package service

import (
	"context"
	"fmt"
	"strings"
	"time"
	"unicode/utf8"

	"model-gateway/dao"
	"model-gateway/model/entity"

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

var AsyncWorker = &asyncWorker{}

type asyncWorker struct {
}

// RunOnce 由上层定时任务触发：一次性抢占并处理一批任务
// - batchSize: 本次抢占数量
// - goroutines: 本次并发数（协程池大小）
func (w *asyncWorker) RunOnce(ctx context.Context, batchSize, goroutines int) (claimed int, err error) {
	if batchSize <= 0 {
		batchSize = 10
	}
	if goroutines <= 0 {
		goroutines = 1
	}
	tasks, err := dao.Task.ClaimPendingGlobal(ctx, batchSize)
	if err != nil {
		return 0, err
	}
	if len(tasks) == 0 {
		return 0, nil
	}
	pool := grpool.New(goroutines)
	defer pool.Close()

	claimed = len(tasks)
	done := make(chan struct{}, claimed)
	for _, t := range tasks {
		task := t
		_ = pool.AddWithRecover(ctx, func(ctx context.Context) {
			w.handleOne(ctx, task, 0)
			done <- struct{}{}
		}, func(ctx context.Context, e error) {
			if e != nil {
				_ = dao.Task.UpdateFailedGlobal(ctx, task.Id, fmt.Sprintf("worker panic: %v", e))
				ReleaseQueueSlot(ctx, task.ModelName, task.TaskID)
			}
			done <- struct{}{}
		})
	}
	for i := 0; i < claimed; i++ {
		<-done
	}
	return claimed, nil
}

// RunByTaskID 创建任务后立即异步尝试执行当前任务：
// - 只定向抢占当前 taskId 对应的 pending 任务
// - 若任务已被其它 worker 抢走/已不在 pending，则直接返回
func (w *asyncWorker) RunByTaskID(ctx context.Context, taskID string, epicycleId int64) error {
	task, err := dao.Task.ClaimPendingByTaskIDGlobal(ctx, taskID)
	if err != nil {
		return err
	}
	if task == nil {
		return nil
	}
	w.handleOne(ctx, task, epicycleId)
	return nil
}

func (w *asyncWorker) handleOne(ctx context.Context, t *entity.AsynchTask, epicycleId int64) {
	// 从任务入库的 request_payload 里恢复 payload + headers
	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())
		ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)
		// ============ 失败回调 ============
		t.State = 3
		t.ErrorMsg = err.Error()
		go triggerCallback(context.WithoutCancel(ctx), t)
		// ================================
		return
	}
	if m == nil || (m.Enabled != nil && *m.Enabled != 1) {
		errMsg := "模型不存在或未启用"
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, errMsg)
		ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)
		// ============ 失败回调 ============
		t.State = 3
		t.ErrorMsg = errMsg
		go triggerCallback(context.WithoutCancel(ctx), t)
		// ================================
		return
	}

	// 2) 分布式并发限制
	semKey := fmt.Sprintf("asynch:sem:%s", t.ModelName)
	leaseSeconds := int64(3600)
	maxC := GetRuntimeMaxConcurrency(ctx, t.ModelName, m.MaxConcurrency)
	acquired, err := acquireSemaphore(ctx, semKey, maxC, leaseSeconds)
	if err != nil {
		_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
		ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)
		// ============ 失败回调 ============
		t.State = 3
		t.ErrorMsg = err.Error()
		go triggerCallback(context.WithoutCancel(ctx), t)
		// ================================
		return
	}
	if !acquired {
		// 并发满了：放回排队，不回调（不是失败）
		_ = 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,
		}
	}
	var (
		data        []byte
		contentType string
		ext         string
		textResult  string
	)

	// phase=1 表示模型已成功但 OSS 上传失败：优先从临时文件加载
	if t.Phase == 1 && strings.TrimSpace(t.TmpFile) != "" {
		data, err = loadTmpResult(t.TmpFile)
		if err == nil && len(data) > 0 {
			contentType, ext = DetectFileType(data)
		} else {
			data = nil
		}
	}
	if data == nil {
		// 统计
		_ = dao.Stat.IncRequestCount(ctx, time.Now(), int64(t.TenantId), t.Creator, t.ModelName)
		// 核心调用
		data, err = InvokeModel(ctx, m, payload, t.ModelKey)
		if err != nil {
			_ = dao.Task.UpdateFailedGlobal(ctx, t.Id, err.Error())
			ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)
			// ============ 失败回调 ============
			t.State = 3
			t.ErrorMsg = err.Error()
			go triggerCallback(context.WithoutCancel(ctx), t)
			// ================================
			return
		}
		contentType, ext = DetectFileType(data)
		if utf8.Valid(data) && (strings.HasPrefix(contentType, "text/") || contentType == "application/json") {
			textResult = string(data)
		}
		tmpPath, err := saveTmpResult(t.TaskID, data, ext)
		if err == nil && tmpPath != "" {
			t.TmpFile = tmpPath
			t.Phase = 1
			_ = dao.Task.UpdateTmpAfterModelGlobal(ctx, t.Id, tmpPath)
		}
	}

	// 4) 存储 OSS
	ossURL, err := Storage.UploadByTask(ctx, t, data, ext, contentType)
	if err != nil {
		// OSS 阶段失败：保留临时文件，下一轮仅重试 OSS
		_ = dao.Task.UpdateFailedKeepTmpGlobal(ctx, t.Id, err.Error())
		ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)
		// ============ OSS失败不回调（还会重试） ============
		// 注意：OSS失败保留临时文件，下次重试，所以这里不触发最终回调
		// 如果已经重试多次还没成功，需要在任务超时或超过最大重试次数时才回调失败
		return
	}

	// 5) 更新任务状态成功
	fileType := strings.TrimPrefix(ext, ".")
	if fileType == "" {
		fileType = contentType
	}
	if err := dao.Task.UpdateSuccessGlobal(
		ctx,
		t.Id,
		ossURL,
		fileType,
		textResult,
		int64(len(data)),
		nil,
		GetExpendTokens(m.TokenMapping, textResult),
	); err != nil {
		g.Log().Errorf(ctx, "[worker] update success failed: %v", err)
		return
	}

	// 成功/失败均不再占用 queue_limit
	ReleaseQueueSlot(ctx, t.ModelName, t.TaskID)

	// 6) 成功回调
	t.State = 2
	t.OssFile = ossURL
	t.FileType = fileType
	t.TextResult = textResult
	g.Log().Infof(ctx, "[CALLBACK][DISPATCH] taskId=%s bizName=%s callbackUrl=%s", t.TaskID, t.BizName, t.CallbackURL)
	go triggerCallback(context.WithoutCancel(ctx), t)
	// ============ 如果有 epicycleId，也触发业务回调 ============
	if epicycleId != 0 {
		go triggerPromptsCallback(context.WithoutCancel(ctx), t, epicycleId)
	}

	// 成功后清理临时文件
	deleteTmpResult(t.TmpFile)
}

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

// GetExpendTokens 根据映射路径从 textResult 中提取消耗 token 值
func GetExpendTokens(tokenMapping string, textResult string) int {
	value := gjson.Get(textResult, tokenMapping)
	if value.Exists() {
		return int(value.Int())
	} else {
		return len(textResult)
	}
}