package adminapi

import (
	"context"
	"encoding/json"
	"net/http"
	"strconv"

	"github.com/dariuszjaniak/warp/server/internal/httputil"
	"github.com/dariuszjaniak/warp/server/internal/storage"
	"github.com/dariuszjaniak/warp/server/internal/userapi"
)

// The actions the audit log records, one per kind of change the admin API
// can make. They are part of the API: the panel filters on them.
const (
	auditFederationSwitch   = "federation.switch"
	auditFederationLists    = "federation.lists"
	auditFederationReset    = "federation.lists_reset"
	auditDestinationReset   = "federation.destination_reset"
	auditRegistrationSwitch = "registration.switch"
	auditUserCreate         = "user.create"
	auditUserAdmin          = "user.admin"
	auditUserDeactivate     = "user.deactivate"
	auditUserReactivate     = "user.reactivate"
	auditUserPassword       = "user.password"
	auditUserDeviceDelete   = "user.device_delete"
	auditUserMediaQuota     = "user.media_quota"
	auditRoomPurge          = "room.purge"
	auditRoomForceLeave     = "room.force_leave"
	auditTokenCreate        = "registration_token.create"
	auditTokenUpdate        = "registration_token.update"
	auditTokenDelete        = "registration_token.delete"
	auditServerNotice       = "server_notice.send"
)

// audit records a change made through the admin API, after it has been
// made.
//
// A failure to write the entry is logged and does not fail the request:
// the change has happened, and answering 500 for something that worked
// would have the panel retry it. The log line carries the same
// information, so nothing is lost but the convenience of the table.
func (a *AdminAPI) audit(ctx context.Context, auth userapi.Authenticated, action, target string, details map[string]any) {
	raw := []byte("{}")
	if len(details) > 0 {
		var err error
		if raw, err = json.Marshal(details); err != nil {
			raw = []byte("{}")
		}
	}
	a.log.Info("admin action", "action", action, "target", target, "by", auth.UserID, "details", string(raw))
	if a.adminStore == nil {
		return
	}
	if _, err := a.adminStore.AppendAudit(context.WithoutCancel(ctx), storage.AuditEntry{
		TSMS:    a.now().UnixMilli(),
		Actor:   auth.UserID,
		Action:  action,
		Target:  target,
		Details: raw,
	}); err != nil {
		a.log.Error("could not write the audit log", "action", action, "target", target, "error", err)
	}
}

// auditEntry is one entry as the API shows it.
type auditEntry struct {
	ID      int64           `json:"id"`
	TSMS    int64           `json:"ts_ms"`
	Actor   string          `json:"actor"`
	Action  string          `json:"action"`
	Target  string          `json:"target,omitempty"`
	Details json.RawMessage `json:"details"`
}

type auditResponse struct {
	Entries []auditEntry `json:"entries"`

	// NextBefore is the ?before= of the next page, absent on the last.
	NextBefore int64 `json:"next_before,omitempty"`
}

// defaultAuditPageLimit is what a request without ?limit= gets, and
// maxAuditPageLimit the most it may ask for.
const (
	defaultAuditPageLimit = 50
	maxAuditPageLimit     = 1000
)

// handleGetAuditLog implements GET /_warp/admin/v1/audit_log.
//
// It pages backwards from the newest entry by ID rather than by offset:
// the log grows at the top while an admin reads it, and an offset would
// shift under them.
func (a *AdminAPI) handleGetAuditLog(w http.ResponseWriter, r *http.Request, _ userapi.Authenticated) error {
	if a.adminStore == nil {
		return httputil.NotFound("This server keeps no audit log")
	}
	query := r.URL.Query()
	limit, err := intParam(query.Get("limit"), defaultAuditPageLimit)
	if err != nil || limit < 0 {
		return httputil.InvalidParam("limit must be a non-negative number")
	}
	// Clamped here rather than left to the store, so that "a full page"
	// below means the same thing the store does.
	if limit == 0 {
		limit = defaultAuditPageLimit
	}
	limit = min(limit, maxAuditPageLimit)
	var before int64
	if raw := query.Get("before"); raw != "" {
		if before, err = strconv.ParseInt(raw, 10, 64); err != nil || before < 0 {
			return httputil.InvalidParam("before must be an entry ID")
		}
	}

	entries, err := a.adminStore.AuditLog(r.Context(), storage.AuditFilter{
		Before: before,
		Limit:  limit,
		Actor:  query.Get("actor"),
		Action: query.Get("action"),
	})
	if err != nil {
		return err
	}
	resp := auditResponse{Entries: make([]auditEntry, 0, len(entries))}
	for _, e := range entries {
		resp.Entries = append(resp.Entries, auditEntry{
			ID: e.ID, TSMS: e.TSMS, Actor: e.Actor, Action: e.Action, Target: e.Target,
			Details: json.RawMessage(e.Details),
		})
	}
	// A full page may have more behind it; a short one cannot.
	if len(entries) == limit {
		resp.NextBefore = entries[len(entries)-1].ID
	}
	httputil.NoCache(w)
	httputil.WriteJSON(w, http.StatusOK, resp)
	return nil
}