package handler

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"path/filepath"
	"time"

	"github.com/enterprise-ai-platform/server/internal/middleware"
	"github.com/enterprise-ai-platform/server/internal/response"
	"github.com/go-chi/chi/v5"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/redis/go-redis/v9"
)

type PPTHandler struct {
	pool      *pgxpool.Pool
	rdb       *redis.Client
	workerURL string
}

func NewPPTHandler(pool *pgxpool.Pool, rdb *redis.Client, workerURL string) *PPTHandler {
	return &PPTHandler{pool: pool, rdb: rdb, workerURL: workerURL}
}

// ==================== 请求/响应结构 ====================

type createPPTRequest struct {
	Title         string         `json:"title"`
	SourceType    string         `json:"source_type"`    // text / url
	SourceContent string         `json:"source_content"` // 文本内容或 URL
	Config        map[string]any `json:"config"`
}

type pptTaskResponse struct {
	TaskID        string  `json:"task_id"`
	Status        string  `json:"status"`
	Progress      int     `json:"progress"`
	StatusMessage *string `json:"status_message,omitempty"`
	ErrorMessage  *string `json:"error_message,omitempty"`
	OutputFile    *string `json:"output_file,omitempty"`
	PageCount     *int    `json:"page_count,omitempty"`
	Title         string  `json:"title"`
	CreatedAt     string  `json:"created_at"`
}

// ==================== 接口实现 ====================

// CreateTask 创建 PPT 生成任务（文本/URL 输入）
func (h *PPTHandler) CreateTask(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())

	var req createPPTRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		response.BadRequest(w, "无效的请求格式")
		return
	}

	if req.Title == "" {
		response.BadRequest(w, "标题不能为空")
		return
	}
	if req.SourceType == "" {
		req.SourceType = "text"
	}
	if req.SourceContent == "" {
		response.BadRequest(w, "请提供源内容")
		return
	}

	taskID := uuid.New().String()
	configJSON, _ := json.Marshal(req.Config)

	// 写入数据库
	_, err := h.pool.Exec(r.Context(),
		`INSERT INTO ppt_tasks (id, user_id, title, source_type, source_content, config)
		 VALUES ($1, $2, $3, $4, $5, $6)`,
		taskID, userID, req.Title, req.SourceType, req.SourceContent, configJSON,
	)
	if err != nil {
		response.InternalError(w, "创建任务失败: "+err.Error())
		return
	}

	// 推送到 Redis 队列
	taskMsg, _ := json.Marshal(map[string]string{"task_id": taskID})
	h.rdb.LPush(r.Context(), "ppt:tasks", taskMsg)

	response.JSON(w, http.StatusCreated, map[string]string{
		"task_id": taskID,
		"status":  "pending",
	})
}

// CreateTaskWithFile 创建带文件上传的 PPT 生成任务
func (h *PPTHandler) CreateTaskWithFile(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())

	if err := r.ParseMultipartForm(50 << 20); err != nil { // 50MB 限制
		response.BadRequest(w, "文件过大或请求格式错误")
		return
	}

	title := r.FormValue("title")
	if title == "" {
		response.BadRequest(w, "标题不能为空")
		return
	}

	configStr := r.FormValue("config")
	var taskConfig map[string]any
	if configStr != "" {
		json.Unmarshal([]byte(configStr), &taskConfig)
	}
	if taskConfig == nil {
		taskConfig = map[string]any{}
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		response.BadRequest(w, "请上传文件")
		return
	}
	defer file.Close()

	// 将文件转发到 PPT Worker
	taskID := uuid.New().String()
	configJSON, _ := json.Marshal(taskConfig)

	// 转发文件到 Worker 服务
	err = h.forwardFileToWorker(r.Context(), taskID, userID.String(), title, string(configJSON), file, header)
	if err != nil {
		response.InternalError(w, "提交任务失败: "+err.Error())
		return
	}

	response.JSON(w, http.StatusCreated, map[string]string{
		"task_id": taskID,
		"status":  "pending",
	})
}

// GetTaskStatus 查询任务状态
func (h *PPTHandler) GetTaskStatus(w http.ResponseWriter, r *http.Request) {
	taskID := chi.URLParam(r, "taskId")
	userID := middleware.GetUserID(r.Context())

	// 先从 Redis 快速查询
	key := "ppt:status:" + taskID
	cached, err := h.rdb.HGetAll(r.Context(), key).Result()
	if err == nil && len(cached) > 0 {
		progress := 0
		fmt.Sscanf(cached["progress"], "%d", &progress)
		msg := cached["message"]
		response.JSON(w, http.StatusOK, pptTaskResponse{
			TaskID:        taskID,
			Status:        cached["status"],
			Progress:      progress,
			StatusMessage: &msg,
		})
		return
	}

	// 回退到数据库
	var task pptTaskResponse
	var statusMsg, errMsg, outputFile *string
	var pageCount *int
	var createdAt time.Time

	err = h.pool.QueryRow(r.Context(),
		`SELECT id, status, progress, status_message, error_message, output_file, page_count, title, created_at
		 FROM ppt_tasks WHERE id = $1 AND user_id = $2`, taskID, userID,
	).Scan(&task.TaskID, &task.Status, &task.Progress, &statusMsg, &errMsg, &outputFile, &pageCount, &task.Title, &createdAt)
	if err != nil {
		response.NotFound(w, "任务不存在")
		return
	}

	task.StatusMessage = statusMsg
	task.ErrorMessage = errMsg
	task.OutputFile = outputFile
	task.PageCount = pageCount
	task.CreatedAt = createdAt.Format(time.RFC3339)

	response.JSON(w, http.StatusOK, task)
}

// ListTasks 列出用户的 PPT 任务
func (h *PPTHandler) ListTasks(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())

	rows, err := h.pool.Query(r.Context(),
		`SELECT id, status, progress, status_message, error_message, output_file, page_count, title, created_at
		 FROM ppt_tasks WHERE user_id = $1 ORDER BY created_at DESC LIMIT 50`, userID,
	)
	if err != nil {
		response.InternalError(w, "查询失败")
		return
	}
	defer rows.Close()

	var tasks []pptTaskResponse
	for rows.Next() {
		var t pptTaskResponse
		var statusMsg, errMsg, outputFile *string
		var pageCount *int
		var createdAt time.Time

		if err := rows.Scan(&t.TaskID, &t.Status, &t.Progress, &statusMsg, &errMsg, &outputFile, &pageCount, &t.Title, &createdAt); err != nil {
			continue
		}
		t.StatusMessage = statusMsg
		t.ErrorMessage = errMsg
		t.OutputFile = outputFile
		t.PageCount = pageCount
		t.CreatedAt = createdAt.Format(time.RFC3339)
		tasks = append(tasks, t)
	}

	if tasks == nil {
		tasks = []pptTaskResponse{}
	}
	response.JSON(w, http.StatusOK, tasks)
}

// DownloadTask 下载生成的 PPTX 文件
func (h *PPTHandler) DownloadTask(w http.ResponseWriter, r *http.Request) {
	taskID := chi.URLParam(r, "taskId")
	userID := middleware.GetUserID(r.Context())

	var status, title string
	var outputFile *string
	err := h.pool.QueryRow(r.Context(),
		`SELECT status, title, output_file FROM ppt_tasks WHERE id = $1 AND user_id = $2`,
		taskID, userID,
	).Scan(&status, &title, &outputFile)
	if err != nil {
		response.NotFound(w, "任务不存在")
		return
	}

	if status != "completed" {
		response.BadRequest(w, "任务未完成")
		return
	}

	// 代理下载请求到 Worker 服务
	workerResp, err := http.Get(h.workerURL + "/api/tasks/" + taskID + "/download")
	if err != nil {
		response.InternalError(w, "下载服务不可用")
		return
	}
	defer workerResp.Body.Close()

	if workerResp.StatusCode != http.StatusOK {
		response.InternalError(w, "文件下载失败")
		return
	}

	filename := title + ".pptx"
	w.Header().Set("Content-Type", "application/vnd.openxmlformats-officedocument.presentationml.presentation")
	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, filename))
	io.Copy(w, workerResp.Body)
}

// ==================== 内部方法 ====================

func (h *PPTHandler) forwardFileToWorker(ctx context.Context, taskID, userID, title, configJSON string, file multipart.File, header *multipart.FileHeader) error {
	// 构造 multipart 请求转发到 Worker
	var buf bytes.Buffer
	writer := multipart.NewWriter(&buf)

	writer.WriteField("task_id", taskID)
	writer.WriteField("user_id", userID)
	writer.WriteField("title", title)
	writer.WriteField("config_json", configJSON)

	part, err := writer.CreateFormFile("file", filepath.Base(header.Filename))
	if err != nil {
		return err
	}
	if _, err := io.Copy(part, file); err != nil {
		return err
	}
	writer.Close()

	req, err := http.NewRequestWithContext(ctx, "POST", h.workerURL+"/api/tasks/upload", &buf)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", writer.FormDataContentType())

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("worker 返回错误 %d: %s", resp.StatusCode, string(body))
	}
	return nil
}