import { BadRequestException } from '@nestjs/common';
import { InspectionEvidenceKind } from '../database/entities';

export const MAX_INSPECTION_EVIDENCE_BYTES = 15 * 1024 * 1024;

export interface UploadedInspectionEvidenceFile {
  buffer: Buffer;
  originalname: string;
  mimetype?: string;
  size: number;
}

export interface InspectedInspectionEvidenceFile {
  originalName: string;
  mimeType: 'image/jpeg' | 'image/png' | 'image/webp' | 'application/pdf';
  extension: '.jpg' | '.png' | '.webp' | '.pdf';
}

function invalidFile(message: string): BadRequestException {
  return new BadRequestException({ code: 'INVALID_INSPECTION_EVIDENCE_FILE', message });
}

function detectedType(
  buffer: Buffer,
): Omit<InspectedInspectionEvidenceFile, 'originalName'> | null {
  if (buffer.length >= 4 && buffer[0] === 0xff && buffer[1] === 0xd8 && buffer[2] === 0xff) {
    return { mimeType: 'image/jpeg', extension: '.jpg' };
  }
  if (
    buffer.length >= 8
    && buffer.subarray(0, 8).equals(Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]))
  ) {
    return { mimeType: 'image/png', extension: '.png' };
  }
  if (
    buffer.length >= 12
    && buffer.subarray(0, 4).toString('ascii') === 'RIFF'
    && buffer.subarray(8, 12).toString('ascii') === 'WEBP'
  ) {
    return { mimeType: 'image/webp', extension: '.webp' };
  }
  if (buffer.length >= 5 && buffer.subarray(0, 5).toString('ascii') === '%PDF-') {
    return { mimeType: 'application/pdf', extension: '.pdf' };
  }
  return null;
}

export function inspectInspectionEvidenceFile(
  file: UploadedInspectionEvidenceFile | undefined,
  kind: InspectionEvidenceKind,
): InspectedInspectionEvidenceFile {
  if (!file?.buffer || file.size <= 0 || file.buffer.length <= 0) {
    throw invalidFile('Debe seleccionar un archivo no vacío');
  }
  if (
    file.size > MAX_INSPECTION_EVIDENCE_BYTES
    || file.buffer.length > MAX_INSPECTION_EVIDENCE_BYTES
  ) {
    throw invalidFile('El archivo supera el máximo permitido de 15 MB');
  }
  const detected = detectedType(file.buffer);
  if (!detected) {
    throw invalidFile('Sólo se permiten JPG, PNG, WebP y PDF válidos');
  }
  if (kind === InspectionEvidenceKind.PHOTO && !detected.mimeType.startsWith('image/')) {
    throw invalidFile('Una fotografía debe ser JPG, PNG o WebP');
  }
  if (kind === InspectionEvidenceKind.DOCUMENT && detected.mimeType !== 'application/pdf') {
    throw invalidFile('Un documento debe ser un archivo PDF');
  }
  const originalName = file.originalname
    .replace(/[\u0000-\u001f\u007f]/g, '')
    .trim()
    .slice(0, 255);
  if (!originalName) throw invalidFile('El nombre original del archivo no es válido');
  return { ...detected, originalName };
}