<?php

namespace App\Core\Database;

/**
 * NovaCore Database Migrator
 * Handle database migrations
 */
class Migrator
{
    private Connection $connection;
    private string $migrationsPath;

    public function __construct()
    {
        $this->connection = $this->getConnection();
        $this->migrationsPath = __DIR__ . '/../../database/migrations';
    }

    /**
     * Get database connection
     */
    protected function getConnection(): Connection
    {
        $config = include __DIR__ . '/../../Config/database.php';
        $connectionConfig = $config['connections'][$config['default']];

        return new Connection($connectionConfig);
    }

    /**
     * Run all pending migrations
     */
    public function run(): void
    {
        $this->createMigrationsTable();

        $migrations = $this->getPendingMigrations();

        foreach ($migrations as $migration) {
            $this->runMigration($migration);
        }

        echo "Migrations completed successfully!\n";
    }

    /**
     * Create migrations table
     */
    private function createMigrationsTable(): void
    {
        $sql = "CREATE TABLE IF NOT EXISTS migrations (
            id INT AUTO_INCREMENT PRIMARY KEY,
            migration VARCHAR(255) NOT NULL,
            batch INT NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )";

        $this->connection->execute($sql);
    }

    /**
     * Get pending migrations
     */
    private function getPendingMigrations(): array
    {
        $migrationFiles = glob($this->migrationsPath . '/*.php');
        $migratedFiles = $this->getMigratedFiles();

        $pending = [];
        foreach ($migrationFiles as $file) {
            $filename = basename($file);
            if (!in_array($filename, $migratedFiles)) {
                $pending[] = $file;
            }
        }

        sort($pending);
        return $pending;
    }

    /**
     * Get already migrated files
     */
    private function getMigratedFiles(): array
    {
        $sql = "SELECT migration FROM migrations ORDER BY id";
        $results = $this->connection->fetchAll($sql);

        return array_column($results, 'migration');
    }

    /**
     * Run single migration
     */
    private function runMigration(string $file): void
    {
        $filename = basename($file);
        $className = $this->getMigrationClassName($filename);

        require_once $file;

        if (!class_exists($className)) {
            throw new \Exception("Migration class {$className} not found in {$file}");
        }

        $migration = new $className();
        $migration->up();

        // Record migration
        $this->recordMigration($filename);

        echo "✓ {$filename}\n";
    }

    /**
     * Get migration class name
     */
    private function getMigrationClassName(string $filename): string
    {
        $name = pathinfo($filename, PATHINFO_FILENAME);
        $parts = explode('_', $name);

        // Remove timestamp
        array_shift($parts);

        // Convert to PascalCase
        $className = '';
        foreach ($parts as $part) {
            $className .= ucfirst($part);
        }

        return $className;
    }

    /**
     * Record migration
     */
    private function recordMigration(string $filename): void
    {
        $batch = $this->getNextBatchNumber();

        $sql = "INSERT INTO migrations (migration, batch) VALUES (?, ?)";
        $this->connection->execute($sql, [$filename, $batch]);
    }

    /**
     * Get next batch number
     */
    private function getNextBatchNumber(): int
    {
        $sql = "SELECT MAX(batch) as max_batch FROM migrations";
        $result = $this->connection->fetch($sql);

        return ($result['max_batch'] ?? 0) + 1;
    }

    /**
     * Rollback last batch
     */
    public function rollback(): void
    {
        $lastBatch = $this->getLastBatchNumber();

        if (!$lastBatch) {
            echo "No migrations to rollback.\n";
            return;
        }

        $migrations = $this->getMigrationsByBatch($lastBatch);

        foreach (array_reverse($migrations) as $migration) {
            $this->rollbackMigration($migration);
        }

        echo "Rollback completed successfully!\n";
    }

    /**
     * Get last batch number
     */
    private function getLastBatchNumber(): ?int
    {
        $sql = "SELECT MAX(batch) as max_batch FROM migrations";
        $result = $this->connection->fetch($sql);

        return $result['max_batch'] ?? null;
    }

    /**
     * Get migrations by batch
     */
    private function getMigrationsByBatch(int $batch): array
    {
        $sql = "SELECT migration FROM migrations WHERE batch = ? ORDER BY id DESC";
        $results = $this->connection->fetchAll($sql, [$batch]);

        return array_column($results, 'migration');
    }

    /**
     * Rollback single migration
     */
    private function rollbackMigration(string $filename): void
    {
        $file = $this->migrationsPath . '/' . $filename;

        if (!file_exists($file)) {
            echo "Warning: Migration file {$filename} not found.\n";
            return;
        }

        $className = $this->getMigrationClassName($filename);

        require_once $file;

        if (!class_exists($className)) {
            echo "Warning: Migration class {$className} not found.\n";
            return;
        }

        $migration = new $className();
        $migration->down();

        // Remove migration record
        $sql = "DELETE FROM migrations WHERE migration = ?";
        $this->connection->execute($sql, [$filename]);

        echo "✓ Rolled back {$filename}\n";
    }

    /**
     * Get migration status
     */
    public function status(): void
    {
        $migrationFiles = glob($this->migrationsPath . '/*.php');
        $migratedFiles = $this->getMigratedFiles();

        echo "Migration Status:\n";
        echo "================\n";

        foreach ($migrationFiles as $file) {
            $filename = basename($file);
            $status = in_array($filename, $migratedFiles) ? '✓' : '✗';
            echo "{$status} {$filename}\n";
        }
    }
}