package handler

import (
	"encoding/json"
	"errors"
	"net/http"
	"time"

	"github.com/enterprise-ai-platform/server/internal/middleware"
	"github.com/enterprise-ai-platform/server/internal/response"
	"github.com/enterprise-ai-platform/server/internal/service/research"
	"github.com/go-chi/chi/v5"
)

// ResearchHandler 深度研究任务的 HTTP 入口（薄层：仅解析参数与组织响应）。
type ResearchHandler struct {
	svc *research.Service
}

func NewResearchHandler(svc *research.Service) *ResearchHandler {
	return &ResearchHandler{svc: svc}
}

type createResearchRequest struct {
	Topic  string         `json:"topic"`
	AppID  string         `json:"app_id,omitempty"`
	Config map[string]any `json:"config"`
}

type researchTaskResponse struct {
	TaskID        string          `json:"task_id"`
	Topic         string          `json:"topic"`
	Status        string          `json:"status"`
	Progress      int             `json:"progress"`
	StatusMessage *string         `json:"status_message,omitempty"`
	ErrorMessage  *string         `json:"error_message,omitempty"`
	Report        *string         `json:"report,omitempty"`
	Sources       json.RawMessage `json:"sources,omitempty"`
	TokensUsed    int             `json:"tokens_used"`
	CreatedAt     string          `json:"created_at"`
}

func toResearchResponse(t *research.Task) researchTaskResponse {
	resp := researchTaskResponse{
		TaskID:        t.ID,
		Topic:         t.Topic,
		Status:        t.Status,
		Progress:      t.Progress,
		StatusMessage: t.StatusMessage,
		ErrorMessage:  t.ErrorMessage,
		Report:        t.Report,
		TokensUsed:    t.TokensUsed,
		CreatedAt:     t.CreatedAt.Format(time.RFC3339),
	}
	if len(t.Sources) > 0 {
		resp.Sources = json.RawMessage(t.Sources)
	}
	return resp
}

// CreateTask 创建深度研究任务。
func (h *ResearchHandler) CreateTask(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())

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

	in := research.CreateInput{UserID: userID.String(), Topic: req.Topic, Config: req.Config}
	if req.AppID != "" {
		in.AppID = &req.AppID
	}

	id, err := h.svc.Create(r.Context(), in)
	if err != nil {
		if errors.Is(err, research.ErrEmptyTopic) {
			response.BadRequest(w, "研究题目不能为空")
			return
		}
		response.InternalError(w, "创建任务失败")
		return
	}
	response.JSON(w, http.StatusCreated, map[string]string{"task_id": id, "status": "pending"})
}

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

	t, err := h.svc.Status(r.Context(), userID.String(), taskID)
	if err != nil {
		response.NotFound(w, "任务不存在")
		return
	}
	response.JSON(w, http.StatusOK, toResearchResponse(t))
}

// ListTasks 列出当前用户的研究任务。
func (h *ResearchHandler) ListTasks(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())

	tasks, err := h.svc.List(r.Context(), userID.String())
	if err != nil {
		response.InternalError(w, "查询失败")
		return
	}
	out := make([]researchTaskResponse, 0, len(tasks))
	for i := range tasks {
		out = append(out, toResearchResponse(&tasks[i]))
	}
	response.JSON(w, http.StatusOK, out)
}

// CancelTask 取消进行中的研究任务。
func (h *ResearchHandler) CancelTask(w http.ResponseWriter, r *http.Request) {
	userID := middleware.GetUserID(r.Context())
	taskID := chi.URLParam(r, "taskId")

	if err := h.svc.Cancel(r.Context(), userID.String(), taskID); err != nil {
		if errors.Is(err, research.ErrNotFound) {
			response.NotFound(w, "任务不存在或无法取消")
			return
		}
		response.InternalError(w, "取消失败")
		return
	}
	response.JSON(w, http.StatusOK, map[string]string{"message": "已取消"})
}