package server

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

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

// 系统管理台：细粒度 system:* 权限（phase-2：管理员 all-or-nothing）。

func (s *Server) handleAdminSystemOverview(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemPermission(w, r, authz.PermSystemOverview); !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.requireSystemPermission(w, r, authz.PermSystemKBRead); !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.requireSystemPermission(w, r, authz.PermSystemFeaturesRead); !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.requireSystemPermission(w, r, authz.PermSystemSettingsRead); !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 {
		writeDomainError(w, r, http.StatusInternalServerError, err)
		return
	}
	writeJSONResponse(w, http.StatusOK, map[string]any{"settings": settings})
}

func (s *Server) handleAdminSystemSettingByKey(w http.ResponseWriter, r *http.Request) {
	user, ok := s.requireSystemPermission(w, r, authz.PermSystemSettingsWrite)
	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:
		writeDomainError(w, r, http.StatusInternalServerError, err)
	default:
		writeJSONResponse(w, http.StatusOK, setting)
	}
}

func (s *Server) handleAdminSystemSettingAudits(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemPermission(w, r, authz.PermSystemAuditRead); !ok {
		return
	}
	if s.sysadmin() == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "sysadmin service unavailable")
		return
	}
	key := r.PathValue("key")
	limit := 50
	if raw := r.URL.Query().Get("limit"); raw != "" {
		n, err := strconv.Atoi(raw)
		if err != nil || n < 0 {
			writeSafeError(w, r, http.StatusBadRequest, "无效的 limit")
			return
		}
		limit = n
	}
	audits, err := s.sysadmin().ListPolicyAudits(r.Context(), key, limit)
	switch {
	case errors.Is(err, sysadmin.ErrUnknownSetting):
		writeSafeError(w, r, http.StatusBadRequest, "未知的设置键")
	case errors.Is(err, sysadmin.ErrStoreUnavailable):
		writeSafeError(w, r, http.StatusServiceUnavailable, "设置存储不可用")
	case err != nil:
		writeDomainError(w, r, http.StatusInternalServerError, err)
	default:
		writeJSONResponse(w, http.StatusOK, map[string]any{"audits": audits})
	}
}

func (s *Server) handleAdminErrorEvents(w http.ResponseWriter, r *http.Request) {
	if _, ok := s.requireSystemPermission(w, r, authz.PermSystemAuditRead); !ok {
		return
	}
	store := errorevents.Active()
	if store == nil {
		writeSafeError(w, r, http.StatusServiceUnavailable, "错误审计存储不可用")
		return
	}
	q := r.URL.Query()
	limit := 50
	if raw := q.Get("limit"); raw != "" {
		n, err := strconv.Atoi(raw)
		if err != nil || n < 0 {
			writeSafeError(w, r, http.StatusBadRequest, "无效的 limit")
			return
		}
		limit = n
	}
	filter := errorevents.Filter{
		Code:      q.Get("code"),
		RequestID: q.Get("request_id"),
		Class:     q.Get("class"),
		Limit:     limit,
	}
	if raw := strings.TrimSpace(q.Get("since")); raw != "" {
		ts, err := time.Parse(time.RFC3339, raw)
		if err != nil {
			writeSafeError(w, r, http.StatusBadRequest, "无效的 since")
			return
		}
		filter.Since = ts
	}
	if raw := strings.TrimSpace(q.Get("until")); raw != "" {
		ts, err := time.Parse(time.RFC3339, raw)
		if err != nil {
			writeSafeError(w, r, http.StatusBadRequest, "无效的 until")
			return
		}
		filter.Until = ts
	}
	events, err := store.List(r.Context(), filter)
	if err != nil {
		writeDomainError(w, r, http.StatusInternalServerError, err)
		return
	}
	writeJSONResponse(w, http.StatusOK, map[string]any{"events": events})
}