var util = require("../util");
var b    = require("recast").types.builders;
var _    = require("lodash");

var getSpreadLiteral = function (spread, file) {
  var literal = spread.argument;
  if (literal.type !== "ArrayExpression") {
    literal = util.template("call", {
      OBJECT: file.addDeclaration("slice"),
      CONTEXT: literal
    });
  }
  return literal;
};

var hasSpread = function (nodes) {
  return nodes.length && _.last(nodes).type === "SpreadElement";
};

exports.ArrayExpression = function (node, parent, file) {
  var elements = node.elements;
  if (!hasSpread(elements)) return;

  var spread = elements.pop();

  var concat = util.template("array-concat", {
    ARGUMENT: getSpreadLiteral(spread, file)
  });

  concat.callee.object.elements = elements;

  return concat;
};

exports.CallExpression = function (node, parent, file) {
  var args = node.arguments;
  if (!hasSpread(args)) return;

  var spread = args.pop();

  var spreadLiteral  = getSpreadLiteral(spread, file);
  var contextLiteral = b.literal(null);

  node.arguments = [];

  if (args.length) {
    var concat = util.template("array-concat");
    concat.arguments = [spreadLiteral];
    concat.callee.object.elements = args;
    node.arguments.push(concat);
  } else {
    node.arguments.push(spreadLiteral);
  }

  var callee = node.callee;

  if (callee.type === "MemberExpression") {
    contextLiteral = callee.object;

    if (callee.computed) {
      callee.object = b.memberExpression(callee.object, callee.property, true);
      callee.property = b.identifier("apply");
      callee.computed = false;
    } else {
      callee.property = b.memberExpression(callee.property, b.identifier("apply"), false);
    }
  } else {
    node.callee = b.memberExpression(node.callee, b.identifier("apply"), false);
  }

  node.arguments.unshift(contextLiteral);
};