/**
 * File import via drag-and-drop and file picker on the landing page.
 * Handles reading files, creating encrypted documents, and navigating
 * to the editor with pending import data.
 *
 * Extracted from landing.ts for decomposition.
 */

import type { FolderAssignments } from './landing-types.js';
import { generateKey, exportKey } from './lib/crypto.js';
import { storeKey } from './lib/key-sync.js';
import { createDocument as createLocalDoc } from './lib/local-store.js';
import { moveToFolder } from './landing-utils.js';
import {
  getFileType,
  getImportType,
  pendingImportKey,
  buildEditorUrl,
} from './landing-dragdrop.js';
import { showToast } from './landing-toast.js';

// ── Deps interface ───────────────────────────────────────────

export interface ImportDeps {
  getCurrentFolderId: () => string | null;
  getFolderAssignments: () => FolderAssignments;
  setFolderAssignments: (a: FolderAssignments) => void;
}

// ── Import a single file ────────────────────────────────────

export async function importFile(deps: ImportDeps, file: File): Promise<void> {
  const docType = getFileType(file.name);
  const importType = getImportType(file.name);

  if (!docType || !importType) {
    showToast(`Unsupported file type: .${file.name.split('.').pop()}`, 4000, true);
    return;
  }

  try {
    // Generate encryption key
    const key = await generateKey();
    const keyStr = await exportKey(key);

    // Use filename (without extension) as the document name
    const fileBaseName = file.name.replace(/\.[^.]+$/, '');
    const defaultName = fileBaseName || (docType === 'doc' ? 'Untitled Document' : 'Untitled Spreadsheet');

    // Create document in IndexedDB
    const doc = await createLocalDoc(
      docType as 'doc' | 'sheet' | 'form' | 'slide' | 'diagram' | 'calendar',
      defaultName,
      new ArrayBuffer(0),
      key,
    );
    const id = doc.id;

    await storeKey(id, keyStr);

    // If inside a folder, assign to it
    const currentFolderId = deps.getCurrentFolderId();
    if (currentFolderId) {
      const updated = moveToFolder(deps.getFolderAssignments(), id, currentFolderId);
      deps.setFolderAssignments(updated);
      localStorage.setItem('atmos-folder-assignments', JSON.stringify(updated));
    }

    // Read file and store in sessionStorage for the editor to pick up
    const reader = new FileReader();
    reader.onload = () => {
      const payload = JSON.stringify({
        name: file.name,
        type: importType,
        data: reader.result, // data URL (base64-encoded)
      });
      sessionStorage.setItem(pendingImportKey(id), payload);

      // Navigate to the editor
      window.location.href = buildEditorUrl(docType, id, keyStr);
    };
    reader.onerror = () => {
      showToast('Failed to read file', 4000, true);
    };
    reader.readAsDataURL(file);
  } catch (err) {
    showToast('Failed to create document for import', 4000, true);
  }
}

// ── Drag-and-drop setup ─────────────────────────────────────

export function setupDragAndDrop(deps: ImportDeps): void {
  const dropOverlay = document.getElementById('drop-overlay');
  let dragCounter = 0;

  function showDropOverlay() {
    if (dropOverlay) dropOverlay.style.display = '';
  }

  function hideDropOverlay() {
    if (dropOverlay) dropOverlay.style.display = 'none';
  }

  document.addEventListener('dragenter', (e) => {
    e.preventDefault();
    dragCounter++;
    if (dragCounter === 1) showDropOverlay();
  });

  document.addEventListener('dragover', (e) => {
    e.preventDefault();
    if (e.dataTransfer) e.dataTransfer.dropEffect = 'copy';
  });

  document.addEventListener('dragleave', (e) => {
    e.preventDefault();
    dragCounter--;
    if (dragCounter <= 0) {
      dragCounter = 0;
      hideDropOverlay();
    }
  });

  document.addEventListener('drop', async (e) => {
    e.preventDefault();
    dragCounter = 0;
    hideDropOverlay();

    const file = e.dataTransfer?.files[0];
    if (!file) return;
    importFile(deps, file);
  });

  // File import button (mobile-friendly alternative to drag-drop)
  const fileImportBtn = document.getElementById('file-import-btn');
  const fileImportInput = document.getElementById('file-import-input') as HTMLInputElement | null;
  if (fileImportBtn && fileImportInput) {
    fileImportBtn.addEventListener('click', () => fileImportInput.click());
    fileImportInput.addEventListener('change', () => {
      const file = fileImportInput.files?.[0];
      if (file) importFile(deps, file);
      fileImportInput.value = '';
    });
  }
}