InputHistory.js

'use strict';

var crossvent = require('crossvent');
var InputState = require('./InputState');

function InputHistory (surface, mode) {
  var state = this;

  state.inputMode = mode;
  state.surface = surface;
  state.reset();

  listen(surface.textarea);
  listen(surface.editable);

  function listen (el) {
    var pasteHandler = selfie(handlePaste);
    crossvent.add(el, 'keypress', preventCtrlYZ);
    crossvent.add(el, 'keydown', selfie(handleCtrlYZ));
    crossvent.add(el, 'keydown', selfie(handleModeChange));
    crossvent.add(el, 'mousedown', setMoving);
    el.onpaste = pasteHandler;
    el.ondrop = pasteHandler;
  }

  function setMoving () {
    state.setMode('moving');
  }

  function selfie (fn) {
    return function handler (e) { return fn.call(null, state, e); };
  }
}

InputHistory.prototype.setInputMode = function (mode) {
  var state = this;
  state.inputMode = mode;
  state.reset();
};

InputHistory.prototype.reset = function () {
  var state = this;
  state.inputState = null;
  state.lastState = null;
  state.history = [];
  state.historyPointer = 0;
  state.historyMode = 'none';
  state.refreshing = null;
  state.refreshState(true);
  state.saveState();
  return state;
};

InputHistory.prototype.setCommandMode = function () {
  var state = this;
  state.historyMode = 'command';
  state.saveState();
  state.refreshing = setTimeout(function () {
    state.refreshState();
  }, 0);
};

InputHistory.prototype.canUndo = function () {
  return this.historyPointer > 1;
};

InputHistory.prototype.canRedo = function () {
  return this.history[this.historyPointer + 1];
};

InputHistory.prototype.undo = function () {
  var state = this;
  if (state.canUndo()) {
    if (state.lastState) {
      state.lastState.restore();
      state.lastState = null;
    } else {
      state.history[state.historyPointer] = new InputState(state.surface, state.inputMode);
      state.history[--state.historyPointer].restore();
    }
  }
  state.historyMode = 'none';
  state.surface.focus(state.inputMode);
  state.refreshState();
};

InputHistory.prototype.redo = function () {
  var state = this;
  if (state.canRedo()) {
    state.history[++state.historyPointer].restore();
  }

  state.historyMode = 'none';
  state.surface.focus(state.inputMode);
  state.refreshState();
};

InputHistory.prototype.setMode = function (value) {
  var state = this;
  if (state.historyMode !== value) {
    state.historyMode = value;
    state.saveState();
  }
  state.refreshing = setTimeout(function () {
    state.refreshState();
  }, 1);
};

InputHistory.prototype.refreshState = function (initialState) {
  var state = this;
  state.inputState = new InputState(state.surface, state.inputMode, initialState);
  state.refreshing = null;
};

InputHistory.prototype.saveState = function () {
  var state = this;
  var current = state.inputState || new InputState(state.surface, state.inputMode);

  if (state.historyMode === 'moving') {
    if (!state.lastState) {
      state.lastState = current;
    }
    return;
  }
  if (state.lastState) {
    if (state.history[state.historyPointer - 1].text !== state.lastState.text) {
      state.history[state.historyPointer++] = state.lastState;
    }
    state.lastState = null;
  }
  state.history[state.historyPointer++] = current;
  state.history[state.historyPointer + 1] = null;
};

function handleCtrlYZ (state, e) {
  var handled = false;
  var keyCode = e.charCode || e.keyCode;
  var keyCodeChar = String.fromCharCode(keyCode);

  if (e.ctrlKey || e.metaKey) {
    switch (keyCodeChar.toLowerCase()) {
      case 'y':
        state.redo();
        handled = true;
        break;

      case 'z':
        if (e.shiftKey) {
          state.redo();
        } else {
          state.undo();
        }
        handled = true;
        break;
    }
  }

  if (handled && e.preventDefault) {
    e.preventDefault();
  }
}

function handleModeChange (state, e) {
  if (e.ctrlKey || e.metaKey) {
    return;
  }

  var keyCode = e.keyCode;

  if ((keyCode >= 33 && keyCode <= 40) || (keyCode >= 63232 && keyCode <= 63235)) {
    state.setMode('moving');
  } else if (keyCode === 8 || keyCode === 46 || keyCode === 127) {
    state.setMode('deleting');
  } else if (keyCode === 13) {
    state.setMode('newlines');
  } else if (keyCode === 27) {
    state.setMode('escape');
  } else if ((keyCode < 16 || keyCode > 20) && keyCode !== 91) {
    state.setMode('typing');
  }
}

function handlePaste (state) {
  if (state.inputState && state.inputState.text !== state.surface.read(state.inputMode) && state.refreshing === null) {
    state.historyMode = 'paste';
    state.saveState();
    state.refreshState();
  }
}

function preventCtrlYZ (e) {
  var keyCode = e.charCode || e.keyCode;
  var yz = keyCode === 89 || keyCode === 90;
  var ctrl = e.ctrlKey || e.metaKey;
  if (ctrl && yz) {
    e.preventDefault();
  }
}

module.exports = InputHistory;