#!/usr/bin/env php
<?php
/**
 * Database Migration Runner
 *
 * Runs SQL migration files in order. Tracks completed migrations
 * to prevent re-running them.
 *
 * Usage:
 *   php migrate.php            # Run all pending migrations
 *   php migrate.php --status   # Show migration status
 *   php migrate.php --dry-run  # Show what would be run without executing
 */

// Prevent web access
if (php_sapi_name() !== 'cli') {
    http_response_code(403);
    exit('CLI access only');
}

require_once dirname(__DIR__) . '/config/config.php';
require_once dirname(__DIR__) . '/helpers/Database.php';

$dryRun = in_array('--dry-run', $argv);
$statusOnly = in_array('--status', $argv);

echo "=== Database Migration Runner ===\n\n";

try {
    $conn = Database::getConnection();
} catch (Exception $e) {
    echo "Error: Could not connect to database: " . $e->getMessage() . "\n";
    exit(1);
}

// Create migrations tracking table if it doesn't exist
$createTable = "CREATE TABLE IF NOT EXISTS migrations (
    id INT AUTO_INCREMENT PRIMARY KEY,
    filename VARCHAR(255) NOT NULL UNIQUE,
    applied_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    INDEX idx_filename (filename)
)";

if (!$conn->query($createTable)) {
    echo "Error: Could not create migrations table: " . $conn->error . "\n";
    exit(1);
}

// Tracks per-statement progress within a migration file. MySQL DDL statements
// (ALTER/CREATE TABLE, etc.) cause an implicit commit, so begin_transaction()/
// rollback() around a whole file can't actually undo DDL already executed
// earlier in that same file. This table lets a re-run after a partial failure
// resume from the statement after the last one that succeeded, instead of
// re-executing already-applied DDL and wedging on "already exists" errors.
$createProgressTable = "CREATE TABLE IF NOT EXISTS migration_progress (
    filename VARCHAR(255) NOT NULL PRIMARY KEY,
    last_statement_index INT NOT NULL,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
)";

if (!$conn->query($createProgressTable)) {
    echo "Error: Could not create migration_progress table: " . $conn->error . "\n";
    exit(1);
}

// Get list of completed migrations
$completed = [];
$result = $conn->query("SELECT filename FROM migrations ORDER BY id");
while ($row = $result->fetch_assoc()) {
    $completed[] = $row['filename'];
}

// Get list of migration files
$migrationsDir = __DIR__;
$files = glob($migrationsDir . '/*.sql');
sort($files);

if (empty($files)) {
    echo "No migration files found.\n";
    exit(0);
}

if ($statusOnly) {
    echo "Migration Status:\n";
    echo str_repeat('-', 60) . "\n";
    foreach ($files as $file) {
        $filename = basename($file);
        $status = in_array($filename, $completed) ? '[DONE]' : '[PENDING]';
        echo sprintf("  %s %s\n", $status, $filename);
    }
    exit(0);
}

// Find pending migrations
$pending = [];
foreach ($files as $file) {
    $filename = basename($file);
    if (!in_array($filename, $completed)) {
        $pending[] = $file;
    }
}

if (empty($pending)) {
    echo "All migrations are up to date.\n";
    exit(0);
}

echo sprintf("Found %d pending migration(s):\n", count($pending));
foreach ($pending as $file) {
    echo "  - " . basename($file) . "\n";
}
echo "\n";

if ($dryRun) {
    echo "[DRY RUN] No changes made.\n";
    exit(0);
}

// Run pending migrations
$success = 0;
$failed = 0;

foreach ($pending as $file) {
    $filename = basename($file);
    echo "Running: $filename... ";

    $sql = file_get_contents($file);
    if ($sql === false) {
        echo "FAILED (could not read file)\n";
        $failed++;
        continue;
    }

    // Execute migration statement-by-statement, tracking progress as we go.
    // No begin_transaction()/rollback() here: DDL statements auto-commit in
    // MySQL/MariaDB regardless, so a transaction wrapper around the whole
    // file would only create the illusion of atomicity while giving no real
    // protection. Instead, each statement commits immediately (autocommit),
    // and its index is durably recorded so a later re-run can resume exactly
    // where a previous run left off rather than re-executing already-applied
    // DDL.
    try {
        // Split by semicolon but respect statements properly
        // Note: This doesn't handle semicolons in strings, but our migrations are simple
        $statements = array_values(array_filter(
            array_map('trim', explode(';', $sql)),
            function($stmt) {
                // Remove comments and check if there's actual SQL
                $cleaned = preg_replace('/--.*$/m', '', $stmt);
                return !empty(trim($cleaned));
            }
        ));

        $resumeFrom = 0;
        $progressStmt = $conn->prepare(
            "SELECT last_statement_index FROM migration_progress WHERE filename = ?"
        );
        $progressStmt->bind_param('s', $filename);
        $progressStmt->execute();
        $progressRow = $progressStmt->get_result()->fetch_assoc();
        $progressStmt->close();
        if ($progressRow) {
            $resumeFrom = (int)$progressRow['last_statement_index'] + 1;
            echo "\n  Resuming from statement " . ($resumeFrom + 1) . " of " . count($statements)
                . " after a previous partial failure... ";
        }

        foreach ($statements as $index => $statement) {
            if ($index < $resumeFrom) {
                continue;
            }

            if (!$conn->query($statement)) {
                // Some "errors" are acceptable (like "index already exists")
                $error = $conn->error;
                if (strpos($error, 'Duplicate key name') !== false ||
                    strpos($error, 'already exists') !== false) {
                    // Index already exists, that's fine
                } else {
                    throw new Exception($error);
                }
            }

            // Record progress after every statement so a later run can
            // resume from here even if a subsequent statement fails.
            $upsert = $conn->prepare(
                "INSERT INTO migration_progress (filename, last_statement_index) VALUES (?, ?)
                 ON DUPLICATE KEY UPDATE last_statement_index = VALUES(last_statement_index)"
            );
            $upsert->bind_param('si', $filename, $index);
            $upsert->execute();
            $upsert->close();
        }

        // Record the migration as fully complete and clear its progress marker
        $stmt = $conn->prepare("INSERT INTO migrations (filename) VALUES (?)");
        $stmt->bind_param('s', $filename);
        if (!$stmt->execute()) {
            throw new Exception("Could not record migration: " . $conn->error);
        }

        $clearProgress = $conn->prepare("DELETE FROM migration_progress WHERE filename = ?");
        $clearProgress->bind_param('s', $filename);
        $clearProgress->execute();
        $clearProgress->close();

        echo "OK\n";
        $success++;

    } catch (Exception $e) {
        // Nothing to roll back: every statement up to the failure already
        // committed (DDL implicitly, everything else via autocommit). The
        // progress marker recorded above reflects exactly how far this file
        // got, so the next run will resume right after the last success.
        echo "FAILED (" . $e->getMessage() . ")\n";
        $failed++;
    }
}

echo "\n";
echo "=== Migration Complete ===\n";
echo sprintf("  Success: %d\n", $success);
echo sprintf("  Failed:  %d\n", $failed);

exit($failed > 0 ? 1 : 0);