package sqlite

import (
	"database/sql"

	"gorm.io/gorm"
	"gorm.io/gorm/callbacks"
	"gorm.io/gorm/clause"
	"gorm.io/gorm/logger"
	"gorm.io/gorm/migrator"
	"gorm.io/gorm/schema"
	_ "github.com/mattn/go-sqlite3"
)

type Dialector struct {
	DSN string
}

func Open(dsn string) gorm.Dialector {
	return &Dialector{DSN: dsn}
}

func (dialector Dialector) Name() string {
	return "sqlite"
}

func (dialector Dialector) Initialize(db *gorm.DB) (err error) {
	// register callbacks
	callbacks.RegisterDefaultCallbacks(db, &callbacks.Config{
		LastInsertIDReversed: true,
	})
	db.ConnPool, err = sql.Open("sqlite3", dialector.DSN)
	return
}

func (dialector Dialector) Migrator(db *gorm.DB) gorm.Migrator {
	return Migrator{migrator.Migrator{Config: migrator.Config{
		DB:                          db,
		Dialector:                   dialector,
		CreateIndexAfterCreateTable: true,
	}}}
}

func (dialector Dialector) BindVarTo(writer clause.Writer, stmt *gorm.Statement, v interface{}) {
	writer.WriteByte('?')
}

func (dialector Dialector) QuoteTo(writer clause.Writer, str string) {
	writer.WriteByte('`')
	writer.WriteString(str)
	writer.WriteByte('`')
}

func (dialector Dialector) Explain(sql string, vars ...interface{}) string {
	return logger.ExplainSQL(sql, nil, `"`, vars...)
}

func (dialector Dialector) DataTypeOf(field *schema.Field) string {
	switch field.DataType {
	case schema.Bool:
		return "numeric"
	case schema.Int, schema.Uint:
		if field.AutoIncrement {
			// https://www.sqlite.org/autoinc.html
			return "integer PRIMARY KEY AUTOINCREMENT"
		} else {
			return "integer"
		}
	case schema.Float:
		return "real"
	case schema.String:
		return "text"
	case schema.Time:
		return "datetime"
	case schema.Bytes:
		return "blob"
	}

	return ""
}