package db

import (
	"database/sql"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

type Migration struct {
	Version string
	Name    string
	SQL     string
}

func RunMigrations(db *sql.DB, migrationsDir string) error {
	// Ensure migrations table exists
	if _, err := db.Exec(`
		CREATE TABLE IF NOT EXISTS boc_schema_migrations (
			version TEXT PRIMARY KEY,
			applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
		)
	`); err != nil {
		return fmt.Errorf("create migrations table: %w", err)
	}

	// Read migration files
	files, err := os.ReadDir(migrationsDir)
	if err != nil {
		return fmt.Errorf("read migrations dir: %w", err)
	}

	var migrations []Migration
	for _, f := range files {
		if f.IsDir() || !strings.HasSuffix(f.Name(), ".sql") {
			continue
		}

		content, err := os.ReadFile(filepath.Join(migrationsDir, f.Name()))
		if err != nil {
			return fmt.Errorf("read migration %s: %w", f.Name(), err)
		}

		version := strings.Split(f.Name(), "_")[0]
		migrations = append(migrations, Migration{
			Version: version,
			Name:    f.Name(),
			SQL:     string(content),
		})
	}

	// Sort by version
	sort.Slice(migrations, func(i, j int) bool {
		return migrations[i].Version < migrations[j].Version
	})

	// Apply migrations in transaction
	for _, m := range migrations {
		var applied bool
		err := db.QueryRow("SELECT EXISTS(SELECT 1 FROM boc_schema_migrations WHERE version = $1)", m.Version).Scan(&applied)
		if err != nil {
			return fmt.Errorf("check migration %s: %w", m.Version, err)
		}
		if applied {
			continue
		}

		tx, err := db.Begin()
		if err != nil {
			return fmt.Errorf("begin transaction: %w", err)
		}

		if _, err := tx.Exec(m.SQL); err != nil {
			tx.Rollback()
			return fmt.Errorf("apply migration %s: %w", m.Name, err)
		}

		if _, err := tx.Exec("INSERT INTO boc_schema_migrations (version) VALUES ($1)", m.Version); err != nil {
			tx.Rollback()
			return fmt.Errorf("record migration %s: %w", m.Name, err)
		}

		if err := tx.Commit(); err != nil {
			return fmt.Errorf("commit migration %s: %w", m.Name, err)
		}

		fmt.Printf("✅ Applied migration: %s\n", m.Name)
	}

	return nil
}