package rabbit

import (
	"encoding/json"
	"errors"
	"fmt"
	"github.com/streadway/amqp"
	"log"
	"os"
	"sync"
	"sync/atomic"
	"time"
)

const (
	defaultLogPrefix = "[rabbit-pool]"
)

var (
	ErrInvalidConfig     = errors.New("invalid pool config\n")
	ErrFailedConnection  = errors.New("failed to establish connection\n")
	ErrConnectionMaximum = errors.New("the number of connections exceeds the maximum\n")
	ErrChannelMaximum    = errors.New("the number of channels exceeds the maximum\n")
	ErrGetChannelTimeOut = errors.New("get channel timeout\n")
)

type LoggerInter interface {
	Print(v ...interface{})
}

type Config struct {
	Host              string // MQ的地址
	MinConn           int    // 最少建立的连接数
	MaxConn           int    // 最大建立的连接数
	MaxChannelPerConn int    // 每个连接最多建立的信道数量
	MaxLifetime       time.Duration
}

// 连接池
type Pool struct {
	mu                     *sync.Mutex
	conf                   *Config
	logger                 LoggerInter
	connectionNum          int32
	connections            map[int64]*Connection
	connectionSerialNumber int64
	idleChannels           chan *Channel
}

func NewPool(conf *Config, logger ...LoggerInter) (*Pool, error) {
	if conf.MaxConn <= 0 || conf.MinConn > conf.MaxConn {
		return nil, ErrInvalidConfig
	}
	p := &Pool{
		mu:           new(sync.Mutex),
		connections:  make(map[int64]*Connection),
		idleChannels: make(chan *Channel, conf.MaxConn*conf.MaxChannelPerConn),
	}

	if conf.MaxLifetime == 0 {
		conf.MaxLifetime = time.Duration(3600)
	}

	if len(logger) > 0 {
		p.SetLogger(logger[0])
	} else {
		p.SetLogger(log.New(os.Stdout, defaultLogPrefix, log.LstdFlags))
	}
	p.conf = conf

	var conn *Connection
	var err error
	// 建立最少连接数
	for i := 0; i < conf.MinConn; i++ {
		conn, err = p.NewConnection()
		if err != nil {
			p.GetLogger().Print(ErrFailedConnection.Error())
			return nil, ErrFailedConnection
		}
		p.connections[conn.connIdentity] = conn
	}
	return p, nil
}

func (p *Pool) SetConfig(conf *Config) *Pool {
	p.conf = conf
	return p
}

func (p *Pool) GetConfig() *Config {
	return p.conf
}

func (p *Pool) SetLogger(logger LoggerInter) *Pool {
	p.logger = logger
	return p
}

func (p *Pool) GetLogger() LoggerInter {
	return p.logger
}

func (p *Pool) NewConnection() (*Connection, error) {
	// 判断连接是否达到最大值
	if atomic.AddInt32(&p.connectionNum, 1) > int32(p.conf.MaxConn) {
		atomic.AddInt32(&p.connectionNum, -1)
		return nil, ErrConnectionMaximum
	}
	conn, err := amqp.Dial(p.conf.Host)
	if err != nil {
		atomic.AddInt32(&p.connectionNum, -1)
		return nil, err
	}

	return &Connection{
		mu:           new(sync.Mutex),
		conn:         conn,
		pool:         p,
		channelNum:   0,
		expireTime:   time.Duration(time.Now().Unix()) + p.conf.MaxLifetime,
		connIdentity: atomic.AddInt64(&p.connectionSerialNumber, 1),
	}, nil
}

func (p *Pool) CloseConnection(c *Connection) error {
	p.mu.Lock()
	defer p.mu.Unlock()
	atomic.AddInt32(&p.connectionNum, -1)
	delete(p.connections, c.connIdentity)
	return c.conn.Close()
}

func (p *Pool) GetChannel() (*Channel, error) {
	ch, _ := p.getOrCreate()
	if ch != nil {
		return ch, nil
	}

	C := time.After(time.Second * 10)
	for {
		ch, _ := p.getOrCreate()
		if ch != nil {
			return ch, nil
		}
		select {
		case <-C:
			p.GetLogger().Print(ErrGetChannelTimeOut.Error())
			return nil, ErrGetChannelTimeOut
		default:
		}
	}
}

func (p *Pool) getOrCreate() (*Channel, error) {
	// 池中是否有空闲channel
	var (
		ch  *Channel
		err error
	)
	select {
	case ch = <-p.idleChannels:
		return ch, nil
	default:
	}

	p.mu.Lock()
	defer p.mu.Unlock()
	// 池中已有连接是否可以建立新的channel
	for _, conn := range p.connections {
		if conn.CheckExpire() {
			continue
		}
		ch, err = conn.NewChannel()
		if ch != nil {
			return ch, nil
		}
	}
	// 新建连接获取新的channel
	var conn *Connection
	conn, err = p.NewConnection()
	if err != nil {
		return nil, err
	}
	p.connections[conn.connIdentity] = conn
	ch, err = conn.NewChannel()
	if err != nil {
		return nil, err
	}
	return ch, nil
}

func (p *Pool) ReleaseChannel(ch *Channel) error {
	p.idleChannels <- ch
	return nil
}

type Connection struct {
	mu                  *sync.Mutex
	conn                *amqp.Connection
	pool                *Pool
	expireTime          time.Duration
	isExpire            bool
	connIdentity        int64 // 连接标记
	channelNum          int32 // 该连接的信道数量
	channelSerialNumber int64 // 第几个channel
}

func (c *Connection) NewChannel() (*Channel, error) {
	c.mu.Lock()
	defer c.mu.Unlock()
	if atomic.AddInt32(&c.channelNum, 1) > int32(c.pool.conf.MaxChannelPerConn) {
		atomic.AddInt32(&c.channelNum, -1)
		return nil, ErrChannelMaximum
	}
	ch, err := c.conn.Channel()
	if err != nil {
		atomic.AddInt32(&c.channelNum, -1)
		return nil, err
	}
	return &Channel{
		Channel:      ch,
		conn:         c,
		chanIdentity: atomic.AddInt64(&c.channelSerialNumber, 1),
	}, nil
}

func (c *Connection) ReleaseChannel(ch *Channel) error {
	if c.CheckExpire() {
		return c.CloseChannel(ch)
	}
	return c.pool.ReleaseChannel(ch)
}

func (c *Connection) CloseChannel(ch *Channel) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	atomic.AddInt32(&c.channelNum, -1)
	var err = ch.Channel.Close()
	if atomic.LoadInt32(&c.channelNum) <= 0 && c.CheckExpire() {
		return c.pool.CloseConnection(c)
	}
	return err
}

// 检查是否过期
func (c *Connection) CheckExpire() bool {
	if c.isExpire {
		return true
	}
	if time.Duration(time.Now().Unix()) > c.expireTime {
		c.isExpire = true
	}
	return c.isExpire
}

/************************************************************************************************************/

type Channel struct {
	*amqp.Channel
	conn         *Connection
	chanIdentity int64 // 该连接的第几个channel
	Name         string
	exchange     string
}

func (ch *Channel) Release() error {
	return ch.conn.ReleaseChannel(ch)
}

func (ch *Channel) Close() error {
	return ch.conn.CloseChannel(ch)
}

// QueueDeclare 声明交换机
func (ch *Channel) QueueDeclare(queue string) {
	_, e := ch.Channel.QueueDeclare(queue, false, true, false, false, nil)
	failOnError(e, "声明交换机！")
}

// QueueDelete 删除交换机
func (ch *Channel) QueueDelete(queue string) {
	_, e := ch.Channel.QueueDelete(queue, false, true, false)
	failOnError(e, "删除队列失败！")
}

//初始化队列
func (ch *Channel) NewQueue(name string, args ...bool) {
	var durable, autoDelete, exclusive, noWait = true, false, false, false
	if len(args) > 0 {
		durable = args[0]
	}
	if len(args) > 1 {
		autoDelete = args[1]
	}
	if len(args) > 2 {
		exclusive = args[2]
	}
	if len(args) > 3 {
		noWait = args[3]
	}
	q, e := ch.Channel.QueueDeclare(
		name,       //队列名
		durable,    //是否开启持久化
		autoDelete, //不使用时删除
		exclusive,  //排他
		noWait,     //不等待
		nil,        //参数
	)
	failOnError(e, "初始化队列失败！")
	ch.Name = q.Name
}

// NewExchange 初始化交换机
//s：rabbitmq服务器的链接，name：交换机名字，typename：交换机类型
func (ch *Channel) NewExchange(name string, typename string, args ...bool) {
	var durable, autoDelete, internal, noWait = true, false, false, false
	if len(args) > 0 {
		durable = args[0]
	}
	if len(args) > 1 {
		autoDelete = args[1]
	}
	if len(args) > 2 {
		internal = args[2]
	}
	if len(args) > 3 {
		noWait = args[3]
	}
	e := ch.ExchangeDeclare(
		name,       // name
		typename,   // type
		durable,    // durable
		autoDelete, // auto-deleted
		internal,   // 是否只在rabbitmq server内部使用
		noWait,     // no-wait
		nil,        // arguments
	)
	failOnError(e, "初始化交换机失败！")
}

// ExchangeDelete 删除交换机
func (ch *Channel) ExchangeDelete(exchange string) {
	e := ch.Channel.ExchangeDelete(exchange, false, true)
	failOnError(e, "绑定队列失败！")
}

// Bind 绑定消息队列到哪个exchange
func (ch *Channel) Bind(queueName string, exchange string, key string) {
	e := ch.Channel.QueueBind(
		queueName,
		key,
		exchange,
		false,
		nil,
	)
	failOnError(e, "绑定队列失败！")
	ch.exchange = exchange
}

// Qos 配置队列参数
func (ch *Channel) Qos(prefetchCount int) {
	e := ch.Channel.Qos(prefetchCount, 0, false)
	failOnError(e, "无法设置QoS")
}

//Send 向消息队列发送消息
//可以往某个消息队列发送消息
func (ch *Channel) Send(queue string, body interface{}) {
	str, e := json.Marshal(body)
	failOnError(e, "消息序列化失败！")
	e = ch.Channel.Publish(
		"",    //交换机
		queue, //路由键
		false, //必填
		false, //立即
		amqp.Publishing{
			ReplyTo: ch.Name,
			Body:    []byte(str),
		})
	msg := "向队列:" + ch.Name + "发送消息失败！"
	failOnError(e, msg)
}

// Publish 向exchange发送消息
// 可以往某个exchange发送消息
func (ch *Channel) Publish(exchange string, body interface{}, key string) {
	str, e := json.Marshal(body)
	failOnError(e, "消息序列化失败！")
	e = ch.Channel.Publish(
		exchange,
		key,
		false,
		false,
		amqp.Publishing{
			ContentType:  "text/plain",
			DeliveryMode: amqp.Transient,
			Priority:     0,
			Body:         []byte(str)},
	)
	failOnError(e, "向路由发送消息失败！")
}

// 接收某个消息队列的消息
func (ch *Channel) Consume(name string) <-chan amqp.Delivery {
	c, e := ch.Channel.Consume(
		name,  // 指定从哪个队列中接收消息
		"",    // 用来区分多个消费者
		false, // 是否自动应答
		false, // 是否独有
		false, // 如果设置为true，表示不能将同一个connection中发送的消息传递给这个connection中的消费者
		false, // 列是否阻塞
		nil,
	)
	failOnError(e, "接收消息失败！")
	return c
}

//错误处理函数
func failOnError(err error, msg string) {
	if err != nil {
		log.Fatalf("%s: %s", msg, err)
		panic(fmt.Sprintf("%s:%s", msg, err))
	}
}