// Copyright 2012 Gary Burd
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.

package redis

import (
	"errors"
	"fmt"
	"strconv"
)

var ErrNil = errors.New("redigo: nil returned")

func Values(multiBulk []interface{}, values ...interface{}) ([]interface{}, error) {
	if len(multiBulk) < len(values) {
		return nil, errors.New("redigo Values: short multibulk")
	}
	var err error
	for i, value := range values {
		bulk := multiBulk[i]
		if bulk != nil {
			switch value := value.(type) {
			case *string:
				*value, err = String(bulk, nil)
			case *int:
				*value, err = Int(bulk, nil)
			case *bool:
				*value, err = Bool(bulk, nil)
			case *[]byte:
				*value, err = Bytes(bulk, nil)
			default:
				panic("Value type not supported")
			}
			if err != nil {
				break
			}
		}
	}
	return multiBulk[len(values):], err
}

// Int is a helper that converts a Redis reply to an int.
func Int(v interface{}, err error) (int, error) {
	if err != nil {
		return 0, err
	}
	switch v := v.(type) {
	case int64:
		return int(v), nil
	case []byte:
		n, err := strconv.ParseInt(string(v), 10, 0)
		return int(n), err
	case nil:
		return 0, ErrNil
	case Error:
		return 0, v
	}
	return 0, fmt.Errorf("redigo: unexpected type for Int, got type %T", v)
}

// String is a helper that converts a Redis reply to a string. 
func String(v interface{}, err error) (string, error) {
	if err != nil {
		return "", err
	}
	switch v := v.(type) {
	case []byte:
		return string(v), nil
	case int64:
		return strconv.FormatInt(v, 10), nil
	case nil:
		return "", ErrNil
	case Error:
		return "", v
	}
	panic("FOOBAR")
	return "", fmt.Errorf("redigo: unexpected type for String, got type %T", v)
}

// Bytes is a helper that converts a Redis reply to slice of bytes. 
func Bytes(v interface{}, err error) ([]byte, error) {
	if err != nil {
		return nil, err
	}
	switch v := v.(type) {
	case []byte:
		return v, nil
	case int64:
		return strconv.AppendInt(nil, v, 10), nil
	case nil:
		return nil, ErrNil
	case Error:
		return nil, v
	}
	return nil, fmt.Errorf("redigo: unexpected type for Bytes, got type %T", v)
}

// Bool is a helper that converts a Redis reply to a bool. Bool converts the
// integer 0 and the bulk values "0" and "" to false. All other integer and
// bulk values are converted to true. If the reply is not an integer or bulk
// value or err is not equal to nil, then Bool returns an error.
func Bool(v interface{}, err error) (bool, error) {
	if err != nil {
		return false, err
	}
	switch v := v.(type) {
	case int64:
		return v != 0, nil
	case []byte:
		if len(v) == 0 || (len(v) == 1 && v[0] == '0') {
			return false, nil
		}
		return true, nil
	case nil:
		return false, ErrNil
	case Error:
		return false, v
	}
	return false, fmt.Errorf("redigo: unexpected type for Bool, got type %T", v)
}

// MultiBulk is a helper that converts a Redis reply to a []interface{}. If err
// is not equal to nil or the reply is not a multi-bulk reply, then MultiBulk
// returns an error.
func MultiBulk(v interface{}, err error) ([]interface{}, error) {
	if err != nil {
		return nil, err
	}
	switch v := v.(type) {
	case []interface{}:
		return v, nil
	case nil:
		return nil, ErrNil
	case Error:
		return nil, v
	}
	return nil, fmt.Errorf("redigo: unexpected type for MultiBulk, got type %T", v)
}

// Subscribe represents a subscribe or unsubscribe notification.
type Subscription struct {

	// Kind is "subscribe", "unsubscribe", "psubscribe" or "punsubscribe"
	Kind string

	// The channel that was changed.
	Channel string

	// The current number of subscriptions for connection.
	Count int
}

// Message represents a message notification.
type Message struct {

	// The originating channel.
	Channel string

	// The message data.
	Data []byte
}

// Notification is a helper that returns a pub/sub notification as a
// Subscription or a Message.
func Notification(reply interface{}, err error) (interface{}, error) {
	multiBulk, err := MultiBulk(reply, err)
	if err != nil {
		return nil, err
	}

	var kind, channel string
	multiBulk, err = Values(multiBulk, &kind, &channel)
	if err != nil {
		return nil, err
	}

	if kind == "message" {
		var data []byte
		if _, err := Values(multiBulk, &data); err != nil {
			return nil, err
		}
		return Message{channel, data}, nil
	}

	var count int
	if _, err := Values(multiBulk, &count); err != nil {
		return nil, err
	}
	return Subscription{kind, channel, count}, nil
}