// Preload for the Master Electron window.
//
// Exposes `window.oradioNative` to the renderer via `contextBridge`. This is
// the single source of truth for "are we running inside Electron?" — the
// master UI uses `oradioNative?.isElectron` to gate features that don't work
// in a plain browser tab (real audio-output enumeration/selection, the live
// spectrum visualizer's cross-origin PCM tap, etc.).
//
// Runs in a sandboxed isolated world (sandbox: true, contextIsolation: true),
// so it has access to a limited subset of Electron APIs and to the renderer's
// `navigator.mediaDevices`. No Node built-ins.
//
// Written in CommonJS (`.cjs`) on purpose: the repo's package.json sets
// `"type": "module"`, and Electron's preload loader expects CJS.

const { contextBridge } = require('electron');

// ---- Audio output enumeration / selection ------------------------------

// Classify a device label into a coarse `kind` so the master UI can show an
// appropriate icon. Falls back to 'speakers' for the system default.
function classifyKind(label) {
    const s = String(label || '').toLowerCase();
    if (/bluetooth|\bbt\b|airpods|buds|stanmore|bose|sonos/.test(s)) return 'bluetooth';
    if (/hdmi|display|tv|monitor/.test(s)) return 'hdmi';
    if (/usb|audient|focusrite|scarlett|presonus|motu/.test(s)) return 'usb';
    if (/headphone|headset|earphone|jack/.test(s)) return 'headphones';
    return 'speakers';
}

let labelsUnlocked = false;
const currentListeners = new Set();
let lastCurrentId = 'default';

async function unlockDeviceLabels() {
    if (labelsUnlocked) return;
    // Asking for an audio input stream gives Chromium permission to expose
    // device LABELS in subsequent enumerateDevices() calls. The Electron main
    // process auto-grants the `media` permission so this is silent.
    try {
        const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
        for (const t of stream.getTracks()) t.stop();
        labelsUnlocked = true;
    } catch (err) {
        // Permission denied or no input device — labels will be empty but we
        // can still surface the IDs (and the system default).
        console.warn('[preload] could not unlock device labels:', err?.message || err);
    }
}

async function listOutputs() {
    if (!navigator.mediaDevices?.enumerateDevices) return [];
    await unlockDeviceLabels();
    const all = await navigator.mediaDevices.enumerateDevices();
    const out = all
        .filter((d) => d.kind === 'audiooutput')
        .map((d, i) => ({
            id: d.deviceId,
            label: d.label || (d.deviceId === 'default' ? 'System default' : `Audio output ${i + 1}`),
            kind: classifyKind(d.label)
        }));
    // Ensure 'default' is always first when present.
    out.sort((a, b) => (a.id === 'default' ? -1 : b.id === 'default' ? 1 : 0));
    return out;
}

async function setOutput(id) {
    lastCurrentId = String(id || 'default');
    // The actual `audio.setSinkId(id)` call has to happen on the renderer's
    // <audio> element, which lives in the master's main-world context. The
    // master code calls setSinkId directly after this resolves — preload only
    // tracks the selection and notifies listeners.
    for (const cb of currentListeners) {
        try { cb(lastCurrentId); } catch { /* ignore listener errors */ }
    }
    return lastCurrentId;
}

function getCurrent() {
    return lastCurrentId;
}

function onCurrentChanged(cb) {
    if (typeof cb !== 'function') return () => { };
    currentListeners.add(cb);
    return () => currentListeners.delete(cb);
}

// Re-notify when the OS device set changes (cable plug/unplug, Bluetooth
// connect/disconnect). The renderer can call listOutputs() again on this.
if (navigator.mediaDevices?.addEventListener) {
    navigator.mediaDevices.addEventListener('devicechange', () => {
        for (const cb of currentListeners) {
            try { cb(lastCurrentId); } catch { /* ignore */ }
        }
    });
}

// ---- Bridge ------------------------------------------------------------

contextBridge.exposeInMainWorld('oradioNative', {
    isElectron: true,
    listOutputs,
    setOutput,
    getCurrent,
    onCurrentChanged
});