#!/usr/bin/env node

const fs = require('node:fs');
const path = require('node:path');
const { execFileSync } = require('node:child_process');

const UNSCOPED_PATHS = [
  '.gitignore', // Repository plumbing has no product surface.
  'assets/logo-mark.svg', // One legacy brand asset does not justify a scope taxonomy.
  'test/*.test.js', // Tests inherit the scope of the production surface changed beside them.
];

function parseArgs(argv) {
  const options = {
    config: path.join(process.cwd(), '.github', 'labels.conf'),
    apiUrl: process.env.FORGE_API_URL
      || `${(process.env.FORGE_SERVER_URL || 'https://forgejo.heavyduty.builders').replace(/\/$/, '')}/api/v1`,
  };
  for (let index = 0; index < argv.length; index += 1) {
    const flag = argv[index];
    if (flag !== '--config' && flag !== '--api-url') {
      throw new Error(`unknown option: ${flag}`);
    }
    const value = argv[index + 1];
    if (!value) throw new Error(`${flag} requires a value`);
    options[flag === '--config' ? 'config' : 'apiUrl'] = value;
    index += 1;
  }
  return options;
}

function parseConfig(contents, filename) {
  let panel;
  let triageActors = [];
  const scopes = [];
  for (const line of contents.split(/\r?\n/)) {
    if (!line) continue;
    if (line.startsWith('panel=')) {
      if (panel) throw new Error(`duplicate panel line in ${filename}`);
      panel = line.slice('panel='.length).trim().split(/\s+/).filter(Boolean);
      if (panel.length === 0) throw new Error(`panel must name at least one reviewer in ${filename}`);
      continue;
    }
    if (line.startsWith('triage-actors=')) {
      triageActors = line.slice('triage-actors='.length).trim().split(/\s+/).filter(Boolean);
      continue;
    }
    const fields = line.split('|');
    if (fields.length !== 3 || !fields[0] || !/^[0-9A-Fa-f]{6}$/.test(fields[1]) || !fields[2]) {
      throw new Error(`malformed label row: ${line} in ${filename}`);
    }
    scopes.push(line);
  }
  if (!panel) throw new Error(`missing panel= line in ${filename}`);

  const identities = [...new Set([...panel, ...triageActors])];
  for (const login of identities) {
    if (!/^[A-Za-z0-9-]+$/.test(login)) {
      throw new Error(`malformed login in ${filename}: ${login}`);
    }
  }
  return { identities, scopes };
}

function parseLabeler(contents, filename) {
  const mappings = new Map();
  let current;
  for (const line of contents.split(/\r?\n/)) {
    const label = line.match(/^"([^"]+)":$/);
    if (label) {
      current = label[1];
      if (mappings.has(current)) throw new Error(`duplicate scope mapping in ${filename}: ${current}`);
      mappings.set(current, []);
      continue;
    }
    const matcher = line.match(/^\s+- any-glob-to-any-file:\s*(\[[^\n]+\])$/);
    if (!matcher) continue;
    if (!current) throw new Error(`scope matcher has no label in ${filename}`);
    let globs;
    try {
      globs = JSON.parse(matcher[1]);
    } catch {
      throw new Error(`malformed scope matcher for ${current} in ${filename}`);
    }
    if (!Array.isArray(globs) || globs.length === 0 || globs.some((glob) => typeof glob !== 'string')) {
      throw new Error(`malformed scope matcher for ${current} in ${filename}`);
    }
    mappings.get(current).push(...globs);
  }
  for (const [label, globs] of mappings) {
    if (globs.length === 0) throw new Error(`scope mapping has no globs in ${filename}: ${label}`);
  }
  return mappings;
}

function validateScopeNames(scopes, mappings) {
  const configNames = new Set(scopes.map((scope) => scope.split('|', 1)[0]));
  const labelerNames = new Set(mappings.keys());
  const onlyInConfig = [...configNames].filter((name) => !labelerNames.has(name)).sort();
  const onlyInLabeler = [...labelerNames].filter((name) => !configNames.has(name)).sort();
  const errors = [];
  if (onlyInConfig.length > 0) errors.push(`scope names only in labels.conf: ${onlyInConfig.join(', ')}`);
  if (onlyInLabeler.length > 0) errors.push(`scope names only in labeler.yml: ${onlyInLabeler.join(', ')}`);
  if (errors.length > 0) throw new Error(errors.join('; '));
}

function validateTrackedPaths(mappings) {
  let tracked;
  try {
    tracked = execFileSync('git', ['ls-files'], { encoding: 'utf8' }).trim().split('\n').filter(Boolean);
  } catch (error) {
    throw new Error(`cannot enumerate tracked paths: ${error.message}`);
  }
  const globs = [...mappings.values()].flat();
  const uncovered = tracked.filter((filename) => (
    !UNSCOPED_PATHS.some((glob) => path.matchesGlob(filename, glob))
    && !globs.some((glob) => path.matchesGlob(filename, glob))
  ));
  if (uncovered.length > 0) {
    throw new Error(`tracked paths have no scope mapping: ${uncovered.join(', ')}`);
  }
}

async function validateIdentities(apiUrl, identities) {
  for (const login of identities) {
    const endpoint = `${apiUrl.replace(/\/$/, '')}/users/${encodeURIComponent(login)}`;
    let response;
    try {
      response = await fetch(endpoint, { redirect: 'manual' });
    } catch (error) {
      throw new Error(`${login}: fetch failed: ${error.message}`);
    }
    if (response.status !== 200) throw new Error(`${login}: HTTP ${response.status} from ${endpoint}`);
  }
}

async function main() {
  const options = parseArgs(process.argv.slice(2));
  const contents = fs.readFileSync(options.config, 'utf8');
  const { identities, scopes } = parseConfig(contents, options.config);
  const labeler = path.join(path.dirname(options.config), 'labeler.yml');
  const mappings = parseLabeler(fs.readFileSync(labeler, 'utf8'), labeler);
  validateScopeNames(scopes, mappings);
  validateTrackedPaths(mappings);
  await validateIdentities(options.apiUrl, identities);
  console.log(`governance: ${identities.length} identities resolved; ${scopes.length} scope rows valid`);
}

main().catch((error) => {
  console.error(`governance: ${error.message}`);
  process.exitCode = 1;
});