import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import { pipeline } from 'stream/promises';
import { spawn } from 'child_process';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const DATASET_PAGE_URL =
'https://www.data.gov.uk/dataset/c1e0176d-59fb-4a8c-92c9-c8b376a80687/code-point-open2';
const OS_DIRECT_DOWNLOAD_URL =
'https://api.os.uk/downloads/v1/products/CodePointOpen/downloads?area=GB&format=CSV&redirect';
const REPO_ROOT = path.join(__dirname, '..');
const DEFAULT_TARGET_DIR = path.join(REPO_ROOT, 'codepo_gb');
const DEFAULT_TMP_DIR = path.join(REPO_ROOT, 'tmp');
function hasCsvDir(dir) {
return fs.existsSync(path.join(dir, 'Data', 'CSV'));
}
function parseArgs(argv) {
const args = {
url: process.env.CODEPO_ZIP_URL || null,
targetDir: process.env.CODEPO_DIR ? path.resolve(process.env.CODEPO_DIR) : DEFAULT_TARGET_DIR,
tmpDir: process.env.CODEPO_TMP_DIR ? path.resolve(process.env.CODEPO_TMP_DIR) : DEFAULT_TMP_DIR,
force: false,
noExtract: false,
};
for (let i = 2; i < argv.length; i++) {
const token = argv[i];
if (token === '--force') args.force = true;
else if (token === '--no-extract') args.noExtract = true;
else if (token === '--url') args.url = argv[++i] ?? null;
else if (token === '--dir') args.targetDir = path.resolve(argv[++i] ?? '');
else if (token === '--tmp') args.tmpDir = path.resolve(argv[++i] ?? '');
else if (token === '--help' || token === '-h') {
console.log(`
Downloads Ordnance Survey Code-Point Open and places it in ./codepo_gb for building postcodes.
Usage:
npm run fetch:codepo -- [--url <zipUrl>] [--dir <targetDir>] [--tmp <tmpDir>] [--force] [--no-extract]
Environment:
CODEPO_ZIP_URL Direct zip URL to download (optional)
CODEPO_DIR Target directory (default: ./codepo_gb)
CODEPO_TMP_DIR Temp directory (default: ./tmp)
If automatic download fails, download manually from:
${OS_DIRECT_DOWNLOAD_URL}
Info page:
${DATASET_PAGE_URL}
`.trim());
process.exit(0);
}
}
return args;
}
async function downloadToFile(url, filePath) {
const res = await fetch(url);
if (!res.ok || !res.body) {
throw new Error(`Download failed: ${res.status} ${res.statusText}`);
}
await pipeline(res.body, fs.createWriteStream(filePath));
}
async function runUnzip(zipPath, outDir) {
await new Promise((resolve, reject) => {
const child = spawn('unzip', ['-o', zipPath, '-d', outDir], { stdio: 'inherit' });
child.on('error', reject);
child.on('exit', code => {
if (code === 0) resolve();
else reject(new Error(`unzip exited with code ${code}`));
});
});
}
function findDatasetRoot(extractedDir) {
const queue = [extractedDir];
const visited = new Set();
while (queue.length) {
const current = queue.shift();
if (!current || visited.has(current)) continue;
visited.add(current);
if (hasCsvDir(current)) return current;
let entries;
try {
entries = fs.readdirSync(current, { withFileTypes: true });
} catch {
continue;
}
for (const entry of entries) {
if (!entry.isDirectory()) continue;
if (entry.name.startsWith('.')) continue;
queue.push(path.join(current, entry.name));
}
}
return null;
}
async function main() {
const args = parseArgs(process.argv);
if (hasCsvDir(args.targetDir)) {
console.log(`✅ Code-Point Open already present at ${path.relative(REPO_ROOT, args.targetDir)}`);
return;
}
if (fs.existsSync(args.targetDir) && !args.force) {
throw new Error(
`Target directory exists but doesn't look like Code-Point Open: ${args.targetDir}\n` +
`Delete it or rerun with --force.`
);
}
fs.mkdirSync(args.tmpDir, { recursive: true });
const zipUrl = args.url || OS_DIRECT_DOWNLOAD_URL;
const zipPath = path.join(args.tmpDir, 'codepo.zip');
console.log(`⬇️ Downloading Code-Point Open...`);
console.log(` - URL: ${zipUrl}`);
console.log(` - ZIP: ${path.relative(REPO_ROOT, zipPath)}`);
await downloadToFile(zipUrl, zipPath);
if (args.noExtract) {
console.log('ℹ️ Skipped extraction (--no-extract).');
console.log(`Unzip ${path.relative(REPO_ROOT, zipPath)} into ${path.relative(REPO_ROOT, args.targetDir)}.`);
return;
}
const extractDir = path.join(args.tmpDir, 'codepo_extracted');
fs.rmSync(extractDir, { recursive: true, force: true });
fs.mkdirSync(extractDir, { recursive: true });
console.log(`🗜️ Extracting ZIP...`);
try {
await runUnzip(zipPath, extractDir);
} catch (error) {
console.error(`❌ Failed to extract ZIP automatically (requires 'unzip' on PATH).`);
console.error(`Unzip ${path.relative(REPO_ROOT, zipPath)} into ${path.relative(REPO_ROOT, args.targetDir)}.`);
throw error;
}
const datasetRoot = findDatasetRoot(extractDir);
if (!datasetRoot) {
throw new Error(
`Extracted ZIP but couldn't find a folder containing Data/CSV under ${path.relative(
REPO_ROOT,
extractDir
)}`
);
}
fs.rmSync(args.targetDir, { recursive: true, force: true });
fs.mkdirSync(path.dirname(args.targetDir), { recursive: true });
console.log(`📁 Installing into ${path.relative(REPO_ROOT, args.targetDir)}...`);
fs.renameSync(datasetRoot, args.targetDir);
console.log(`✅ Code-Point Open installed.`);
console.log(`Next: npm run build:postcodes`);
}
main().catch(err => {
console.error(`\n❌ ${err instanceof Error ? err.message : String(err)}`);
console.error(`Manual download: ${OS_DIRECT_DOWNLOAD_URL}`);
console.error(`Info page: ${DATASET_PAGE_URL}`);
process.exit(1);
});
