/*
 * Copyright (c) 2021, Ali Mohammad Pur <mpfard@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <LibCore/FileStream.h>
#include <LibWasm/AbstractMachine/AbstractMachine.h>
#include <LibWasm/Printer/Printer.h>
#include <LibWasm/Types.h>

int main(int argc, char* argv[])
{
    const char* filename = nullptr;
    bool print = false;
    bool attempt_instantiate = false;
    String exported_function_to_execute;
    Vector<u64> values_to_push;

    Core::ArgsParser parser;
    parser.add_positional_argument(filename, "File name to parse", "file");
    parser.add_option(print, "Print the parsed module", "print", 'p');
    parser.add_option(attempt_instantiate, "Attempt to instantiate the module", "instantiate", 'i');
    parser.add_option(exported_function_to_execute, "Attempt to execute the named exported function from the module (implies -i)", "execute", 'e', "name");
    parser.add_option(Core::ArgsParser::Option {
        .requires_argument = true,
        .help_string = "Supply arguments to the function (default=0) (expects u64, casts to required type)",
        .long_name = "arg",
        .short_name = 0,
        .value_name = "u64",
        .accept_value = [&](const char* str) -> bool {
            if (auto v = StringView { str }.to_uint<u64>(); v.has_value()) {
                values_to_push.append(v.value());
                return true;
            }
            return false;
        },
    });
    parser.parse(argc, argv);

    if (!exported_function_to_execute.is_empty())
        attempt_instantiate = true;

    auto result = Core::File::open(filename, Core::OpenMode::ReadOnly);
    if (result.is_error()) {
        warnln("Failed to open {}: {}", filename, result.error());
        return 1;
    }

    auto stream = Core::InputFileStream(result.release_value());
    auto parse_result = Wasm::Module::parse(stream);
    if (parse_result.is_error()) {
        warnln("Something went wrong, either the file is invalid, or there's a bug with LibWasm!");
        warnln("The parse error was {}", Wasm::parse_error_to_string(parse_result.error()));
        return 2;
    }

    if (print && !attempt_instantiate) {
        auto out_stream = Core::OutputFileStream::standard_output();
        Wasm::Printer printer(out_stream);
        printer.print(parse_result.value());
    }

    if (attempt_instantiate) {
        Wasm::AbstractMachine machine;
        auto result = machine.instantiate(parse_result.value(), {});
        if (result.is_error()) {
            warnln("Module instantiation failed: {}", result.error().error);
            return 1;
        }
        auto module_instance = result.release_value();

        auto stream = Core::OutputFileStream::standard_output();
        auto print_func = [&](const auto& address) {
            Wasm::FunctionInstance* fn = machine.store().get(address);
            stream.write(String::formatted("- Function with address {}, ptr = {}\n", address.value(), fn).bytes());
            if (fn) {
                stream.write(String::formatted("    wasm function? {}\n", fn->has<Wasm::WasmFunction>()).bytes());
                fn->visit(
                    [&](const Wasm::WasmFunction& func) {
                        Wasm::Printer printer { stream, 3 };
                        stream.write("    type:\n"sv.bytes());
                        printer.print(func.type());
                        stream.write("    code:\n"sv.bytes());
                        printer.print(func.code());
                    },
                    [](const Wasm::HostFunction&) {});
            }
        };
        if (print) {
            // Now, let's dump the functions!
            for (auto& address : module_instance.functions()) {
                print_func(address);
            }
        }

        if (!exported_function_to_execute.is_empty()) {
            Optional<Wasm::FunctionAddress> run_address;
            Vector<Wasm::Value> values;
            for (auto& entry : module_instance.exports()) {
                if (entry.name() == exported_function_to_execute) {
                    if (auto addr = entry.value().get_pointer<Wasm::FunctionAddress>())
                        run_address = *addr;
                }
            }
            if (!run_address.has_value()) {
                warnln("No such exported function, sorry :(");
                return 1;
            }

            auto instance = machine.store().get(*run_address);
            VERIFY(instance);

            if (instance->has<Wasm::HostFunction>()) {
                warnln("Exported function is a host function, cannot run that yet");
                return 1;
            }

            for (auto& param : instance->get<Wasm::WasmFunction>().type().parameters()) {
                if (values_to_push.is_empty())
                    values.append(Wasm::Value { param, 0ull });
                else
                    values.append(Wasm::Value { param, values_to_push.take_last() });
            }

            if (print) {
                outln("Executing ");
                print_func(*run_address);
                outln();
            }

            auto result = machine.invoke(run_address.value(), move(values));
            if (result.is_trap())
                warnln("Execution trapped!");
            if (!result.values().is_empty())
                warnln("Returned:");
            for (auto& value : result.values()) {
                value.value().visit(
                    [&](const auto& value) {
                        if constexpr (requires { value.value(); })
                            out("  -> addr{} ", value.value());
                        else
                            out("  -> {} ", value);
                    });
                Wasm::Printer printer { stream };
                printer.print(value.type());
            }
        }
    }

    return 0;
}