module.exports = function (grunt) {
  function runNpmScript (command, cb) {
    var opts = {
      cmd: 'npm',
      args: ['run', command],
      opts: {
        stdio: 'inherit'
      }
    }

    grunt.util.spawn(opts, function (error, result, code) {
      if (error) {
        grunt.fail.warn(command + ' failed.')
      }
      cb()
    })
  }

  var autoStartBrowsers = ['Chrome', 'Firefox', 'Safari']

  var STREAM_SOURCE_PORT_HTTP = 4567

  var FILES_TRIGGERING_KARMA = [
    'src/**/*.js',
    'test/specs/*.spec.js',
    'test/libs/*.js',
    'test/*.js'
  ]

  grunt.initConfig({

    pkg: grunt.file.readJSON('package.json'),

    clean: ['dist/*.js', 'build/*.js'],

    karma: {
      options: {
        singleRun: true,
        proxies: {
          '/testServer': 'http://localhost:' + STREAM_SOURCE_PORT_HTTP
        },
        // test results reporter to use
        // possible values: 'dots', 'progress', 'junit'
        reporters: ['progress'],

        // enable / disable colors in the output (reporters and logs)
        colors: true
      },

      'coverage': {
        reporters: ['coverage'],
        preprocessors: {
          // source files to generate coverage for
          // (these files will be instrumented by Istanbul)
          'src/**/*.js': ['coverage']
        },
        'browsers': ['PhantomJS'],
        configFile: 'test/unit.conf.js'
      },

      'precaptured-dev': {
        // for doing a single test run with already captured browsers during development.
        // this is good for running tests in browsers karma can't easily start such as
        // IE running inside a Windows VM on a unix dev environment
        browsers: [],
        configFile: 'test/unit.conf.js',
        singleRun: 'true'
      },

      'single-dev': {
        browsers: autoStartBrowsers,
        configFile: 'test/unit.conf.js'
      },

      'single-concat': {
        browsers: autoStartBrowsers,
        configFile: 'test/concat.conf.js'
      },

      'single-minified': {
        browsers: autoStartBrowsers,
        configFile: 'test/min.conf.js'
      },

      'single-amd': {
        browsers: autoStartBrowsers,
        configFile: 'test/amd.conf.js'
      },

      'single-browser-http': {
        browsers: autoStartBrowsers,
        configFile: 'test/http.conf.js'
      },

      'persist': {
        // for setting up a persistent karma server.
        // To start the server, the task is:
        //    karma:persist
        // To run these, the task is:
        //    karma:persist:run
        configFile: 'test/unit.conf.js',
        browsers: [],
        singleRun: false,
        background: true
      },

      'single-heap': {
        configFile: 'test/heap.conf.js'
      }
    },

    exec: {
      // these might not go too well on Windows :-) - get Cygwin.
      reportMinifiedSize: {
        command: 'echo minified size is `wc -c < dist/oboe-browser.min.js` bytes'
      },
      reportMinifiedAndGzippedSize: {
        command: 'echo Size after gzip is `gzip --best --stdout dist/oboe-browser.min.js | wc -c` bytes - max 5120'
      },
      createGitVersionJs: {
        command: 'echo "`git describe`" > build/version.txt'
      },
      webpackBrowser: {
        command: 'npm run webpack'
      },
      webpackNode: {
        command: 'npm run webpack -- --config webpack.config.node.js'
      },
      standard: {
        command: 'npm run standard -- --fix --envs jasmine'
      }
    },

    watch: {
      karma: {
        files: FILES_TRIGGERING_KARMA,
        tasks: ['karma:persist:run']
      },

      // like above but reports the file size. This is good for
      // watching while developing to make sure it doesn't get
      // too big. Doesn't run tests against minified.
      karmaAndSize: {
        files: FILES_TRIGGERING_KARMA,
        tasks: [
          'karma:persist:run',
          'browser-build',
          'dist-sizes']
      },

      // like above but reports the file size. This is good for
      // watching while developing to make sure it doesn't get
      // too big. Doesn't run tests against minified.
      testNode: {
        files: FILES_TRIGGERING_KARMA,
        tasks: [
          'node-build']
      },

      restartStreamSourceAndRunTests: {
        // this fails at the moment because start-stream-source
        // fails if run more than once - the port is taken.
        files: ['test/streamsource.js'],
        tasks: ['start-stream-source', 'karma:persist:run']
      },

      standard: {
        files: FILES_TRIGGERING_KARMA,
        tasks: ['exec:standard']
      }
    },

    concurrent: {
      watchDev: {
        tasks: [ 'watch:karmaAndSize', 'watch:restartStreamSourceAndRunTests' ],
        options: {
          logConcurrentOutput: true
        }
      }
    }

  })

  require('matchdep').filterDev('grunt-*').forEach(grunt.loadNpmTasks)

  var streamSource

  grunt.registerTask('start-stream-source', function () {
    grunt.log.ok('do we have a streaming source already?', !!streamSource)

    // if we previously loaded the streamsource, stop it to let the new one in:
    if (streamSource) {
      grunt.log.ok('there seems to be a streaming server already, let\'s stop it')
      streamSource.stop()
    }

    streamSource = require('./test/streamsource.js')
    streamSource.start(STREAM_SOURCE_PORT_HTTP, grunt)
  })

  grunt.registerTask('jasmine_node_oboe', 'Runs jasmine-node.', function () {
    runNpmScript('test-node', this.async())
  })

  // change the auto-starting browsers so that future tests will use
  // phantomjs instead of actual browsers. Can do:
  //    grunt headless-mode default
  // to run without any actual browsers
  grunt.registerTask('headless-mode', function () {
    autoStartBrowsers.length = 0
    autoStartBrowsers.push('PhantomJS')
  })

  grunt.registerTask('test-start-server', [
    'karma:persist'
  ])

  grunt.registerTask('test-run', [
    'karma:persist:run'
  ])

  grunt.registerTask('dist-sizes', [
    'exec:reportMinifiedAndGzippedSize'
  ])

  grunt.registerTask('node-build', [
    'exec:createGitVersionJs',
    'exec:webpackNode'
  ])

  grunt.registerTask('node-build-test', [
    'node-build',
    'jasmine_node_oboe'
  ])

  grunt.registerTask('node', [
    'start-stream-source',
    'node-build-test'
  ])

  grunt.registerTask('browser-build', [
    'exec:createGitVersionJs',
    'exec:webpackBrowser'
  ])

  grunt.registerTask('browser-build-test', [
    'karma:single-dev',
    'karma:single-browser-http',
    'browser-build',
    'karma:single-concat',
    'karma:single-minified',
    'karma:single-amd'
  ])

  grunt.registerTask('build', [
    'exec:webpackBrowser'
  ])

  // build and run just the integration tests.
  grunt.registerTask('build-integration-test', [
    'build',
    'start-stream-source',
    'karma:single-concat',
    'jasmine_node_oboe',
    'dist-sizes'
  ])

  grunt.registerTask('default', [

    'clear',
    'clean',
    'start-stream-source',

    'browser-build-test',

    'node-build-test',

    'dist-sizes'
  ])

  // browser-test-auto-run or node-test-auto-run
  //
  // The most useful for developing. Start this task, capture some browsers
  // (unless node) then edit the code. Tests will be run as the code is
  // saved.
  grunt.registerTask('browser-test-auto-run', [
    'start-stream-source',
    'karma:persist',
    'concurrent:watchDev'
  ])
  grunt.registerTask('node-test-auto-run', [
    'start-stream-source',
    'watch:testNode'
  ])
  grunt.registerTask('coverage', [
    'karma:coverage'
  ])
}