/**
 * 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,
  rightVersion: null,
  diffText: '',
  diffLeft: '',
  diffRight: '',
  diffMode: 'unified',
};

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

export async function openBackupViewer(vault, path) {
  state.vault = vault;
  state.path = path;
  state.backups = [];
  state.leftVersion = null;
  state.rightVersion = null;
  state.diffText = '';
  state.diffLeft = '';
  state.diffRight = '';

  const overlay = createOverlay();
  document.body.appendChild(overlay);
  state.overlay = overlay;
  requestAnimationFrame(function() { overlay.classList.add('active'); });

  setBody(renderLoading());

  try {
    var url = '/api/file/' + encodeURIComponent(vault) + '/backups?path=' + encodeURIComponent(path);
    var data = await api(url);
    state.backups = data.backups || [];
  } catch (err) {
    var msg = err && err.detail || err && err.message || 'Erreur inconnue';
    setBody(renderError('Erreur API: ' + msg));
    return;
  }

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

  state.leftVersion = state.backups[0].timestamp;
  state.rightVersion = null;
  renderMainView();
  await loadDiff();
}

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

var _escHandler = null;

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

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

  // Close button -- static, never replaced by innerHTML
  var closeBtn = document.createElement('button');
  closeBtn.className = 'editor-btn backup-close-btn';
  closeBtn.id = 'backup-close';
  closeBtn.title = 'Fermer';
  closeBtn.style.cssText = 'position:absolute;top:12px;right:12px;z-index:1002;flex-shrink:0';
  closeBtn.innerHTML = '<i data-lucide="x" style="width:15px;height:15px"></i>';
  closeBtn.addEventListener('click', function(e) {
    e.stopPropagation();
    close();
  });
  overlay.appendChild(closeBtn);

  // Escape key
  _escHandler = function(e) {
    if (e.key === 'Escape' && state.overlay) close();
  };
  document.addEventListener('keydown', _escHandler);

  return overlay;
}

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

function close() {
  if (!state.overlay) return;
  if (_escHandler) {
    document.removeEventListener('keydown', _escHandler);
    _escHandler = null;
  }
  state.overlay.classList.remove('active');
  setTimeout(function() {
    if (state.overlay) state.overlay.remove();
    state.overlay = null;
  }, 200);
}

// Global click handler for close button
document.addEventListener('click', function(e) {
  var btn = e.target.closest ? e.target.closest('#backup-close') : null;
  if (btn && state.overlay) close();
});

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

function renderLoading() {
  return '<div class="backup-header"><h3>Backups</h3></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></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></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 crees automatiquement avant chaque modification.</p>' +
    '</div>';
}

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

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

  var 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>' +
    '</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>' +
    '<button class="backup-diff-mode-btn" id="backup-diff-mode-btn" title="Vue cote a cote">' +
    '<i data-lucide="columns-2" class="icon-sm"></i> Cote-a-cote' +
    '</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 crees lors de la sauvegarde manuelle (Ctrl+S)</span>' +
    '<button class="backup-footer-manage-btn" id="backup-manage-btn">Gerer tous les backups</button>' +
    '</div>';

  setBody(html);
  bindEvents();
}

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

function bindEvents() {
  var leftSelect = document.getElementById('backup-left-select');
  if (leftSelect) {
    leftSelect.addEventListener('change', async function() {
      state.leftVersion = parseInt(leftSelect.value);
      await loadDiff();
    });
  }

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

  var restoreBtn = document.getElementById('backup-restore-btn');
  if (restoreBtn) {
    restoreBtn.addEventListener('click', async function() {
      await restoreBackup();
    });
  }

  var modeBtn = document.getElementById('backup-diff-mode-btn');
  var manageBtn = document.getElementById('backup-manage-btn');
  if (manageBtn) {
    manageBtn.addEventListener('click', function() {
      close();
      import('./backup-manager.js').then(function(m) { m.openBackupManager(); });
    });
  }

  if (modeBtn) {
    modeBtn.addEventListener('click', function() {
      state.diffMode = state.diffMode === 'sidebyside' ? 'unified' : 'sidebyside';
      var container = document.getElementById('backup-diff-container');
      if (container) {
        container.innerHTML = state.diffMode === 'sidebyside'
          ? renderDiffSideBySide(state.diffLeft, state.diffRight)
          : renderDiff(state.diffText);
      }
      var icon = modeBtn.querySelector('i');
      if (icon) icon.setAttribute('data-lucide', state.diffMode === 'sidebyside' ? 'columns-2' : 'align-justify');
      var textNodes = [];
      for (var i = 0; i < modeBtn.childNodes.length; i++) {
        if (modeBtn.childNodes[i].nodeType === 3) textNodes.push(modeBtn.childNodes[i]);
      }
      textNodes.forEach(function(n) { n.remove(); });
      modeBtn.appendChild(document.createTextNode(state.diffMode === 'sidebyside' ? ' Unifiee' : ' Cote-a-cote'));
      safeCreateIcons();
    });
  }
}

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

async function loadDiff() {
  var 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>';

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

  try {
    var data = await api(url);
    state.diffText = data.diff || '';
    state.diffLeft = data.left_content || '';
    state.diffRight = data.right_content || '';
    container.innerHTML = state.diffMode === 'sidebyside'
      ? renderDiffSideBySide(state.diffLeft, state.diffRight)
      : renderDiff(state.diffText);
  } catch (err) {
    container.innerHTML = '<div class="backup-diff-error">Erreur: ' + escapeHtml((err && err.detail) || (err && err.message) || 'Unknown') + '</div>';
  }
}

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

  var confirmed = confirm(
    'Restaurer "' + state.path + '" a la version du ' + formatTimestamp(state.leftVersion) + ' ?\n\n' +
    'La version actuelle sera sauvegardee avant la restauration.'
  );
  if (!confirmed) return;

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

  try {
    var 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 restaure avec succes', 'success');
      await refreshSidebarTreePreservingState();
      close();
      if (typeof TabManager !== 'undefined' && TabManager.reloadCurrent) {
        TabManager.reloadCurrent();
      }
    } else {
      showToast('Echec de la restauration', 'error');
    }
  } catch (err) {
    showToast('Erreur: ' + ((err && err.detail) || (err && 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 difference - les versions sont identiques.</div>';
  }

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

  for (var i = 0; i < lines.length; i++) {
    var line = lines[i];
    var cssClass = 'diff-context';
    var prefix = ' ';
    if (line.indexOf('@@') === 0) { cssClass = 'diff-hunk'; prefix = ''; }
    else if (line.indexOf('+') === 0) { cssClass = 'diff-add'; prefix = '+'; }
    else if (line.indexOf('-') === 0) { cssClass = 'diff-del'; prefix = '-'; }
    else if (line.indexOf('---') === 0 || line.indexOf('+++') === 0) { 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;
}

// ---------------------------------------------------------------------------
// Side-by-side diff rendering
// ---------------------------------------------------------------------------

function renderDiffSideBySide(leftText, rightText) {
  if (!leftText && !rightText) {
    return '<div class="backup-diff-empty">Aucune difference - les versions sont identiques.</div>';
  }

  var leftLines = (leftText || '').split('\n');
  var rightLines = (rightText || '').split('\n');
  var sm = new DifflibSeqMatcher(leftLines, rightLines);
  var ops = sm.getOpcodes();

  var html = '<div class="backup-diff-output backup-diff-sidebyside"><table class="backup-diff-table sidebyside"><colgroup><col style="width:50%"><col style="width:50%"></colgroup><tbody>';

  for (var oi = 0; oi < ops.length; oi++) {
    var op = ops[oi];
    var tag = op[0], i1 = op[1], i2 = op[2], j1 = op[3], j2 = op[4];

    if (tag === 'equal') {
      for (var k = 0; k < (i2 - i1); k++) {
        html += '<tr class="diff-context"><td class="diff-content sidebyside-left"><pre>' + escapeHtml(leftLines[i1 + k]) + '</pre></td><td class="diff-content sidebyside-right"><pre>' + escapeHtml(rightLines[j1 + k]) + '</pre></td></tr>';
      }
    } else if (tag === 'delete') {
      for (var k2 = i1; k2 < i2; k2++) {
        html += '<tr class="diff-del"><td class="diff-content sidebyside-left"><pre>' + escapeHtml(leftLines[k2]) + '</pre></td><td class="diff-content sidebyside-right diff-empty-cell"></td></tr>';
      }
    } else if (tag === 'insert') {
      for (var k3 = j1; k3 < j2; k3++) {
        html += '<tr class="diff-add"><td class="diff-content sidebyside-left diff-empty-cell"></td><td class="diff-content sidebyside-right"><pre>' + escapeHtml(rightLines[k3]) + '</pre></td></tr>';
      }
    } else if (tag === 'replace') {
      var maxLen = Math.max(i2 - i1, j2 - j1);
      for (var k4 = 0; k4 < maxLen; k4++) {
        var leftLine = (i1 + k4 < i2) ? escapeHtml(leftLines[i1 + k4]) : '';
        var rightLine = (j1 + k4 < j2) ? escapeHtml(rightLines[j1 + k4]) : '';
        var leftClass = (i1 + k4 < i2) ? 'diff-del' : 'diff-empty-cell';
        var rightClass = (j1 + k4 < j2) ? 'diff-add' : 'diff-empty-cell';
        html += '<tr><td class="diff-content sidebyside-left ' + leftClass + '"><pre>' + leftLine + '</pre></td><td class="diff-content sidebyside-right ' + rightClass + '"><pre>' + rightLine + '</pre></td></tr>';
      }
    }
  }

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

// Minimal SequenceMatcher for line-based diff
function DifflibSeqMatcher(a, b) {
  this.a = a;
  this.b = b;
}

DifflibSeqMatcher.prototype.getOpcodes = function() {
  var m = this.a.length, n = this.b.length;
  var dp = [];
  for (var i = 0; i <= m; i++) { dp[i] = []; for (var j = 0; j <= n; j++) dp[i][j] = 0; }
  for (var i = 1; i <= m; i++) {
    for (var j = 1; j <= n; j++) {
      if (this.a[i - 1] === this.b[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;
      else dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
    }
  }
  var ops = [];
  var i = m, j = n;
  while (i > 0 || j > 0) {
    if (i > 0 && j > 0 && this.a[i - 1] === this.b[j - 1]) {
      var ei = i - 1, ej = j - 1;
      while (ei > 0 && ej > 0 && this.a[ei - 1] === this.b[ej - 1]) { ei--; ej--; }
      if (ei < i) ops.unshift(['equal', ei, i, ej, j]);
      i = ei; j = ej;
    } else if (j > 0 && (i === 0 || dp[i][j - 1] >= dp[i - 1][j])) {
      ops.unshift(['insert', i, i, j - 1, j]);
      j--;
    } else if (i > 0 && (j === 0 || dp[i][j - 1] < dp[i - 1][j])) {
      ops.unshift(['delete', i - 1, i, j, j]);
      i--;
    }
  }
  var merged = [];
  for (var k = 0; k < ops.length; k++) {
    if (merged.length > 0 && merged[merged.length - 1][0] === 'delete' && ops[k][0] === 'insert' &&
        merged[merged.length - 1][4] === ops[k][3]) {
      var del = merged.pop();
      merged.push(['replace', del[1], del[2], ops[k][3], ops[k][4]]);
    } else {
      merged.push(ops[k]);
    }
  }
  return merged;
};

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

function formatTimestamp(ts) {
  var d = new Date(ts * 1000);
  var pad = function(n) { return 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) {
  var div = document.createElement('div');
  div.textContent = str;
  return div.innerHTML;
}