/**
 * Copyright 2013-2014 Facebook, Inc.
 *
 * 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.
 *
 * @providesModule ReactDefaultPerfAnalysis
 */

var merge = require('merge');

// Don't try to save users less than 1.2ms (a number I made up)
var DONT_CARE_THRESHOLD = 1.2;
var DOM_OPERATION_TYPES = {
  'mountImageIntoNode': 'set innerHTML',
  INSERT_MARKUP: 'set innerHTML',
  MOVE_EXISTING: 'move',
  REMOVE_NODE: 'remove',
  TEXT_CONTENT: 'set textContent',
  'updatePropertyByID': 'update attribute',
  'deletePropertyByID': 'delete attribute',
  'updateStylesByID': 'update styles',
  'updateInnerHTMLByID': 'set innerHTML',
  'dangerouslyReplaceNodeWithMarkupByID': 'replace'
};

function getTotalTime(measurements) {
  // TODO: return number of DOM ops? could be misleading.
  // TODO: measure dropped frames after reconcile?
  // TODO: log total time of each reconcile and the top-level component
  // class that triggered it.
  var totalTime = 0;
  for (var i = 0; i < measurements.length; i++) {
    var measurement = measurements[i];
    totalTime += measurement.totalTime;
  }
  return totalTime;
}

function getDOMSummary(measurements) {
  var items = [];
  for (var i = 0; i < measurements.length; i++) {
    var measurement = measurements[i];
    var id;

    for (id in measurement.writes) {
      measurement.writes[id].forEach(function(write) {
        items.push({
          id: id,
          type: DOM_OPERATION_TYPES[write.type] || write.type,
          args: write.args
        });
      });
    }
  }
  return items;
}

function getExclusiveSummary(measurements) {
  var candidates = {};
  var displayName;

  for (var i = 0; i < measurements.length; i++) {
    var measurement = measurements[i];
    var allIDs = merge(measurement.exclusive, measurement.inclusive);

    for (var id in allIDs) {
      displayName = measurement.displayNames[id].current;

      candidates[displayName] = candidates[displayName] || {
        componentName: displayName,
        inclusive: 0,
        exclusive: 0,
        count: 0
      };
      if (measurement.exclusive[id]) {
        candidates[displayName].exclusive += measurement.exclusive[id];
      }
      if (measurement.inclusive[id]) {
        candidates[displayName].inclusive += measurement.inclusive[id];
      }
      if (measurement.counts[id]) {
        candidates[displayName].count += measurement.counts[id];
      }
    }
  }

  // Now make a sorted array with the results.
  var arr = [];
  for (displayName in candidates) {
    if (candidates[displayName].exclusive >= DONT_CARE_THRESHOLD) {
      arr.push(candidates[displayName]);
    }
  }

  arr.sort(function(a, b) {
    return b.exclusive - a.exclusive;
  });

  return arr;
}

function getInclusiveSummary(measurements, onlyClean) {
  var candidates = {};
  var inclusiveKey;

  for (var i = 0; i < measurements.length; i++) {
    var measurement = measurements[i];
    var allIDs = merge(measurement.exclusive, measurement.inclusive);
    var cleanComponents;

    if (onlyClean) {
      cleanComponents = getUnchangedComponents(measurement);
    }

    for (var id in allIDs) {
      if (onlyClean && !cleanComponents[id]) {
        continue;
      }

      var displayName = measurement.displayNames[id];

      // Inclusive time is not useful for many components without knowing where
      // they are instantiated. So we aggregate inclusive time with both the
      // owner and current displayName as the key.
      inclusiveKey = displayName.owner + ' > ' + displayName.current;

      candidates[inclusiveKey] = candidates[inclusiveKey] || {
        componentName: inclusiveKey,
        time: 0,
        count: 0
      };

      if (measurement.inclusive[id]) {
        candidates[inclusiveKey].time += measurement.inclusive[id];
      }
      if (measurement.counts[id]) {
        candidates[inclusiveKey].count += measurement.counts[id];
      }
    }
  }

  // Now make a sorted array with the results.
  var arr = [];
  for (inclusiveKey in candidates) {
    if (candidates[inclusiveKey].time >= DONT_CARE_THRESHOLD) {
      arr.push(candidates[inclusiveKey]);
    }
  }

  arr.sort(function(a, b) {
    return b.time - a.time;
  });

  return arr;
}

function getUnchangedComponents(measurement) {
  // For a given reconcile, look at which components did not actually
  // render anything to the DOM and return a mapping of their ID to
  // the amount of time it took to render the entire subtree.
  var cleanComponents = {};
  var dirtyLeafIDs = Object.keys(measurement.writes);
  var allIDs = merge(measurement.exclusive, measurement.inclusive);

  for (var id in allIDs) {
    var isDirty = false;
    // For each component that rendered, see if a component that triggerd
    // a DOM op is in its subtree.
    for (var i = 0; i < dirtyLeafIDs.length; i++) {
      if (dirtyLeafIDs[i].indexOf(id) === 0) {
        isDirty = true;
        break;
      }
    }
    if (!isDirty && measurement.counts[id] > 0) {
      cleanComponents[id] = true;
    }
  }
  return cleanComponents;
}

var ReactDefaultPerfAnalysis = {
  getExclusiveSummary: getExclusiveSummary,
  getInclusiveSummary: getInclusiveSummary,
  getDOMSummary: getDOMSummary,
  getTotalTime: getTotalTime
};

module.exports = ReactDefaultPerfAnalysis;
