const parser = require("@babel/parser");
const t = require("@babel/types");
const generator = require("@babel/generator");
const fs = require("fs");

function wtofile(path, flags, code) {
    var fd = fs.openSync(path,flags);
    fs.writeSync(fd, code);
    fs.closeSync(fd);
}

function run(loader_path, out_path, modular_path) {
    let js_code = fs.readFileSync(loader_path, {
        encoding: "utf-8"
    });

    // 转换为AST语法树
    let loader_ast = parser.parse(js_code);

    // 获取加载器代码
    let loader_body = loader_ast.program.body[0].expression.argument.callee.body.body;
    for (let i = 0; i < loader_body.length; i++){
        if (loader_body[i].type === 'VariableDeclaration'){
            loader_ast.program.body[0].expression.argument.callee.body.body.splice(i+3, (loader_body.length- i-3));
            loader_ast.program.body[0].expression.argument.callee.body.body.splice(0, i);
            loader_ast.program.body[0].expression.argument.callee.body.body.push(t.assignmentExpression("=", t.identifier("export_function"), t.identifier(loader_ast.program.body[0].expression.argument.callee.body.body[1].id.name)));
            break
        }
    }

    // 导入加载器中的函数体
    if (loader_ast.program.body[0].expression.argument.arguments[0].type === 'ArrayExpression'){
        let tempobjectexpression = t.objectExpression([]);
        loader_ast.program.body[0].expression.argument.arguments[0].elements.forEach(function (item, index) {
            if (item && item.type === 'FunctionExpression'){
                tempobjectexpression.properties.push(t.objectProperty(
                    t.numericLiteral(index),
                    item,
                    false,
                    false
                ));
            }
        });
        loader_ast.program.body[0].expression.argument.arguments[0] = tempobjectexpression;
    }

    // 加载外部函数体
    modular_path.forEach(function (item, index) {
        var jscode = fs.readFileSync(item, {
            encoding: "utf-8"
        });

        let modular_ast = parser.parse(jscode);
        modular_ast.program.body[0].expression.arguments[0].elements.forEach(function (item2, index2) {
            if (item2.type === 'ArrayExpression'){
                item2.elements.forEach(function (item3, index3) {
                    if (item3 && item3.type === 'FunctionExpression'){
                        loader_arguments.properties.push(t.objectProperty(
                            t.numericLiteral(index3),
                            item3,
                            false,
                            false
                        ));
                    }
                });
            }else {
                item2.properties.forEach(function (item3, index3) {
                    loader_arguments.properties.push(item3)
                })
            }
        });
    });

    // 申请全局导出函数
    loader_ast.program.body.splice(0, 0, t.variableDeclaration("var",[t.variableDeclarator(t.identifier("export_function"))]));
    // 导出函数
    loader_ast.program.body.push(t.expressionStatement(t.assignmentExpression("=", t.memberExpression(t.identifier("module"), t.identifier("exports"), false), t.identifier("export_function"))));

    let code = generator.default(loader_ast, {
        compact: false,  // 压缩格式
        comments: false,  // 注释
        jsescOption: {
            minimal: false // 转义
        }
    }).code;
    wtofile(out_path, 'w', code);
}

!function () {
    let loader_path, out_path;
    let modular_path = [];
    for(let i = 0; i < process.argv.length; i++){
        if (process.argv[i] === '-l'){
            loader_path = process.argv[i + 1];
            i += 1;
        }else if(process.argv[i] === '-m'){
            modular_path.push(process.argv[i + 1]);
            i += 1;
        }else if(process.argv[i] === '-o'){
            out_path = process.argv[i + 1];
            i += 1;
        }
    }
    if (loader_path && out_path){
        run(loader_path, out_path, modular_path)
    }
}();