/* ObsiGate — Desktop (Tauri) bridge.
 * Bridges the vanilla-JS frontend to the Rust/Tauri shell.
 *
 * On desktop, the frontend is served by the Python backend over
 * http://127.0.0.1:<port> (the webview redirects there after boot).
 * Tauri exposes its API globally via `window.__TAURI__` (withGlobalTauri).
 * Remote IPC access for that origin is granted in capabilities/default.json.
 *
 * On web (Docker), `window.__TAURI__` is absent — every function degrades
 * to a no-op so the same bundle runs unchanged in the browser.
 *
 * Usage: import { initDesktopIntegration } from './desktop.js';
 */

// ── Detection ──────────────────────────────────────────────────────────────
// window.__TAURI__ is injected by Tauri when app.withGlobalTauri === true.
// window.__TAURI_INTERNALS__ is a secondary signal used by some Tauri builds.

export function isTauriEnv() {
  if (typeof window === 'undefined') return false;
  return !!(window.__TAURI__ || window.__TAURI_INTERNALS__);
}

// ── invoke wrapper ─────────────────────────────────────────────────────────
// Safely invokes a Tauri command. Resolves to undefined on web or on any
// IPC error, so callers never crash the app.

export async function invoke(cmd, args) {
  if (!isTauriEnv()) return undefined;
  try {
    const core = window.__TAURI__ && window.__TAURI__.core;
    if (!core || typeof core.invoke !== 'function') return undefined;
    return await core.invoke(cmd, args);
  } catch (e) {
    console.warn('[desktop] invoke(' + cmd + ') failed:', e);
    return undefined;
  }
}

// ── System theme ───────────────────────────────────────────────────────────
// Returns 'dark' or 'light' from the OS. Falls back to the CSS media query
// (which the system WebView also honours) if the Tauri command is unavailable.

export async function getSystemTheme() {
  const tauriTheme = await invoke('get_system_theme');
  if (tauriTheme === 'dark' || tauriTheme === 'light') return tauriTheme;
  try {
    if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) {
      return 'dark';
    }
  } catch (e) { /* ignore */ }
  return 'light';
}

// ── Theme preference detection ─────────────────────────────────────────────
// The real theme engine is themes.js: it persists the *mode* under
// 'obsigate-theme-mode' (dark/light/high-contrast/sepia). Absence of that key
// means "no explicit user choice yet" — the desktop app should then follow
// the OS theme instead of defaulting to dark.

export function hasExplicitThemeMode() {
  try {
    return localStorage.getItem('obsigate-theme-mode') !== null;
  } catch (e) {
    return false;
  }
}

// Apply the OS theme mode, but ONLY if the user hasn't chosen one explicitly.
export async function syncSystemTheme() {
  if (!isTauriEnv()) return;
  if (hasExplicitThemeMode()) return;
  const sys = await getSystemTheme();
  // Map OS light/dark onto the theme engine's mode axis (never override
  // high-contrast/sepia, which are explicit choices stored in the same key).
  const current = (function () {
    try { return localStorage.getItem('obsigate-theme-mode'); } catch (e) { return null; }
  })();
  if (current === 'high-contrast' || current === 'sepia') return;
  try { localStorage.setItem('obsigate-theme-mode', sys); } catch (e) { /* ignore */ }
}

// ── Crash banner ───────────────────────────────────────────────────────────
// The Rust shell calls `showBackendCrashBanner()` via window.eval when the
// backend process dies. Define it globally (idempotent) so the call always
// resolves. On web this is never triggered, but defining it is harmless.

export function defineBackendCrashBanner() {
  if (typeof window === 'undefined') return;
  if (window.showBackendCrashBanner) return;

  window.showBackendCrashBanner = function () {
    // Avoid stacking duplicates
    if (document.getElementById('backend-crash-banner')) return;
    const banner = document.createElement('div');
    banner.id = 'backend-crash-banner';
    banner.setAttribute('role', 'alert');
    banner.style.cssText = [
      'position:fixed', 'top:0', 'left:0', 'right:0', 'z-index:99999',
      'background:#7f1d1d', 'color:#fef2f2', 'padding:10px 16px',
      'font-size:13px', 'display:flex', 'align-items:center', 'justify-content:space-between',
      'box-shadow:0 2px 8px rgba(0,0,0,0.4)',
    ].join(';');
    const msg = document.createElement('span');
    msg.textContent = '⚠ Le backend ObsiGate s\u2019est arrêté. Redémarrage en cours…';
    const btn = document.createElement('button');
    btn.textContent = 'Recharger';
    btn.style.cssText = 'background:#fff;color:#7f1d1d;border:none;border-radius:4px;padding:4px 12px;cursor:pointer;font-weight:600;';
    btn.addEventListener('click', function () { window.location.reload(); });
    banner.appendChild(msg);
    banner.appendChild(btn);
    document.body.appendChild(banner);
  };
}

// ── Vault picker ───────────────────────────────────────────────────────────
// Opens the native folder picker and registers the chosen folder as a vault,
// then restarts the backend so the new VAULT_N_* env vars take effect.

export async function pickVaultFolder() {
  if (!isTauriEnv()) return undefined;
  const path = await invoke('pick_vault_folder');
  return typeof path === 'string' ? path : undefined;
}

// ── First-run wizard ───────────────────────────────────────────────────────
// Decides whether the first-run "choose your vault" wizard should be shown.
// Pure function (no DOM) so it is unit-testable.
//
// Returns true when: desktop env, the wizard has never been dismissed, and
// the user has no explicitly-picked vault folder yet.

const WIZARD_DISMISSED_KEY = 'obsigate-desktop-wizard-dismissed';

export function shouldShowWizard(opts) {
  opts = opts || {};
  const isDesktop = opts.isDesktop !== undefined ? opts.isDesktop : isTauriEnv();
  const dismissed = opts.dismissed !== undefined ? opts.dismissed : (function () {
    try { return localStorage.getItem(WIZARD_DISMISSED_KEY) === '1'; } catch (e) { return false; }
  })();
  const hasVaultPath = !!opts.hasVaultPath;
  return isDesktop && !dismissed && !hasVaultPath;
}

export async function dismissWizard() {
  try { localStorage.setItem(WIZARD_DISMISSED_KEY, '1'); } catch (e) { /* ignore */ }
  // Persist on the Rust side too, so clearing the webview's localStorage does
  // not resurrect the wizard on the next launch.
  await invoke('complete_wizard');
}

export function getWizardDismissedKey() { return WIZARD_DISMISSED_KEY; }

// ── Vault management (native) ──────────────────────────────────────────────
// pickAndAddVault opens the native folder picker, registers the chosen folder
// as a vault in the desktop config, restarts the backend (so VAULT_N_* env
// vars are re-injected) and reloads. Returns the chosen path, or undefined
// if cancelled / not on desktop.

export async function pickAndAddVault() {
  if (!isTauriEnv()) return undefined;
  const path = await pickVaultFolder();
  if (!path) return undefined;

  // Derive a display name from the final path segment.
  const name = lastPathSegment(path) || 'Vault';

  await invoke('add_vault', { name: name, path: path });
  await invoke('restart_backend');
  return path;
}

// ── Vault & root-directory management (#159) ────────────────────────────
// The Tauri shell injects vaults (VAULT_N_*) and root directories (DIR_N_*)
// into the backend as environment variables. These helpers unregister them
// from the desktop config, restart the backend and reload the page.

// Pure: classify a root name against the desktop config lists.
// Returns 'vault' | 'dir' | null.
export function resolveRootKind(vaults, dirs, name) {
  if ((vaults || []).some((v) => v.name === name)) return 'vault';
  if ((dirs || []).some((d) => d.name === name)) return 'dir';
  return null;
}

// Pure: last path segment, Windows or POSIX separators, trailing
// separators ignored ('' for root-ish inputs).
export function lastPathSegment(path) {
  const segments = String(path).replace(/[\\/]+$/, '').split(/[\\/]/);
  return segments[segments.length - 1] || '';
}

// Remove a vault or a root directory from the desktop config. `confirmMsg`
// (already translated) gates the destructive step; nothing on disk is
// deleted. Returns 'vault' | 'dir', or undefined when not on desktop,
// cancelled, unknown root, or a command failed.
export async function removeRoot(name, confirmMsg) {
  if (!isTauriEnv() || !name) return undefined;
  if (confirmMsg && !window.confirm(confirmMsg)) return undefined;
  const vaults = (await invoke('list_vaults')) || [];
  const dirs = (await invoke('list_dirs')) || [];
  const kind = resolveRootKind(vaults, dirs, name);
  if (!kind) return undefined;
  const res = await invoke(kind === 'vault' ? 'remove_vault' : 'remove_dir', { name: name });
  if (res === undefined) return undefined; // command failed (see invoke wrapper)
  await invoke('restart_backend');
  window.location.reload();
  return kind;
}

// Add a root directory: side-effect-free native folder picker, register it,
// restart the backend and reload. Mirrors pickAndAddVault.
export async function pickAndAddDir() {
  if (!isTauriEnv()) return undefined;
  const path = await invoke('pick_folder');
  if (typeof path !== 'string' || !path) return undefined;
  const name = lastPathSegment(path) || 'Dossier';
  await invoke('add_dir', { name: name, path: path });
  await invoke('restart_backend');
  window.location.reload();
  return path;
}

// ── First-run wizard (DOM) ─────────────────────────────────────────────────
// Shows a dismissible welcome banner on first desktop launch offering to pick
// the user's Obsidian vault folder. Non-blocking; the default vault created
// by the Rust shell remains available if the user dismisses it.

export async function initDesktopWizard() {
  if (typeof window === 'undefined' || typeof document === 'undefined') return;

  // The authoritative "already done" signal lives in the desktop config
  // (survives localStorage clears). Defaults to false when not on desktop.
  const wizardDone = (await invoke('get_wizard_state')) === true;
  if (!shouldShowWizard({ hasVaultPath: wizardDone })) return;

  // Defer so the app shell is fully rendered before injecting the banner.
  setTimeout(function () {
    if (document.getElementById('obsigate-desktop-wizard')) return;
    const banner = document.createElement('div');
    banner.id = 'obsigate-desktop-wizard';
    banner.setAttribute('role', 'dialog');
    banner.style.cssText = [
      'position:fixed', 'bottom:16px', 'left:16px', 'right:16px', 'z-index:99998',
      'background:var(--surface2,#161b22)', 'border:1px solid var(--border,#21262d)',
      'border-radius:10px', 'padding:14px 16px', 'display:flex',
      'align-items:center', 'gap:12px', 'flex-wrap:wrap',
      'box-shadow:0 8px 24px rgba(0,0,0,0.35)',
    ].join(';');

    const text = document.createElement('span');
    text.style.cssText = 'flex:1;min-width:220px;font-size:13px;color:var(--text,#e6edf3);';
    text.textContent = 'Bienvenue dans ObsiGate Desktop. Choisissez le dossier de vos vaults Obsidian pour commencer.';

    const pickBtn = document.createElement('button');
    pickBtn.textContent = 'Choisir mon dossier';
    pickBtn.style.cssText = 'background:#7c3aed;color:#fff;border:none;border-radius:6px;padding:8px 14px;cursor:pointer;font-weight:600;font-size:13px;';
    pickBtn.addEventListener('click', async function () {
      const p = await pickAndAddVault();
      if (p) { dismissWizard(); window.location.reload(); }
    });

    const laterBtn = document.createElement('button');
    laterBtn.textContent = 'Plus tard';
    laterBtn.style.cssText = 'background:transparent;color:var(--text-2,#8b949e);border:1px solid var(--border,#21262d);border-radius:6px;padding:8px 14px;cursor:pointer;font-size:13px;';
    laterBtn.addEventListener('click', function () {
      dismissWizard();
      banner.remove();
    });

    banner.appendChild(text);
    banner.appendChild(pickBtn);
    banner.appendChild(laterBtn);
    document.body.appendChild(banner);
  }, 800);
}

// ── Integration entry point ────────────────────────────────────────────────

export async function initDesktopIntegration() {
  defineBackendCrashBanner();
  if (!isTauriEnv()) return false;

  // Desktop marker for CSS (wider reading layouts, e.g. the user guide #105).
  try { document.body.classList.add('desktop-mode'); } catch (e) { /* ignore */ }

  // Follow the OS theme on first run, before the theme engine renders.
  await syncSystemTheme();

  // Refresh the OS theme when the system preference changes at runtime.
  try {
    const mq = window.matchMedia('(prefers-color-scheme: dark)');
    if (mq && mq.addEventListener) {
      mq.addEventListener('change', function () { syncSystemTheme(); });
    }
  } catch (e) { /* ignore */ }

  // First-run vault wizard.
  await initDesktopWizard();

  return true;
}

export default {
  isTauriEnv,
  invoke,
  getSystemTheme,
  hasExplicitThemeMode,
  syncSystemTheme,
  defineBackendCrashBanner,
  pickVaultFolder,
  pickAndAddVault,
  shouldShowWizard,
  dismissWizard,
  getWizardDismissedKey,
  initDesktopWizard,
  initDesktopIntegration,
};