package schema

import (
	"git.fsdpf.net/go/db"
)

type Builder struct {
	db     *db.Database // The database connection instance
	schema Schema       // The schema grammar instance
}

func New(db *db.Database) *Builder {
	return &Builder{
		db:     db,
		schema: GetSchemaDialect(db),
	}
}

// 判断数据表是否存在
func (this Builder) HasTable(table string) (bool, error) {
	return this.schema.TableExists(table)
}

// 判断数据库列是否存在
func (this Builder) GetColumnListing(table string) (columns []string, err error) {
	return this.schema.GetColumnListing(table)
}

// 修改表
func (this Builder) Table(table string, cb func(*Blueprint)) error {
	bp := NewBlueprint(table)
	cb(bp)
	return this.Build(bp)
}

// 创建表
func (this Builder) Create(table string, cb func(*Blueprint)) error {
	bp := NewBlueprint(table)
	bp.Create()
	cb(bp)
	return this.Build(bp)
}

// 修改表名
func (this Builder) Rename(from, to string) error {
	bp := NewBlueprint(from)
	bp.Rename(to)
	return this.Build(bp)
}

// 修改表备注
func (this Builder) ModifyComment(table, comment string) error {
	bp := NewBlueprint(table)
	bp.ModifyComment(comment)
	return this.Build(bp)
}

// 删除表
func (this Builder) Drop(table string) error {
	bp := NewBlueprint(table)
	bp.Drop()
	return this.Build(bp)
}

// 删除表, 先判断再删除
func (this Builder) DropIfExists(table string) error {
	bp := NewBlueprint(table)
	bp.DropIfExists()
	return this.Build(bp)
}

// toSql
func (this Builder) ToSQL(bp *Blueprint) []string {
	return bp.ToSql(this.schema)
}

// Build execute the blueprint to build / modify the table
func (this Builder) Build(bp *Blueprint) error {
	sqls := this.ToSQL(bp)

	if len(sqls) == 0 {
		return nil
	}

	tx, err := this.db.Begin()

	if err != nil {
		return err
	}

	err = tx.Wrap(func() error {
		for _, sql := range sqls {
			if _, err := tx.Exec(sql); err != nil {
				return err
			}
		}

		return nil
	})

	return err
}