package ants

import (
	"fmt"
	"git.bvbej.com/bvbej/base-golang/pkg/ticker"
	"github.com/panjf2000/ants/v2"
	"go.uber.org/zap"
	"runtime/debug"
	"time"
)

var _ GoroutinePool = (*goroutinePool)(nil)

type GoroutinePool interface {
	run()

	Submit(task func())
	Stop()

	Size() int
	Running() int
	Free() int
}

type goroutinePool struct {
	pool   *ants.Pool
	logger *zap.Logger
	ticker ticker.Ticker
	step   int
}

type poolLogger struct {
	zap *zap.Logger
}

func (l *poolLogger) Printf(format string, args ...any) {
	l.zap.Sugar().Infof(format, args)
}

func NewPool(zapLogger *zap.Logger, step int) (GoroutinePool, error) {
	ttl := time.Minute * 5

	options := ants.Options{
		Nonblocking:    true,
		ExpiryDuration: ttl,
		PanicHandler: func(err any) {
			zapLogger.Sugar().Error(
				"GoroutinePool panic",
				zap.String("error", fmt.Sprintf("%+v", err)),
				zap.String("stack", string(debug.Stack())),
			)
		},
		Logger: &poolLogger{zap: zapLogger},
	}

	antsPool, err := ants.NewPool(step, ants.WithOptions(options))
	if err != nil {
		return nil, err
	}

	pool := &goroutinePool{
		pool:   antsPool,
		logger: zapLogger,
		ticker: ticker.New(ttl),
		step:   step,
	}
	pool.run()

	return pool, nil
}

func (p *goroutinePool) run() {
	p.ticker.Process(func() {
		if p.Free() > p.step {
			mul := p.Free() / p.step
			p.pool.Tune(p.Size() - p.step*mul)
		}
	})
}

func (p *goroutinePool) Submit(task func()) {
	if p.pool.IsClosed() {
		return
	}
	err := p.pool.Submit(task)
	if err == ants.ErrPoolOverload {
		p.pool.Tune(p.Size() + p.step)
		p.Submit(task)
	}
}

func (p *goroutinePool) Size() int {
	return p.pool.Cap()
}

func (p *goroutinePool) Running() int {
	return p.pool.Running()
}

func (p *goroutinePool) Free() int {
	return p.pool.Free()
}

func (p *goroutinePool) Stop() {
	p.ticker.Stop()
	p.pool.Release()
}