package db

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"sort"

	"github.com/jackc/pgx/v5/pgxpool"
)

const defaultDSN = "postgres://writekit:writekit@localhost:5432/writekit?sslmode=disable"

type DB struct {
	pool *pgxpool.Pool
}

func Connect(migrationsDir string) (*DB, error) {
	dsn := os.Getenv("DATABASE_URL")
	if dsn == "" {
		dsn = defaultDSN
	}

	pool, err := pgxpool.New(context.Background(), dsn)
	if err != nil {
		return nil, fmt.Errorf("connect: %w", err)
	}

	if err := pool.Ping(context.Background()); err != nil {
		pool.Close()
		return nil, fmt.Errorf("ping: %w", err)
	}

	db := &DB{pool: pool}

	if err := db.RunMigrations(migrationsDir); err != nil {
		pool.Close()
		return nil, fmt.Errorf("migrations: %w", err)
	}

	return db, nil
}

func (db *DB) RunMigrations(dir string) error {
	entries, err := os.ReadDir(dir)
	if err != nil {
		return fmt.Errorf("read migrations dir: %w", err)
	}

	var files []string
	for _, entry := range entries {
		if entry.IsDir() || filepath.Ext(entry.Name()) != ".sql" {
			continue
		}
		files = append(files, entry.Name())
	}
	sort.Strings(files)

	for _, name := range files {
		content, err := os.ReadFile(filepath.Join(dir, name))
		if err != nil {
			return fmt.Errorf("read %s: %w", name, err)
		}

		if _, err := db.pool.Exec(context.Background(), string(content)); err != nil {
			return fmt.Errorf("run %s: %w", name, err)
		}
	}

	return nil
}

func (db *DB) Close() {
	db.pool.Close()
}

func (db *DB) Pool() *pgxpool.Pool {
	return db.pool
}