"use strict";

var isFunction = require("min-dash").isFunction,
  isObject = require("min-dash").isObject,
  some = require("min-dash").some;

var WILDCARD = "*";

function CamundaModdleExtension(eventBus) {
  var self = this;

  eventBus.on("moddleCopy.canCopyProperty", function(context) {
    var property = context.property,
      parent = context.parent;

    return self.canCopyProperty(property, parent);
  });
}

CamundaModdleExtension.$inject = ["eventBus"];

/**
 * Check wether to disallow copying property.
 */
CamundaModdleExtension.prototype.canCopyProperty = function(property, parent) {
  // (1) check wether property is allowed in parent
  if (isObject(property) && !isAllowedInParent(property, parent)) {
    return false;
  }

  // (2) check more complex scenarios

  if (is(property, "camunda:InputOutput") && !this.canHostInputOutput(parent)) {
    return false;
  }

  if (isAny(property, ["camunda:Connector", "camunda:Field"]) && !this.canHostConnector(parent)) {
    return false;
  }

  if (is(property, "camunda:In") && !this.canHostIn(parent)) {
    return false;
  }
};

CamundaModdleExtension.prototype.canHostInputOutput = function(parent) {
  // allowed in camunda:Connector
  var connector = getParent(parent, "camunda:Connector");

  if (connector) {
    return true;
  }

  // special rules inside bpmn:FlowNode
  var flowNode = getParent(parent, "bpmn:FlowNode");

  if (!flowNode) {
    return false;
  }

  if (isAny(flowNode, ["bpmn:StartEvent", "bpmn:Gateway", "bpmn:BoundaryEvent"])) {
    return false;
  }

  if (is(flowNode, "bpmn:SubProcess") && flowNode.get("triggeredByEvent")) {
    return false;
  }

  return true;
};

CamundaModdleExtension.prototype.canHostConnector = function(parent) {
  var serviceTaskLike = getParent(parent, "camunda:ServiceTaskLike");

  if (is(serviceTaskLike, "bpmn:MessageEventDefinition")) {
    // only allow on throw and end events
    return getParent(parent, "bpmn:IntermediateThrowEvent") || getParent(parent, "bpmn:EndEvent");
  }

  return true;
};

CamundaModdleExtension.prototype.canHostIn = function(parent) {
  var callActivity = getParent(parent, "bpmn:CallActivity");

  if (callActivity) {
    return true;
  }

  var signalEventDefinition = getParent(parent, "bpmn:SignalEventDefinition");

  if (signalEventDefinition) {
    // only allow on throw and end events
    return getParent(parent, "bpmn:IntermediateThrowEvent") || getParent(parent, "bpmn:EndEvent");
  }

  return true;
};

module.exports = CamundaModdleExtension;

// helpers //////////

function is(element, type) {
  return element && isFunction(element.$instanceOf) && element.$instanceOf(type);
}

function isAny(element, types) {
  return some(types, function(t) {
    return is(element, t);
  });
}

function getParent(element, type) {
  if (!type) {
    return element.$parent;
  }

  if (is(element, type)) {
    return element;
  }

  if (!element.$parent) {
    return;
  }

  return getParent(element.$parent, type);
}

function isAllowedInParent(property, parent) {
  // (1) find property descriptor
  var descriptor = property.$type && property.$model.getTypeDescriptor(property.$type);

  var allowedIn = descriptor && descriptor.meta && descriptor.meta.allowedIn;

  if (!allowedIn || isWildcard(allowedIn)) {
    return true;
  }

  // (2) check wether property has parent of allowed type
  return some(allowedIn, function(type) {
    return getParent(parent, type);
  });
}

function isWildcard(allowedIn) {
  return allowedIn.indexOf(WILDCARD) !== -1;
}