package orm

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

type SqliteDialect struct{}

func NewSqliteDialect() *SqliteDialect {
	return &SqliteDialect{}
}

func convertType(f dbfield) string {
	switch f.stype {
	case "string", "*string":
		return "text"
	case "bool", "int", "*int", "time.Time", "*time.Time":
		return "numeric"
	case "[]byte":
		return "blob"
	}
	return "text"
}

func defaultValue(f dbfield) string {
	if f.dbname == "_date_created" {
		return "current_timestamp"
	}
	switch f.stype {
	case "string":
		return "''"
	case "bool", "int", "time.Time":
		return "0"
	}
	return "''"
}

func (d *SqliteDialect) TableExists(db *sql.DB, tableName string) (bool, error) {
	sql := "select name from sqlite_schema where type='table' and name=$1"
	rows, err := db.Query(sql, tableName)
	if err != nil {
		return false, err
	}
	if rows.Next() {
		rows.Close()
		return true, nil
	}
	return false, nil
}

func (d *SqliteDialect) ColumnSpec(f dbfield) (string, error) {
	if f.dbname == "id" {
		return "id text not null primary key", nil
	}
	if strings.HasPrefix(f.stype, "*") || strings.HasPrefix(f.stype, "[]") {
		return fmt.Sprintf("%s %s", f.dbname, convertType(f)), nil
	}
	return fmt.Sprintf("%s %s not null default %s", f.dbname, convertType(f), defaultValue(f)), nil
}