package image

import (
	"sync"

	"github.com/golang/freetype/truetype"

	"douyu_go/internal/logger"
	"douyu_go/internal/types"
)

const (
	defaultSuccessImageWorkers = 1
	defaultSuccessImageQueue   = 256
)

type successImageJob struct {
	Account  types.Account
	Product  types.Product
	RoleName string
}

// SuccessImageSaver 用后台队列生成成功图片，避免图片编码和磁盘写入占用抢购链路。
type SuccessImageSaver struct {
	font       *truetype.Font
	successDir string
	ch         chan successImageJob
	wg         sync.WaitGroup

	mu     sync.Mutex
	closed bool
}

// NewSuccessImageSaver 创建成功图片后台保存器。
func NewSuccessImageSaver(font *truetype.Font, successDir string, workers, queueSize int) *SuccessImageSaver {
	if font == nil {
		return nil
	}
	if workers <= 0 {
		workers = defaultSuccessImageWorkers
	}
	if queueSize <= 0 {
		queueSize = defaultSuccessImageQueue
	}
	saver := &SuccessImageSaver{
		font:       font,
		successDir: successDir,
		ch:         make(chan successImageJob, queueSize),
	}
	for i := 0; i < workers; i++ {
		saver.wg.Add(1)
		go saver.run()
	}
	return saver
}

// Enqueue 投递成功图片任务；队列满时丢弃图片任务，优先保护抢购请求。
func (s *SuccessImageSaver) Enqueue(account types.Account, product types.Product, roleName string) {
	if s == nil {
		return
	}
	job := successImageJob{
		Account:  account,
		Product:  product,
		RoleName: roleName,
	}

	s.mu.Lock()
	defer s.mu.Unlock()
	if s.closed {
		return
	}
	select {
	case s.ch <- job:
	default:
		logger.LogEvent("图片", "warn", "成功图片队列已满，已跳过: 账号=%s 商品=%s", account.Name, product.CommodityID)
	}
}

func (s *SuccessImageSaver) run() {
	defer s.wg.Done()
	for job := range s.ch {
		SaveSuccessImage(job.Account, job.Product, job.RoleName, s.font, s.successDir)
	}
}

// Close 关闭后台队列并等待已投递图片保存完成。
func (s *SuccessImageSaver) Close() {
	if s == nil {
		return
	}
	s.mu.Lock()
	if s.closed {
		s.mu.Unlock()
		return
	}
	s.closed = true
	close(s.ch)
	s.mu.Unlock()
	s.wg.Wait()
}