package service

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	"model-asynch/dao"
	"model-asynch/model/entity"

	"github.com/gogf/gf/v2/frame/g"
	"github.com/gogf/gf/v2/os/grpool"
)

var AsyncWorker = &asyncWorker{}

type asyncWorker struct {
	mu     sync.Mutex
	pool   *grpool.Pool
	closed bool
}

func (w *asyncWorker) Start(ctx context.Context) {
	if !g.Cfg().MustGet(ctx, "asynch.worker.enabled", true).Bool() {
		g.Log().Warningf(ctx, "[worker] asynch.worker.enabled=false，worker 未启动")
		return
	}
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.pool != nil && !w.pool.IsClosed() {
		return
	}
	limit := g.Cfg().MustGet(ctx, "asynch.worker.goroutines", 4).Int()
	if limit <= 0 {
		limit = 1
	}
	w.pool = grpool.New(limit)
	w.closed = false
	go w.pollLoop(ctx)
	g.Log().Infof(ctx, "[worker] started, grpool limit=%d", limit)
}

// Stop 关闭协程池，确保 Ctrl+C 能完整退出。
func (w *asyncWorker) Stop(ctx context.Context) {
	w.mu.Lock()
	defer w.mu.Unlock()
	if w.pool != nil && !w.pool.IsClosed() {
		w.pool.Close()
		w.closed = true
		g.Log().Infof(ctx, "[worker] stopped")
	}
}

func (w *asyncWorker) pollLoop(ctx context.Context) {
	pollIntervalStr := g.Cfg().MustGet(ctx, "asynch.worker.pollInterval", "1s").String()
	pollInterval, _ := time.ParseDuration(pollIntervalStr)
	if pollInterval <= 0 {
		pollInterval = time.Second
	}
	batchSize := g.Cfg().MustGet(ctx, "asynch.worker.batchSize", 5).Int()
	if batchSize <= 0 {
		batchSize = 1
	}

	g.Log().Infof(ctx, "[worker] poll loop started, poll=%s batch=%d", pollInterval, batchSize)
	ticker := time.NewTicker(pollInterval)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			w.Stop(ctx)
			return
		case <-ticker.C:
			tasks, err := dao.Task.ClaimPendingGlobal(ctx, batchSize)
			if err != nil {
				g.Log().Errorf(ctx, "[worker] claim pending error: %v", err)
				continue
			}
			if len(tasks) == 0 {
				continue
			}
			for _, t := range tasks {
				task := t // 防止闭包捕获循环变量
				w.mu.Lock()
				p := w.pool
				w.mu.Unlock()
				if p == nil || p.IsClosed() {
					// 池已关闭，回滚任务
					_ = w.rollbackToPending(ctx, task.Id)
					continue
				}
				_ = p.AddWithRecover(ctx, func(ctx context.Context) {
					w.handleOne(ctx, task)
				}, func(ctx context.Context, err error) {
					if err != nil {
						_ = dao.Task.UpdateFailedGlobal(ctx, task.Id, fmt.Sprintf("worker panic: %v", err))
					}
				})
			}
		}
	}
}

func (w *asyncWorker) handleOne(ctx context.Context, t *entity.AsynchTask) {
	// 从任务入库的 request_payload 里恢复 payload + headers，给 OSS 上传透传鉴权用
	payload, headers := parseStoredPayload(t.RequestPayload)
	if len(headers) > 0 {
		ctx = setTaskHeadersToCtx(ctx, headers)
	}

	// 1) 拉取模型配置
	m, err := dao.Model.GetByModelNameForTenant(ctx, t.TenantId, t.ModelName)
	if err != nil {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
		return
	}
	if m == nil || m.Enabled != 1 {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, "模型不存在或未启用")
		return
	}

	// 2) 分布式并发限制（按 tenant+model）
	semKey := fmt.Sprintf("asynch:sem:%d:%s", t.TenantId, t.ModelName)
	leaseSeconds := int64(3600) // 兜底1小时
	acquired, err := acquireSemaphore(ctx, semKey, m.MaxConcurrency, leaseSeconds)
	if err != nil {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
		return
	}
	if !acquired {
		// 并发满了：放回排队（重新置回 state=0），下一轮再抢占
		_ = w.rollbackToPending(ctx, t.Id)
		return
	}
	defer func() {
		_ = releaseSemaphore(ctx, semKey)
	}()

	// 3) 调用模型服务
	if payload == nil {
		payload = map[string]any{
			"taskId":   t.TaskID,
			"inputRef": t.InputRef,
		}
	}
	data, err := InvokeModel(ctx, m, payload)
	if err != nil {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
		return
	}

	// 4) 存储 OSS/MinIO
	contentType, ext := DetectFileType(data)
	ossURL, err := Storage.UploadByTask(ctx, t, data, ext, contentType)
	if err != nil {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
		return
	}

	// 5) 更新任务状态成功
	// 注意：expire_at 的计算改为“已下载(state=4)后开始计时”，因此成功(state=2)不写 expire_at。
	fileType := strings.TrimPrefix(ext, ".")
	if fileType == "" {
		fileType = contentType
	}
	if err := dao.Task.UpdateSuccessGlobal(ctx, t.Id, ossURL, fileType, int64(len(data)), nil); err != nil {
		g.Log().Errorf(ctx, "[worker] update success failed: %v", err)
		return
	}
}

func (w *asyncWorker) rollbackToPending(ctx context.Context, id int64) error {
	return dao.Task.RollbackToPendingGlobal(ctx, id)
}