const workspace = document.querySelector('#workspace');
const statusText = document.querySelector('#statusText');
const API_BASE = window.UNAV_API_BASE || '/api';
const state = {
  config: null,
  windows: [],
  focusedId: null,
  selectedEntry: null,
  contextMenu: null,
  draggedEntry: null,
  pointerDrag: null,
  suppressClickPath: null,
  jobs: new Map(),
  nextWindowId: 1,
  zIndex: 20
};

const icons = {
  directory: 'Folder',
  file: 'File',
  symlink: 'Link',
  other: 'Item'
};

document.querySelector('#newExplorerButton').addEventListener('click', () => openExplorer());
document.querySelector('#newPropertiesButton').addEventListener('click', () => openProperties());
document.querySelector('#newQueueButton').addEventListener('click', () => openQueue());

init();

async function init() {
  try {
    state.config = await api(apiUrl('config.php'));
    if (!state.config.roots?.length) {
      throw new Error('No U-Navigator roots configured');
    }
    statusText.textContent = `${state.config.roots.length} Root, ${state.config.readOnly ? 'Read-only' : 'Schreibzugriff aktiv'}`;
    openExplorer(state.config.roots[0].path);
    openProperties();
    openQueue();
  } catch (error) {
    statusText.textContent = error.message;
  }
}

function openExplorer(initialPath = state.config?.roots?.[0]?.path) {
  if (!initialPath) {
    statusText.textContent = 'Kein Root-Pfad konfiguriert';
    return null;
  }
  const win = createWindow('Explorer', 'explorer', {
    width: 760,
    height: 460,
    x: 24 + state.windows.length * 24,
    y: 20 + state.windows.length * 20,
    data: {
      path: initialPath,
      entries: [],
      selectedPath: null,
      loading: false,
      error: null
    }
  });
  loadExplorer(win, initialPath);
  return win;
}

function openProperties() {
  return createWindow('Eigenschaften', 'properties', {
    width: 420,
    height: 320,
    x: 160,
    y: 90,
    data: {}
  });
}

function openQueue() {
  return createWindow('Transfers', 'queue', {
    width: 440,
    height: 340,
    x: 250,
    y: 130,
    data: {}
  });
}

function createWindow(title, kind, options) {
  const id = `win-${state.nextWindowId++}`;
  const win = {
    id,
    kind,
    title,
    x: options.x,
    y: options.y,
    width: options.width,
    height: options.height,
    maximized: false,
    zIndex: ++state.zIndex,
    data: options.data || {}
  };
  state.windows.push(win);
  state.focusedId = id;
  render();
  return win;
}

function render() {
  workspace.innerHTML = '';
  for (const win of state.windows) {
    workspace.appendChild(renderWindow(win));
  }
  if (state.contextMenu) {
    workspace.appendChild(renderContextMenu());
  }
}

function renderWindow(win) {
  const el = document.createElement('section');
  el.className = `window ${state.focusedId === win.id ? 'focused' : ''} ${win.maximized ? 'maximized' : ''}`;
  el.style.left = `${win.maximized ? 0 : win.x}px`;
  el.style.top = `${win.maximized ? 0 : win.y}px`;
  el.style.width = `${win.maximized ? workspace.clientWidth : win.width}px`;
  el.style.height = `${win.maximized ? workspace.clientHeight : win.height}px`;
  el.style.zIndex = win.zIndex;
  el.dataset.windowId = win.id;
  el.addEventListener('pointerdown', () => focusWindow(win));

  const titlebar = document.createElement('div');
  titlebar.className = 'titlebar';
  titlebar.innerHTML = `
    <strong>${escapeHtml(windowTitle(win))}</strong>
    <div class="window-actions">
      <button class="icon" data-action="maximize" title="Maximieren">${win.maximized ? '↙' : '□'}</button>
      <button class="icon" data-action="close" title="Schließen">×</button>
    </div>
  `;
  titlebar.addEventListener('pointerdown', (event) => startDragWindow(event, win));
  titlebar.querySelector('[data-action="maximize"]').addEventListener('click', (event) => {
    event.stopPropagation();
    win.maximized = !win.maximized;
    focusWindow(win);
    render();
  });
  titlebar.querySelector('[data-action="close"]').addEventListener('click', (event) => {
    event.stopPropagation();
    state.windows = state.windows.filter((item) => item.id !== win.id);
    state.focusedId = state.windows.at(-1)?.id || null;
    render();
  });

  const body = document.createElement('div');
  body.className = 'window-body';
  if (win.kind === 'explorer') renderExplorer(body, win);
  if (win.kind === 'properties') renderProperties(body);
  if (win.kind === 'queue') renderQueue(body);
  body.addEventListener('scroll', () => {
    if (win.data.lockScroll) {
      body.scrollTop = win.data.lockScrollTop || 0;
      body.scrollLeft = win.data.lockScrollLeft || 0;
      return;
    }
    win.data.scrollTop = body.scrollTop;
    win.data.scrollLeft = body.scrollLeft;
  });

  el.append(titlebar, body);
  requestAnimationFrame(() => {
    body.scrollTop = win.data.scrollTop || 0;
    body.scrollLeft = win.data.scrollLeft || 0;
  });
  if (!win.maximized) {
    const resize = document.createElement('div');
    resize.className = 'resize-handle';
    resize.addEventListener('pointerdown', (event) => startResizeWindow(event, win));
    el.appendChild(resize);
  }
  return el;
}

function renderExplorer(body, win) {
  const data = win.data;
  body.innerHTML = `
    <div class="pathbar">
      <button data-action="up">Auf</button>
      <input value="${escapeAttr(data.path || '')}" aria-label="Pfad">
      <button data-action="go">Öffnen</button>
      <button data-action="refresh">Neu laden</button>
    </div>
    <div class="drop-zone ${data.dragOver ? 'drag-over' : ''}">
      ${data.error ? `<p class="muted">${escapeHtml(data.error)}</p>` : ''}
      ${data.loading ? '<p class="muted">Lade...</p>' : renderFileTable(data.entries || [])}
    </div>
  `;

  const input = body.querySelector('input');
  body.querySelector('[data-action="go"]').addEventListener('click', () => loadExplorer(win, input.value));
  body.querySelector('[data-action="refresh"]').addEventListener('click', () => loadExplorer(win, data.path));
  body.querySelector('[data-action="up"]').addEventListener('click', () => loadExplorer(win, parentPath(data.path)));

  const dropZone = body.querySelector('.drop-zone');
  dropZone.addEventListener('dragenter', (event) => {
    if (hasDropPayload(event)) {
      event.preventDefault();
      data.dragOver = true;
      dropZone.classList.add('drag-over');
    }
  });
  dropZone.addEventListener('dragover', (event) => {
    if (hasDropPayload(event)) {
      event.preventDefault();
      setDropEffect(event, event.altKey ? 'copy' : 'move');
      data.dragOver = true;
      dropZone.classList.add('drag-over');
    }
  });
  dropZone.addEventListener('dragleave', () => {
    data.dragOver = false;
    dropZone.classList.remove('drag-over');
  });
  dropZone.addEventListener('drop', async (event) => {
    event.preventDefault();
    data.dragOver = false;
    dropZone.classList.remove('drag-over');
    try {
      await handleDrop(event, win, data.path);
    } catch (error) {
      showError(error);
    }
  });
  dropZone.addEventListener('contextmenu', (event) => {
    event.preventDefault();
    showContextMenu(event, win, null);
  });

  for (const row of body.querySelectorAll('.file-row')) {
    const entry = data.entries.find((item) => item.path === row.dataset.path);
    row.addEventListener('pointerdown', (event) => {
      lockExplorerScroll(win, body);
      startItemPointerDrag(event, win, entry);
    });
    row.addEventListener('click', () => selectEntry(win, entry, body));
    row.addEventListener('dblclick', () => {
      if (entry.type === 'directory') {
        loadExplorer(win, entry.path);
      }
    });
    row.addEventListener('contextmenu', (event) => {
      event.preventDefault();
      event.stopPropagation();
      selectEntry(win, entry);
      showContextMenu(event, win, entry);
    });
  }
}

function renderFileTable(entries) {
  if (!entries.length) {
    return '<p class="muted">Dieser Ordner ist leer. Dateien können hier abgelegt werden.</p>';
  }

  const rows = entries.map((entry) => `
    <tr class="file-row ${entry.path === state.selectedEntry?.path ? 'selected' : ''}" data-path="${escapeAttr(entry.path)}" data-type="${escapeAttr(entry.type)}">
      <td><span class="name-cell"><span class="badge">${icons[entry.type] || 'Item'}</span>${escapeHtml(entry.name)}</span></td>
      <td>${entry.type}</td>
      <td>${entry.type === 'file' ? formatBytes(entry.size) : ''}</td>
      <td>${new Date(entry.modifiedAt).toLocaleString()}</td>
    </tr>
  `).join('');

  return `
    <table class="file-table">
      <thead><tr><th>Name</th><th>Typ</th><th>Größe</th><th>Geändert</th></tr></thead>
      <tbody>${rows}</tbody>
    </table>
  `;
}

function renderProperties(body) {
  const entry = state.selectedEntry;
  if (!entry) {
    body.innerHTML = '<p class="muted">Keine Datei ausgewählt.</p>';
    return;
  }

  body.classList.add('properties');
  body.innerHTML = `
    <dl>
      <dt>Name</dt><dd>${escapeHtml(entry.name)}</dd>
      <dt>Typ</dt><dd>${escapeHtml(entry.type)}</dd>
      <dt>Pfad</dt><dd>${escapeHtml(entry.path)}</dd>
      <dt>Größe</dt><dd>${formatBytes(entry.size)}</dd>
      <dt>Geändert</dt><dd>${new Date(entry.modifiedAt).toLocaleString()}</dd>
    </dl>
  `;
}

function renderQueue(body) {
  const jobs = [...state.jobs.values()].reverse();
  if (!jobs.length) {
    body.innerHTML = '<p class="muted">Keine Transfers.</p>';
    return;
  }

  body.innerHTML = `<div class="queue-list">${jobs.map((job) => `
    <article class="job">
      <strong>${escapeHtml(job.type)} #${escapeHtml(job.id)}</strong>
      <div class="muted">${escapeHtml(job.status)} · ${escapeHtml(job.message || '')}</div>
      <div class="progress"><div style="width:${Number(job.progress) || 0}%"></div></div>
    </article>
  `).join('')}</div>`;
}

async function loadExplorer(win, targetPath) {
  win.data.loading = true;
  win.data.error = null;
  win.data.path = targetPath;
  render();
  try {
    const result = await api(apiUrl(`list.php?path=${encodeURIComponent(targetPath)}`));
    win.data.path = result.path;
    win.data.entries = result.entries;
  } catch (error) {
    win.data.error = error.message;
  } finally {
    win.data.loading = false;
    render();
  }
}

async function handleDrop(event, win, targetPath) {
  if (state.config.readOnly) {
    alert('Read-only mode ist aktiv.');
    return;
  }

  const internalPath = state.draggedEntry?.path || '';
  if (internalPath) {
    const name = internalPath.split('/').filter(Boolean).at(-1);
    const destination = `${targetPath.replace(/\/$/, '')}/${name}`;
    if (internalPath === destination) {
      throw new Error('Quelle und Ziel sind identisch.');
    }
    await createJob(event.altKey ? 'copy' : 'move', internalPath, destination);
    await reloadExplorerWindows([win.id, state.draggedEntry?.sourceWindowId].filter(Boolean));
    return;
  }

  const files = getDroppedFiles(event);
  if (files.length) {
    const form = new FormData();
    for (const file of files) {
      form.append('files', file, file.name);
    }
    await fetchChecked(apiUrl(`upload.php?path=${encodeURIComponent(targetPath)}`), {
      method: 'POST',
      body: form
    });
    await loadExplorer(win, targetPath);
  }
}

async function createJob(type, source, destination) {
  const job = await api(apiUrl(`job.php?action=${encodeURIComponent(type)}`), {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ source, destination })
  });
  state.jobs.set(job.id, job);
  pollJob(job.id);
  render();
}

async function reloadExplorerWindows(ids) {
  const uniqueIds = new Set(ids);
  const targets = state.windows.filter((win) => win.kind === 'explorer' && (uniqueIds.has(win.id) || !uniqueIds.size));
  await Promise.all(targets.map((win) => loadExplorer(win, win.data.path)));
}

function hasDropPayload(event) {
  return Boolean(state.draggedEntry || getDroppedFiles(event).length);
}

function showError(error) {
  const message = error?.message || String(error);
  alert(message);
}

function getDroppedFiles(event) {
  try {
    return [...(event.dataTransfer?.files || [])];
  } catch {
    return [];
  }
}

function setEffectAllowed(event) {
  try {
    event.dataTransfer.effectAllowed = 'copyMove';
  } catch {}
}

function setDropEffect(event, effect) {
  try {
    event.dataTransfer.dropEffect = effect;
  } catch {
    // Browser rejected the requested cursor hint; the app-state drop still works.
  }
}

async function renameEntry(win, entry) {
  const nextName = prompt('Neuer Name', entry.name);
  if (!nextName || nextName === entry.name) {
    return;
  }
  if (nextName.includes('/')) {
    alert('Der Name darf keinen Slash enthalten.');
    return;
  }
  await createJob('move', entry.path, `${dirname(entry.path)}/${nextName}`);
  await loadExplorer(win, win.data.path);
}

async function promptTransfer(win, entry, type) {
  const targetDir = prompt(type === 'copy' ? 'Kopieren nach Ordner' : 'Verschieben nach Ordner', win.data.path);
  if (!targetDir) {
    return;
  }
  await createJob(type, entry.path, `${targetDir.replace(/\/$/, '')}/${entry.name}`);
  await loadExplorer(win, win.data.path);
}

function showContextMenu(event, win, entry) {
  const rect = workspace.getBoundingClientRect();
  state.contextMenu = {
    x: event.clientX - rect.left,
    y: event.clientY - rect.top,
    winId: win.id,
    entryPath: entry?.path || null
  };
  render();
}

function renderContextMenu() {
  const menu = document.createElement('div');
  menu.className = 'context-menu';
  menu.style.left = `${state.contextMenu.x}px`;
  menu.style.top = `${state.contextMenu.y}px`;

  const win = state.windows.find((item) => item.id === state.contextMenu.winId);
  const entry = win?.data.entries?.find((item) => item.path === state.contextMenu.entryPath) || null;
  const actions = [];

  if (entry) {
    if (entry.type === 'directory') {
      actions.push(['Öffnen', () => loadExplorer(win, entry.path)]);
    }
    actions.push(['Umbenennen', () => renameEntry(win, entry)]);
    actions.push(['Kopieren nach...', () => promptTransfer(win, entry, 'copy')]);
    actions.push(['Verschieben nach...', () => promptTransfer(win, entry, 'move')]);
  } else {
    actions.push(['Neu laden', () => loadExplorer(win, win.data.path)]);
  }

  for (const [label, action] of actions) {
    const button = document.createElement('button');
    button.type = 'button';
    button.textContent = label;
    button.addEventListener('click', async () => {
      state.contextMenu = null;
      render();
      try {
        await action();
      } catch (error) {
        alert(error.message);
      }
    });
    menu.appendChild(button);
  }

  setTimeout(() => {
    const close = () => {
      state.contextMenu = null;
      render();
      document.removeEventListener('click', close);
      document.removeEventListener('keydown', keyClose);
    };
    const keyClose = (event) => {
      if (event.key === 'Escape') close();
    };
    document.addEventListener('click', close);
    document.addEventListener('keydown', keyClose);
  }, 0);

  return menu;
}

async function pollJob(id) {
  const job = await api(apiUrl(`job.php?id=${encodeURIComponent(id)}`));
  state.jobs.set(id, job);
  render();
  if (['queued', 'running', 'cancel_requested'].includes(job.status)) {
    setTimeout(() => pollJob(id), 700);
  }
}

function selectEntry(win, entry, scrollBody = null) {
  if (state.suppressClickPath === entry.path) {
    state.suppressClickPath = null;
    restoreExplorerScroll(win, scrollBody);
    return;
  }
  win.data.selectedPath = entry.path;
  state.selectedEntry = entry;
  focusWindow(win);
  updateSelectedRows();
  updatePropertiesWindows();
  restoreExplorerScroll(win, scrollBody);
}

function focusWindow(win) {
  state.focusedId = win.id;
  win.zIndex = ++state.zIndex;
  for (const windowEl of workspace.querySelectorAll('.window')) {
    windowEl.classList.toggle('focused', windowEl.dataset.windowId === win.id);
  }
  const current = workspace.querySelector(`.window[data-window-id="${win.id}"]`);
  if (current) {
    current.style.zIndex = win.zIndex;
  }
}

function updateSelectedRows() {
  for (const row of workspace.querySelectorAll('.file-row')) {
    row.classList.toggle('selected', row.dataset.path === state.selectedEntry?.path);
  }
}

function updatePropertiesWindows() {
  for (const win of state.windows.filter((item) => item.kind === 'properties')) {
    const body = workspace.querySelector(`.window[data-window-id="${win.id}"] .window-body`);
    if (body) {
      renderProperties(body);
    }
  }
}

function startItemPointerDrag(event, win, entry) {
  if (event.button !== 0) return;

  state.pointerDrag = {
    sourceWindowId: win.id,
    path: entry.path,
    name: entry.name,
    startX: event.clientX,
    startY: event.clientY,
    active: false,
    targetWindowId: null,
    targetPath: null
  };

  const move = (moveEvent) => updateItemPointerDrag(moveEvent);
  const up = (upEvent) => finishItemPointerDrag(upEvent, move, up);
  document.addEventListener('pointermove', move);
  document.addEventListener('pointerup', up, { once: true });
}

function updateItemPointerDrag(event) {
  const drag = state.pointerDrag;
  if (!drag) return;

  const distance = Math.hypot(event.clientX - drag.startX, event.clientY - drag.startY);
  if (!drag.active && distance < 6) {
    return;
  }

  drag.active = true;
  event.preventDefault();
  document.body.classList.add('u-nav-dragging');
  markDraggingRow(drag.path, true);
  updatePointerDropTarget(event);
}

async function finishItemPointerDrag(event, move, up) {
  document.removeEventListener('pointermove', move);
  document.removeEventListener('pointerup', up);

  const drag = state.pointerDrag;
  clearPointerDropTarget();
  document.body.classList.remove('u-nav-dragging');
  if (!drag) return;

  markDraggingRow(drag.path, false);
  state.pointerDrag = null;

  if (!drag.active) {
    return;
  }

  state.suppressClickPath = drag.path;
  const target = findPointerDropTarget(event);
  if (!target) {
    return;
  }

  try {
    const destination = `${target.path.replace(/\/$/, '')}/${drag.name}`;
    if (destination === drag.path) {
      throw new Error('Quelle und Ziel sind identisch.');
    }
    await createJob(event.altKey ? 'copy' : 'move', drag.path, destination);
    await reloadExplorerWindows([drag.sourceWindowId, target.windowId]);
  } catch (error) {
    showError(error);
  }
}

function updatePointerDropTarget(event) {
  clearPointerDropTarget();
  const target = findPointerDropTarget(event);
  if (!target) return;

  state.pointerDrag.targetWindowId = target.windowId;
  state.pointerDrag.targetPath = target.path;
  const windowEl = workspace.querySelector(`.window[data-window-id="${target.windowId}"]`);
  windowEl?.querySelector('.drop-zone')?.classList.add('drag-over');
  if (target.row) {
    target.row.classList.add('drop-target');
  }
}

function clearPointerDropTarget() {
  for (const item of workspace.querySelectorAll('.drop-zone.drag-over')) {
    item.classList.remove('drag-over');
  }
  for (const item of workspace.querySelectorAll('.file-row.drop-target')) {
    item.classList.remove('drop-target');
  }
}

function findPointerDropTarget(event) {
  const element = document.elementFromPoint(event.clientX, event.clientY);
  const windowEl = element?.closest?.('.window');
  if (!windowEl) return null;

  const win = state.windows.find((item) => item.id === windowEl.dataset.windowId);
  if (!win || win.kind !== 'explorer') return null;

  const row = element.closest?.('.file-row');
  if (row?.dataset.type === 'directory') {
    return { windowId: win.id, path: row.dataset.path, row };
  }

  return { windowId: win.id, path: win.data.path, row: null };
}

function markDraggingRow(path, dragging) {
  for (const row of workspace.querySelectorAll('.file-row')) {
    if (row.dataset.path === path) {
      row.classList.toggle('dragging', dragging);
    }
  }
}

function lockExplorerScroll(win, body) {
  win.data.lockScroll = true;
  win.data.lockScrollTop = body.scrollTop;
  win.data.lockScrollLeft = body.scrollLeft;
}

function restoreExplorerScroll(win, body) {
  if (!body) {
    body = workspace.querySelector(`.window[data-window-id="${win.id}"] .window-body`);
  }
  if (!body) return;

  const top = win.data.lockScrollTop ?? win.data.scrollTop ?? 0;
  const left = win.data.lockScrollLeft ?? win.data.scrollLeft ?? 0;
  const restore = () => {
    body.scrollTop = top;
    body.scrollLeft = left;
  };

  restore();
  requestAnimationFrame(restore);
  setTimeout(restore, 0);
  setTimeout(() => {
    restore();
    win.data.lockScroll = false;
    win.data.scrollTop = body.scrollTop;
    win.data.scrollLeft = body.scrollLeft;
  }, 120);
}

function startDragWindow(event, win) {
  if (event.target.closest('button') || win.maximized) return;
  event.preventDefault();
  const startX = event.clientX;
  const startY = event.clientY;
  const originX = win.x;
  const originY = win.y;
  const pointerId = event.pointerId;
  event.currentTarget.setPointerCapture(pointerId);

  const move = (moveEvent) => {
    win.x = clamp(originX + moveEvent.clientX - startX, 0, Math.max(0, workspace.clientWidth - 120));
    win.y = clamp(originY + moveEvent.clientY - startY, 0, Math.max(0, workspace.clientHeight - 80));
    render();
  };
  const up = () => {
    window.removeEventListener('pointermove', move);
    window.removeEventListener('pointerup', up);
  };
  window.addEventListener('pointermove', move);
  window.addEventListener('pointerup', up);
}

function startResizeWindow(event, win) {
  event.preventDefault();
  event.stopPropagation();
  const startX = event.clientX;
  const startY = event.clientY;
  const originWidth = win.width;
  const originHeight = win.height;

  const move = (moveEvent) => {
    win.width = Math.max(320, originWidth + moveEvent.clientX - startX);
    win.height = Math.max(280, originHeight + moveEvent.clientY - startY);
    render();
  };
  const up = () => {
    window.removeEventListener('pointermove', move);
    window.removeEventListener('pointerup', up);
  };
  window.addEventListener('pointermove', move);
  window.addEventListener('pointerup', up);
}

async function api(url, options) {
  const response = await fetchChecked(url, options);
  return response.json();
}

async function fetchChecked(url, options) {
  const response = await fetch(url, options);
  if (!response.ok) {
    let message = `${response.status} ${response.statusText}`;
    try {
      message = (await response.json()).error || message;
    } catch {}
    throw new Error(message);
  }
  return response;
}

function windowTitle(win) {
  if (win.kind === 'explorer') {
    return `Explorer · ${win.data.path || ''}`;
  }
  return win.title;
}

function parentPath(value) {
  const parts = String(value || '').split('/').filter(Boolean);
  if (parts.length <= 1) return value;
  return `/${parts.slice(0, -1).join('/')}`;
}

function dirname(value) {
  const parts = String(value || '').split('/').filter(Boolean);
  if (parts.length <= 1) return '/';
  return `/${parts.slice(0, -1).join('/')}`;
}

function formatBytes(bytes) {
  const value = Number(bytes || 0);
  if (value < 1024) return `${value} B`;
  if (value < 1024 * 1024) return `${(value / 1024).toFixed(1)} KB`;
  if (value < 1024 * 1024 * 1024) return `${(value / 1024 / 1024).toFixed(1)} MB`;
  return `${(value / 1024 / 1024 / 1024).toFixed(1)} GB`;
}

function escapeHtml(value) {
  return String(value ?? '').replace(/[&<>"']/g, (char) => ({
    '&': '&amp;',
    '<': '&lt;',
    '>': '&gt;',
    '"': '&quot;',
    "'": '&#39;'
  })[char]);
}

function escapeAttr(value) {
  return escapeHtml(value);
}

function clamp(value, min, max) {
  return Math.max(min, Math.min(max, value));
}

function apiUrl(path) {
  return `${API_BASE.replace(/\/$/, '')}/${path.replace(/^\//, '')}`;
}