// Lightweight UI-side restart/cold-load timing.
//
// Records a few key marks using performance.now(), then POSTs them to
// /api/diag/timing/ui once 'ui.first_state' has fired. Disabled by
// setting window.BBCTRL_TRACE = false before this module is loaded.
//
// Marks collected:
//   script.load    -- this module evaluated
//   ws.open        -- websocket onopen
//   ws.first_msg   -- first message from controller
//   ui.first_state -- first message that contained controller state
//   window.load    -- window 'load' event
//
// Aligning these with /api/diag/timing on the server gives the full
// picture from systemd start -> bbctrl up -> WS open -> UI rendered.
"use strict";

const _enabled = typeof window !== "undefined" && window.BBCTRL_TRACE !== false;
const _t0 = (typeof performance !== "undefined" && performance.now)
    ? performance.now()
    : Date.now();
const _navStart = (typeof performance !== "undefined" && performance.timeOrigin)
    ? performance.timeOrigin
    : Date.now();

const marks = [];
let posted = false;

function _now() {
    return (typeof performance !== "undefined" && performance.now)
        ? performance.now() - _t0
        : Date.now() - _t0;
}

function mark(name, fields) {
    if (!_enabled) return;
    marks.push(Object.assign({ n: name, t: Math.round(_now()) }, fields || {}));
}

function _post() {
    if (!_enabled || posted) return;
    posted = true;
    const body = JSON.stringify({
        navStart: _navStart,
        t0_perf: _t0,
        href: typeof location !== "undefined" ? location.href : "",
        ua: typeof navigator !== "undefined" ? navigator.userAgent : "",
        marks: marks,
    });
    try {
        if (typeof fetch === "function") {
            fetch("/api/diag/timing/ui", {
                method: "PUT",
                headers: { "Content-Type": "application/json" },
                body: body,
                keepalive: true,
            }).catch(() => {});
        }
    } catch (e) { /* swallow */ }
}

// Record window load too; doesn't block posting.
if (_enabled && typeof window !== "undefined") {
    window.addEventListener("load", () => mark("window.load"));
}

mark("script.load");

module.exports = {
    enabled: _enabled,
    mark: mark,
    onWsOpen: () => mark("ws.open"),
    onWsFirstMessage: () => mark("ws.first_msg"),
    onFirstState: () => {
        mark("ui.first_state");
        // Defer slightly so any synchronous render finishes first.
        setTimeout(_post, 100);
    },
    flush: _post,
};