//! Database-agnostic migration system
//!
//! This module provides a unified interface for database migrations
//! that works with both SQLite and PostgreSQL databases.

use super::{Database, DatabaseType};
use anyhow::Result;
use async_trait::async_trait;
use serde::{Deserialize, Serialize};
use sqlx::Row;
use std::collections::HashMap;
use std::path::Path;

/// Migration status
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MigrationStatus {
    pub version: i64,
    pub name: String,
    pub applied: bool,
    pub applied_at: Option<chrono::DateTime<chrono::Utc>>,
}

/// Migration definition
#[derive(Debug, Clone)]
pub struct Migration {
    pub version: i64,
    pub name: String,
    pub up_sql_postgres: String,
    #[allow(dead_code)]
    pub down_sql_postgres: String,
    pub up_sql_sqlite: String,
    #[allow(dead_code)]
    pub down_sql_sqlite: String,
}

#[allow(dead_code)]
impl Migration {
    /// Create a new migration
    pub fn new(
        version: i64,
        name: String,
        up_sql_postgres: String,
        down_sql_postgres: String,
        up_sql_sqlite: String,
        down_sql_sqlite: String,
    ) -> Self {
        Self {
            version,
            name,
            up_sql_postgres,
            down_sql_postgres,
            up_sql_sqlite,
            down_sql_sqlite,
        }
    }

    /// Get the appropriate up SQL for the database type
    pub fn up_sql(&self, db_type: &DatabaseType) -> &str {
        match db_type {
            DatabaseType::PostgreSQL => &self.up_sql_postgres,
            DatabaseType::SQLite => &self.up_sql_sqlite,
        }
    }

    /// Get the appropriate down SQL for the database type
    pub fn down_sql(&self, db_type: &DatabaseType) -> &str {
        match db_type {
            DatabaseType::PostgreSQL => &self.down_sql_postgres,
            DatabaseType::SQLite => &self.down_sql_sqlite,
        }
    }
}

/// Database-agnostic migration runner trait
#[async_trait]
#[allow(dead_code)]
pub trait MigrationRunnerTrait: Send + Sync {
    /// Run all pending migrations
    async fn run_migrations(&self) -> Result<Vec<MigrationStatus>>;

    /// Run migrations up to a specific version
    async fn migrate_to(&self, target_version: i64) -> Result<Vec<MigrationStatus>>;

    /// Rollback the last migration
    async fn rollback_last(&self) -> Result<Option<MigrationStatus>>;

    /// Rollback to a specific version
    async fn rollback_to(&self, target_version: i64) -> Result<Vec<MigrationStatus>>;

    /// Get migration status
    async fn get_status(&self) -> Result<Vec<MigrationStatus>>;

    /// Check if all migrations are applied
    async fn is_up_to_date(&self) -> Result<bool>;

    /// Reset database (drop all tables)
    async fn reset(&self) -> Result<()>;

    /// Validate migration integrity
    async fn validate(&self) -> Result<()>;
}

/// Database-agnostic migration runner implementation
#[derive(Debug, Clone)]
pub struct MigrationRunner {
    database: Database,
    migrations: Vec<Migration>,
}

#[allow(dead_code)]
impl MigrationRunner {
    /// Create a new migration runner
    pub fn new(database: Database) -> Self {
        Self {
            database,
            migrations: Self::get_default_migrations(),
        }
    }

    /// Create migration runner with custom migrations
    pub fn with_migrations(database: Database, migrations: Vec<Migration>) -> Self {
        Self {
            database,
            migrations,
        }
    }

    /// Add a migration
    pub fn add_migration(&mut self, migration: Migration) {
        self.migrations.push(migration);
        self.migrations.sort_by_key(|m| m.version);
    }

    /// Get the database type
    pub fn database_type(&self) -> DatabaseType {
        self.database.pool().database_type()
    }

    /// Load migrations from directory
    pub fn load_migrations_from_dir<P: AsRef<Path>>(&mut self, migrations_dir: P) -> Result<()> {
        let dir = migrations_dir.as_ref();
        if !dir.exists() {
            return Ok(());
        }

        let mut entries: Vec<_> = std::fs::read_dir(dir)?
            .filter_map(|entry| entry.ok())
            .filter(|entry| {
                entry.path().is_file() && entry.path().extension().map_or(false, |ext| ext == "sql")
            })
            .collect();

        entries.sort_by_key(|entry| entry.path());

        for entry in entries {
            let path = entry.path();
            let filename = path.file_stem().unwrap().to_string_lossy();

            // Parse filename format: "001_create_users_table"
            let parts: Vec<&str> = filename.splitn(2, '_').collect();
            if parts.len() != 2 {
                continue;
            }

            let version: i64 = parts[0].parse().map_err(|_| {
                anyhow::anyhow!("Invalid migration version in filename: {}", filename)
            })?;

            let name = parts[1].replace('_', " ");
            let content = std::fs::read_to_string(&path)?;

            // Look for database-specific sections
            let postgres_sql = self.extract_sql_section(&content, "postgres")?;
            let sqlite_sql = self.extract_sql_section(&content, "sqlite")?;

            let migration = Migration::new(
                version,
                name,
                postgres_sql.up,
                postgres_sql.down,
                sqlite_sql.up,
                sqlite_sql.down,
            );

            self.add_migration(migration);
        }

        Ok(())
    }

    /// Extract SQL sections from migration file
    fn extract_sql_section(&self, content: &str, db_type: &str) -> Result<SqlSection> {
        let up_marker = format!("-- {} up", db_type);
        let down_marker = format!("-- {} down", db_type);

        let lines = content.lines();
        let mut up_sql = String::new();
        let mut down_sql = String::new();
        let mut current_section = None;

        for line in lines {
            let line_lower = line.to_lowercase();

            if line_lower.starts_with(&up_marker) {
                current_section = Some("up");
                continue;
            } else if line_lower.starts_with(&down_marker) {
                current_section = Some("down");
                continue;
            } else if line_lower.starts_with("--") && line_lower.contains("up") {
                current_section = None;
                continue;
            } else if line_lower.starts_with("--") && line_lower.contains("down") {
                current_section = None;
                continue;
            }

            match current_section {
                Some("up") => {
                    up_sql.push_str(line);
                    up_sql.push('\n');
                }
                Some("down") => {
                    down_sql.push_str(line);
                    down_sql.push('\n');
                }
                _ => {}
            }
        }

        Ok(SqlSection {
            up: up_sql.trim().to_string(),
            down: down_sql.trim().to_string(),
        })
    }

    /// Get default migrations for auth system
    fn get_default_migrations() -> Vec<Migration> {
        vec![
            Migration::new(
                1,
                "create_users_table".to_string(),
                // PostgreSQL up
                r#"
                CREATE TABLE IF NOT EXISTS users (
                    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
                    email VARCHAR(255) UNIQUE NOT NULL,
                    password_hash VARCHAR(255),
                    display_name VARCHAR(255),
                    is_verified BOOLEAN DEFAULT FALSE,
                    is_active BOOLEAN DEFAULT TRUE,
                    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
                    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
                );

                CREATE INDEX idx_users_email ON users(email);
                CREATE INDEX idx_users_active ON users(is_active);
                "#
                .to_string(),
                // PostgreSQL down
                r#"
                DROP TABLE IF EXISTS users CASCADE;
                "#
                .to_string(),
                // SQLite up
                r#"
                CREATE TABLE IF NOT EXISTS users (
                    id TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
                    email TEXT UNIQUE NOT NULL,
                    password_hash TEXT,
                    display_name TEXT,
                    is_verified BOOLEAN DEFAULT 0,
                    is_active BOOLEAN DEFAULT 1,
                    created_at TEXT DEFAULT (datetime('now')),
                    updated_at TEXT DEFAULT (datetime('now'))
                );

                CREATE INDEX idx_users_email ON users(email);
                CREATE INDEX idx_users_active ON users(is_active);
                "#
                .to_string(),
                // SQLite down
                r#"
                DROP TABLE IF EXISTS users;
                "#
                .to_string(),
            ),
            Migration::new(
                2,
                "create_sessions_table".to_string(),
                // PostgreSQL up
                r#"
                CREATE TABLE IF NOT EXISTS user_sessions (
                    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
                    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
                    token VARCHAR(255) UNIQUE NOT NULL,
                    expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
                    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
                    last_used_at TIMESTAMP WITH TIME ZONE,
                    user_agent TEXT,
                    ip_address INET,
                    is_active BOOLEAN DEFAULT TRUE
                );

                CREATE INDEX idx_sessions_token ON user_sessions(token);
                CREATE INDEX idx_sessions_user_id ON user_sessions(user_id);
                CREATE INDEX idx_sessions_expires_at ON user_sessions(expires_at);
                "#
                .to_string(),
                // PostgreSQL down
                r#"
                DROP TABLE IF EXISTS user_sessions CASCADE;
                "#
                .to_string(),
                // SQLite up
                r#"
                CREATE TABLE IF NOT EXISTS user_sessions (
                    id TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
                    user_id TEXT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
                    token TEXT UNIQUE NOT NULL,
                    expires_at TEXT NOT NULL,
                    created_at TEXT DEFAULT (datetime('now')),
                    last_used_at TEXT,
                    user_agent TEXT,
                    ip_address TEXT,
                    is_active BOOLEAN DEFAULT 1
                );

                CREATE INDEX idx_sessions_token ON user_sessions(token);
                CREATE INDEX idx_sessions_user_id ON user_sessions(user_id);
                CREATE INDEX idx_sessions_expires_at ON user_sessions(expires_at);
                "#
                .to_string(),
                // SQLite down
                r#"
                DROP TABLE IF EXISTS user_sessions;
                "#
                .to_string(),
            ),
            Migration::new(
                3,
                "create_roles_table".to_string(),
                // PostgreSQL up
                r#"
                CREATE TABLE IF NOT EXISTS user_roles (
                    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
                    name VARCHAR(50) UNIQUE NOT NULL,
                    description TEXT,
                    is_active BOOLEAN DEFAULT TRUE,
                    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
                );

                CREATE TABLE IF NOT EXISTS user_role_assignments (
                    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
                    role_id UUID NOT NULL REFERENCES user_roles(id) ON DELETE CASCADE,
                    assigned_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
                    PRIMARY KEY (user_id, role_id)
                );

                INSERT INTO user_roles (name, description) VALUES
                    ('admin', 'Administrator with full access'),
                    ('user', 'Regular user with basic access')
                ON CONFLICT (name) DO NOTHING;
                "#
                .to_string(),
                // PostgreSQL down
                r#"
                DROP TABLE IF EXISTS user_role_assignments CASCADE;
                DROP TABLE IF EXISTS user_roles CASCADE;
                "#
                .to_string(),
                // SQLite up
                r#"
                CREATE TABLE IF NOT EXISTS user_roles (
                    id TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
                    name TEXT UNIQUE NOT NULL,
                    description TEXT,
                    is_active BOOLEAN DEFAULT 1,
                    created_at TEXT DEFAULT (datetime('now'))
                );

                CREATE TABLE IF NOT EXISTS user_role_assignments (
                    user_id TEXT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
                    role_id TEXT NOT NULL REFERENCES user_roles(id) ON DELETE CASCADE,
                    assigned_at TEXT DEFAULT (datetime('now')),
                    PRIMARY KEY (user_id, role_id)
                );

                INSERT OR IGNORE INTO user_roles (name, description) VALUES
                    ('admin', 'Administrator with full access'),
                    ('user', 'Regular user with basic access');
                "#
                .to_string(),
                // SQLite down
                r#"
                DROP TABLE IF EXISTS user_role_assignments;
                DROP TABLE IF EXISTS user_roles;
                "#
                .to_string(),
            ),
        ]
    }
}

#[async_trait]
impl MigrationRunnerTrait for MigrationRunner {
    async fn run_migrations(&self) -> Result<Vec<MigrationStatus>> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.run_postgres_migrations(&pool).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.run_sqlite_migrations(&pool).await
            }
        }
    }

    async fn migrate_to(&self, target_version: i64) -> Result<Vec<MigrationStatus>> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.migrate_to_postgres(&pool, target_version).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.migrate_to_sqlite(&pool, target_version).await
            }
        }
    }

    async fn rollback_last(&self) -> Result<Option<MigrationStatus>> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.rollback_last_postgres(&pool).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.rollback_last_sqlite(&pool).await
            }
        }
    }

    async fn rollback_to(&self, target_version: i64) -> Result<Vec<MigrationStatus>> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.rollback_to_postgres(&pool, target_version).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.rollback_to_sqlite(&pool, target_version).await
            }
        }
    }

    async fn get_status(&self) -> Result<Vec<MigrationStatus>> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.get_status_postgres(&pool).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.get_status_sqlite(&pool).await
            }
        }
    }

    async fn is_up_to_date(&self) -> Result<bool> {
        let status = self.get_status().await?;
        Ok(status.iter().all(|s| s.applied))
    }

    async fn reset(&self) -> Result<()> {
        match self.database.pool().database_type() {
            DatabaseType::PostgreSQL => {
                let pool = self
                    .database
                    .as_pg_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected PostgreSQL pool"))?;
                self.reset_postgres(&pool).await
            }
            DatabaseType::SQLite => {
                let pool = self
                    .database
                    .as_sqlite_pool()
                    .ok_or_else(|| anyhow::anyhow!("Expected SQLite pool"))?;
                self.reset_sqlite(&pool).await
            }
        }
    }

    async fn validate(&self) -> Result<()> {
        // Check for duplicate versions
        let mut versions = HashMap::new();
        for migration in &self.migrations {
            if versions.contains_key(&migration.version) {
                return Err(anyhow::anyhow!(
                    "Duplicate migration version: {}",
                    migration.version
                ));
            }
            versions.insert(migration.version, &migration.name);
        }

        // Validate SQL syntax (basic check)
        for migration in &self.migrations {
            if migration.up_sql_postgres.trim().is_empty() {
                return Err(anyhow::anyhow!(
                    "Empty PostgreSQL up migration for version {}",
                    migration.version
                ));
            }
            if migration.up_sql_sqlite.trim().is_empty() {
                return Err(anyhow::anyhow!(
                    "Empty SQLite up migration for version {}",
                    migration.version
                ));
            }
        }

        Ok(())
    }
}

impl MigrationRunner {
    /// Initialize migrations table for PostgreSQL
    async fn init_postgres_migrations_table(&self, pool: &sqlx::PgPool) -> Result<()> {
        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS _migrations (
                version BIGINT PRIMARY KEY,
                name VARCHAR(255) NOT NULL,
                applied_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
            )
            "#,
        )
        .execute(pool)
        .await?;
        Ok(())
    }

    /// Initialize migrations table for SQLite
    async fn init_sqlite_migrations_table(&self, pool: &sqlx::SqlitePool) -> Result<()> {
        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS _migrations (
                version INTEGER PRIMARY KEY,
                name TEXT NOT NULL,
                applied_at TEXT DEFAULT (datetime('now'))
            )
            "#,
        )
        .execute(pool)
        .await?;
        Ok(())
    }

    /// Run PostgreSQL migrations
    async fn run_postgres_migrations(&self, pool: &sqlx::PgPool) -> Result<Vec<MigrationStatus>> {
        self.init_postgres_migrations_table(pool).await?;

        let applied_versions = self.get_applied_versions_postgres(pool).await?;
        let mut results = Vec::new();

        for migration in &self.migrations {
            if !applied_versions.contains(&migration.version) {
                tracing::info!(
                    "Applying migration {}: {}",
                    migration.version,
                    migration.name
                );

                sqlx::query(&migration.up_sql_postgres)
                    .execute(pool)
                    .await?;

                sqlx::query("INSERT INTO _migrations (version, name) VALUES ($1, $2)")
                    .bind(migration.version)
                    .bind(&migration.name)
                    .execute(pool)
                    .await?;

                results.push(MigrationStatus {
                    version: migration.version,
                    name: migration.name.clone(),
                    applied: true,
                    applied_at: Some(chrono::Utc::now()),
                });
            }
        }

        Ok(results)
    }

    /// Run SQLite migrations
    async fn run_sqlite_migrations(&self, pool: &sqlx::SqlitePool) -> Result<Vec<MigrationStatus>> {
        self.init_sqlite_migrations_table(pool).await?;

        let applied_versions = self.get_applied_versions_sqlite(pool).await?;
        let mut results = Vec::new();

        for migration in &self.migrations {
            if !applied_versions.contains(&migration.version) {
                tracing::info!(
                    "Applying migration {}: {}",
                    migration.version,
                    migration.name
                );

                sqlx::query(&migration.up_sql_sqlite).execute(pool).await?;

                sqlx::query("INSERT INTO _migrations (version, name) VALUES (?1, ?2)")
                    .bind(migration.version)
                    .bind(&migration.name)
                    .execute(pool)
                    .await?;

                results.push(MigrationStatus {
                    version: migration.version,
                    name: migration.name.clone(),
                    applied: true,
                    applied_at: Some(chrono::Utc::now()),
                });
            }
        }

        Ok(results)
    }

    /// Get applied migration versions for PostgreSQL
    async fn get_applied_versions_postgres(&self, pool: &sqlx::PgPool) -> Result<Vec<i64>> {
        let rows = sqlx::query("SELECT version FROM _migrations ORDER BY version")
            .fetch_all(pool)
            .await?;

        Ok(rows.into_iter().map(|row| row.get("version")).collect())
    }

    /// Get applied migration versions for SQLite
    async fn get_applied_versions_sqlite(&self, pool: &sqlx::SqlitePool) -> Result<Vec<i64>> {
        let rows = sqlx::query("SELECT version FROM _migrations ORDER BY version")
            .fetch_all(pool)
            .await?;

        Ok(rows.into_iter().map(|row| row.get("version")).collect())
    }

    // Placeholder implementations for other methods
    async fn migrate_to_postgres(
        &self,
        _pool: &sqlx::PgPool,
        _target_version: i64,
    ) -> Result<Vec<MigrationStatus>> {
        // TODO: Implement
        Ok(vec![])
    }

    async fn migrate_to_sqlite(
        &self,
        _pool: &sqlx::SqlitePool,
        _target_version: i64,
    ) -> Result<Vec<MigrationStatus>> {
        // TODO: Implement
        Ok(vec![])
    }

    async fn rollback_last_postgres(
        &self,
        _pool: &sqlx::PgPool,
    ) -> Result<Option<MigrationStatus>> {
        // TODO: Implement
        Ok(None)
    }

    async fn rollback_last_sqlite(
        &self,
        _pool: &sqlx::SqlitePool,
    ) -> Result<Option<MigrationStatus>> {
        // TODO: Implement
        Ok(None)
    }

    async fn rollback_to_postgres(
        &self,
        _pool: &sqlx::PgPool,
        _target_version: i64,
    ) -> Result<Vec<MigrationStatus>> {
        // TODO: Implement
        Ok(vec![])
    }

    async fn rollback_to_sqlite(
        &self,
        _pool: &sqlx::SqlitePool,
        _target_version: i64,
    ) -> Result<Vec<MigrationStatus>> {
        // TODO: Implement
        Ok(vec![])
    }

    async fn get_status_postgres(&self, pool: &sqlx::PgPool) -> Result<Vec<MigrationStatus>> {
        self.init_postgres_migrations_table(pool).await?;
        let applied_versions = self.get_applied_versions_postgres(pool).await?;

        let mut status = Vec::new();
        for migration in &self.migrations {
            status.push(MigrationStatus {
                version: migration.version,
                name: migration.name.clone(),
                applied: applied_versions.contains(&migration.version),
                applied_at: None, // TODO: Get actual applied_at from database
            });
        }

        Ok(status)
    }

    async fn get_status_sqlite(&self, pool: &sqlx::SqlitePool) -> Result<Vec<MigrationStatus>> {
        self.init_sqlite_migrations_table(pool).await?;
        let applied_versions = self.get_applied_versions_sqlite(pool).await?;

        let mut status = Vec::new();
        for migration in &self.migrations {
            status.push(MigrationStatus {
                version: migration.version,
                name: migration.name.clone(),
                applied: applied_versions.contains(&migration.version),
                applied_at: None, // TODO: Get actual applied_at from database
            });
        }

        Ok(status)
    }

    async fn reset_postgres(&self, pool: &sqlx::PgPool) -> Result<()> {
        sqlx::query("DROP SCHEMA public CASCADE; CREATE SCHEMA public;")
            .execute(pool)
            .await?;
        Ok(())
    }

    async fn reset_sqlite(&self, pool: &sqlx::SqlitePool) -> Result<()> {
        // Get all table names
        let rows = sqlx::query(
            "SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'",
        )
        .fetch_all(pool)
        .await?;

        // Drop all tables
        for row in rows {
            let table_name: String = row.get("name");
            sqlx::query(&format!("DROP TABLE IF EXISTS {};", table_name))
                .execute(pool)
                .await?;
        }

        Ok(())
    }
}

/// Helper structure for SQL sections
#[allow(dead_code)]
struct SqlSection {
    up: String,
    down: String,
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_migration_creation() {
        let migration = Migration::new(
            1,
            "test_migration".to_string(),
            "CREATE TABLE test_pg ();".to_string(),
            "DROP TABLE test_pg;".to_string(),
            "CREATE TABLE test_sqlite ();".to_string(),
            "DROP TABLE test_sqlite;".to_string(),
        );

        assert_eq!(migration.version, 1);
        assert_eq!(migration.name, "test_migration");
        assert_eq!(
            migration.up_sql(&DatabaseType::PostgreSQL),
            "CREATE TABLE test_pg ();"
        );
        assert_eq!(
            migration.up_sql(&DatabaseType::SQLite),
            "CREATE TABLE test_sqlite ();"
        );
    }

    #[test]
    fn test_default_migrations() {
        let migrations = MigrationRunner::get_default_migrations();
        assert!(!migrations.is_empty());
        assert_eq!(migrations[0].version, 1);
        assert!(migrations[0].name.contains("users"));
    }
}