '.webp', $sourcePath);
    if ($webpPath !== null && is_file($webpPath)) {
        $existing++;
        continue;
    }
    $pending[] = $sourcePath;
}

$skipped = 0;
if ($dryRun) {
    foreach ($pending as $p) {
        printf("DRY-RUN → %s  (%d bytes)\n", $p, (int) filesize($p));
    }
    printf(
        "Found %d cover file(s): %d already have a .webp thumbnail, %d pending.\n",
        count($covers),
        $existing,
        count($pending)
    );
    echo "Re-run with --no-dry-run to generate them.\n";
    exit(0);
}

foreach ($pending as $sourcePath) {
    $targetPath = preg_replace('/\.[a-z0-9]+$/i', '.webp', $sourcePath);
    $cmd = sprintf(
        'cwebp -quiet -resize %d 0 -q %d %s -o %s 2>/dev/null',
        $maxWidth,
        $quality,
        escapeshellarg((string) $sourcePath),
        escapeshellarg((string) $targetPath)
    );

    exec($cmd, $_, $code);
    $ok = $code === 0 && $targetPath !== null && is_file($targetPath);

    // cwebp can't read CMYK JPEGs; fall back to GD (php-gd) which handles
    // CMYK->RGB on decode, same resize + quality.
    if (!$ok && function_exists('imagecreatefromjpeg') && function_exists('imagewebp')) {
        $im = @imagecreatefromjpeg((string) $sourcePath);
        if ($im !== false && $targetPath !== null) {
            $srcW = imagesx($im);
            $srcH = imagesy($im);
            $dstW = min($maxWidth, $srcW);
            $dstH = (int) round($srcH * $dstW / $srcW);
            $tgt  = imagecreatetruecolor($dstW, $dstH);
            imagecopyresampled($tgt, $im, 0, 0, 0, 0, $dstW, $dstH, $srcW, $srcH);
            $ok = imagewebp($tgt, $targetPath, $quality);
            imagedestroy($im);
            imagedestroy($tgt);
            if ($ok) {
                @chmod($targetPath, 0644);
            }
        }
    }

    if ($ok && $targetPath !== null && is_file($targetPath)) {
        @chmod($targetPath, 0644);
        printf("✓ %s  (%d → %d bytes)\n", basename($targetPath), (int) filesize($sourcePath), (int) filesize($targetPath));
    } else {
        printf("✗ failed: %s (cwebp exit %d)\n", (string) $sourcePath, $code);
        $skipped++;
    }
}

printf(
    "Generated %d WebP thumbnail(s); %d failed. %d already present.\n",
    count($pending) - $skipped,
    $skipped,
    $existing
);
exit($skipped > 0 ? 1 : 0);