// Package database owns the Bun connection and the migration registry.
package database

import (
	"database/sql"
	"fmt"
	"strings"

	"github.com/uptrace/bun"
	"github.com/uptrace/bun/dialect/pgdialect"
	"github.com/uptrace/bun/dialect/sqlitedialect"
	"github.com/uptrace/bun/driver/pgdriver"
	"github.com/uptrace/bun/driver/sqliteshim"
	"github.com/uptrace/bun/extra/bundebug"
	"github.com/uptrace/bun/migrate"
	"github.com/uptrace/bun/schema"

	"git.k6n.net/mats/fullstack-template/internal/config"
	migrations "git.k6n.net/mats/fullstack-template/internal/database/migrations"
)

// Open connects to the database named by cfg.DatabaseURL:
//
//	sqlite:FILE?params    Bun + modernc sqlite (pure Go, no CGO) — dev default
//	postgres://…          Bun + pgdriver against Postgres
//
// It does not ping — call PingContext during startup to fail fast.
func Open(cfg config.Config) (*bun.DB, error) {
	var sqldb *sql.DB
	var dialect schema.Dialect

	switch {
	case strings.HasPrefix(cfg.DatabaseURL, "sqlite:"):
		dsn := strings.TrimPrefix(cfg.DatabaseURL, "sqlite:")
		// Sensible dev defaults when the DSN brings no pragmas of its own:
		// WAL keeps readers unblocked during writes, busy_timeout waits out
		// the remaining write locks instead of erroring, foreign_keys is
		// what everyone expects to be on.
		if !strings.Contains(dsn, "_pragma") {
			sep := "?"
			if strings.Contains(dsn, "?") {
				sep = "&"
			}
			dsn += sep + "_pragma=busy_timeout(5000)&_pragma=journal_mode(WAL)&_pragma=foreign_keys(1)"
		}
		var err error
		sqldb, err = sql.Open(sqliteshim.ShimName, dsn)
		if err != nil {
			return nil, fmt.Errorf("open sqlite %q: %w", dsn, err)
		}
		dialect = sqlitedialect.New()
	default:
		sqldb = sql.OpenDB(pgdriver.NewConnector(pgdriver.WithDSN(cfg.DatabaseURL)))
		dialect = pgdialect.New()
	}

	db := bun.NewDB(sqldb, dialect)
	if cfg.DebugQueries {
		db.AddQueryHook(bundebug.NewQueryHook(bundebug.WithVerbose(true)))
	}
	return db, nil
}

// NewMigrator returns a bun migrator over the migrations registered in
// internal/database/migrations. See cmd/migrate for the CLI around it.
func NewMigrator(db *bun.DB) *migrate.Migrator {
	return migrate.NewMigrator(db, migrations.Migrations)
}