// Package handler provides HTTP handlers for various endpoints.
package handler

import (
	"net/http"
	"time"

	"modelRT/database"
	"modelRT/logger"
	"modelRT/network"
	"modelRT/orm"

	"github.com/gin-gonic/gin"
	"github.com/gofrs/uuid"
	"gorm.io/gorm"
)

// AsyncTaskCancelHandler handles cancellation of an async task
// @Summary 取消异步任务
// @Description 取消指定ID的异步任务（如果任务尚未开始执行）
// @Tags AsyncTask
// @Accept json
// @Produce json
// @Param task_id path string true "任务ID"
// @Success 200 {object} network.SuccessResponse "任务取消成功"
// @Failure 400 {object} network.FailureResponse "请求参数错误或任务无法取消"
// @Failure 404 {object} network.FailureResponse "任务不存在"
// @Failure 500 {object} network.FailureResponse "服务器内部错误"
// @Router /task/async/{task_id}/cancel [post]
func AsyncTaskCancelHandler(c *gin.Context) {
	ctx := c.Request.Context()

	// Parse task ID from path parameter
	taskIDStr := c.Param("task_id")
	if taskIDStr == "" {
		logger.Error(ctx, "task_id parameter is required")
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusBadRequest,
			Msg:  "task_id parameter is required",
		})
		return
	}

	taskID, err := uuid.FromString(taskIDStr)
	if err != nil {
		logger.Error(ctx, "invalid task ID format", "task_id", taskIDStr, "error", err)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusBadRequest,
			Msg:  "invalid task ID format",
		})
		return
	}

	pgClient := database.GetPostgresDBClient()
	if pgClient == nil {
		logger.Error(ctx, "database connection not found in context")
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusInternalServerError,
			Msg:  "database connection error",
		})
		return
	}

	// Query task from database
	asyncTask, err := database.GetAsyncTaskByID(ctx, pgClient, taskID)
	if err != nil {
		if err == gorm.ErrRecordNotFound {
			logger.Error(ctx, "async task not found", "task_id", taskID)
			c.JSON(http.StatusOK, network.FailureResponse{
				Code: http.StatusNotFound,
				Msg:  "task not found",
			})
			return
		}
		logger.Error(ctx, "failed to query async task from database", "error", err)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusInternalServerError,
			Msg:  "failed to query task",
		})
		return
	}

	// Check if task can be cancelled (only SUBMITTED tasks can be cancelled)
	if asyncTask.Status != orm.AsyncTaskStatusSubmitted {
		logger.Error(ctx, "task cannot be cancelled", "task_id", taskID, "status", asyncTask.Status)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusBadRequest,
			Msg:  "task cannot be cancelled (already running or completed)",
		})
		return
	}

	// Update task status to failed with cancellation reason
	timestamp := time.Now().Unix()
	err = database.FailAsyncTask(ctx, pgClient, taskID, timestamp)
	if err != nil {
		logger.Error(ctx, "failed to cancel async task", "task_id", taskID, "error", err)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusInternalServerError,
			Msg:  "failed to cancel task",
		})
		return
	}

	// Update task result with cancellation error
	err = database.UpdateAsyncTaskResultWithError(ctx, pgClient, taskID, 40003, "task cancelled by user", orm.JSONMap{
		"cancelled_at": timestamp,
		"cancelled_by": "user",
	})
	if err != nil {
		logger.Error(ctx, "failed to update task result with cancellation error", "task_id", taskID, "error", err)
		// Continue anyway since task is already marked as failed
	}

	c.JSON(http.StatusOK, network.SuccessResponse{
		Code: 2000,
		Msg:  "task cancelled successfully",
	})
}