package redis

// Not thread-safe.
type Pipeline struct {
	*Client
}

func (c *Client) Pipeline() *Pipeline {
	return &Pipeline{
		Client: &Client{
			baseClient: &baseClient{
				opt:      c.opt,
				connPool: c.connPool,

				cmds: make([]Cmder, 0),
			},
		},
	}
}

func (c *Client) Pipelined(f func(*Pipeline)) ([]Cmder, error) {
	pc := c.Pipeline()
	f(pc)
	cmds, err := pc.Exec()
	pc.Close()
	return cmds, err
}

func (c *Pipeline) Close() error {
	return nil
}

func (c *Pipeline) Discard() error {
	c.cmds = c.cmds[:0]
	return nil
}

// Always returns list of commands and error of the first failed
// command if any.
func (c *Pipeline) Exec() ([]Cmder, error) {
	cmds := c.cmds
	c.cmds = make([]Cmder, 0)

	if len(cmds) == 0 {
		return []Cmder{}, nil
	}

	cn, err := c.conn()
	if err != nil {
		return cmds, err
	}

	if err := c.execCmds(cmds, cn); err != nil {
		c.freeConn(cn, err)
		return cmds, err
	}

	c.putConn(cn)
	return cmds, nil
}

func (c *Pipeline) execCmds(cmds []Cmder, cn *conn) error {
	err := c.writeCmd(cn, cmds...)
	if err != nil {
		for _, cmd := range cmds {
			cmd.setErr(err)
		}
		return err
	}

	var firstCmdErr error
	for _, cmd := range cmds {
		val, err := cmd.parseReply(cn.rd)
		if err != nil {
			cmd.setErr(err)
			if firstCmdErr == nil {
				firstCmdErr = err
			}
		} else {
			cmd.setVal(val)
		}
	}

	return firstCmdErr
}