package db

import (
	"context"
	"database/sql"
	_ "embed" // Required for go:embed
	"fmt"
	"log/slog"
	"os"
	"path/filepath"

	_ "github.com/mattn/go-sqlite3" // SQLite driver
)

//go:embed schema.sql
var ddl string

// DBConfig holds database configuration.
type DBConfig struct {
	DSN string // Data Source Name for SQLite
}

// NewDB initializes and returns a new database connection pool and runs migrations.
func NewDB(ctx context.Context, logger *slog.Logger, dsn string) (*sql.DB, error) {
	// Ensure the directory for the SQLite file exists
	dbDir := filepath.Dir(dsn)
	if err := os.MkdirAll(dbDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create database directory %s: %w", dbDir, err)
	}

	db, err := sql.Open("sqlite3", dsn+"?_foreign_keys=on") // Enable foreign key constraints
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	if err = db.PingContext(ctx); err != nil {
		return nil, fmt.Errorf("failed to ping database: %w", err)
	}

	logger.Info("database connection established", slog.String("dsn", dsn))

	// Execute schema.
	if _, err := db.ExecContext(ctx, ddl); err != nil {
		return nil, fmt.Errorf("failed to execute DDL: %w", err)
	}
	logger.Info("database schema applied")

	return db, nil
}