<?php
/**
 * Migration 016 — merge banners into covers
 *
 * 1. For every thesis that has a banner_path:
 *    a. Copy the file from storage/banners/<file> to storage/covers/<file>
 *    b. Insert a thesis_files row with file_type='cover'
 *    c. Clear theses.banner_path
 * 2. Remove the now-empty storage/banners/ directory (best-effort).
 *
 * Safe to re-run: if a cover record already exists for a thesis, the banner
 * migration for that thesis is skipped.
 */

defined('APP_ROOT') || define('APP_ROOT', dirname(__DIR__, 2));
defined('STORAGE_ROOT') || define('STORAGE_ROOT', APP_ROOT . '/storage');

$dbPath = APP_ROOT . '/storage/xamxam.db';
if (!file_exists($dbPath)) {
    echo "ERROR: database not found at $dbPath\n";
    exit(1);
}

$pdo = new PDO('sqlite:' . $dbPath);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$pdo->exec('PRAGMA foreign_keys = ON');

$coverDir  = STORAGE_ROOT . '/covers/';
$bannerDir = STORAGE_ROOT . '/banners/';

if (!is_dir($coverDir)) {
    mkdir($coverDir, 0755, true);
    echo "Created covers/ directory.\n";
}

// Fetch all theses with a non-null banner_path
$stmt = $pdo->query("SELECT id, banner_path FROM theses WHERE banner_path IS NOT NULL");
$rows = $stmt->fetchAll();

if (empty($rows)) {
    echo "No banners to migrate.\n";
} else {
    foreach ($rows as $row) {
        $thesisId   = (int)$row['id'];
        $bannerPath = $row['banner_path']; // e.g. "banners/abc123.png"

        // Skip if a cover record already exists for this thesis
        $check = $pdo->prepare("SELECT id FROM thesis_files WHERE thesis_id = ? AND file_type = 'cover' LIMIT 1");
        $check->execute([$thesisId]);
        if ($check->fetch()) {
            echo "  Thesis $thesisId: cover record already exists — skipping banner migration.\n";
            // Still clear banner_path so UI stays clean
            $pdo->prepare("UPDATE theses SET banner_path = NULL WHERE id = ?")->execute([$thesisId]);
            continue;
        }

        $srcAbs  = STORAGE_ROOT . '/' . $bannerPath;
        $filename = basename($bannerPath);
        $dstAbs  = $coverDir . $filename;
        $dstRel  = 'covers/' . $filename;

        if (!file_exists($srcAbs)) {
            echo "  Thesis $thesisId: source file missing ($srcAbs) — inserting DB record with new path anyway, skipping file copy.\n";
        } else {
            if (!copy($srcAbs, $dstAbs)) {
                echo "  ERROR: could not copy $srcAbs → $dstAbs — skipping thesis $thesisId.\n";
                continue;
            }
            chmod($dstAbs, 0644);
            echo "  Thesis $thesisId: copied $bannerPath → $dstRel\n";
        }

        // Determine MIME from extension
        $ext  = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
        $mime = match($ext) {
            'jpg', 'jpeg' => 'image/jpeg',
            'png'         => 'image/png',
            'webp'        => 'image/webp',
            default       => 'image/jpeg',
        };

        // Get file size
        $size = file_exists($dstAbs) ? filesize($dstAbs) : 0;

        // Insert cover record
        $ins = $pdo->prepare(
            "INSERT INTO thesis_files (thesis_id, file_type, file_path, file_name, file_size, mime_type, sort_order)
             VALUES (?, 'cover', ?, ?, ?, ?, 0)"
        );
        $ins->execute([$thesisId, $dstRel, $filename, $size, $mime]);
        echo "  Thesis $thesisId: inserted cover record → $dstRel\n";

        // Clear banner_path
        $pdo->prepare("UPDATE theses SET banner_path = NULL WHERE id = ?")->execute([$thesisId]);
        echo "  Thesis $thesisId: cleared banner_path.\n";
    }
}

// Remove old banner files that were successfully copied
$remaining = glob($bannerDir . '*') ?: [];
$allClear   = true;
foreach ($remaining as $f) {
    $basename = basename($f);
    if (file_exists($coverDir . $basename)) {
        @unlink($f);
        echo "Removed migrated banner file: banners/$basename\n";
    } else {
        echo "WARNING: banners/$basename has no corresponding cover — leaving in place.\n";
        $allClear = false;
    }
}

// Remove the now-empty banners/ directory (best-effort, ignoring .gitkeep)
if ($allClear && is_dir($bannerDir)) {
    $leftovers = array_diff(scandir($bannerDir), ['.', '..', '.gitkeep']);
    if (empty($leftovers)) {
        // Remove .gitkeep if present, then the dir
        $gitkeep = $bannerDir . '.gitkeep';
        if (file_exists($gitkeep)) {
            @unlink($gitkeep);
        }
        @rmdir($bannerDir);
        echo "Removed banners/ directory.\n";
    } else {
        echo "WARNING: banners/ directory still has files after migration — leaving in place.\n";
    }
}

echo "\nMigration 016 complete.\n";