package database

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

	"github.com/jmoiron/sqlx"
	_ "modernc.org/sqlite"
)

// InitDB opens a SQLite connection and configures PRAGMAs per review-resolutions #28 and #45.
//
// modernc.org/sqlite is a pure-Go driver (CGO_ENABLED=0) — acceptable write-performance
// tradeoff for a personal tool. To switch to mattn/go-sqlite3 (CGO), just change the
// import and driver name; the interface stays the same.
func InitDB(path string) (*sqlx.DB, error) {
	dir := filepath.Dir(path)
	if dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0755); err != nil {
			return nil, fmt.Errorf("create db directory: %w", err)
		}
	}

	dsn := fmt.Sprintf("file:%s?_pragma=busy_timeout(5000)&_pragma=foreign_keys(1)", path)
	db, err := sqlx.Connect("sqlite", dsn)
	if err != nil {
		return nil, fmt.Errorf("open sqlite: %w", err)
	}

	// Single connection avoids "database is locked" under concurrent writes.
	// WAL mode allows readers to proceed while a write is in progress.
	db.SetMaxOpenConns(1)

	for _, pragma := range []string{
		"PRAGMA journal_mode = WAL",
		"PRAGMA busy_timeout = 5000",
		"PRAGMA foreign_keys = ON",
		"PRAGMA synchronous = NORMAL",
	} {
		if _, err := db.Exec(pragma); err != nil {
			db.Close()
			return nil, fmt.Errorf("exec %s: %w", pragma, err)
		}
	}

	return db, nil
}