/*
 * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/ByteString.h>
#include <AK/LexicalPath.h>
#include <AK/SourceGenerator.h>
#include <AK/StringBuilder.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <LibIDL/IDLParser.h>
#include <LibIDL/Types.h>
#include <LibMain/Main.h>

static ErrorOr<void> add_to_interface_sets(IDL::Interface&, Vector<IDL::Interface&>& intrinsics, Vector<IDL::Interface&>& window_exposed, Vector<IDL::Interface&>& dedicated_worker_exposed, Vector<IDL::Interface&>& shared_worker_exposed, Vector<IDL::Interface&>& shadow_realm_exposed);
static ByteString s_error_string;

struct LegacyConstructor {
    ByteString name;
    ByteString constructor_class;
};

static void consume_whitespace(GenericLexer& lexer)
{
    bool consumed = true;
    while (consumed) {
        consumed = lexer.consume_while(is_ascii_space).length() > 0;

        if (lexer.consume_specific("//"sv)) {
            lexer.consume_until('\n');
            lexer.ignore();
            consumed = true;
        }
    }
}

static Optional<LegacyConstructor> const& lookup_legacy_constructor(IDL::Interface& interface)
{
    static HashMap<StringView, Optional<LegacyConstructor>> s_legacy_constructors;
    if (auto cache = s_legacy_constructors.get(interface.name); cache.has_value())
        return cache.value();

    auto attribute = interface.extended_attributes.get("LegacyFactoryFunction"sv);
    if (!attribute.has_value()) {
        s_legacy_constructors.set(interface.name, {});
        return s_legacy_constructors.get(interface.name).value();
    }

    GenericLexer function_lexer(attribute.value());
    consume_whitespace(function_lexer);

    auto name = function_lexer.consume_until([](auto ch) { return is_ascii_space(ch) || ch == '('; });
    auto constructor_class = ByteString::formatted("{}Constructor", name);

    s_legacy_constructors.set(interface.name, LegacyConstructor { name, move(constructor_class) });
    return s_legacy_constructors.get(interface.name).value();
}

static ErrorOr<void> generate_intrinsic_definitions(StringView output_path, Vector<IDL::Interface&>& exposed_interfaces)
{
    StringBuilder builder;
    SourceGenerator generator(builder);

    generator.append(R"~~~(
#include <LibGC/DeferGC.h>
#include <LibJS/Runtime/Object.h>
#include <LibWeb/Bindings/Intrinsics.h>)~~~");

    for (auto& interface : exposed_interfaces) {
        auto gen = generator.fork();
        gen.set("namespace_class", interface.namespace_class);
        gen.set("prototype_class", interface.prototype_class);
        gen.set("constructor_class", interface.constructor_class);

        if (interface.is_namespace) {
            gen.append(R"~~~(
#include <LibWeb/Bindings/@namespace_class@.h>)~~~");
        } else {
            gen.append(R"~~~(
#include <LibWeb/Bindings/@constructor_class@.h>
#include <LibWeb/Bindings/@prototype_class@.h>)~~~");

            if (auto const& legacy_constructor = lookup_legacy_constructor(interface); legacy_constructor.has_value()) {
                gen.set("legacy_constructor_class", legacy_constructor->constructor_class);
                gen.append(R"~~~(
#include <LibWeb/Bindings/@legacy_constructor_class@.h>)~~~");
            }
        }
    }

    generator.append(R"~~~(

namespace Web::Bindings {
)~~~");

    auto add_namespace = [&](SourceGenerator& gen, StringView name, StringView namespace_class) {
        gen.set("interface_name", name);
        gen.set("namespace_class", namespace_class);

        gen.append(R"~~~(
template<>
void Intrinsics::create_web_namespace<@namespace_class@>(JS::Realm& realm)
{
    auto namespace_object = realm.create<@namespace_class@>(realm);
    m_namespaces.set("@interface_name@"_fly_string, namespace_object);

    [[maybe_unused]] static constexpr u8 attr = JS::Attribute::Writable | JS::Attribute::Configurable;)~~~");

        for (auto& interface : exposed_interfaces) {
            if (interface.extended_attributes.get("LegacyNamespace"sv) != name)
                continue;

            gen.set("owned_interface_name", interface.name);
            gen.set("owned_prototype_class", interface.prototype_class);

            gen.append(R"~~~(
    namespace_object->define_intrinsic_accessor("@owned_interface_name@", attr, [](auto& realm) -> JS::Value { return &Bindings::ensure_web_constructor<@owned_prototype_class@>(realm, "@interface_name@.@owned_interface_name@"_fly_string); });)~~~");
        }

        gen.append(R"~~~(
}
)~~~");
    };

    auto add_interface = [](SourceGenerator& gen, StringView name, StringView prototype_class, StringView constructor_class, Optional<LegacyConstructor> const& legacy_constructor, StringView named_properties_class) {
        gen.set("interface_name", name);
        gen.set("prototype_class", prototype_class);
        gen.set("constructor_class", constructor_class);

        gen.append(R"~~~(
template<>
void Intrinsics::create_web_prototype_and_constructor<@prototype_class@>(JS::Realm& realm)
{
    auto& vm = realm.vm();

)~~~");
        if (!named_properties_class.is_empty()) {
            gen.set("named_properties_class", named_properties_class);
            gen.append(R"~~~(
    auto named_properties_object = realm.create<@named_properties_class@>(realm);
    m_prototypes.set("@named_properties_class@"_fly_string, named_properties_object);

)~~~");
        }
        gen.append(R"~~~(
    auto prototype = realm.create<@prototype_class@>(realm);
    m_prototypes.set("@interface_name@"_fly_string, prototype);

    auto constructor = realm.create<@constructor_class@>(realm);
    m_constructors.set("@interface_name@"_fly_string, constructor);

    prototype->define_direct_property(vm.names.constructor, constructor.ptr(), JS::Attribute::Writable | JS::Attribute::Configurable);
)~~~");

        if (legacy_constructor.has_value()) {
            gen.set("legacy_interface_name", legacy_constructor->name);
            gen.set("legacy_constructor_class", legacy_constructor->constructor_class);
            gen.append(R"~~~(
    auto legacy_constructor = realm.create<@legacy_constructor_class@>(realm);
    m_constructors.set("@legacy_interface_name@"_fly_string, legacy_constructor);)~~~");
        }

        gen.append(R"~~~(
}
)~~~");
    };

    for (auto& interface : exposed_interfaces) {
        auto gen = generator.fork();

        String named_properties_class;
        if (interface.extended_attributes.contains("Global") && interface.supports_named_properties()) {
            named_properties_class = MUST(String::formatted("{}Properties", interface.name));
        }

        if (interface.is_namespace)
            add_namespace(gen, interface.name, interface.namespace_class);
        else
            add_interface(gen, interface.namespaced_name, interface.prototype_class, interface.constructor_class, lookup_legacy_constructor(interface), named_properties_class);
    }

    generator.append(R"~~~(
}
)~~~");

    auto generated_intrinsics_path = LexicalPath(output_path).append("IntrinsicDefinitions.cpp"sv).string();
    auto generated_intrinsics_file = TRY(Core::File::open(generated_intrinsics_path, Core::File::OpenMode::Write));
    TRY(generated_intrinsics_file->write_until_depleted(generator.as_string_view().bytes()));

    return {};
}

static ErrorOr<void> generate_exposed_interface_header(StringView class_name, StringView output_path)
{
    StringBuilder builder;
    SourceGenerator generator(builder);

    generator.set("global_object_snake_name", ByteString(class_name).to_snakecase());
    generator.append(R"~~~(
#pragma once

#include <LibJS/Forward.h>

namespace Web::Bindings {

void add_@global_object_snake_name@_exposed_interfaces(JS::Object&);

}

)~~~");

    auto generated_header_path = LexicalPath(output_path).append(ByteString::formatted("{}ExposedInterfaces.h", class_name)).string();
    auto generated_header_file = TRY(Core::File::open(generated_header_path, Core::File::OpenMode::Write));
    TRY(generated_header_file->write_until_depleted(generator.as_string_view().bytes()));

    return {};
}

static ErrorOr<void> generate_exposed_interface_implementation(StringView class_name, StringView output_path, Vector<IDL::Interface&>& exposed_interfaces)
{
    StringBuilder builder;
    SourceGenerator generator(builder);

    generator.set("global_object_name", class_name);
    generator.set("global_object_snake_name", ByteString(class_name).to_snakecase());

    generator.append(R"~~~(
#include <LibJS/Runtime/Object.h>
#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/Bindings/@global_object_name@ExposedInterfaces.h>
)~~~");
    for (auto& interface : exposed_interfaces) {
        auto gen = generator.fork();
        gen.set("namespace_class", interface.namespace_class);
        gen.set("prototype_class", interface.prototype_class);
        gen.set("constructor_class", interface.constructor_class);

        if (interface.is_namespace) {
            gen.append(R"~~~(#include <LibWeb/Bindings/@namespace_class@.h>
)~~~");
        } else {

            gen.append(R"~~~(#include <LibWeb/Bindings/@constructor_class@.h>
#include <LibWeb/Bindings/@prototype_class@.h>
)~~~");

            if (auto const& legacy_constructor = lookup_legacy_constructor(interface); legacy_constructor.has_value()) {
                gen.set("legacy_constructor_class", legacy_constructor->constructor_class);
                gen.append(R"~~~(#include <LibWeb/Bindings/@legacy_constructor_class@.h>
)~~~");
            }
        }
    }

    generator.append(R"~~~(
namespace Web::Bindings {

void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
{
    static constexpr u8 attr = JS::Attribute::Writable | JS::Attribute::Configurable;
)~~~");

    auto add_interface = [](SourceGenerator& gen, StringView name, StringView prototype_class, Optional<LegacyConstructor> const& legacy_constructor, Optional<ByteString const&> legacy_alias_name) {
        gen.set("interface_name", name);
        gen.set("prototype_class", prototype_class);

        gen.append(R"~~~(
    global.define_intrinsic_accessor("@interface_name@", attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@interface_name@"_fly_string); });)~~~");

        // https://webidl.spec.whatwg.org/#LegacyWindowAlias
        if (legacy_alias_name.has_value()) {
            if (legacy_alias_name->starts_with('(')) {
                auto legacy_alias_names = legacy_alias_name->substring_view(1).split_view(',');
                for (auto legacy_alias_name : legacy_alias_names) {
                    gen.set("interface_alias_name", legacy_alias_name.trim_whitespace());
                    gen.append(R"~~~(
    global.define_intrinsic_accessor("@interface_alias_name@", attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@interface_name@"_fly_string); });)~~~");
                }
            } else {
                gen.set("interface_alias_name", *legacy_alias_name);
                gen.append(R"~~~(
    global.define_intrinsic_accessor("@interface_alias_name@", attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@interface_name@"_fly_string); });)~~~");
            }
        }

        if (legacy_constructor.has_value()) {
            gen.set("legacy_interface_name", legacy_constructor->name);
            gen.append(R"~~~(
    global.define_intrinsic_accessor("@legacy_interface_name@", attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@legacy_interface_name@"_fly_string); });)~~~");
        }
    };

    auto add_namespace = [](SourceGenerator& gen, StringView name, StringView namespace_class) {
        gen.set("interface_name", name);
        gen.set("namespace_class", namespace_class);

        gen.append(R"~~~(
    global.define_intrinsic_accessor("@interface_name@", attr, [](auto& realm) -> JS::Value { return &ensure_web_namespace<@namespace_class@>(realm, "@interface_name@"_fly_string); });)~~~");
    };

    for (auto& interface : exposed_interfaces) {
        auto gen = generator.fork();

        if (interface.is_namespace) {
            add_namespace(gen, interface.name, interface.namespace_class);
        } else if (!interface.extended_attributes.contains("LegacyNamespace"sv)) {
            if (interface.extended_attributes.contains("LegacyNoInterfaceObject")) {
                continue;
            }
            if (class_name == "Window") {
                add_interface(gen, interface.namespaced_name, interface.prototype_class, lookup_legacy_constructor(interface), interface.extended_attributes.get("LegacyWindowAlias"sv));
            } else {
                add_interface(gen, interface.namespaced_name, interface.prototype_class, lookup_legacy_constructor(interface), {});
            }
        }
    }

    generator.append(R"~~~(
}

}
)~~~");

    auto generated_implementation_path = LexicalPath(output_path).append(ByteString::formatted("{}ExposedInterfaces.cpp", class_name)).string();
    auto generated_implementation_file = TRY(Core::File::open(generated_implementation_path, Core::File::OpenMode::Write));
    TRY(generated_implementation_file->write_until_depleted(generator.as_string_view().bytes()));

    return {};
}

ErrorOr<int> serenity_main(Main::Arguments arguments)
{
    Core::ArgsParser args_parser;

    StringView output_path;
    Vector<ByteString> base_paths;
    Vector<ByteString> paths;

    args_parser.add_option(output_path, "Path to output generated files into", "output-path", 'o', "output-path");
    args_parser.add_option(Core::ArgsParser::Option {
        .argument_mode = Core::ArgsParser::OptionArgumentMode::Required,
        .help_string = "Path to root of IDL file tree(s)",
        .long_name = "base-path",
        .short_name = 'b',
        .value_name = "base-path",
        .accept_value = [&](StringView s) {
            base_paths.append(s);
            return true;
        },
    });
    args_parser.add_positional_argument(paths, "Paths of every IDL file that could be Exposed", "paths");
    args_parser.parse(arguments);

    VERIFY(!paths.is_empty());
    VERIFY(!base_paths.is_empty());

    Vector<ByteString> lexical_bases;
    for (auto const& base_path : base_paths) {
        VERIFY(!base_path.is_empty());
        lexical_bases.append(base_path);
    }

    // Read in all IDL files, we must own the storage for all of these for the lifetime of the program
    Vector<ByteString> file_contents;
    for (ByteString const& path : paths) {
        auto file_or_error = Core::File::open(path, Core::File::OpenMode::Read);
        if (file_or_error.is_error()) {
            s_error_string = ByteString::formatted("Unable to open file {}", path);
            return Error::from_string_view(s_error_string.view());
        }
        auto file = file_or_error.release_value();
        auto string = MUST(file->read_until_eof());
        file_contents.append(ByteString(ReadonlyBytes(string)));
    }
    VERIFY(paths.size() == file_contents.size());

    Vector<IDL::Parser> parsers;
    Vector<IDL::Interface&> intrinsics;
    Vector<IDL::Interface&> window_exposed;
    Vector<IDL::Interface&> dedicated_worker_exposed;
    Vector<IDL::Interface&> shared_worker_exposed;
    Vector<IDL::Interface&> shadow_realm_exposed;
    // TODO: service_worker_exposed

    for (size_t i = 0; i < paths.size(); ++i) {
        auto const& path = paths[i];
        IDL::Parser parser(path, file_contents[i], lexical_bases);
        auto& interface = parser.parse();
        if (interface.name.is_empty()) {
            s_error_string = ByteString::formatted("Interface for file {} missing", path);
            return Error::from_string_view(s_error_string.view());
        }

        TRY(add_to_interface_sets(interface, intrinsics, window_exposed, dedicated_worker_exposed, shared_worker_exposed, shadow_realm_exposed));
        parsers.append(move(parser));
    }

    TRY(generate_intrinsic_definitions(output_path, intrinsics));

    TRY(generate_exposed_interface_header("Window"sv, output_path));
    TRY(generate_exposed_interface_header("DedicatedWorker"sv, output_path));
    TRY(generate_exposed_interface_header("SharedWorker"sv, output_path));
    TRY(generate_exposed_interface_header("ShadowRealm"sv, output_path));
    // TODO: ServiceWorkerExposed.h

    TRY(generate_exposed_interface_implementation("Window"sv, output_path, window_exposed));
    TRY(generate_exposed_interface_implementation("DedicatedWorker"sv, output_path, dedicated_worker_exposed));
    TRY(generate_exposed_interface_implementation("SharedWorker"sv, output_path, shared_worker_exposed));
    TRY(generate_exposed_interface_implementation("ShadowRealm"sv, output_path, shadow_realm_exposed));
    // TODO: ServiceWorkerExposed.cpp

    return 0;
}

enum ExposedTo {
    Nobody = 0x0,
    DedicatedWorker = 0x1,
    SharedWorker = 0x2,
    ServiceWorker = 0x4,
    AudioWorklet = 0x8,
    Window = 0x10,
    ShadowRealm = 0x20,
    Worklet = 0x40,
    AllWorkers = DedicatedWorker | SharedWorker | ServiceWorker | AudioWorklet, // FIXME: Is "AudioWorklet" a Worker? We'll assume it is for now (here, and line below)
    All = AllWorkers | Window | ShadowRealm | Worklet,
};
AK_ENUM_BITWISE_OPERATORS(ExposedTo);

static ErrorOr<ExposedTo> parse_exposure_set(IDL::Interface& interface)
{
    // NOTE: This roughly follows the definitions of https://webidl.spec.whatwg.org/#Exposed
    //       It does not remotely interpret all the abstract operations therein though.

    auto maybe_exposed = interface.extended_attributes.get("Exposed");
    if (!maybe_exposed.has_value()) {
        s_error_string = ByteString::formatted("Interface {} is missing extended attribute Exposed", interface.name);
        return Error::from_string_view(s_error_string.view());
    }
    auto exposed = maybe_exposed.value().trim_whitespace();
    if (exposed == "*"sv)
        return ExposedTo::All;
    if (exposed == "Nobody"sv)
        return ExposedTo::Nobody;
    if (exposed == "Window"sv)
        return ExposedTo::Window;
    if (exposed == "Worker"sv)
        return ExposedTo::AllWorkers;
    if (exposed == "DedicatedWorker"sv)
        return ExposedTo::DedicatedWorker;
    if (exposed == "SharedWorker"sv)
        return ExposedTo::SharedWorker;
    if (exposed == "ServiceWorker"sv)
        return ExposedTo::ServiceWorker;
    if (exposed == "AudioWorklet"sv)
        return ExposedTo::AudioWorklet;
    if (exposed == "Worklet"sv)
        return ExposedTo::Worklet;
    if (exposed == "ShadowRealm"sv)
        return ExposedTo::ShadowRealm;

    if (exposed[0] == '(') {
        ExposedTo whom = Nobody;
        for (StringView candidate : exposed.substring_view(1, exposed.length() - 1).split_view(',')) {
            candidate = candidate.trim_whitespace();
            if (candidate == "Window"sv) {
                whom |= ExposedTo::Window;
            } else if (candidate == "Worker"sv) {
                whom |= ExposedTo::AllWorkers;
            } else if (candidate == "DedicatedWorker"sv) {
                whom |= ExposedTo::DedicatedWorker;
            } else if (candidate == "SharedWorker"sv) {
                whom |= ExposedTo::SharedWorker;
            } else if (candidate == "ServiceWorker"sv) {
                whom |= ExposedTo::ServiceWorker;
            } else if (candidate == "AudioWorklet"sv) {
                whom |= ExposedTo::AudioWorklet;
            } else if (candidate == "Worklet"sv) {
                whom |= ExposedTo::Worklet;
            } else if (candidate == "ShadowRealm"sv) {
                whom |= ExposedTo::ShadowRealm;
            } else {
                s_error_string = ByteString::formatted("Unknown Exposed attribute candidate {} in {} in {}", candidate, exposed, interface.name);
                return Error::from_string_view(s_error_string.view());
            }
        }
        if (whom == ExposedTo::Nobody) {
            s_error_string = ByteString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
            return Error::from_string_view(s_error_string.view());
        }
        return whom;
    }

    s_error_string = ByteString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
    return Error::from_string_view(s_error_string.view());
}

ErrorOr<void> add_to_interface_sets(IDL::Interface& interface, Vector<IDL::Interface&>& intrinsics, Vector<IDL::Interface&>& window_exposed, Vector<IDL::Interface&>& dedicated_worker_exposed, Vector<IDL::Interface&>& shared_worker_exposed, Vector<IDL::Interface&>& shadow_realm_exposed)
{
    // TODO: Add service worker exposed and audio worklet exposed
    auto whom = TRY(parse_exposure_set(interface));

    intrinsics.append(interface);

    if (whom & ExposedTo::Window)
        window_exposed.append(interface);

    if (whom & ExposedTo::DedicatedWorker)
        dedicated_worker_exposed.append(interface);

    if (whom & ExposedTo::SharedWorker)
        shared_worker_exposed.append(interface);

    if (whom & ExposedTo::ShadowRealm)
        shadow_realm_exposed.append(interface);

    return {};
}