var Q = require('q');
var readline = require('readline');
var spawn = require('child_process').spawn;
var path = require('path');
var glob = require('glob');
var fs = require('fs');
var util = require('./util');
var yaml = require('js-yaml');

module.exports = function(gulp, plugins, config) {
  return function() {
    var tempFile = '_analyzer.dart';
    return util.forEachSubDirSequential(config.dest, function(dir) {
      var pubspecContents = fs.readFileSync(path.join(dir, 'pubspec.yaml'));
      var pubspec = yaml.safeLoad(pubspecContents);
      var packageName = pubspec.name;

      var libFiles = [].slice.call(glob.sync('lib/**/*.dart', {cwd: dir}));
      var webFiles = [].slice.call(glob.sync('web/**/*.dart', {cwd: dir}));
      var testFiles = [].slice.call(glob.sync('test/**/*_spec.dart', {cwd: dir}));

      var analyzeFile = ['library _analyzer;'];
      libFiles.concat(testFiles).concat(webFiles).forEach(function(fileName, index) {
        if (fileName !== tempFile && fileName.indexOf("/packages/") === -1) {
          if (fileName.indexOf('lib') == 0) {
            fileName = 'package:' + packageName + '/' + path.relative('lib', fileName).replace(/\\/g, '/');
          }
          analyzeFile.push('import "' + fileName + '" as mod' + index + ';');
        }
      });
      fs.writeFileSync(path.join(dir, tempFile), analyzeFile.join('\n'));
      var defer = Q.defer();
      if (config.use_ddc) {
        analyze(dir, defer.makeNodeResolver(), true);
      } else {
        analyze(dir, defer.makeNodeResolver());
      }
      return defer.promise;
    });

    function analyze(dirName, done, useDdc) {
      // TODO remove --package-warnings once dartanalyzer handles transitive libraries
      var flags = ['--fatal-warnings', '--package-warnings', '--format=machine'];

      if (useDdc) {
        console.log('Using DDC analyzer to analyze', dirName);
        flags.push('--strong');
      }

      var args = flags.concat(tempFile);

      var stream = spawn(config.command, args, {
        // inherit stdin and stderr, but filter stdout
        stdio: [process.stdin, process.stdout, 'pipe'],
        cwd: dirName
      });
      // Filter out unused imports from our generated file.
      // We don't reexports from the generated file
      // as this could lead to name clashes when two files
      // export the same thing.
      var rl = readline.createInterface(
          {input: stream.stderr, output: process.stdout, terminal: false});
      var hintCount = 0;
      var errorCount = 0;
      var warningCount = 0;
      rl.on('line', function(line) {
        if (line == "find: >     bin [: No such file or directory") {
          //Skip bad output from Dart SDK .bat files on Windows
          return;
        }
        var parsedLine = _AnalyzerOutputLine.parse(line);
        if (!parsedLine) {
          errorCount++;
          console.log('Unexpected output: ' + line);
          return;
        }
        // TODO remove once dartanalyzer handles transitive libraries
        // skip errors in third-party packages
        if (parsedLine.sourcePath.indexOf(dirName) == -1) {
          return;
        }
        if (parsedLine.shouldIgnore()) {
          return;
        }

        if (parsedLine.isHint) {
          hintCount++;
        } else if (parsedLine.isWarning) {
          warningCount++;
        } else {
          errorCount++;
        }
        console.log(dirName + ':' + parsedLine);
      });
      stream.on('close', function() {
        var error;
        var report = [];
        if (errorCount > 0) {
          report.push(errorCount + ' error(s)');
        }
        if (warningCount > 0) {
          report.push(warningCount + ' warning(s)');
        }
        if (hintCount > 0) {
          report.push(hintCount + ' hint(s)');
        }
        if (report.length > 0) {
          error = 'Dartanalyzer showed ' + report.join(', ');
        }
        if (useDdc) {
          // TODO(yjbanov): fail the build when:
          //  - DDC analyzer is stable enough
          //  - We have cleaned up all DDC warnings
          console.log(error);
          done();
        } else {
          done(error);
        }
      });
      stream.on('error', function(e) {
        // TODO(yjbanov): fail the build when DDC is stable enough
        console.log('ERROR: failed to run DDC at all: ' + e);
      });
    }
  };
};

// See https://github.com/dart-lang/analyzer_cli/blob/master/lib/src/error_formatter.dart
function _AnalyzerOutputLine(result) {
  this.severity = result[1];
  this.errorType = result[2];
  this.errorCode = result[3];
  this.sourcePath = result[4];
  this.lineNum = result[5];
  this.colNum = result[6];
  this.asciiLineLength = parseInt(result[7], 10);
  this.errorMsg = result[8];

  this.isError = Boolean(this.severity.match(/ERROR/i));
  this.isHint = Boolean(this.severity.match(/INFO/i));
  this.isWarning = Boolean(this.severity.match(/WARNING/i));
}

_AnalyzerOutputLine.parse = function(line) {
  var result = _AnalyzerOutputLine._analyzerParseRegExp.exec(line);
  return result ? new _AnalyzerOutputLine(result) : null;
};

_AnalyzerOutputLine._analyzerParseRegExp =
    new RegExp('([^\|]+)\\|' +           // #1, severity (NONE, INFO, WARNING, ERROR)
               '([^\|]+)\\|' +           // #2, errorCode.type (HINT, *_WARNING, *_ERROR, etc)
               '([^\|]+)\\|' +           // #3, errorCode (UNUSED_IMPORT, UNUSED_CATCH_STACK, etc)
               '([^\|]+[^\|\\\\])\\|' +  // #4, sourcePath with '|' chars backslash-escaped.
               '([^\|]+)\\|' +           // #5, line number
               '([^\|]+)\\|' +           // #6, column number
               '([^\|]+)\\|' +           // #7, length of the ASCII line to draw
               '(.*)$');                 // #8, error message

/* Maps file path (as string) to file source (an array of strings, one per line). */
_AnalyzerOutputLine.cache = {};

_AnalyzerOutputLine.ERR_NO_SOURCE = '(Could not find source line).';

_AnalyzerOutputLine.prototype = {
  toString: function() {
    var sourceLine = this._getSourceLine();
    var lineText = _AnalyzerOutputLine.ERR_NO_SOURCE;
    if (sourceLine) {
      var repeat = function(str, num) {
        if (str.repeat) return str.repeat(num);
        return Array.prototype.join.call({length: num}, str);
      };

      lineText =
          '\n' + sourceLine + '\n' + repeat(' ', this.colNum) + repeat('^', this.asciiLineLength);
    }
    return '[' + this.severity + '] ' + this.errorMsg + ' (' + this.sourcePath + ', line ' +
           this.lineNum + ', col ' + this.colNum + ')' + lineText;
  },

  shouldIgnore: function() {
    if (this.errorCode.match(/UNUSED_IMPORT/i)) {
      if (this.sourcePath.match(/_analyzer\.dart/)) {
        return true;
      }
    }
    // TODO: https://github.com/angular/ts2dart/issues/168
    if (this.errorCode.match(/UNUSED_CATCH_STACK/i)) {
      return true;
    }

    // Don't worry about hints in generated files.
    if (this.isHint && this.sourcePath.match(/generated/i)) {
      return true;
    }
    return false;
  },

  // Reads the source file for the Analyzer output, caching it for future use.
  _getSourceLine: function() {
    var cache = _AnalyzerOutputLine.cache;
    var sourceLines = null;
    if (cache.hasOwnProperty(this.sourcePath)) {
      sourceLines = cache[this.sourcePath];
    } else {
      try {
        sourceLines = String(fs.readFileSync(this.sourcePath));
        sourceLines = sourceLines.split('\n');
      } catch (e) {
        sourceLines = null;
      } finally {
        // Even if this fails, cache `null` so we don't try again.
        cache[this.sourcePath] = sourceLines;
      }
    }
    return sourceLines && this.lineNum <= sourceLines.length ? sourceLines[this.lineNum - 1] : null;
  }
};