// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
//
// Runner V8 script for testing dart2wasm, takes ".wasm" files as arguments.
//
// Run as follows:
//
// $> d8 --experimental-wasm-gc --wasm-gc-js-interop run_wasm.js -- <dart_module>.wasm [<ffi_module>.wasm]
//
// If an FFI module is specified, it will be instantiated first, and its
// exports will be supplied as imports to the Dart module under the 'ffi'
// module name.

function stringFromDartString(string) {
    var length = dartInstance.exports.$stringLength(string);
    var array = new Array(length);
    for (var i = 0; i < length; i++) {
        array[i] = dartInstance.exports.$stringRead(string, i);
    }
    return String.fromCharCode(...array);
}

function stringToDartString(string) {
    var length = string.length;
    var range = 0;
    for (var i = 0; i < length; i++) {
        range |= string.codePointAt(i);
    }
    if (range < 256) {
        var dartString = dartInstance.exports.$stringAllocate1(length);
        for (var i = 0; i < length; i++) {
            dartInstance.exports.$stringWrite1(dartString, i, string.codePointAt(i));
        }
        return dartString;
    } else {
        var dartString = dartInstance.exports.$stringAllocate2(length);
        for (var i = 0; i < length; i++) {
            dartInstance.exports.$stringWrite2(dartString, i, string.codePointAt(i));
        }
        return dartString;
    }
}

// Converts a JS array to a Dart List, and also recursively converts the items
// in the array.
function arrayToDartList(array, allocator, adder) {
    var length = array.length;
    var dartList = dartInstance.exports.$listAllocate();
    for (var i = 0; i < length; i++) {
        dartInstance.exports.$listAdd(dartList, array[i]);
    }
    return dartList;
}

// Converts a Dart List to a JS array. Any Dart objects will be converted, but
// this will be cheap for JSValues.
function arrayFromDartList(list, reader) {
    var length = dartInstance.exports.$listLength(list);
    var array = new Array(length);
    for (var i = 0; i < length; i++) {
        array[i] = dartInstance.exports.$listRead(list, i);
    }
    return array;
}

// TODO(joshualitt): Once we can properly return functions, then we can also try
// returning a regular closure with some custom keys and a special symbol to
// disambiguate it from other functions. I suspect this will also be necessary
// for CSP.
class WrappedDartCallback extends Function {
    constructor(dartCallback, exportFunctionName) {
        super('dartCallback', '...args',
            `return dartInstance.exports['${exportFunctionName}'](
                dartCallback, ...args.map(dartify));`);
        this.bound = this.bind(this, dartCallback);
        this.bound.dartCallback = dartCallback;
        return this.bound;
    }
}

// Recursively converts a JS object into a Dart object.
function dartify(object) {
    if (typeof object === "string") {
        return stringToDartString(object);
    } else if (object instanceof Array) {
        return arrayToDartList(object);
    } else if (object instanceof WrappedDartCallback) {
        return object.dartCallback;
    } else if (object instanceof Object) {
        return dartInstance.exports.$boxJSValue(object);
    } else {
        return object;
    }
}

// Imports for printing and event loop
var dart2wasm = {
    printToConsole: function(string) {
        console.log(stringFromDartString(string))
    },
    scheduleCallback: function(milliseconds, closure) {
        setTimeout(function() {
            dartInstance.exports.$call0(closure);
        }, milliseconds);
    },
    getCurrentStackTrace: function() {
        // [Error] should be supported in most browsers.
        // A possible future optimization we could do is to just save the
        // `Error` object here, and stringify the stack trace when it is
        // actually used.
        let stackString = new Error().stack.toString();

        // We remove the last three lines of the stack trace to prevent including
        // `Error`, `getCurrentStackTrace`, and `StackTrace.current` in the
        // stack trace.
        let userStackString = stackString.split('\n').slice(3).join('\n');
        return stringToDartString(userStackString);
    },
    arrayFromDartList: arrayFromDartList,
    arrayToDartList: arrayToDartList,
    stringFromDartString: stringFromDartString,
    stringToDartString: stringToDartString,
    wrapDartCallback: function(dartCallback, exportFunctionName) {
        return new WrappedDartCallback(dartCallback, exportFunctionName);
    },
    dartify: dartify,
    newObject: function() {
        return {};
    },
    globalThis: function() {
        return globalThis;
    },
    getProperty: function(object, name) {
        return object[name];
    },
    hasProperty: function(object, name) {
        return name in object;
    },
    setProperty: function(object, name, value) {
        return object[name] = value;
    },
    callMethodVarArgs: function(object, name, args) {
        return object[name].apply(object, args);
    },
    callConstructorVarArgs: function(constructor, args) {
        // Apply bind to the constructor. We pass `null` as the first argument
        // to `bind.apply` because this is `bind`'s unused context
        // argument(`new` will explicitly create a new context).
        var factoryFunction = constructor.bind.apply(constructor, [null, ...args]);
        return new factoryFunction();
    },
};

function instantiate(filename, imports) {
    // Create a Wasm module from the binary wasm file.
    var bytes = readbuffer(filename);
    var module = new WebAssembly.Module(bytes);
    return new WebAssembly.Instance(module, imports);
}

// Import from the global scope.
var importObject = (typeof window !== 'undefined')
    ? window
    : Realm.global(Realm.current());

// Is an FFI module specified?
if (arguments.length > 1) {
    // instantiate FFI module
    var ffiInstance = instantiate(arguments[1], {});
    // Make its exports available as imports under the 'ffi' module name
    importObject.ffi = ffiInstance.exports;
}

// Instantiate the Dart module, importing from the global scope.
var dartInstance = instantiate(arguments[0], importObject);

var result = dartInstance.exports.main();
if (result) console.log(result);