package proxy

import (
	"log"
	"sync"
	"time"
)

type ConnPool interface {
	initAutoFill(async bool) (err error)

	Get() (conn any, err error)
	Put(conn any)
	ReleaseAll()
	Len() (length int)
}

type netPool struct {
	connects chan any
	lock     *sync.Mutex
	config   poolConfig
}

type poolConfig struct {
	Factory    func() (any, error)
	IsActive   func(any) bool
	Release    func(any)
	InitialCap int
	MaxCap     int
}

func NewConnPool(poolConfig poolConfig) (pool ConnPool, err error) {
	p := netPool{
		config:   poolConfig,
		connects: make(chan any, poolConfig.MaxCap),
		lock:     &sync.Mutex{},
	}

	if poolConfig.MaxCap > 0 {
		err = p.initAutoFill(false)
		if err == nil {
			_ = p.initAutoFill(true)
		}
	}
	return &p, nil
}

func (p *netPool) initAutoFill(async bool) (err error) {
	var worker = func() (err error) {
		for {
			if p.Len() <= p.config.InitialCap/2 {
				p.lock.Lock()
				errN := 0
				for i := 0; i < p.config.InitialCap; i++ {
					c, factoryErr := p.config.Factory()
					if factoryErr != nil {
						errN++
						if async {
							continue
						} else {
							p.lock.Unlock()
							return factoryErr
						}
					}
					select {
					case p.connects <- c:
					default:
						p.config.Release(c)
						break
					}
					if p.Len() >= p.config.InitialCap {
						break
					}
				}
				if errN > 0 {
					log.Printf("fill conn pool fail , ERRN:%d", errN)
				}
				p.lock.Unlock()
			}
			if !async {
				return
			}
			time.Sleep(time.Second * 2)
		}
	}
	if async {
		go func() {
			_ = worker()
		}()
	} else {
		err = worker()
	}
	return

}

func (p *netPool) Get() (conn any, err error) {
	// defer func() {
	// 	log.Printf("pool len : %d", p.Len())
	// }()
	p.lock.Lock()
	defer p.lock.Unlock()
	// for {
	select {
	case conn = <-p.connects:
		if p.config.IsActive(conn) {
			return
		}
		p.config.Release(conn)
	default:
		conn, err = p.config.Factory()
		if err != nil {
			return nil, err
		}
		return conn, nil
	}
	// }
	return
}

func (p *netPool) Put(conn any) {
	if conn == nil {
		return
	}
	p.lock.Lock()
	defer p.lock.Unlock()
	if !p.config.IsActive(conn) {
		p.config.Release(conn)
	}
	select {
	case p.connects <- conn:
	default:
		p.config.Release(conn)
	}
}

func (p *netPool) ReleaseAll() {
	p.lock.Lock()
	defer p.lock.Unlock()
	close(p.connects)
	for c := range p.connects {
		p.config.Release(c)
	}
	p.connects = make(chan any, p.config.InitialCap)

}

func (p *netPool) Len() (length int) {
	return len(p.connects)
}