// ============================================================
// app.backup.js — AUTO-BACKUP module (extracted from app.js, §3.1)
// ============================================================
//
// Silent scheduled encrypted exports (config in DPAPI prefs, files via the
// folder/file bridge cmds). Pure declarations + two consts, no top-level
// side effects → loads BEFORE app.js. Uses encryptExportPayload (app.import.js),
// Bridge, api, state — all resolved via shared global scope at call time.
//
// ============================================================
// AUTO-BACKUP (silent encrypted exports on a schedule)
// ============================================================
// All config is device-local (folder paths and passwords don't sync
// meaningfully across machines) and persisted via Delphi DPAPI prefs
// so it survives the port-rotation localStorage wipe.

const ABK = {
    enabled:  'autoBackupEnabled',   // '1' | ''
    dir:      'autoBackupDir',       // absolute Windows path
    interval: 'autoBackupInterval',  // days, int as string
    keep:     'autoBackupKeep',      // count, int as string
    last:     'autoBackupLast',      // ISO timestamp of last successful run
    pwd:      'autoBackupPwd',       // user-chosen pwd, used silently
};
const AUTO_BACKUP_PREFIX = 'vault-autobackup-';

async function loadAutoBackupConfig() {
    if (!Bridge.active) return null;
    const [enabled, dir, interval, keep, last, pwd] = await Promise.all([
        Bridge.getPref(ABK.enabled),
        Bridge.getPref(ABK.dir),
        Bridge.getPref(ABK.interval),
        Bridge.getPref(ABK.keep),
        Bridge.getPref(ABK.last),
        Bridge.getPref(ABK.pwd),
    ]);
    return {
        enabled:  enabled === '1',
        dir:      dir || '',
        interval: Math.max(1, parseInt(interval, 10) || 7),
        keep:     Math.max(1, parseInt(keep,     10) || 10),
        last:     last || '',
        hasPwd:   !!pwd,
        pwd,
    };
}

function refreshAutoBackupUI(cfg) {
    if (!cfg) {
        $('#autoBackupField').style.display = 'none';
        return;
    }
    $('#autoBackupField').style.display = '';
    $('#settingAutoBackupEnabled').checked = cfg.enabled;
    $('#autoBackupConfig').style.display = cfg.enabled ? '' : 'none';
    $('#autoBackupDir').textContent = cfg.dir || '(not set)';
    $('#settingAutoBackupInterval').value = cfg.interval;
    $('#settingAutoBackupKeep').value = cfg.keep;
    $('#autoBackupLast').textContent = cfg.last
        ? 'Last run: ' + cfg.last.replace('T', ' ').slice(0, 16)
        : 'Never run yet';
}

async function pickAutoBackupFolder() {
    const path = await Bridge.pickFolder();
    if (!path) return;
    Bridge.setPref(ABK.dir, path);
    $('#autoBackupDir').textContent = path;
    toast('Backup folder set');
}

async function promptAndStoreBackupPwd() {
    let lastError = '';
    let attempts = 0;
    const MAX_ATTEMPTS = 5;
    for (;;) {
        const pwd = await promptDialog({
            title: 'Choose a backup password',
            message: 'You will need this to restore the auto-backups. Save it somewhere safe — it is independent of your master password.',
            placeholder: 'At least 6 characters',
            password: true,
            okText: 'Save',
            error: lastError,
        });
        if (!pwd) return false;   // cancelled (false / null / '' / undefined)
        if (pwd.length >= 6) {
            Bridge.setPref(ABK.pwd, pwd);
            return true;
        }
        attempts++;
        if (attempts >= MAX_ATTEMPTS) {
            toast('Too many invalid attempts', 'error');
            return false;
        }
        lastError = 'Password must be at least 6 characters (attempt ' +
                    attempts + ' / ' + MAX_ATTEMPTS + ').';
    }
}

async function onToggleAutoBackup(ev) {
    const enabled = ev.target.checked;
    if (enabled) {
        const cfg = await loadAutoBackupConfig();
        if (!cfg.hasPwd && !(await promptAndStoreBackupPwd())) {
            ev.target.checked = false;
            return;
        }
        Bridge.setPref(ABK.enabled, '1');
        $('#autoBackupConfig').style.display = '';
        toast('Auto-backup enabled');
        // Refresh the dir/last display in case we came from cold state.
        const fresh = await loadAutoBackupConfig();
        refreshAutoBackupUI(fresh);
    } else {
        Bridge.setPref(ABK.enabled, '');
        // Forget the stored backup pwd so re-enabling prompts fresh —
        // gives the user a way to change it without extra UI.
        Bridge.setPref(ABK.pwd, '');
        $('#autoBackupConfig').style.display = 'none';
        toast('Auto-backup disabled');
    }
}

async function runAutoBackupNow(silent) {
    const cfg = await loadAutoBackupConfig();
    if (!cfg) return silent || toast('Bridge not available', 'error');
    if (!cfg.dir) return silent || toast('Choose a backup folder first', 'warning');
    if (!cfg.hasPwd) return silent || toast('Backup password not set', 'warning');
    if (!state.cryptoKey) return silent || toast('Vault is locked', 'warning');

    // Manual "Backup now" shows a spinner (big vaults take ~30s). The
    // scheduled on-unlock run stays silent (no overlay stealing focus).
    if (!silent) {
        showBusy('Reading vault…');
        await new Promise(r => setTimeout(r, 0));
    }
    try {
        const payload = {
            version: 1,
            exported_at: new Date().toISOString(),
            username: state.username,
            folders: (state.folders || [])
                       .filter(f => f && f.name && f.name !== 'All')
                       .map(f => ({
                           name:  f.name,
                           color: f.color || '',
                           icon:  f.icon  || '',
                       })),
            entries: [],
        };
        let _bkDone = 0;
        const _bkTotal = state.entries.length;
        for (const e of state.entries) {
            _bkDone++;
            if (!silent && _bkTotal > 10 && (_bkDone % 5 === 0 || _bkDone === _bkTotal))
                updateBusy('Reading vault… ' + _bkDone + '/' + _bkTotal);
            const plain = await decryptPwd(e.encrypted_password, e.iv);
            let plainTotp = '';
            if (e.totp_secret && e.totp_iv) {
                plainTotp = await decryptTotpSecret(e.totp_secret, e.totp_iv);
                if (plainTotp === '[ERROR]') plainTotp = '';
            }
            let plainCustom = [];
            if (e.custom_fields && e.custom_fields_iv) {
                try { plainCustom = await decryptCustomFields(
                    e.custom_fields, e.custom_fields_iv); }
                catch (_) { plainCustom = []; }
            }
            let attachments = [];
            try {
                const metas = await api('/entries/' + e.id + '/attachments',
                                        { headers: authHeaders() });
                for (const m of (metas || [])) {
                    const full = await api('/attachments/' + m.id,
                                           { headers: authHeaders() });
                    const bytes = await decryptBlobBytes(
                        full.encrypted_blob, full.iv);
                    attachments.push({
                        filename:    m.filename,
                        mime:        m.mime,
                        size_bytes:  m.size_bytes,
                        content_b64: bytesToBase64(bytes),
                    });
                }
            } catch (_) {}
            payload.entries.push({
                uuid: e.uuid || '',
                site: e.site, title: e.title || '', username: e.username,
                password: plain, folder: e.folder, tags: parseTags(e.tags),
                favorite: !!e.favorite, totp_secret: plainTotp,
                kind: e.kind || 'login',
                template: e.template || '',
                custom_fields: plainCustom,
                attachments: attachments,
                icon_b64: e.icon_b64 || '',
                created_at: e.created_at, updated_at: e.updated_at,
            });
        }
        if (!silent) updateBusy('Encrypting backup…');
        const container = await encryptExportPayload(payload, cfg.pwd);
        const json = JSON.stringify(container, null, 2);
        // Filename: yyyymmdd-HHMMSS for filesystem-sort-friendliness.
        const ts = new Date().toISOString()
            .replace(/[-:]/g, '').replace('T', '-').slice(0, 15);
        const fname = AUTO_BACKUP_PREFIX + ts + '.json';
        const path = cfg.dir.replace(/[\\/]+$/, '') + '\\' + fname;
        if (!silent) updateBusy('Writing file…');
        const res = await Bridge.writeFile(path, json, pct => {
            if (!silent) updateBusy('Writing file… ' + pct + '%');
        });
        if (!res.ok) {
            if (!silent) toast('Backup failed: ' + (res.error || 'unknown'), 'error');
            return;
        }
        const now = new Date().toISOString();
        Bridge.setPref(ABK.last, now);
        $('#autoBackupLast').textContent = 'Last run: ' + now.replace('T', ' ').slice(0, 16);
        if (!silent) toast(payload.entries.length + ' entries backed up');
        applyAutoBackupRetention(cfg.dir, cfg.keep);
    } catch (err) {
        if (!silent) toast('Backup failed: ' + (err && err.message ? err.message : err), 'error');
    } finally {
        if (!silent) hideBusy();
    }
}

async function applyAutoBackupRetention(dir, keep) {
    try {
        const files = await Bridge.listFiles(dir, AUTO_BACKUP_PREFIX);
        if (files.length <= keep) return;
        // Sort by name desc (timestamps in filename → lexical = chronological)
        files.sort((a, b) => (a.name < b.name ? 1 : -1));
        const toDelete = files.slice(keep);
        for (const f of toDelete) {
            const path = dir.replace(/[\\/]+$/, '') + '\\' + f.name;
            await Bridge.deleteFile(path);
        }
    } catch (e) {
        // Retention is best-effort; user can clean up manually.
    }
}

async function runAutoBackupIfDue() {
    if (!Bridge.active) return;
    const cfg = await loadAutoBackupConfig();
    if (!cfg || !cfg.enabled || !cfg.dir || !cfg.hasPwd) return;
    if (!state.cryptoKey) return;
    const intervalMs = cfg.interval * 24 * 3600 * 1000;
    const last = cfg.last ? Date.parse(cfg.last) : 0;
    if (last && (Date.now() - last) < intervalMs) return;
    await runAutoBackupNow(true);   // silent — no spinner on the scheduled run
}