/**
 * Backup & Diff viewer module for ObsiGate.
 *
 * Provides a modal UI to browse file backups, compare versions with
 * a unified diff view, and restore previous versions.
 *
 * Usage:
 *   import { openBackupViewer } from './backups.js';
 *   openBackupViewer(vaultName, filePath);
 */

import { api } from './auth.js';
import { showToast } from './ui.js';
import { refreshSidebarTreePreservingState } from './sidebar.js';
import { safeCreateIcons } from './utils.js';

// ---------------------------------------------------------------------------
// State
// ---------------------------------------------------------------------------

const state = {
  vault: null,
  path: null,
  backups: [],
  overlay: null,
  leftVersion: null,   // timestamp of backup shown on left
  rightVersion: null,  // timestamp of backup shown on right, or null for current
  diffText: '',
};

// ---------------------------------------------------------------------------
// Public API
// ---------------------------------------------------------------------------

/**
 * Open the backup/diff viewer for a file.
 * @param {string} vault - Vault name
 * @param {string} path - Relative file path
 */
export async function openBackupViewer(vault, path) {
  state.vault = vault;
  state.path = path;
  state.backups = [];
  state.leftVersion = null;
  state.rightVersion = null;
  state.diffText = '';

  // Create and show overlay
  const overlay = createOverlay();
  document.body.appendChild(overlay);
  state.overlay = overlay;
  requestAnimationFrame(() => overlay.classList.add('active'));

  // Show loading state
  setBody(renderLoading());

  // Fetch backups
  try {
    const data = await api(`/api/file/${encodeURIComponent(vault)}/backups?path=${encodeURIComponent(path)}`);
    state.backups = data.backups || [];
  } catch (err) {
    setBody(renderError('Failed to load backups'));
    return;
  }

  if (state.backups.length === 0) {
    setBody(renderEmpty());
    return;
  }

  // Auto-select: left = most recent, right = current
  state.leftVersion = state.backups[0].timestamp;
  state.rightVersion = null;

  // Render version selectors
  renderMainView();

  // Load initial diff
  await loadDiff();
}

// ---------------------------------------------------------------------------
// DOM helpers
// ---------------------------------------------------------------------------

function createOverlay() {
  const overlay = document.createElement('div');
  overlay.className = 'obsigate-modal-overlay backup-viewer-overlay';
  overlay.addEventListener('click', (e) => {
    if (e.target === overlay) close();
  });

  const panel = document.createElement('div');
  panel.className = 'backup-viewer-panel';
  panel.id = 'backup-viewer-panel';
  overlay.appendChild(panel);

  return overlay;
}

function setBody(html) {
  const panel = document.getElementById('backup-viewer-panel');
  if (panel) panel.innerHTML = html;
}

function close() {
  if (state.overlay) {
    state.overlay.classList.remove('active');
    setTimeout(() => {
      if (state.overlay) state.overlay.remove();
      state.overlay = null;
    }, 200);
  }
}

// ---------------------------------------------------------------------------
// Rendering
// ---------------------------------------------------------------------------

function renderLoading() {
  return `
    <div class="backup-header">
      <h3>Backups</h3>
      <button class="backup-close-btn" title="Fermer">&times;</button>
    </div>
    <div class="backup-body">
      <div class="tree-loading" style="padding:2rem;text-align:center">
        <div class="loading-spinner" style="width:24px;height:24px;border-width:3px;margin:0 auto"></div>
        <p style="margin-top:0.75rem;color:var(--text-muted);font-size:0.85rem">Chargement des backups...</p>
      </div>
    </div>`;
}

function renderError(msg) {
  return `
    <div class="backup-header">
      <h3>Backups</h3>
      <button class="backup-close-btn" title="Fermer">&times;</button>
    </div>
    <div class="backup-body" style="text-align:center;padding:2rem;color:var(--text-muted)">
      <p>${escapeHtml(msg)}</p>
    </div>`;
}

function renderEmpty() {
  return `
    <div class="backup-header">
      <h3>Backups — ${escapeHtml(state.path)}</h3>
      <button class="backup-close-btn" title="Fermer">&times;</button>
    </div>
    <div class="backup-body" style="text-align:center;padding:2rem;color:var(--text-muted)">
      <p>Aucun backup disponible pour ce fichier.</p>
      <p style="font-size:0.8rem;margin-top:0.5rem">Les backups sont créés automatiquement avant chaque modification.</p>
    </div>`;
}

function renderMainView() {
  const b = state.backups;
  const leftOpts = b.map(bk => {
    const sel = bk.timestamp === state.leftVersion ? 'selected' : '';
    return `<option value="${bk.timestamp}" ${sel}>${formatTimestamp(bk.timestamp)} (${formatSize(bk.size)})</option>`;
  }).join('');

  const rightOpts = [
    `<option value="current" ${state.rightVersion === null ? 'selected' : ''}>Version actuelle</option>`,
    ...b.map(bk => {
      const sel = bk.timestamp === state.rightVersion ? 'selected' : '';
      return `<option value="${bk.timestamp}" ${sel}>${formatTimestamp(bk.timestamp)} (${formatSize(bk.size)})</option>`;
    }),
  ].join('');

  const html = `
    <div class="backup-header">
      <div class="backup-header-left">
        <h3>Backups</h3>
        <span class="backup-file-path">${escapeHtml(state.path)}</span>
      </div>
      <div class="backup-header-right">
        <span class="backup-count">${b.length} backup${b.length > 1 ? 's' : ''}</span>
        <button class="backup-close-btn" title="Fermer">&times;</button>
      </div>
    </div>

    <div class="backup-toolbar">
      <div class="backup-selector-group">
        <label>Comparer :</label>
        <select class="backup-select" id="backup-left-select">${leftOpts}</select>
      </div>
      <span class="backup-vs-label">vs</span>
      <div class="backup-selector-group">
        <select class="backup-select" id="backup-right-select">${rightOpts}</select>
      </div>
      <button class="backup-restore-btn" id="backup-restore-btn" title="Restaurer la version de gauche">
        <i data-lucide="rotate-ccw" class="icon-sm"></i> Restaurer
      </button>
    </div>

    <div class="backup-diff-container" id="backup-diff-container">
      <div class="backup-diff-loading">
        <div class="loading-spinner" style="width:24px;height:24px;border-width:3px;margin:0 auto"></div>
      </div>
    </div>

    <div class="backup-footer">
      <span class="backup-footer-hint">Backups automatiques avant chaque modification</span>
    </div>`;

  setBody(html);

  // Bind events
  bindEvents();
  safeCreateIcons();
}

// ---------------------------------------------------------------------------
// Event bindings
// ---------------------------------------------------------------------------

function bindEvents() {
  const panel = document.getElementById('backup-viewer-panel');
  if (!panel) return;

  // Close button
  panel.querySelector('.backup-close-btn')?.addEventListener('click', close);

  // Left select
  const leftSelect = document.getElementById('backup-left-select');
  leftSelect?.addEventListener('change', async () => {
    state.leftVersion = parseInt(leftSelect.value);
    await loadDiff();
  });

  // Right select
  const rightSelect = document.getElementById('backup-right-select');
  rightSelect?.addEventListener('change', async () => {
    const val = rightSelect.value;
    state.rightVersion = val === 'current' ? null : parseInt(val);
    await loadDiff();
  });

  // Restore button
  const restoreBtn = document.getElementById('backup-restore-btn');
  restoreBtn?.addEventListener('click', async () => {
    await restoreBackup();
  });
}

// ---------------------------------------------------------------------------
// Data loading
// ---------------------------------------------------------------------------

async function loadDiff() {
  const container = document.getElementById('backup-diff-container');
  if (!container) return;

  container.innerHTML = `
    <div class="backup-diff-loading">
      <div class="loading-spinner" style="width:24px;height:24px;border-width:3px;margin:0 auto"></div>
    </div>`;

  let url = `/api/file/${encodeURIComponent(state.vault)}/diff?path=${encodeURIComponent(state.path)}&version=${state.leftVersion}`;
  if (state.rightVersion !== null) {
    url += `&compare_with=${state.rightVersion}`;
  }

  try {
    const data = await api(url);
    state.diffText = data.diff || '';
    container.innerHTML = renderDiff(state.diffText);
  } catch (err) {
    container.innerHTML = `<div class="backup-diff-error">Erreur: ${escapeHtml(err?.detail || err?.message || 'Unknown')}</div>`;
  }
}

async function restoreBackup() {
  if (!state.leftVersion) return;

  const confirmed = confirm(
    `Restaurer "${state.path}" à la version du ${formatTimestamp(state.leftVersion)} ?\n\n` +
    `La version actuelle sera sauvegardée avant la restauration.`
  );
  if (!confirmed) return;

  const restoreBtn = document.getElementById('backup-restore-btn');
  if (restoreBtn) {
    restoreBtn.disabled = true;
    restoreBtn.textContent = 'Restauration...';
  }

  try {
    const resp = await api(
      `/api/file/${encodeURIComponent(state.vault)}/restore?path=${encodeURIComponent(state.path)}`,
      {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ version: state.leftVersion }),
      }
    );

    if (resp && resp.success) {
      showToast('Fichier restauré avec succès', 'success');
      // Refresh sidebar and close
      await refreshSidebarTreePreservingState();
      close();
      // Reload current file if open
      if (typeof TabManager !== 'undefined' && TabManager.reloadCurrent) {
        TabManager.reloadCurrent();
      }
    } else {
      showToast('Échec de la restauration', 'error');
    }
  } catch (err) {
    showToast(`Erreur: ${err?.detail || err?.message || 'Unknown'}`, 'error');
  } finally {
    if (restoreBtn) {
      restoreBtn.disabled = false;
      restoreBtn.innerHTML = '<i data-lucide="rotate-ccw" class="icon-sm"></i> Restaurer';
      safeCreateIcons();
    }
  }
}

// ---------------------------------------------------------------------------
// Diff rendering
// ---------------------------------------------------------------------------

function renderDiff(diffText) {
  if (!diffText) {
    return '<div class="backup-diff-empty">Aucune différence — les versions sont identiques.</div>';
  }

  let html = '<div class="backup-diff-output"><table class="backup-diff-table">';
  const lines = diffText.split('\n');

  for (const line of lines) {
    let cssClass = 'diff-context';
    let prefix = ' ';

    if (line.startsWith('@@')) {
      cssClass = 'diff-hunk';
      prefix = '';
    } else if (line.startsWith('+')) {
      cssClass = 'diff-add';
      prefix = '+';
    } else if (line.startsWith('-')) {
      cssClass = 'diff-del';
      prefix = '-';
    } else if (line.startsWith('---') || line.startsWith('+++')) {
      cssClass = 'diff-header-line';
      prefix = '';
    }

    html += `<tr class="${cssClass}"><td class="diff-prefix">${prefix}</td><td class="diff-content"><pre>${escapeHtml(line)}</pre></td></tr>`;
  }

  html += '</table></div>';
  return html;
}

// ---------------------------------------------------------------------------
// Utility
// ---------------------------------------------------------------------------

function formatTimestamp(ts) {
  const d = new Date(ts * 1000);
  const pad = (n) => String(n).padStart(2, '0');
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}`;
}

function formatSize(bytes) {
  if (bytes < 1024) return bytes + ' o';
  if (bytes < 1024 * 1024) return (bytes / 1024).toFixed(1) + ' Ko';
  return (bytes / (1024 * 1024)).toFixed(1) + ' Mo';
}

function escapeHtml(str) {
  const div = document.createElement('div');
  div.textContent = str;
  return div.innerHTML;
}