package pier

import (
	"log/slog"
	"time"

	"git.golem15.com/golem15/summercms/modules/diary"
)

// LogComponent is the diary component pier logs under.
const LogComponent = "pier"

// sessionPrefixLen is how much of a session id the audit lines show.
const sessionPrefixLen = 8

// stateless is the session value of a call served on the stateless path.
const stateless = "stateless"

// logger is the module's logger (component pier).
func logger() *slog.Logger {
	return diary.For(LogComponent)
}

// sessionPrefix shortens a session id for logging; a stateless call logs
// "stateless" and a call served without a session on the stateful path
// "ephemeral".
func sessionPrefix(id string) string {
	if id == "" {
		return stateless
	}
	if id == ephemeralSession {
		return ephemeralSession
	}
	if len(id) > sessionPrefixLen {
		return id[:sessionPrefixLen]
	}
	return id
}

// logToolCall writes the one audit line per tool call (D-23): the tool,
// its guard, the frontend user id (0 when none), the backend admin id (0
// when none), the OAuth client id, the token kind, the session prefix, the
// route's status and the duration. Never the arguments, the body or a token.
func logToolCall(log *slog.Logger, id Identity, t *tool, session string, status int, took time.Duration) {
	var userID, adminID uint
	var clientID string
	if id.Frontend != nil {
		userID = id.Frontend.UserID
		clientID = id.Frontend.ClientID
	}
	if id.Backend != nil {
		adminID = id.Backend.UserID
		if clientID == "" {
			clientID = id.Backend.ClientID
		}
	}
	log.Info("pier: tool call",
		"tool", t.name,
		"guard", t.guardName,
		"user_id", userID,
		"admin_id", adminID,
		"client_id", clientID,
		"token_kind", id.TokenKind,
		"session", sessionPrefix(session),
		"status", status,
		"duration_ms", took.Milliseconds(),
	)
}

// logSession writes one line per session lifecycle step with the session
// prefix and the binding, never the token. The steps: open (serveNew),
// rehydrate (lookup), end (DELETE), binding_refused (another binding
// presented the id), revoked (a revocation or deletion event),
// stream_closed (a GET stream whose bearer or record is gone) and expired
// (the reaper closed a local copy whose record expired).
func logSession(log *slog.Logger, step, session, binding string) {
	log.Info("pier: session", "step", step, "session", sessionPrefix(session), "binding", binding)
}