'use strict';

// Forked from https://github.com/evanw/node-source-map-support to support
// Node's vm module.

/**
The MIT License (MIT)

Copyright (c) 2014 Evan Wallace

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

var SourceMapConsumer = require('source-map').SourceMapConsumer;
var path = require('path');
var fs = require('fs');

// Wrap the existing module's guts so we can inject a custom Error object. For fun,
// also call install() with the only option we care about.
function sourceMapSupport(Error, retrieveFileOverride) {
  var exports = {};

  // Only install once if called multiple times
  var alreadyInstalled = false;

  // If true, the caches are reset before a stack trace formatting operation
  var emptyCacheBetweenOperations = false;

  // Maps a file path to a string containing the file contents
  var fileContentsCache = {};

  // Maps a file path to a source map for that file
  var sourceMapCache = {};

  // Regex for detecting source maps
  var reSourceMap = /^data:application\/json[^,]+base64,/;

  function isInBrowser() {
    return ((typeof window !== 'undefined') && (typeof XMLHttpRequest === 'function'));
  }

  function hasGlobalProcessEventEmitter() {
    return ((typeof process === 'object') && (process !== null) && (typeof process.on === 'function'));
  }

  function retrieveFile(path) {
    // Trim the path to make sure there is no extra whitespace.
    path = path.trim();
    if (path in fileContentsCache) {
      return fileContentsCache[path];
    }

    try {
      // Use SJAX if we are in the browser
      if (isInBrowser()) {
        var xhr = new XMLHttpRequest();
        xhr.open('GET', path, false);
        xhr.send(null);
        var contents = null
        if (xhr.readyState === 4 && xhr.status === 200) {
          contents = xhr.responseText
        }
      }

      // Otherwise, use the filesystem
      else {
        var contents = fs.readFileSync(path, 'utf8');
      }
    } catch (e) {
      var contents = null;
    }

    return fileContentsCache[path] = contents;
  }

  // Support URLs relative to a directory, but be careful about a protocol prefix
  // in case we are in the browser (i.e. directories may start with "http://")
  function supportRelativeURL(file, url) {
    if (!file) return url;
    var dir = path.dirname(file);
    var match = /^\w+:\/\/[^\/]*/.exec(dir);
    var protocol = match ? match[0] : '';
    return protocol + path.resolve(dir.slice(protocol.length), url);
  }

  function retrieveSourceMapURL(source) {
    var fileData;

    if (isInBrowser()) {
      var xhr = new XMLHttpRequest();
      xhr.open('GET', source, false);
      xhr.send(null);
      fileData = xhr.readyState === 4 ? xhr.responseText : null;

      // Support providing a sourceMappingURL via the SourceMap header
      var sourceMapHeader = xhr.getResponseHeader("SourceMap") ||
                            xhr.getResponseHeader("X-SourceMap");
      if (sourceMapHeader) {
        return sourceMapHeader;
      }
    }

    // Get the URL of the source map
    fileData = retrieveFile(source);
    //        //# sourceMappingURL=foo.js.map                       /*# sourceMappingURL=foo.js.map */
    var re = /(?:\/\/[@#][ \t]+sourceMappingURL=([^\s'"]+?)[ \t]*$)|(?:\/\*[@#][ \t]+sourceMappingURL=([^\*]+?)[ \t]*(?:\*\/)[ \t]*$)/mg;
    // Keep executing the search to find the *last* sourceMappingURL to avoid
    // picking up sourceMappingURLs from comments, strings, etc.
    var lastMatch, match;
    while (match = re.exec(fileData)) lastMatch = match;
    if (!lastMatch) return null;
    return lastMatch[1];
  };

  // Can be overridden by the retrieveSourceMap option to install. Takes a
  // generated source filename; returns a {map, optional url} object, or null if
  // there is no source map.  The map field may be either a string or the parsed
  // JSON object (ie, it must be a valid argument to the SourceMapConsumer
  // constructor).
  function retrieveSourceMap(source) {
    var sourceMappingURL = retrieveSourceMapURL(source);
    if (!sourceMappingURL) return null;

    // Read the contents of the source map
    var sourceMapData;
    if (reSourceMap.test(sourceMappingURL)) {
      // Support source map URL as a data url
      var rawData = sourceMappingURL.slice(sourceMappingURL.indexOf(',') + 1);
      sourceMapData = new Buffer(rawData, "base64").toString();
      sourceMappingURL = null;
    } else {
      // Support source map URLs relative to the source URL
      sourceMappingURL = supportRelativeURL(source, sourceMappingURL);
      sourceMapData = retrieveFile(sourceMappingURL);
    }

    if (!sourceMapData) {
      return null;
    }

    return {
      url: sourceMappingURL,
      map: sourceMapData
    };
  }

  function mapSourcePosition(position) {
    var sourceMap = sourceMapCache[position.source];
    if (!sourceMap) {
      // Call the (overrideable) retrieveSourceMap function to get the source map.
      var urlAndMap = retrieveSourceMap(position.source);
      if (urlAndMap) {
        sourceMap = sourceMapCache[position.source] = {
          url: urlAndMap.url,
          map: new SourceMapConsumer(urlAndMap.map)
        };

        // Load all sources stored inline with the source map into the file cache
        // to pretend like they are already loaded. They may not exist on disk.
        if (sourceMap.map.sourcesContent) {
          sourceMap.map.sources.forEach(function(source, i) {
            var contents = sourceMap.map.sourcesContent[i];
            if (contents) {
              var url = supportRelativeURL(sourceMap.url, source);
              fileContentsCache[url] = contents;
            }
          });
        }
      } else {
        sourceMap = sourceMapCache[position.source] = {
          url: null,
          map: null
        };
      }
    }

    // Resolve the source URL relative to the URL of the source map
    if (sourceMap && sourceMap.map) {
      var originalPosition = sourceMap.map.originalPositionFor(position);

      // Only return the original position if a matching line was found. If no
      // matching line is found then we return position instead, which will cause
      // the stack trace to print the path and line for the compiled file. It is
      // better to give a precise location in the compiled file than a vague
      // location in the original file.
      if (originalPosition.source !== null) {
        originalPosition.source = supportRelativeURL(
          sourceMap.url, originalPosition.source);
        return originalPosition;
      }
    }

    return position;
  }

  // Parses code generated by FormatEvalOrigin(), a function inside V8:
  // https://code.google.com/p/v8/source/browse/trunk/src/messages.js
  function mapEvalOrigin(origin) {
    // Most eval() calls are in this format
    var match = /^eval at ([^(]+) \((.+):(\d+):(\d+)\)$/.exec(origin);
    if (match) {
      var position = mapSourcePosition({
        source: match[2],
        line: match[3],
        column: match[4] - 1
      });
      return 'eval at ' + match[1] + ' (' + position.source + ':' +
        position.line + ':' + (position.column + 1) + ')';
    }

    // Parse nested eval() calls using recursion
    match = /^eval at ([^(]+) \((.+)\)$/.exec(origin);
    if (match) {
      return 'eval at ' + match[1] + ' (' + mapEvalOrigin(match[2]) + ')';
    }

    // Make sure we still return useful information if we didn't find anything
    return origin;
  }

  // This is copied almost verbatim from the V8 source code at
  // https://code.google.com/p/v8/source/browse/trunk/src/messages.js. The
  // implementation of wrapCallSite() used to just forward to the actual source
  // code of CallSite.prototype.toString but unfortunately a new release of V8
  // did something to the prototype chain and broke the shim. The only fix I
  // could find was copy/paste.
  function CallSiteToString() {
    var fileName;
    var fileLocation = "";
    if (this.isNative()) {
      fileLocation = "native";
    } else {
      fileName = this.getScriptNameOrSourceURL();
      if (!fileName && this.isEval()) {
        fileLocation = this.getEvalOrigin();
        fileLocation += ", ";  // Expecting source position to follow.
      }

      if (fileName) {
        fileLocation += fileName;
      } else {
        // Source code does not originate from a file and is not native, but we
        // can still get the source position inside the source string, e.g. in
        // an eval string.
        fileLocation += "<anonymous>";
      }
      var lineNumber = this.getLineNumber();
      if (lineNumber != null) {
        fileLocation += ":" + lineNumber;
        var columnNumber = this.getColumnNumber();
        if (columnNumber) {
          fileLocation += ":" + columnNumber;
        }
      }
    }

    var line = "";
    var functionName = this.getFunctionName();
    var addSuffix = true;
    var isConstructor = this.isConstructor();
    var isMethodCall = !(this.isToplevel() || isConstructor);
    if (isMethodCall) {
      var typeName = this.getTypeName();
      var methodName = this.getMethodName();
      if (functionName) {
        if (typeName && functionName.indexOf(typeName) != 0) {
          line += typeName + ".";
        }
        line += functionName;
        if (methodName && functionName.indexOf("." + methodName) != functionName.length - methodName.length - 1) {
          line += " [as " + methodName + "]";
        }
      } else {
        line += typeName + "." + (methodName || "<anonymous>");
      }
    } else if (isConstructor) {
      line += "new " + (functionName || "<anonymous>");
    } else if (functionName) {
      line += functionName;
    } else {
      line += fileLocation;
      addSuffix = false;
    }
    if (addSuffix) {
      line += " (" + fileLocation + ")";
    }
    return line;
  }

  function cloneCallSite(frame) {
    var object = {};
    Object.getOwnPropertyNames(Object.getPrototypeOf(frame)).forEach(function(name) {
      object[name] = /^(?:is|get)/.test(name) ? function() { return frame[name].call(frame); } : frame[name];
    });
    object.toString = CallSiteToString;
    return object;
  }

  function wrapCallSite(frame) {
    // Most call sites will return the source file from getFileName(), but code
    // passed to eval() ending in "//# sourceURL=..." will return the source file
    // from getScriptNameOrSourceURL() instead
    var source = frame.getFileName() || frame.getScriptNameOrSourceURL();
    if (source) {
      var line = frame.getLineNumber();
      var column = frame.getColumnNumber() - 1;

      // Fix position in Node where some (internal) code is prepended.
      // See https://github.com/evanw/node-source-map-support/issues/36
      if (line === 1 && !isInBrowser() && !frame.isEval()) {
        column -= 62;
      }

      var position = mapSourcePosition({
        source: source,
        line: line,
        column: column
      });
      frame = cloneCallSite(frame);
      frame.getFileName = function() { return position.source; };
      frame.getLineNumber = function() { return position.line; };
      frame.getColumnNumber = function() { return position.column + 1; };
      frame.getScriptNameOrSourceURL = function() { return position.source; };
      return frame;
    }

    // Code called using eval() needs special handling
    var origin = frame.isEval() && frame.getEvalOrigin();
    if (origin) {
      origin = mapEvalOrigin(origin);
      frame = cloneCallSite(frame);
      frame.getEvalOrigin = function() { return origin; };
      return frame;
    }

    // If we get here then we were unable to change the source position
    return frame;
  }

  // This function is part of the V8 stack trace API, for more info see:
  // http://code.google.com/p/v8/wiki/JavaScriptStackTraceApi
  function prepareStackTrace(error, stack) {
    if (emptyCacheBetweenOperations) {
      fileContentsCache = {};
      sourceMapCache = {};
    }

    return error + stack.map(function(frame) {
      return '\n    at ' + wrapCallSite(frame);
    }).join('');
  }

  // Generate position and snippet of original source with pointer
  function getErrorSource(error) {
    var match = /\n    at [^(]+ \((.*):(\d+):(\d+)\)/.exec(error.stack);
    if (match) {
      var source = match[1];
      var line = +match[2];
      var column = +match[3];

      // Support the inline sourceContents inside the source map
      var contents = fileContentsCache[source];

      // Support files on disk
      if (!contents && fs.existsSync(source)) {
        contents = fs.readFileSync(source, 'utf8');
      }

      // Format the line from the original source code like node does
      if (contents) {
        var code = contents.split(/(?:\r\n|\r|\n)/)[line - 1];
        if (code) {
          return source + ':' + line + '\n' + code + '\n' +
            new Array(column).join(' ') + '^';
        }
      }
    }
    return null;
  }

  function printErrorAndExit (error) {
    var source = getErrorSource(error);

    if (source) {
      console.error();
      console.error(source);
    }

    console.error(error.stack);
    process.exit(1);
  }

  function shimEmitUncaughtException () {
    var origEmit = process.emit;

    process.emit = function (type) {
      if (type === 'uncaughtException') {
        var hasStack = (arguments[1] && arguments[1].stack);
        var hasListeners = (this.listeners(type).length > 0);

        if (hasStack && !hasListeners) {
          return printErrorAndExit(arguments[1]);
        }
      }

      return origEmit.apply(this, arguments);
    }
  }

  exports.wrapCallSite = wrapCallSite;
  exports.getErrorSource = getErrorSource;
  exports.mapSourcePosition = mapSourcePosition;
  exports.retrieveSourceMap = retrieveSourceMap;

  exports.install = function(options) {
    if (!alreadyInstalled) {
      alreadyInstalled = true;
      Error.prepareStackTrace = prepareStackTrace;

      // Configure options
      options = options || {};
      var installHandler = 'handleUncaughtExceptions' in options ?
        options.handleUncaughtExceptions : true;
      emptyCacheBetweenOperations = 'emptyCacheBetweenOperations' in options ?
        options.emptyCacheBetweenOperations : false;

      // Allow sources to be found by methods other than reading the files
      // directly from disk.
      if (options.retrieveFile)
        retrieveFile = options.retrieveFile;

      // Allow source maps to be found by methods other than reading the files
      // directly from disk.
      if (options.retrieveSourceMap)
        retrieveSourceMap = options.retrieveSourceMap;

      // Provide the option to not install the uncaught exception handler. This is
      // to support other uncaught exception handlers (in test frameworks, for
      // example). If this handler is not installed and there are no other uncaught
      // exception handlers, uncaught exceptions will be caught by node's built-in
      // exception handler and the process will still be terminated. However, the
      // generated JavaScript code will be shown above the stack trace instead of
      // the original source code.
      if (installHandler && hasGlobalProcessEventEmitter()) {
        shimEmitUncaughtException();
      }
    }
  };

  exports.install({retrieveFile: retrieveFileOverride});
}

module.exports = sourceMapSupport;
