// ── Types ────────────────────────────────────────────────────

interface Paste {
  id: string;
  mimeType: string;
  description: string;
  tags: string[];
  timestamp: number;
  fileName: string;
  fileData: string; // base64 (empty for text-only)
}

// Duck-typed DB interface — all three variants satisfy this
interface PasteDB {
  selectFolder(): Promise<void>;
  hasFolderAccess(): Promise<boolean>;
  requestFolderAccess(): Promise<boolean>;
  sync(): Promise<void>;
  collection(opts: {
    name: string;
    indexes: { name: string; fields: string[] }[];
  }): {
    put(doc: Paste): Promise<void>;
    all(): Promise<Paste[]>;
    delete(id: string): Promise<void>;
  };
  on(event: string, handler: (...args: unknown[]) => void): () => void;
}

// ── Helpers ──────────────────────────────────────────────────

function genId(): string {
  return Date.now().toString(36) + Math.random().toString(36).slice(2, 8);
}

function extractTags(text: string): string[] {
  return text
    .split(/\s+/)
    .filter((w) => w.startsWith('#') && w.length > 1)
    .map((w) => w.slice(1).replace(/[^a-zA-Z0-9_-]+$/, ''))
    .filter((t) => t.length > 0);
}

function fileToBase64(file: Blob): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onload = () => {
      const result = reader.result as string;
      resolve(result.split(',')[1] || '');
    };
    reader.onerror = reject;
    reader.readAsDataURL(file);
  });
}

function escapeHtml(s: string): string {
  const d = document.createElement('div');
  d.textContent = s;
  return d.innerHTML;
}

function fmtTime(ts: number): string {
  const d = new Date(ts);
  const p = (n: number) => String(n).padStart(2, '0');
  return `${d.getFullYear()}-${p(d.getMonth() + 1)}-${p(d.getDate())} ${p(d.getHours())}:${p(d.getMinutes())}:${p(d.getSeconds())}`;
}

const pdfSvg =
  '<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path d="M14 2H6a2 2 0 00-2 2v16a2 2 0 002 2h12a2 2 0 002-2V8z"/><polyline points="14 2 14 8 20 8"/><text x="12" y="17" text-anchor="middle" fill="currentColor" stroke="none" font-size="6" font-weight="bold" font-family="sans-serif">PDF</text></svg>';

const fileSvg =
  '<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path d="M14 2H6a2 2 0 00-2 2v16a2 2 0 002 2h12a2 2 0 002-2V8z"/><polyline points="14 2 14 8 20 8"/><line x1="16" y1="13" x2="8" y2="13"/><line x1="16" y1="17" x2="8" y2="17"/></svg>';

// ── Main init ────────────────────────────────────────────────

export async function initPasteApp(db: PasteDB, variantLabel: string) {
  const pastes = db.collection({
    name: 'pastes',
    indexes: [{ name: 'byTimestamp', fields: ['timestamp'] }],
  });

  const $ = (s: string) => document.querySelector(s)!;
  const input = $('#paste-input') as HTMLInputElement;
  const statusEl = $('#status')!;
  const itemsEl = $('#items')!;
  const selectFolderBtn = $('#select-folder') as HTMLButtonElement;
  const folderStatusEl = $('#folder-status')!;
  const variantEl = $('#variant-label');

  if (variantEl) variantEl.textContent = variantLabel;

  // ── Folder management ────────────────────────────────────

  function updateFolderUI(connected: boolean) {
    if (connected) {
      folderStatusEl.textContent = 'Folder connected';
      folderStatusEl.className = 'status ok';
      selectFolderBtn.textContent = 'Change folder';
    } else {
      folderStatusEl.textContent = 'No folder selected';
      folderStatusEl.className = 'status';
      selectFolderBtn.textContent = 'Select sync folder';
    }
  }

  selectFolderBtn.addEventListener('click', async () => {
    try {
      await db.selectFolder();
      updateFolderUI(true);
      await refreshItems();
    } catch (e: unknown) {
      setStatus('Folder: ' + (e as Error).message, 'err');
    }
  });

  // Check if we already have access from a previous session
  const hasAccess = await db.hasFolderAccess();
  if (hasAccess) {
    const granted = await db.requestFolderAccess();
    updateFolderUI(granted);
  } else {
    updateFolderUI(false);
  }

  // ── Saving spinner ─────────────────────────────────────────

  const spinner = document.createElement('div');
  spinner.className = 'saving-spinner hidden';
  spinner.innerHTML = '<span class="spinner-dot"></span> Syncing...';
  document.body.appendChild(spinner);

  function showSaving(active: boolean) {
    spinner.classList.toggle('hidden', !active);
  }

  // ── Status ───────────────────────────────────────────────

  function setStatus(msg: string, type?: string) {
    statusEl.textContent = msg;
    statusEl.className = 'status' + (type ? ' ' + type : '');
    if (type === 'ok')
      setTimeout(() => {
        statusEl.textContent = '';
        statusEl.className = 'status';
      }, 2500);
  }

  // ── Save text ────────────────────────────────────────────

  async function pasteText(text: string) {
    setStatus('Saving...');
    try {
      const paste: Paste = {
        id: genId(),
        mimeType: 'text/plain',
        description: text,
        tags: extractTags(text),
        timestamp: Date.now(),
        fileName: '',
        fileData: '',
      };
      await pastes.put(paste);
      setStatus('Saved', 'ok');
      await refreshItems();
    } catch (e: unknown) {
      setStatus('Error: ' + (e as Error).message, 'err');
    }
  }

  // ── Save file ────────────────────────────────────────────

  async function pasteFile(
    file: Blob,
    description: string,
    fileName: string,
  ) {
    setStatus('Reading file...');
    try {
      const base64 = await fileToBase64(file);
      const paste: Paste = {
        id: genId(),
        mimeType: file.type || 'application/octet-stream',
        description,
        tags: extractTags(description),
        timestamp: Date.now(),
        fileName,
        fileData: base64,
      };

      // Show spinner — IDB write is fast, but hashing + transport are slow
      showSaving(true);
      await pastes.put(paste);
      // UI refreshes immediately via 'change' event (IDB write triggers it)
      // Transports (folder, Nostr) continue in background
      showSaving(false);
      setStatus('Saved', 'ok');
    } catch (e: unknown) {
      showSaving(false);
      setStatus('Error: ' + (e as Error).message, 'err');
    }
  }

  // ── Refresh & render ─────────────────────────────────────

  async function refreshItems() {
    try {
      const all: Paste[] = await pastes.all();
      all.sort((a, b) => b.timestamp - a.timestamp);
      renderItems(all);
    } catch (e: unknown) {
      setStatus('Load error: ' + (e as Error).message, 'err');
    }
  }

  function renderItems(items: Paste[]) {
    if (!items || items.length === 0) {
      itemsEl.innerHTML =
        '<div class="empty">Nothing here yet. Type something or paste an image.</div>';
      return;
    }

    itemsEl.innerHTML = items
      .map((it) => {
        const time = fmtTime(it.timestamp);
        const shortId = it.id.substring(0, 12);
        const isImage = it.mimeType.startsWith('image/');
        const isPdf = it.mimeType === 'application/pdf';
        const isText = it.mimeType.startsWith('text/');

        let thumb = '';
        if (isImage && it.fileData) {
          const src = `data:${it.mimeType};base64,${it.fileData}`;
          thumb = `<img class="item-thumb" src="${src}" alt="">`;
        } else if (isPdf) {
          thumb = `<div class="item-icon pdf">${pdfSvg}</div>`;
        } else if (!isText && it.fileData) {
          thumb = `<div class="item-icon file">${fileSvg}</div>`;
        }

        let content = '';
        if (isImage && it.fileData) {
          const src = `data:${it.mimeType};base64,${it.fileData}`;
          content = `<div class="item-image"><img src="${src}" alt="pasted image" loading="lazy"></div>`;
        }
        if (it.description) {
          content += `<div class="item-content">${escapeHtml(it.description)}</div>`;
        }

        let fileLink = '';
        if (it.fileName && !isText) {
          fileLink = `<div class="item-filename">${escapeHtml(it.fileName)}</div>`;
        }

        let tagsHtml = '';
        if (it.tags && it.tags.length > 0) {
          tagsHtml =
            '<div class="item-tags">' +
            it.tags
              .map((t) => `<span class="tag">#${escapeHtml(t)}</span>`)
              .join('') +
            '</div>';
        }

        return (
          `<div class="item">` +
          thumb +
          `<div class="item-body">` +
          `<div class="item-meta">` +
          `<span class="time">${time}</span>` +
          `<span class="hash">${shortId}</span>` +
          `<span>${escapeHtml(it.mimeType)}</span>` +
          `</div>` +
          fileLink +
          content +
          tagsHtml +
          `</div></div>`
        );
      })
      .join('');
  }

  // ── Event listeners ──────────────────────────────────────

  input.addEventListener('keydown', (e: KeyboardEvent) => {
    if (e.key === 'Enter' && input.value.trim()) {
      pasteText(input.value.trim());
      input.value = '';
    }
  });

  document.addEventListener('paste', (e: ClipboardEvent) => {
    const items = e.clipboardData?.items;
    if (!items) return;
    for (const item of items) {
      if (item.type.startsWith('image/')) {
        e.preventDefault();
        const blob = item.getAsFile();
        if (blob) {
          const ext =
            blob.type === 'image/png'
              ? '.png'
              : blob.type === 'image/jpeg'
                ? '.jpg'
                : blob.type === 'image/gif'
                  ? '.gif'
                  : blob.type === 'image/webp'
                    ? '.webp'
                    : '.bin';
          pasteFile(blob, input.value.trim(), 'clipboard' + ext);
          input.value = '';
        }
        return;
      }
    }
  });

  const fileInput = $('#file-input') as HTMLInputElement;
  ($('#clip-btn') as HTMLElement).addEventListener('click', () =>
    fileInput.click(),
  );
  fileInput.addEventListener('change', () => {
    const file = fileInput.files?.[0];
    if (file) {
      pasteFile(file, input.value.trim(), file.name);
      input.value = '';
      fileInput.value = '';
    }
  });

  // Live updates from sync
  db.on('change', () => refreshItems());

  // Initial load
  await refreshItems();
}