const path = require('path');
const github = require('github-from-package');
const home = require('os').homedir;
const crypto = require('crypto');
const expandTemplate = require('expand-template')();

function getDownloadUrl(opts) {
  const pkgName = opts.pkg.name.replace(/^@[a-zA-Z0-9_\-.~]+\//, '');
  return expandTemplate(urlTemplate(opts), {
    name: pkgName,
    package_name: pkgName,
    version: opts.pkg.version,
    major: opts.pkg.version.split('.')[0],
    minor: opts.pkg.version.split('.')[1],
    patch: opts.pkg.version.split('.')[2],
    prerelease: opts.pkg.version.split('-')[1],
    build: opts.pkg.version.split('+')[1],
    abi: opts.abi || process.versions.modules,
    node_abi: process.versions.modules,
    runtime: opts.runtime || 'node',
    platform: opts.platform,
    arch: opts.arch,
    libc: opts.libc || '',
    configuration: opts.debug ? 'Debug' : 'Release',
    module_name: opts.pkg.binary && opts.pkg.binary.module_name,
    tag_prefix: opts['tag-prefix'],
  });
}

function getApiUrl(opts) {
  return (
    github(opts.pkg).replace('github.com', 'api.github.com/repos') + '/releases'
  );
}

function getAssetUrl(opts, assetId) {
  return getApiUrl(opts) + '/assets/' + assetId;
}

function urlTemplate(opts) {
  if (typeof opts.download === 'string') {
    return opts.download;
  }

  const packageName =
    '{name}-v{version}-{runtime}-v{abi}-{platform}{libc}-{arch}.tar.gz';
  const hostMirrorUrl = getHostMirrorUrl(opts);

  if (hostMirrorUrl) {
    return hostMirrorUrl + '/{tag_prefix}{version}/' + packageName;
  }

  if (opts.pkg.binary && opts.pkg.binary.host) {
    return [
      opts.pkg.binary.host,
      opts.pkg.binary.remote_path,
      opts.pkg.binary.package_name || packageName,
    ]
      .map(function (path) {
        return trimSlashes(path);
      })
      .filter(Boolean)
      .join('/');
  }

  return (
    github(opts.pkg) + '/releases/download/{tag_prefix}{version}/' + packageName
  );
}

function getEnvPrefix(pkgName) {
  return (
    'npm_config_' +
    (pkgName || '').replace(/[^a-zA-Z0-9]/g, '_').replace(/^_/, '')
  );
}

function getHostMirrorUrl(opts) {
  const propName = getEnvPrefix(opts.pkg.name) + '_binary_host';
  return process.env[propName] || process.env[propName + '_mirror'];
}

function trimSlashes(str) {
  if (str) return str.replace(/^\.\/|^\/|\/$/g, '');
}

function cachedPrebuild(url) {
  const digest = crypto.createHash('md5').update(url).digest('hex').slice(0, 6);
  return path.join(
    prebuildCache(),
    digest + '-' + path.basename(url).replace(/[^a-zA-Z0-9.]+/g, '-')
  );
}

function npmCache() {
  const env = process.env;
  return (
    env.npm_config_cache ||
    (env.APPDATA ?
      path.join(env.APPDATA, 'npm-cache')
    : path.join(home(), '.npm'))
  );
}

function prebuildCache() {
  return path.join(npmCache(), '_prebuilds');
}

function tempFile(cached) {
  return (
    cached +
    '.' +
    process.pid +
    '-' +
    Math.random().toString(16).slice(2) +
    '.tmp'
  );
}

function packageOrigin(env, pkg) {
  // npm <= 6: metadata is stored on disk in node_modules
  if (pkg._from) {
    return pkg._from;
  }

  // npm 7: metadata is exposed to environment by arborist
  if (env.npm_package_from) {
    // NOTE: seems undefined atm (npm 7.0.2)
    return env.npm_package_from;
  }

  if (env.npm_package_resolved) {
    // NOTE: not sure about the difference with _from, but it's all we have
    return env.npm_package_resolved;
  }
}

function localPrebuild(url, opts) {
  const propName = getEnvPrefix(opts.pkg.name) + '_local_prebuilds';
  const prefix =
    process.env[propName] || opts['local-prebuilds'] || 'prebuilds';
  return path.join(prefix, path.basename(url));
}

const noopLogger = {
  http: function () {},
  silly: function () {},
  debug: function () {},
  info: function () {},
  warn: function () {},
  error: function () {},
  critical: function () {},
  alert: function () {},
  emergency: function () {},
  notice: function () {},
  verbose: function () {},
  fatal: function () {},
};

exports.getDownloadUrl = getDownloadUrl;
exports.getApiUrl = getApiUrl;
exports.getAssetUrl = getAssetUrl;
exports.urlTemplate = urlTemplate;
exports.cachedPrebuild = cachedPrebuild;
exports.localPrebuild = localPrebuild;
exports.prebuildCache = prebuildCache;
exports.npmCache = npmCache;
exports.tempFile = tempFile;
exports.packageOrigin = packageOrigin;
exports.noopLogger = noopLogger;