import type { BufferSource } from 'node:stream/web';

import { sha256Base64 } from '../signing/hashing.js';
import { sha256Object } from '../signing/index.js';
import unreachable from '../utils/unreachable.js';
import type { DirectoryEntry } from './types.js';

export async function hashFileContents(contents: string | BufferSource): Promise<string> {
  return sha256Base64(contents);
}

function compareFilenames(str1: string, str2: string): number {
  // JS does string comparison in UTF-16 code units, which might be hard to replicate in other systems.
  // A better approach is to sort by unicode code points. One way to do this is to convert the strings
  // to their UTF-8 representation and compare the bytes. This is equivalent to comparing the unicode
  // code points as it is one of the properties of UTF-8.
  // Note: this code uses node.js specific APIs
  return Buffer.from(str1).compare(Buffer.from(str2));
}

function normalizeEntryForHashing(entry: DirectoryEntry) {
  switch (entry.type) {
    case '-':
      return { type: '-', name: entry.name, executable: entry.executable, hash: entry.hash };
    case 'd':
      return { type: 'd', name: entry.name, hash: entry.hash };
    case 'l':
      return { type: 'l', name: entry.name, target: entry.target };
    default:
      unreachable(entry);
  }
}

export async function hashDirectoryContents(contents: DirectoryEntry[]): Promise<string> {
  const normalizedContents = contents.map(normalizeEntryForHashing).sort((a, b) => compareFilenames(a.name, b.name));
  return await sha256Object(normalizedContents);
}