/**
 * @license
 * Copyright 2017 The Bazel Authors. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 *
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * @fileoverview Patched NodeJS module loader for bazel. This template is
 * expanded to contain module name -> path mappings and then patches the
 * NodeJS require() function to substitute the appropriate paths.
 *
 * @see https://github.com/nodejs/node/blob/master/lib/module.js
 */
'use strict';
var path = require('path');
var fs = require('fs');

const isWindows = /^win/i.test(process.platform);
// Ensure that node is added to the path for any subprocess calls
process.env.PATH = [path.dirname(process.execPath), process.env.PATH].join(isWindows ? ';' : ':');

const VERBOSE_LOGS = !!process.env['VERBOSE_LOGS'];

function log_verbose(...m) {
  // This is a template file so we use __filename to output the actual filename
  if (VERBOSE_LOGS) console.error(`[${path.basename(__filename)}]`, ...m);
}

/**
 * The module roots as pairs of a RegExp to match the require path, and a
 * module_root to substitute for the require path.
 * Ordered by regex length, longest to smallest. 
 * @type {!Array<{module_name: RegExp, module_root: string}>}
 */
var MODULE_ROOTS = [
  TEMPLATED_module_roots
].sort((a, b) => b.module_name.toString().length - a.module_name.toString().length);

/**
 * Array of bootstrap modules that need to be loaded before the entry point.
 */
var BOOTSTRAP = [TEMPLATED_bootstrap];

const USER_WORKSPACE_NAME = 'TEMPLATED_user_workspace_name';
const NODE_MODULES_ROOT = 'TEMPLATED_node_modules_root';
const BIN_DIR = 'TEMPLATED_bin_dir';
const ENTRY_POINT = 'TEMPLATED_entry_point';
const GEN_DIR = 'TEMPLATED_gen_dir';
const INSTALL_SOURCE_MAP_SUPPORT = TEMPLATED_install_source_map_support;
const TARGET = 'TEMPLATED_target';

log_verbose(`running ${TARGET} with
  cwd: ${process.cwd()}
  runfiles: ${process.env.RUNFILES}

  BIN_DIR: ${BIN_DIR}
  BOOTSTRAP: ${JSON.stringify(BOOTSTRAP, undefined, 2)}
  ENTRY_POINT: ${ENTRY_POINT}
  GEN_DIR: ${GEN_DIR}
  INSTALL_SOURCE_MAP_SUPPORT: ${INSTALL_SOURCE_MAP_SUPPORT}
  MODULE_ROOTS: ${JSON.stringify(MODULE_ROOTS, undefined, 2)}
  NODE_MODULES_ROOT: ${NODE_MODULES_ROOT}
  TARGET: ${TARGET}
  USER_WORKSPACE_NAME: ${USER_WORKSPACE_NAME}
`);

function resolveToModuleRoot(path) {
  if (!path) {
    throw new Error('resolveToModuleRoot missing path: ' + path);
  }

  // We want all possible matches.
  const orderedMatches = MODULE_ROOTS.filter(m => m.module_name.test(path));

  if (orderedMatches.length === 0) {
    return null;
  } else {
    // Longest regex wins when multiple match, and the list is already ordered by length.
    const m = orderedMatches[0];
    return path.replace(m.module_name, m.module_root);
  }
}

/**
 * The runfiles manifest maps from short_path
 * https://docs.bazel.build/versions/master/skylark/lib/File.html#short_path
 * to the actual location on disk where the file can be read.
 *
 * In a sandboxed execution, it does not exist. In that case, runfiles must be
 * resolved from a symlink tree under the runfiles dir.
 * See https://github.com/bazelbuild/bazel/issues/3726
 */
function loadRunfilesManifest(manifestPath) {
  // Normalize slashes in manifestPath so they match slashes in manifest file
  manifestPath = manifestPath.replace(/\\/g, '/');

  log_verbose(`using manifest ${manifestPath}`);

  // Create the manifest and reverse manifest maps.
  const runfilesManifest = Object.create(null);
  const reverseRunfilesManifest = Object.create(null);
  const input = fs.readFileSync(manifestPath, {encoding: 'utf-8'});
  const outputBase = manifestPath.substring(0, manifestPath.indexOf('/execroot/'));

  // Absolute path that refers to the local workspace path. We need to determine the absolute
  // path to the local workspace because it allows us to support absolute path resolving
  // for runfiles.
  let localWorkspacePath = null;

  for (const line of input.split('\n')) {
    if (!line) continue;
    const [runfilesPath, realPath] = line.split(' ');
    runfilesManifest[runfilesPath] = realPath;
    reverseRunfilesManifest[realPath] = runfilesPath;

    // We don't need to try determining the local workspace path for the current runfile
    // mapping in case we already determined the local workspace path, the current
    // runfile refers to a different workspace, or the current runfile resolves to a file
    // in the bazel-out directory (bin/genfiles directory).
    if (localWorkspacePath || !runfilesPath.startsWith(USER_WORKSPACE_NAME) ||
        realPath.startsWith(outputBase)) {
      continue;
    }

    // Relative path for the runfile. We can compute that path by removing the leading
    // workspace name. e.g. `my_workspace/src/my-runfile.js` becomes `src/my-runfile.js`.
    const relativeWorkspacePath = runfilesPath.slice(USER_WORKSPACE_NAME.length + 1);

    // TODO(gregmagolan): should not be needed when --nolegacy_external_runfiles is default
    if (relativeWorkspacePath.startsWith('external/')) {
      continue;
    }

    localWorkspacePath = realPath.slice(0, -relativeWorkspacePath.length);
  }

  // Determine bin and gen root to convert absolute paths into runfile paths.
  const binRootIdx = manifestPath.indexOf(BIN_DIR);
  let binRoot, genRoot;
  if (binRootIdx !== -1) {
    const execRoot = manifestPath.slice(0, binRootIdx);
    binRoot = `${execRoot}${BIN_DIR}/`;
    genRoot = `${execRoot}${GEN_DIR}/`;
  }

  log_verbose(`using outputBase ${outputBase}`);
  log_verbose(`using binRoot ${binRoot}`);
  log_verbose(`using genRoot ${genRoot}`);
  log_verbose(`using localWorkspacePath ${localWorkspacePath}`);

  return { runfilesManifest, reverseRunfilesManifest, binRoot, genRoot, localWorkspacePath };
}
const { runfilesManifest, reverseRunfilesManifest, binRoot, genRoot, localWorkspacePath } =
    // On Windows, Bazel sets RUNFILES_MANIFEST_ONLY=1.
    // On every platform, Bazel also sets RUNFILES_MANIFEST_FILE, but on Linux
    // and macOS it's faster to use the symlinks in RUNFILES_DIR rather than resolve
    // through the indirection of the manifest file.
    // We also need to construct a reverse map to resolve relative files from existing
    // manifest entries.
    process.env.RUNFILES_MANIFEST_ONLY === '1' &&
    loadRunfilesManifest(process.env.RUNFILES_MANIFEST_FILE);

function isFile(res) {
  try {
    return fs.statSync(res).isFile();
  } catch (e) {
    return false;
  }
}

function isDirectory(res) {
  try {
    return fs.statSync(res).isDirectory();
  } catch (e) {
    return false;
  }
}

function readDir(dir) {
  return fs.statSync(dir).isDirectory() ?
      Array.prototype.concat(...fs.readdirSync(dir).map(f => readDir(path.join(dir, f)))) :
      dir.replace(/\\/g, '/');
}

function loadAsFileSync(res) {
  if (isFile(res)) {
    return res;
  }
  if (isFile(res + '.js')) {
    return res;
  }
  return null;
}

function loadAsDirectorySync(res) {
  const pkgfile = path.join(res, 'package.json');
  if (isFile(pkgfile)) {
    try {
      const pkg = JSON.parse(fs.readFileSync(pkgfile, 'UTF-8'));
      const main = pkg['main'];
      if (main) {
        if (main === '.' || main === './') {
          main = 'index';
        }

        let maybe = loadAsFileSync(path.resolve(res, main));
        if (maybe) {
          return maybe;
        }

        maybe = loadAsDirectorySync(path.resolve(res, main));
        if (maybe) {
          return maybe;
        }
      }
    } catch (e) {
    }
  }
  return loadAsFileSync(path.resolve(res, 'index'));
}

function resolveManifestFile(res) {
  const maybe = runfilesManifest[res] || runfilesManifest[res + '.js'];
  if (maybe) {
    return maybe;
  }
  // Look for tree artifacts that match and update
  // the runfiles with files that are in the tree artifact.
  // Attempt to resolve again with the updated runfiles
  // if a tree artifact matched.
  let segments = res.split('/');
  segments.pop();
  while (segments.length) {
    const test = segments.join('/');
    const tree = runfilesManifest[test];
    if (tree && isDirectory(tree)) {
      // We have a tree artifact that matches
      const files = readDir(tree).map(f => path.relative(tree, f).replace(/\\/g, '/'));
      files.forEach(f => {
        runfilesManifest[path.posix.join(test, f)] = path.posix.join(tree, f);
      })
      return runfilesManifest[res] || runfilesManifest[res + '.js'];
    }
    segments.pop();
  }
}

function resolveManifestDirectory(res) {
  const pkgfile = runfilesManifest[path.posix.join(res, 'package.json')];
  if (pkgfile) {
    try {
      const pkg = JSON.parse(fs.readFileSync(pkgfile, 'UTF-8'));
      const main = pkg['main'];
      if (main) {
        if (main === '.' || main === './') {
          main = 'index';
        }

        let maybe = resolveManifestFile(path.posix.join(res, main));
        if (maybe) {
          return maybe;
        }

        maybe = resolveManifestDirectory(path.posix.join(res, main));
        if (maybe) {
          return maybe;
        }
      }
    } catch (e) {
    }
  }
  return resolveManifestFile(path.posix.join(res, 'index'));
}

function resolveRunfiles(parent, ...pathSegments) {
  // Remove any empty strings from pathSegments
  // Normalize to forward slash, because even on Windows the runfiles_manifest file
  // is written with forward slash.
  let runfilesEntry = pathSegments.filter(segment => segment).join('/').replace(/\\/g, '/');

  // Trim `${USER_WORKSPACE_NAME}/external/` from start of runfilesEntry
  const externalWorkspacePrefix = `${USER_WORKSPACE_NAME}/external/`;
  if (runfilesEntry.startsWith(externalWorkspacePrefix)) {
    runfilesEntry = runfilesEntry.slice(externalWorkspacePrefix.length);
  }

  const runfilesPath = path.join(process.env.RUNFILES, runfilesEntry);

  if (runfilesManifest) {
    if (parent && runfilesEntry.startsWith('.')) {
      // Resolve relative paths from manifest files.
      const normalizedParent = parent.replace(/\\/g, '/');
      const parentRunfile = reverseRunfilesManifest[normalizedParent];
      if (parentRunfile) {
        runfilesEntry = path.join(path.dirname(parentRunfile), runfilesEntry);
      }
    } else if (runfilesEntry.startsWith(binRoot) || runfilesEntry.startsWith(genRoot)
        || runfilesEntry.startsWith(localWorkspacePath)) {
      // For absolute paths, replace binRoot, genRoot or localWorkspacePath with
      // USER_WORKSPACE_NAME to enable lookups.
      // It's OK to do multiple replacements because all of these are absolute paths with drive
      // names (e.g. C:\), and on Windows you can't have drive names in the middle of paths.
      runfilesEntry = runfilesEntry
        .replace(binRoot, `${USER_WORKSPACE_NAME}/`)
        .replace(genRoot, `${USER_WORKSPACE_NAME}/`)
        .replace(localWorkspacePath, `${USER_WORKSPACE_NAME}/`);
    }

    // Normalize and replace path separators to conform to the ones in the manifest.
    runfilesEntry = path.normalize(runfilesEntry).replace(/\\/g, '/');

    log_verbose('try to resolve in runfiles manifest', runfilesEntry);

    let maybe = resolveManifestFile(runfilesEntry);
    if (maybe) {
      log_verbose('resolved manifest file', maybe);
      return maybe;
    }

    maybe = resolveManifestDirectory(runfilesEntry);
    if (maybe) {
      log_verbose('resolved via manifest directory', maybe);
      return maybe;
    }
  } else {
    log_verbose('try to resolve in runfiles', runfilesPath);

    let maybe = loadAsFileSync(runfilesPath);
    if (maybe) {
      log_verbose('resolved file', maybe);
      return maybe;
    }

    maybe = loadAsDirectorySync(runfilesPath);
    if (maybe) {
      log_verbose('resolved via directory', maybe);
      return maybe;
    }
  }

  return runfilesPath;
}

var originalResolveFilename = module.constructor._resolveFilename;
module.constructor._resolveFilename = function(request, parent, isMain, options) {
  const parentFilename = (parent && parent.filename) ? parent.filename : undefined;
  log_verbose(`resolve ${request} from ${parentFilename}`);

  const failedResolutions = [];

  // Attempt to resolve to module root.
  // This should be the first attempted resolution because:
  // - it's fairly cheap to check (regex over a small array); 
  // - it is be very common when there are a lot of packages built from source;
  if (!isMain) {
    // Don't resolve to module root if this is the main entry point
    // as the main entry point will always be fully qualified with the
    // workspace name and full path.
    // See https://github.com/bazelbuild/rules_nodejs/issues/834
    const moduleRoot = resolveToModuleRoot(request);
    if (moduleRoot) {
      const moduleRootInRunfiles = resolveRunfiles(undefined, moduleRoot);
      const filename = module.constructor._findPath(moduleRootInRunfiles, []);
      if (filename) {
        return filename;
      } else {
        failedResolutions.push(
            `module root ${moduleRoot} - No file ${request} found in module root ${moduleRoot}`);
      }
    }
  }

  // Built-in modules, relative, absolute imports and npm dependencies
  // can be resolved using request
  try {
    const resolved = originalResolveFilename(request, parent, isMain, options);
    if (resolved === request || request.startsWith('.') || request.startsWith('/') ||
        request.match(/^[A-Z]\:[\\\/]/i)) {
      log_verbose(
          `resolved ${request} to built-in, relative or absolute import ` +
          `${resolved} from ${parentFilename}`);
      return resolved;
    } else {
      // Resolved is not a built-in module, relative or absolute import
      // but also allow imports within npm packages that are within the parent files
      // node_modules, meaning it is a dependency of the npm package making the import.
      const parentSegments = parentFilename ? parentFilename.replace(/\\/g, '/').split('/') : [];
      const parentNodeModulesSegment = parentSegments.indexOf('node_modules');
      if (parentNodeModulesSegment != -1) {
        const parentRoot = parentSegments.slice(0, parentNodeModulesSegment).join('/');
        const relative = path.relative(parentRoot, resolved);
        if (!relative.startsWith('..')) {
          // Resolved within parent node_modules
          log_verbose(
              `resolved ${request} within parent node_modules to ` +
              `${resolved} from ${parentFilename}`);
          return resolved;
        } else {
          throw new Error(
              `Resolved to ${resolved} outside of parent node_modules ${parentFilename}`);
        }
      }
      throw new Error('Not a built-in module, relative or absolute import');
    }
  } catch (e) {
    failedResolutions.push(`built-in, relative, absolute, nested node_modules - ${e.toString()}`);
  }

  // If the import is not a built-in module, an absolute, relative import or a
  // dependency of an npm package, attempt to resolve against the runfiles location
  try {
    const resolved = originalResolveFilename(resolveRunfiles(parentFilename, request), parent, isMain, options);
    log_verbose(`resolved ${request} within runfiles to ${resolved} from ${parentFilename}`);
    return resolved;
  } catch (e) {
    failedResolutions.push(`runfiles - ${e.toString()}`);
  }

  // If the parent file is from an external repository, attempt to resolve against
  // the external repositories node_modules (if they exist)
  let relativeParentFilename =
      parentFilename ? path.relative(process.env.RUNFILES, parent.filename) : undefined;
  if (relativeParentFilename && !relativeParentFilename.startsWith('..')) {
    // Remove leading USER_WORKSPACE_NAME/external so that external workspace name is
    // always the first segment
    // TODO(gregmagolan): should not be needed when --nolegacy_external_runfiles is default
    const externalPrefix = `${USER_WORKSPACE_NAME}/external/`;
    if (relativeParentFilename.startsWith(externalPrefix)) {
      relativeParentFilename = relativeParentFilename.substr(externalPrefix.length);
    }
    const parentSegments = relativeParentFilename.split('/');
    if (parentSegments[0] !== USER_WORKSPACE_NAME) {
      try {
        const resolved = originalResolveFilename(resolveRunfiles(undefined, parentSegments[0], 'node_modules', request), parent, isMain, options);
        log_verbose(
            `resolved ${request} within node_modules ` +
            `(${parentSegments[0]}/node_modules) to ${resolved} from ${relativeParentFilename}`);
        return resolved;
      } catch (e) {
        failedResolutions.push(`${parentSegments[0]}/node_modules - ${e.toString()}`);
      }
    }
  }

  // If import was not resolved above then attempt to resolve
  // within the node_modules filegroup in use
  try {
    const resolved = originalResolveFilename(resolveRunfiles(undefined, NODE_MODULES_ROOT, request), parent, isMain, options);
    log_verbose(
        `resolved ${request} within node_modules (${NODE_MODULES_ROOT}) to ` +
        `${resolved} from ${parentFilename}`);
    return resolved;
  } catch (e) {
    failedResolutions.push(`node_modules attribute (${NODE_MODULES_ROOT}) - ${e.toString()}`);
  }

  // Print the same error message that vanilla nodejs does.
  // See https://github.com/bazelbuild/rules_nodejs/issues/1015
  let moduleNotFoundError = `Cannot find module '${request}'. ` +
      'Please verify that the package.json has a valid "main" entry';
  if (VERBOSE_LOGS) {
    moduleNotFoundError += `\nrequired in target ${TARGET} by '${parentFilename}'\n  looked in:\n` +
        failedResolutions.map(r => `    ${r}`).join('\n') + '\n';
  }
  const error = new Error(moduleNotFoundError);
  error.code = 'MODULE_NOT_FOUND';
  // todo - error.path = ?;
  error.requestPath = parentFilename;
  error.bazelTarget = TARGET;
  error.failedResolutions = failedResolutions;

  throw error;
}

// Before loading anything that might print a stack, install the
// source-map-support.
if (INSTALL_SOURCE_MAP_SUPPORT) {
  try {
    const sourcemap_support_package = path.resolve(process.cwd(),
          '../build_bazel_rules_nodejs/third_party/github.com/source-map-support');
    require(sourcemap_support_package).install();
  } catch (_) {
    log_verbose(`WARNING: source-map-support module not installed.
      Stack traces from languages like TypeScript will point to generated .js files.
      Set install_source_map_support = False in ${TARGET} to turn off this warning.`);
  }
}
// Load all bootstrap modules before loading the entrypoint.
for (var i = 0; i < BOOTSTRAP.length; i++) {
  try {
    module.constructor._load(BOOTSTRAP[i], this);
  } catch (e) {
    console.error('bootstrap failure ' + e.stack || e);
    process.exit(1);
  }
}

if (require.main === module) {
  // Set the actual entry point in the arguments list.
  // argv[0] == node, argv[1] == entry point.
  // NB: entry_point below is replaced during the build process.
  var mainScript = process.argv[1] = ENTRY_POINT;
  try {
    module.constructor._load(mainScript, this, /*isMain=*/true);
  } catch (e) {
    console.error(e.stack || e);
    process.exit(1);
  }
}