package handler

import (
	"fmt"
	"net/http"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
	"github.com/redis/go-redis/v9"
	"gorm.io/gorm"

	"spider/internal/model"
	"spider/internal/service"
)

// validTaskTypes is the set of accepted task_type values.
var validTaskTypes = map[string]bool{
	"full":     true,
	"discover": true,
	"search":   true,
	"github":   true,
	"scrape":   true,
	"crawl":    true,
	"clean":    true,
	"score":    true,
}

// TaskHandler handles task-related HTTP and WebSocket requests.
type TaskHandler struct {
	db          *gorm.DB
	taskService *service.TaskService
	redis       *redis.Client
	upgrader    websocket.Upgrader
}

// NewTaskHandler creates a TaskHandler.
func NewTaskHandler(db *gorm.DB, svc *service.TaskService, rdb *redis.Client) *TaskHandler {
	return &TaskHandler{
		db:          db,
		taskService: svc,
		redis:       rdb,
		upgrader: websocket.Upgrader{
			CheckOrigin: func(r *http.Request) bool { return true },
		},
	}
}

// List handles GET /tasks
// Query params: status, page, page_size
func (h *TaskHandler) List(c *gin.Context) {
	status := c.Query("status")
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	if page < 1 {
		page = 1
	}
	if pageSize < 1 || pageSize > 100 {
		pageSize = 20
	}
	offset := (page - 1) * pageSize

	query := h.db.Model(&model.Task{}).Order("created_at DESC")
	if status != "" {
		query = query.Where("status = ?", status)
	}

	var total int64
	query.Count(&total)

	var tasks []model.Task
	if err := query.Limit(pageSize).Offset(offset).Find(&tasks).Error; err != nil {
		Fail(c, 500, err.Error())
		return
	}

	PageOK(c, tasks, total, page, pageSize)
}

// Start handles POST /tasks/start
func (h *TaskHandler) Start(c *gin.Context) {
	var req service.StartTaskRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		Fail(c, 400, err.Error())
		return
	}

	if !validTaskTypes[req.TaskType] {
		Fail(c, 400, fmt.Sprintf("invalid task_type: %s", req.TaskType))
		return
	}

	task, err := h.taskService.StartTask(req)
	if err != nil {
		Fail(c, 409, err.Error())
		return
	}

	c.JSON(http.StatusCreated, Response{Code: 0, Message: "ok", Data: task})
}

// Get handles GET /tasks/:id
func (h *TaskHandler) Get(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		Fail(c, 400, "invalid id")
		return
	}

	var task model.Task
	if err := h.db.First(&task, id).Error; err != nil {
		Fail(c, 404, "task not found")
		return
	}

	progress := h.taskService.GetProgress(&task)

	OK(c, gin.H{
		"task":     task,
		"progress": progress,
	})
}

// Stop handles POST /tasks/:id/stop
func (h *TaskHandler) Stop(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		Fail(c, 400, "invalid id")
		return
	}

	var body struct {
		Force bool `json:"force"`
	}
	_ = c.ShouldBindJSON(&body)

	if err := h.taskService.StopTask(uint(id), body.Force); err != nil {
		Fail(c, 500, err.Error())
		return
	}

	OK(c, gin.H{"message": "stop signal sent"})
}

// Logs handles GET /tasks/:id/logs via WebSocket.
// On connect it immediately sends history logs from Redis, then streams live progress
// until the task finishes or the client disconnects.
func (h *TaskHandler) Logs(c *gin.Context) {
	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid id"})
		return
	}

	conn, err := h.upgrader.Upgrade(c.Writer, c.Request, nil)
	if err != nil {
		return
	}
	defer conn.Close()

	ctx := c.Request.Context()
	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()

	send := func(msg string) bool {
		err := conn.WriteMessage(websocket.TextMessage, []byte(msg))
		return err == nil
	}

	// Fetch task record immediately.
	var task model.Task
	if err := h.db.First(&task, id).Error; err != nil {
		send(fmt.Sprintf("[错误] 任务 #%d 不存在", id))
		return
	}

	// Send history logs from Redis list first.
	logKey := fmt.Sprintf("spider:task:logs:%d", id)
	historyLogs, _ := h.redis.LRange(ctx, logKey, 0, -1).Result()
	for _, line := range historyLogs {
		if !send(line) {
			return
		}
	}

	// If no history logs, send current task status summary.
	if len(historyLogs) == 0 {
		send(fmt.Sprintf("[信息] 任务 #%d (%s) 状态: %s", task.ID, task.TaskType, task.Status))

		// Also send current Redis progress if available.
		progressKey := fmt.Sprintf("spider:task:progress:%d", id)
		vals, _ := h.redis.HGetAll(ctx, progressKey).Result()
		if len(vals) > 0 {
			msg := fmt.Sprintf("[进度] 阶段: %s | 进度: %s/%s | %s",
				vals["phase"], vals["current"], vals["total"], vals["message"])
			send(msg)
		}
	}

	// If the task has already finished, send completion message and close.
	if task.Status == "completed" || task.Status == "failed" || task.Status == "stopped" {
		statusLabel := map[string]string{
			"completed": "完成",
			"failed":    "失败",
			"stopped":   "停止",
		}[task.Status]
		send(fmt.Sprintf("[完成] 任务已%s", statusLabel))
		return
	}

	// Task is still running — handle client close messages in the background.
	clientGone := make(chan struct{})
	go func() {
		for {
			if _, _, err := conn.ReadMessage(); err != nil {
				close(clientGone)
				return
			}
		}
	}()

	progressKey := fmt.Sprintf("spider:task:progress:%d", id)

	for {
		select {
		case <-clientGone:
			return
		case <-ticker.C:
			var t model.Task
			if err := h.db.First(&t, id).Error; err != nil {
				return
			}

			vals, _ := h.redis.HGetAll(ctx, progressKey).Result()
			if len(vals) > 0 {
				msg := fmt.Sprintf("[进度] 阶段: %s | %s/%s | %s",
					vals["phase"], vals["current"], vals["total"], vals["message"])
				if !send(msg) {
					return
				}
			}

			if t.Status == "completed" || t.Status == "failed" || t.Status == "stopped" {
				send(fmt.Sprintf("[完成] 任务已结束，状态: %s", t.Status))
				return
			}
		}
	}
}