package schema

import (
	"errors"
	"strings"

	"git.gdulai.com/gdulai/simpleorm/util"
)

type Constraint struct {
	Name        string
	Type        string
	Columns     []Column
	RefTypeName string
	RefColumns  []Column
}

func (c *Constraint) GetDDL() (string, error) {
	switch c.Type {
	case "pk":
		return c.getPkDDL(), nil
	case "fk":
		return c.getFkDDL(), nil
	}

	return "", errors.New("Unimplemented constraing: " + c.Type)
}

func (c *Constraint) getPkDDL() string {
	var ddl strings.Builder
	ddl.WriteString("CONSTRAINT ")
	ddl.WriteString(c.Name)
	ddl.WriteString(" PRIMARY KEY(")
	for i, col := range c.Columns {
		if i != 0 {
			ddl.WriteString(", ")
		}
		ddl.WriteString(col.Name)
	}
	ddl.WriteString(")")
	return ddl.String()
}

func (c *Constraint) getFkDDL() string {
	var ddl strings.Builder
	ddl.WriteString("CONSTRAINT ")
	ddl.WriteString(c.Name)
	ddl.WriteString(" FOREIGN KEY(")

	for i, col := range c.Columns {
		if i != 0 {
			ddl.WriteString(", ")
		}
		ddl.WriteString(col.Name)
	}

	ddl.WriteString(") REFERENCES ")
	ddl.WriteString(util.CamelToSnake(c.RefTypeName))
	ddl.WriteString("(")

	for i, col := range c.RefColumns {
		if i != 0 {
			ddl.WriteString(", ")
		}
		ddl.WriteString(col.Name)
	}

	ddl.WriteString(")")

	return ddl.String()
}

func (Constraint) GetSelectDML() (string, error) {
	return "", errors.New("No DML for constraints")
}

func (Constraint) GetInsertDML() (string, error) {
	return "", errors.New("No DML for constraints")
}

func (Constraint) GetUpdateDML() (string, error) {
	return "", errors.New("No DML for constraints")
}

func (Constraint) GetDeleteDML() (string, error) {
	return "", errors.New("No DML for constraints")
}