//! Migration commands

use clap::Subcommand;

use crate::{config::Config, error::Result, output};

#[derive(Subcommand)]
pub enum MigrationCommand {
    /// Generate migration code
    Generate {
        /// From schema (ID or version)
        #[arg(short, long)]
        from: String,

        /// To schema (ID or version)
        #[arg(short, long)]
        to: String,

        /// Target language (python, typescript, java, go, sql)
        #[arg(short, long)]
        language: String,

        /// Output file
        #[arg(short, long)]
        output: Option<String>,
    },

    /// Validate migration
    Validate {
        /// Migration file
        file: String,
    },

    /// Generate rollback script
    Rollback {
        /// Migration ID or file
        migration: String,

        /// Output file
        #[arg(short, long)]
        output: Option<String>,
    },

    /// List migrations
    List {
        /// Schema subject
        subject: Option<String>,
    },

    /// Show migration plan
    Plan {
        /// From version
        #[arg(short, long)]
        from: String,

        /// To version
        #[arg(short, long)]
        to: String,
    },

    /// Test migration (dry-run)
    Test {
        /// Migration file
        file: String,

        /// Test data file
        #[arg(short, long)]
        data: Option<String>,
    },
}

pub async fn execute(cmd: MigrationCommand, config: &Config, format: output::OutputFormat) -> Result<()> {
    match cmd {
        MigrationCommand::Generate { from, to, language, output: output_file } => {
            generate_migration(config, &from, &to, &language, output_file.as_deref(), format).await
        }
        MigrationCommand::Validate { file } => {
            validate_migration(config, &file, format).await
        }
        MigrationCommand::Rollback { migration, output: output_file } => {
            generate_rollback(config, &migration, output_file.as_deref(), format).await
        }
        MigrationCommand::List { subject } => {
            list_migrations(config, subject.as_deref(), format).await
        }
        MigrationCommand::Plan { from, to } => {
            show_migration_plan(config, &from, &to, format).await
        }
        MigrationCommand::Test { file, data } => {
            test_migration(config, &file, data.as_deref(), format).await
        }
    }
}

async fn generate_migration(
    _config: &Config,
    from: &str,
    to: &str,
    language: &str,
    output_file: Option<&str>,
    _format: output::OutputFormat,
) -> Result<()> {
    output::print_info(&format!(
        "Generating {} migration: {} -> {}",
        language, from, to
    ));

    let default_output = format!("migration_{}_to_{}.{}", from, to, get_extension(language));
    let output_path = output_file.unwrap_or(&default_output);

    // Mock generation
    println!("\nGenerated migration code:");
    println!("  Language: {}", language);
    println!("  Transformations: 3");
    println!("    - Field added: email_verified (default: false)");
    println!("    - Field renamed: full_name -> display_name");
    println!("    - Type changed: age (int32 -> int64)");
    println!("  Complexity score: 2.5/10");
    println!("  Estimated effort: 1.5 hours");

    output::print_success(&format!("Migration code saved to: {}", output_path));

    Ok(())
}

async fn validate_migration(_config: &Config, file: &str, _format: output::OutputFormat) -> Result<()> {
    output::print_info(&format!("Validating migration: {}", file));

    // Mock validation
    println!("\nValidation results:");
    println!("  ✓ Syntax is valid");
    println!("  ✓ All transformations are reversible");
    println!("  ✓ No data loss detected");
    println!("  ⚠ Warning: Type widening detected (may affect performance)");

    output::print_success("Migration is valid");

    Ok(())
}

async fn generate_rollback(
    _config: &Config,
    migration: &str,
    output_file: Option<&str>,
    _format: output::OutputFormat,
) -> Result<()> {
    output::print_info(&format!("Generating rollback for: {}", migration));

    let output_path = output_file.unwrap_or("rollback.sql");

    // Mock generation
    output::print_success(&format!("Rollback script saved to: {}", output_path));

    Ok(())
}

async fn list_migrations(_config: &Config, subject: Option<&str>, _format: output::OutputFormat) -> Result<()> {
    let scope = subject.map(|s| format!("subject {}", s)).unwrap_or_else(|| "all subjects".to_string());
    output::print_info(&format!("Listing migrations for {}", scope));

    output::print_table(
        vec!["ID", "From", "To", "Language", "Status", "Created"],
        vec![
            vec!["mig-001".to_string(), "1.0.0".to_string(), "2.0.0".to_string(), "Python".to_string(), "Applied".to_string(), "2024-01-10".to_string()],
            vec!["mig-002".to_string(), "2.0.0".to_string(), "2.1.0".to_string(), "TypeScript".to_string(), "Pending".to_string(), "2024-01-12".to_string()],
        ],
    );

    Ok(())
}

async fn show_migration_plan(_config: &Config, from: &str, to: &str, _format: output::OutputFormat) -> Result<()> {
    output::print_info(&format!("Migration plan: {} -> {}", from, to));

    println!("\nMigration Strategy: GRADUAL_ROLLOUT");
    println!("\nSteps:");
    println!("  1. Deploy backward-compatible version {}", to);
    println!("  2. Migrate data in batches (batch size: 1000)");
    println!("  3. Monitor error rates");
    println!("  4. Complete migration after 24h observation");
    println!("\nBreaking Changes: 1");
    println!("  - Field removed: legacy_id");
    println!("\nRisk Level: MEDIUM");
    println!("Estimated Duration: 2-4 hours");

    Ok(())
}

async fn test_migration(_config: &Config, file: &str, data: Option<&str>, _format: output::OutputFormat) -> Result<()> {
    output::print_info(&format!("Testing migration: {} (dry-run)", file));

    if let Some(d) = data {
        println!("Using test data: {}", d);
    }

    // Mock test results
    println!("\nTest Results:");
    println!("  ✓ 100/100 records migrated successfully");
    println!("  ✓ 0 errors");
    println!("  ✓ 0 data integrity issues");
    println!("  ⓘ Average migration time: 2.5ms per record");

    output::print_success("Migration test passed");

    Ok(())
}

fn get_extension(language: &str) -> &str {
    match language.to_lowercase().as_str() {
        "python" => "py",
        "typescript" => "ts",
        "java" => "java",
        "go" => "go",
        "sql" => "sql",
        _ => "txt",
    }
}
