import { FormFileTooLargeError, prepareFormFieldFile } from '@/lib/form-file-compress';
import { compressVoiceFile } from '@/lib/voice-note';

export const ACTIVITY_FILE_MAX_BYTES = 10 * 1024 * 1024;

const FILE_MIME_BY_EXT: Record<string, string> = {
  pdf: 'application/pdf',
  txt: 'text/plain',
  csv: 'text/csv',
  doc: 'application/msword',
  docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
  xls: 'application/vnd.ms-excel',
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  ppt: 'application/vnd.ms-powerpoint',
  pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
  zip: 'application/zip',
};

const IMAGE_EXT = new Set(['jpg', 'jpeg', 'png', 'gif', 'webp']);
const AUDIO_EXT = new Set(['webm', 'ogg', 'mp3', 'm4a', 'aac', 'wav', 'mpeg']);

export type PreparedAttachment = {
  kind: 'image' | 'audio' | 'file';
  name: string;
  file: File;
  previewUrl: string;
};

function extensionOf(name: string): string {
  return name.split('.').pop()?.toLowerCase().replace(/[^a-z0-9]/g, '') ?? '';
}

function kindOf(file: File): 'image' | 'audio' | 'file' {
  const type = file.type.toLowerCase().split(';')[0] ?? '';
  const ext = extensionOf(file.name);
  if (type.startsWith('image/') || IMAGE_EXT.has(ext)) return 'image';
  if (type.startsWith('audio/') || AUDIO_EXT.has(ext)) return 'audio';
  return 'file';
}

export async function prepareActivityAttachment(file: File): Promise<PreparedAttachment> {
  const kind = kindOf(file);
  if (kind === 'image') {
    try {
      const prepared = await prepareFormFieldFile(file);
      return { kind, name: prepared.name, file: prepared.file, previewUrl: prepared.dataUrl };
    } catch (error) {
      if (error instanceof FormFileTooLargeError) {
        throw new Error('حجم عکس باید زیر ۲۰۰ کیلوبایت باشد');
      }
      throw new Error('فشرده‌سازی عکس ناموفق بود.');
    }
  }
  if (kind === 'audio') {
    const compressed = await compressVoiceFile(file);
    return {
      kind,
      name: compressed.name,
      file: compressed,
      previewUrl: URL.createObjectURL(compressed),
    };
  }
  const ext = extensionOf(file.name);
  const mime = FILE_MIME_BY_EXT[ext];
  if (!mime) throw new Error('این نوع فایل مجاز نیست.');
  if (file.size > ACTIVITY_FILE_MAX_BYTES) throw new Error('حجم فایل باید زیر ۱۰ مگابایت باشد');
  const named = file.type === mime ? file : new File([file], file.name, { type: mime });
  return { kind: 'file', name: named.name, file: named, previewUrl: '' };
}