package server

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

	"chat-agent-system/internal/sysadmin"
)

// 系统管理台（一期）：全部端点要求系统管理员。

func (s *Server) handleAdminSystemOverview(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemAdmin(w, r); !ok {
		return
	}
	if s.sysadmin == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	writeJSONResponse(w, http.StatusOK, s.sysadmin.Overview(r.Context()))
}

func (s *Server) handleAdminSystemKB(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemAdmin(w, r); !ok {
		return
	}
	if s.sysadmin == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	writeJSONResponse(w, http.StatusOK, s.sysadmin.KBInfo())
}

func (s *Server) handleAdminSystemFeatures(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemAdmin(w, r); !ok {
		return
	}
	if s.sysadmin == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	writeJSONResponse(w, http.StatusOK, map[string]any{"features": s.sysadmin.Features()})
}

func (s *Server) handleAdminSystemSettings(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemAdmin(w, r); !ok {
		return
	}
	if s.sysadmin == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	settings, err := s.sysadmin.ListSettings(r.Context())
	if err != nil {
		writeSafeError(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	writeJSONResponse(w, http.StatusOK, map[string]any{"settings": settings})
}

func (s *Server) handleAdminSystemSettingByKey(w http.ResponseWriter, r *http.Request) {
	user, ok := s.requireSystemAdmin(w, r)
	if !ok {
		return
	}
	if s.sysadmin == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	key := r.PathValue("key")
	var req struct {
		Value            json.RawMessage `json:"value"`
		ExpectedRevision *int64          `json:"expected_revision"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeSafeError(w, r, http.StatusBadRequest, "无效的请求体")
		return
	}
	setting, err := s.sysadmin.UpdateSettingEx(r.Context(), sysadmin.SettingUpdate{
		Key:              key,
		Value:            req.Value,
		UpdatedBy:        user.ID,
		ExpectedRevision: req.ExpectedRevision,
		RequestID:        r.Header.Get("X-Request-ID"),
	})
	switch {
	case errors.Is(err, sysadmin.ErrUnknownSetting):
		writeSafeError(w, r, http.StatusBadRequest, "未知的设置键")
	case errors.Is(err, sysadmin.ErrSettingReadOnly):
		writeSafeError(w, r, http.StatusForbidden, "该设置为只读")
	case errors.Is(err, sysadmin.ErrInvalidSettingValue):
		writeSafeError(w, r, http.StatusBadRequest, "设置值类型不匹配")
	case errors.Is(err, sysadmin.ErrExpectedRevisionRequired):
		writeSafeError(w, r, http.StatusBadRequest, "该设置需要 expected_revision")
	case errors.Is(err, sysadmin.ErrSettingRevisionConflict):
		writeSafeError(w, r, http.StatusConflict, `{"error":"SETTING_REVISION_CONFLICT","message":"设置版本冲突，请刷新后重试"}`)
	case errors.Is(err, sysadmin.ErrStoreUnavailable):
		writeSafeError(w, r, http.StatusServiceUnavailable, "设置存储不可用")
	case err != nil:
		writeSafeError(w, r, http.StatusInternalServerError, err.Error())
	default:
		writeJSONResponse(w, http.StatusOK, setting)
	}
}