import _ from 'lodash';
import logUtils from '../utils/log-utils';
const warn = logUtils.warn;

import scxml from '@scion-scxml/scxml';

type ScxmlCompiler = typeof scxml;
interface  FixedScxmlCompiler extends ScxmlCompiler {
    documentStringToModel: FixedDocumentStringToModel;
};

type DocumentStringToModel = typeof scxml.documentStringToModel;
type RawModule = {datamodel?: any, module: {_children: {add: (code: any) => void}[]}};
type HandleRawModule = (url: string, rawModule: any, ...args: any[]) => void;
type FixedDocumentStringToModel = DocumentStringToModel &{__handleRawModule: DocumentStringToModel, handleRawModule: HandleRawModule};

/**
 * scxml currently does not correctly declare the datamodel variables
 * -> fix this by injecting the datamodel variables by intercepting documentStringToModel.handleRawModule(url, rawModule, ...)
 *
 * TODO detect if this fix is needed (e.g. when future versions of scion-scxml have fixed this internally)
 *
 * @param       {scxml} [scxmlCompiler] the scxml module, e.g. <code>require('@scion-scxml/scxml')</code>.
 * 																				If omitted, the default scxml module will be used, i.e. <code>require('@scion-scxml/scxml')</code>.
 * 																				If already applied once, multiple calls to this function will be ignored.
 */
export function fixRawCompileInjectDataModule(scxmlCompiler: ScxmlCompiler | FixedScxmlCompiler): FixedScxmlCompiler {
    if(!scxmlCompiler){
        scxmlCompiler = require('@scion-scxml/scxml');
    }
    const fixedScxmlCompiler = scxmlCompiler as FixedScxmlCompiler;
    if(fixedScxmlCompiler.documentStringToModel.__handleRawModule){
        return;
    }
    fixedScxmlCompiler.documentStringToModel.__handleRawModule = fixedScxmlCompiler.documentStringToModel.handleRawModule;
    fixedScxmlCompiler.documentStringToModel.handleRawModule = function(_url, rawModule){
        var invokeConstructor: RawModule;
        for(var i=rawModule.invokeConstructors.length-1; i >= 0; --i){
            invokeConstructor = rawModule.invokeConstructors[i];
            if(invokeConstructor.datamodel) {
                if(!_.isArray(invokeConstructor.module._children) || invokeConstructor.module._children.length < 3 || typeof invokeConstructor.module._children[2].add !== 'function'){
                    warn('[mmir-tooling] could not FIX scxml datamodel variable declaration, because of encountering unknown data structure. Please update mmir-tooling to fix this.')
                } else {
                    var injectionNode = invokeConstructor.module._children[2];
                    injectionNode.add(invokeConstructor.datamodel);
                    injectionNode.add('\n');
                }
            }
        }
        fixedScxmlCompiler.documentStringToModel.__handleRawModule.apply(scxmlCompiler.documentStringToModel, arguments);
    }
}