package runner

import (
	"context"
	"errors"
	"strings"

	"github.com/easyai/easyai-ai-gateway/apps/api/internal/auth"
	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
	"github.com/riverqueue/river/rivertype"
)

var ErrTaskAccessDenied = errors.New("task access denied")

type TaskCancelResult struct {
	TaskID      string `json:"taskId"`
	Cancelled   bool   `json:"cancelled"`
	Cancellable bool   `json:"cancellable"`
	Submitted   bool   `json:"submitted"`
	Message     string `json:"message"`
}

func (s *Service) CancelTask(ctx context.Context, taskID string, user *auth.User) (TaskCancelResult, error) {
	task, err := s.store.GetTask(ctx, taskID)
	if err != nil {
		return TaskCancelResult{}, err
	}
	if !taskAccessibleToUser(task, user) {
		return TaskCancelResult{}, ErrTaskAccessDenied
	}
	if taskCancelTerminalStatus(task.Status) {
		return taskCancelUnavailable(task, "任务已结束，无法取消"), nil
	}
	if strings.TrimSpace(task.RemoteTaskID) != "" {
		return taskCancelUnavailable(task, "任务已提交上游，当前不可取消，请继续查询结果"), nil
	}
	if strings.TrimSpace(task.Status) != "queued" {
		return taskCancelUnavailable(task, "任务已开始执行，当前阶段不可取消，请继续查询结果"), nil
	}
	if task.RiverJobID > 0 {
		if s.riverClient == nil {
			return taskCancelUnavailable(task, "任务取消队列未就绪，请继续查询结果"), nil
		}
		job, err := s.riverClient.JobGet(ctx, task.RiverJobID)
		if errors.Is(err, rivertype.ErrNotFound) {
			return taskCancelUnavailable(task, "任务已不在本地排队队列，可能已提交上游，当前不可取消，请继续查询结果"), nil
		}
		if err != nil {
			return TaskCancelResult{}, err
		}
		if job == nil || !riverJobStateCancellable(job.State) {
			return taskCancelUnavailable(task, "任务已不在可取消队列状态，请继续查询结果"), nil
		}
		if _, err := s.riverClient.JobDelete(ctx, task.RiverJobID); err != nil {
			if errors.Is(err, rivertype.ErrJobRunning) || errors.Is(err, rivertype.ErrNotFound) {
				return taskCancelUnavailable(task, "任务已被工作进程领取，当前不可取消，请继续查询结果"), nil
			}
			return TaskCancelResult{}, err
		}
	}

	cancelledTask, cancelled, err := s.store.CancelQueuedTask(ctx, task.ID, "任务已取消")
	if err != nil {
		return TaskCancelResult{}, err
	}
	if !cancelled {
		latest, latestErr := s.store.GetTask(ctx, task.ID)
		if latestErr == nil {
			return taskCancelUnavailable(latest, "任务状态已变化，当前不可取消，请继续查询结果"), nil
		}
		return taskCancelUnavailable(task, "任务状态已变化，当前不可取消，请继续查询结果"), nil
	}
	if err := s.emit(ctx, cancelledTask.ID, "task.cancelled", "cancelled", "cancelled", 1, "任务已取消", map[string]any{
		"taskId": cancelledTask.ID,
		"reason": "manual_cancel",
	}, cancelledTask.RunMode == "simulation"); err != nil {
		return TaskCancelResult{}, err
	}
	return TaskCancelResult{
		TaskID:      cancelledTask.ID,
		Cancelled:   true,
		Cancellable: true,
		Submitted:   false,
		Message:     "任务已取消",
	}, nil
}

func taskCancelUnavailable(task store.GatewayTask, message string) TaskCancelResult {
	return TaskCancelResult{
		TaskID:      task.ID,
		Cancelled:   false,
		Cancellable: false,
		Submitted:   strings.TrimSpace(task.RemoteTaskID) != "",
		Message:     message,
	}
}

func taskCancelTerminalStatus(status string) bool {
	switch strings.TrimSpace(status) {
	case "succeeded", "failed", "cancelled":
		return true
	default:
		return false
	}
}

func riverJobStateCancellable(state rivertype.JobState) bool {
	switch state {
	case rivertype.JobStateAvailable, rivertype.JobStateScheduled, rivertype.JobStateRetryable, rivertype.JobStatePending:
		return true
	default:
		return false
	}
}

func taskAccessibleToUser(task store.GatewayTask, user *auth.User) bool {
	if user == nil {
		return false
	}
	if apiKeyID := strings.TrimSpace(user.APIKeyID); apiKeyID != "" {
		if strings.TrimSpace(task.APIKeyID) != apiKeyID {
			return false
		}
		if gatewayUserID := gatewayUserIDForAuth(user); gatewayUserID != "" {
			return strings.TrimSpace(task.GatewayUserID) == gatewayUserID
		}
		if userID := strings.TrimSpace(user.ID); userID != "" {
			return strings.TrimSpace(task.UserID) == userID
		}
		return true
	}
	if gatewayUserID := gatewayUserIDForAuth(user); gatewayUserID != "" {
		return strings.TrimSpace(task.GatewayUserID) == gatewayUserID
	}
	userID := strings.TrimSpace(user.ID)
	return userID != "" && strings.TrimSpace(task.UserID) == userID
}

func gatewayUserIDForAuth(user *auth.User) string {
	if user == nil {
		return ""
	}
	if user.GatewayUserID != "" {
		return strings.TrimSpace(user.GatewayUserID)
	}
	if user.Source == "" || user.Source == "gateway" {
		return strings.TrimSpace(user.ID)
	}
	return ""
}