/**
 * Hoover — auth.js (components)
 *
 * Thin ceremony layer over the auth model (hoover/auth_model.js), which is
 * the single source of truth for token storage, refresh scheduling, session
 * validation, and login/logout state transitions.
 *
 * This file only contains:
 *   - logout()    — POST /api/auth/logout then drive the model to terminal
 *   - doLogin()   — drive the model through the 'login' action, then navigate
 *   - WebAuthn (passkey) ceremony helpers — not state management
 */

import { modelFetch } from '../model.js';
import { getAuthData } from '../auth_model.js';

/**
 * Logout: blacklist the current tokens server-side, then drive the model to
 * the terminal all-nulls state. The model's onSuccess clears storage,
 * redirects to #/login, and dispatches auth:logout (app.js closes the WS
 * socket via disconnect() — no explicit WS close here). The server reads
 * jti/username from the request context; refresh_token is sent in the body
 * per the blueprint contract (webui/api/auth.py:75).
 */
export async function logout() {
    const auth = getAuthData();
    if (auth?.token) {
        try {
            await fetch('/api/auth/logout', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'Accept': 'application/json',
                    'Authorization': 'Bearer ' + auth.token,
                    'X-Session-Id': auth.session_id || '',
                },
                credentials: 'same-origin',
                body: JSON.stringify({ refresh_token: auth.refresh || '' }),
            });
        } catch { /* ignore — we're clearing everything anyway */ }
    }
    modelFetch('auth', { action: 'logout' });
}

/**
 * Handle a successful login: drive the auth model through the 'login'
 * action (onSuccess persists the session, schedules the TTL refresh, and
 * fires auth:login), then navigate.
 *
 * @param {object} data — login response data ({ tokens, user, permissions, access_ttl })
 * @param {string} [redirectPath] — where to navigate after login
 */
export function doLogin(data, redirectPath = '/dashboard') {
    modelFetch('auth', { action: 'login', payload: data });
    window.location.hash = redirectPath;
}

/**
 * Check if WebAuthn (passkeys) is supported in this browser.
 *
 * @returns {boolean}
 */
export function webauthnSupported() {
    return typeof window !== 'undefined' && !!window.PublicKeyCredential;
}

/* ─── Base64url helpers ──────────────────────────────────────────────── */

/**
 * Convert base64url string to ArrayBuffer.
 * @param {string} b64url
 * @returns {ArrayBuffer}
 */
function b64urlToArrayBuffer(b64url) {
    const bin = atob(b64url.replace(/-/g, '+').replace(/_/g, '/'));
    const arr = new Uint8Array(bin.length);
    for (let i = 0; i < bin.length; i++) {
        arr[i] = bin.charCodeAt(i);
    }
    return arr.buffer;
}

/**
 * Convert ArrayBuffer to base64url string.
 * @param {ArrayBuffer} buffer
 * @returns {string}
 */
function arrayBufferToB64url(buffer) {
    const bytes = new Uint8Array(buffer);
    const chunks = [];
    for (let i = 0; i < bytes.length; i += 0x8000) {
        chunks.push(String.fromCharCode.apply(null, bytes.slice(i, i + 0x8000)));
    }
    const bin = chunks.join('');
    return btoa(bin)
        .replace(/\+/g, '-')
        .replace(/\//g, '_')
        .replace(/=/g, '');
}

/* ─── WebAuthn navigator wrappers ────────────────────────────────────── */

/**
 * Start a WebAuthn registration ceremony.
 *
 * Calls ``navigator.credentials.create()`` with the provided options,
 * then returns the credential response as a JSON-serializable dict
 * suitable for sending to the server.
 *
 * @param {object} registrationOptions — options from /webauthn/register-begin
 * @returns {Promise<object>} credential response (id, rawId, type, response)
 */
export async function startRegistration(registrationOptions) {
    if (!webauthnSupported()) {
        throw new Error('WebAuthn is not supported in this browser');
    }

    const publicKey = {
        challenge: b64urlToArrayBuffer(registrationOptions.challenge),
        rp: registrationOptions.rp,
        user: {
            id: b64urlToArrayBuffer(registrationOptions.user.id),
            name: registrationOptions.user.name,
            displayName: registrationOptions.user.displayName,
        },
        pubKeyCredParams: registrationOptions.pubKeyCredParams,
        timeout: registrationOptions.timeout,
    };

    if (registrationOptions.excludeCredentials) {
        publicKey.excludeCredentials = registrationOptions.excludeCredentials.map(c => ({
            ...c,
            id: b64urlToArrayBuffer(c.id),
        }));
    }
    if (registrationOptions.authenticatorSelection) {
        publicKey.authenticatorSelection = registrationOptions.authenticatorSelection;
    }

    const credential = await navigator.credentials.create({ publicKey });

    const { id, rawId, type, response } = credential;

    return {
        id: arrayBufferToB64url(rawId),
        rawId: arrayBufferToB64url(rawId),
        type,
        response: {
            clientDataJSON: arrayBufferToB64url(response.clientDataJSON),
            attestationObject: arrayBufferToB64url(response.attestationObject),
            transports: response.getTransports ? response.getTransports() : [],
        },
    };
}

/**
 * Start a WebAuthn authentication ceremony.
 *
 * Calls ``navigator.credentials.get()`` with the provided options,
 * then returns the assertion response as a JSON-serializable dict.
 *
 * @param {object} authenticationOptions — options from /webauthn/authenticate-begin
 * @returns {Promise<object>} assertion response (id, rawId, type, response)
 */
export async function startAuthentication(authenticationOptions) {
    if (!webauthnSupported()) {
        throw new Error('WebAuthn is not supported in this browser');
    }

    const publicKey = {
        challenge: b64urlToArrayBuffer(authenticationOptions.challenge),
        timeout: authenticationOptions.timeout,
        userVerification: authenticationOptions.userVerification || 'preferred',
    };

    if (authenticationOptions.allowCredentials) {
        publicKey.allowCredentials = authenticationOptions.allowCredentials.map(c => ({
            ...c,
            id: b64urlToArrayBuffer(c.id),
        }));
    }

    const credential = await navigator.credentials.get({ publicKey });

    const { id, rawId, type, response } = credential;

    return {
        id: arrayBufferToB64url(rawId),
        rawId: arrayBufferToB64url(rawId),
        type,
        response: {
            clientDataJSON: arrayBufferToB64url(response.clientDataJSON),
            authenticatorData: arrayBufferToB64url(response.authenticatorData),
            signature: arrayBufferToB64url(response.signature),
            userHandle: response.userHandle ? arrayBufferToB64url(response.userHandle) : null,
        },
    };
}