package server

import (
	"encoding/json"
	"errors"
	"net/http"
	"strconv"
	"strings"

	"chat-agent-system/internal/authz"
	"chat-agent-system/internal/freedoc"
)

func (s *Server) requireUserID(w http.ResponseWriter, r *http.Request) (int, bool) {
	user, ok := s.requirePrincipal(w, r)
	if !ok {
		return 0, false
	}
	return int(user.ID), true
}

func extractDocIDFromPath(r *http.Request, actionSuffix string) string {
	path := r.URL.Path
	if actionSuffix != "" {
		suffix := "/" + actionSuffix
		if strings.HasSuffix(path, suffix) {
			path = strings.TrimSuffix(path, suffix)
		}
	}
	parts := strings.Split(strings.Trim(path, "/"), "/")
	if len(parts) >= 4 && parts[0] == "api" && parts[1] == "v1" && parts[2] == "freeform-documents" {
		return parts[3]
	}
	return r.PathValue("doc_id")
}

// POST /api/v1/freeform-documents — 直接创建（上传附件注册服务端事实源，仅 my_private）
func (s *Server) handleCreateFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}
	user, ok := s.requirePrincipal(w, r)
	if !ok {
		return
	}
	var req freedoc.CreateFreeformDocRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_BODY",
			"message":    "请求体格式错误",
		})
		return
	}
	if req.ProjectID <= 0 {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_PARAM",
			"message":    "project_id required",
		})
		return
	}
	space := strings.TrimSpace(req.Space)
	if space == "" {
		space = "my_private"
	}
	if space != "my_private" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_PARAM",
			"message":    "direct create only allows my_private; use share API for project_shared",
		})
		return
	}
	req.Space = "my_private"

	if s.authorizer() == nil {
		if s.failClosedAuthz() {
			writeAuthzError(w, authz.ErrForbidden)
			return
		}
	} else if err := s.authorizer().RequireProjectAccessOrAdmin(r.Context(), int64(req.ProjectID), user.ID, s.isSystemAdminUser(r.Context(), user)); err != nil {
		writeAuthzError(w, err)
		return
	}

	detail, err := s.freeDoc().CreateDocument(r.Context(), int(user.ID), req)
	if err != nil {
		if errors.Is(err, freedoc.ErrInvalidParam) {
			writeJSONResponse(w, http.StatusBadRequest, map[string]any{
				"error_code": "INVALID_PARAM",
				"message":    err.Error(),
			})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{
			"error_code": "CREATE_FAILED",
			"message":    err.Error(),
		})
		return
	}
	writeJSONResponse(w, http.StatusCreated, map[string]any{
		"code":    0,
		"message": "已注册自由文档",
		"data":    detail,
	})
}

// POST /api/v1/freeform-documents/from-message
func (s *Server) handleCreateFreeformDocFromMessage(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	var req freedoc.CreateFromMessageRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_BODY",
			"message":    "请求体格式错误",
		})
		return
	}

	detail, isExisting, err := s.freeDoc().CreateFromMessage(r.Context(), userID, req)
	if err != nil {
		if errors.Is(err, freedoc.ErrMessageNotExportable) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{
				"error_code": "MESSAGE_NOT_EXPORTABLE",
				"message":    "该消息不具备导出或保存资格（纯卡片或未完成）",
			})
			return
		}
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{
				"error_code": "MESSAGE_NOT_FOUND",
				"message":    "指定源消息不存在",
			})
			return
		}
		if errors.Is(err, freedoc.ErrConflict) {
			writeJSONResponse(w, http.StatusConflict, map[string]any{
				"error_code": "CONTENT_SHA_MISMATCH",
				"message":    "消息内容哈希校验冲突",
			})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{
			"error_code": "SAVE_FAILED",
			"message":    err.Error(),
		})
		return
	}

	status := http.StatusCreated
	if isExisting {
		status = http.StatusOK
	}
	writeJSONResponse(w, status, map[string]any{
		"code":        0,
		"message":     "已保存至我的私密",
		"data":        detail,
		"is_existing": isExisting,
	})
}

// GET /api/v1/freeform-documents
func (s *Server) handleListFreeformDocs(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	space := r.URL.Query().Get("space")
	if space == "" {
		space = "my_private"
	}
	projectID := int64(0)
	if pStr := r.URL.Query().Get("project_id"); pStr != "" {
		if parsed, err := strconv.ParseInt(pStr, 10, 64); err == nil {
			projectID = parsed
		}
	}

	list, err := s.freeDoc().ListDocuments(r.Context(), userID, projectID, space)
	if err != nil {
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{
			"error_code": "LIST_FAILED",
			"message":    err.Error(),
		})
		return
	}

	if list == nil {
		list = []freedoc.FreeformDocSummary{}
	}
	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code": 0,
		"data": list,
	})
}

// GET /api/v1/freeform-documents/{doc_id}
func (s *Server) handleGetFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	docID := extractDocIDFromPath(r, "")
	if docID == "" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_DOC_ID",
			"message":    "缺少文档ID",
		})
		return
	}

	detail, err := s.freeDoc().GetDocument(r.Context(), userID, docID)
	if err != nil {
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{
				"error_code": "DOC_NOT_FOUND",
				"message":    "文档不存在或已被删除",
			})
			return
		}
		if errors.Is(err, freedoc.ErrForbidden) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{
				"error_code": "DOC_ACCESS_FORBIDDEN",
				"message":    "该文档为他人私密文档，严格禁止跨用户访问",
			})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{
			"error_code": "GET_FAILED",
			"message":    err.Error(),
		})
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code": 0,
		"data": detail,
	})
}

// PUT /api/v1/freeform-documents/{doc_id}
func (s *Server) handleUpdateFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	docID := extractDocIDFromPath(r, "")
	if docID == "" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_DOC_ID",
			"message":    "缺少文档ID",
		})
		return
	}

	var req freedoc.UpdateFreeformDocRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_BODY",
			"message":    "请求体格式错误",
		})
		return
	}

	// 优先提取 HTTP If-Match 标头作为乐观并发校验
	if ifMatch := r.Header.Get("If-Match"); ifMatch != "" {
		cleanMatch := strings.Trim(ifMatch, "\"")
		if v, err := strconv.Atoi(cleanMatch); err == nil && v > 0 {
			req.ExpectedVersion = &v
		} else {
			req.ExpectedSHA256 = &cleanMatch
		}
	}

	detail, err := s.freeDoc().UpdateDocument(r.Context(), userID, docID, req)
	if err != nil {
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{
				"error_code": "DOC_NOT_FOUND",
				"message":    "文档不存在",
			})
			return
		}
		if errors.Is(err, freedoc.ErrForbidden) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{
				"error_code": "DOC_ACCESS_FORBIDDEN",
				"message":    "无权修改此文档",
			})
			return
		}
		if errors.Is(err, freedoc.ErrConflict) {
			writeJSONResponse(w, http.StatusConflict, map[string]any{
				"error_code": "CONCURRENCY_CONFLICT",
				"message":    "文档已被他人或新版本更新，请刷新重试",
			})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{
			"error_code": "UPDATE_FAILED",
			"message":    err.Error(),
		})
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code":    0,
		"message": "保存成功",
		"data":    detail,
	})
}

// POST /api/v1/freeform-documents/{doc_id}/share
func (s *Server) handleShareFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	docID := extractDocIDFromPath(r, "share")
	if docID == "" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_DOC_ID",
			"message":    "缺少文档ID",
		})
		return
	}

	doc, err := s.freeDoc().ShareDocument(r.Context(), userID, docID)
	if err != nil {
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{"error_code": "DOC_NOT_FOUND", "message": "文档不存在"})
			return
		}
		if errors.Is(err, freedoc.ErrForbidden) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{"error_code": "FORBIDDEN", "message": "仅文档所有者可共享文档"})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{"error_code": "SHARE_FAILED", "message": err.Error()})
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code":    0,
		"message": "已共享至项目参考库",
		"data":    doc,
	})
}

// POST /api/v1/freeform-documents/{doc_id}/unshare
func (s *Server) handleUnshareFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	docID := extractDocIDFromPath(r, "unshare")
	if docID == "" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_DOC_ID",
			"message":    "缺少文档ID",
		})
		return
	}

	doc, err := s.freeDoc().UnshareDocument(r.Context(), userID, docID)
	if err != nil {
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{"error_code": "DOC_NOT_FOUND", "message": "文档不存在"})
			return
		}
		if errors.Is(err, freedoc.ErrForbidden) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{"error_code": "FORBIDDEN", "message": "仅文档所有者可撤回共享"})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{"error_code": "UNSHARE_FAILED", "message": err.Error()})
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code":    0,
		"message": "已撤回为个人私密",
		"data":    doc,
	})
}

// DELETE /api/v1/freeform-documents/{doc_id}
func (s *Server) handleDeleteFreeformDoc(w http.ResponseWriter, r *http.Request) {
	if s.freeDoc() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "freeform doc service not initialized")
		return
	}

	userID, ok := s.requireUserID(w, r)
	if !ok {
		return
	}
	docID := extractDocIDFromPath(r, "")
	if docID == "" {
		writeJSONResponse(w, http.StatusBadRequest, map[string]any{
			"error_code": "INVALID_DOC_ID",
			"message":    "缺少文档ID",
		})
		return
	}

	err := s.freeDoc().DeleteDocument(r.Context(), userID, docID)
	if err != nil {
		if errors.Is(err, freedoc.ErrNotFound) {
			writeJSONResponse(w, http.StatusNotFound, map[string]any{"error_code": "DOC_NOT_FOUND", "message": "文档不存在"})
			return
		}
		if errors.Is(err, freedoc.ErrForbidden) {
			writeJSONResponse(w, http.StatusForbidden, map[string]any{"error_code": "FORBIDDEN", "message": "仅文档所有者可删除"})
			return
		}
		writeJSONResponse(w, http.StatusInternalServerError, map[string]any{"error_code": "DELETE_FAILED", "message": err.Error()})
		return
	}

	writeJSONResponse(w, http.StatusOK, map[string]any{
		"code":    0,
		"message": "已移至回收站",
	})
}