/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/Function.h>
#include <AK/GenericLexer.h>
#include <AK/HashMap.h>
#include <AK/SourceGenerator.h>
#include <AK/StringBuilder.h>
#include <LibCore/File.h>
#include <ctype.h>
#include <stdio.h>

//#define GENERATE_DEBUG_CODE

struct Parameter {
    Vector<String> attributes;
    String type;
    String name;
};

struct Message {
    String name;
    bool is_synchronous { false };
    Vector<Parameter> inputs;
    Vector<Parameter> outputs;

    String response_name() const
    {
        StringBuilder builder;
        builder.append(name);
        builder.append("Response");
        return builder.to_string();
    }
};

struct Endpoint {
    String name;
    int magic;
    Vector<Message> messages;
};

int main(int argc, char** argv)
{
    if (argc != 2) {
        outln("usage: {} <IPC endpoint definition file>", argv[0]);
        return 0;
    }

    auto file = Core::File::construct(argv[1]);
    if (!file->open(Core::IODevice::ReadOnly)) {
        warnln("Error: Cannot open {}: {}", argv[1], file->error_string());
        return 1;
    }

    auto file_contents = file->read_all();
    GenericLexer lexer(file_contents);

    Vector<Endpoint> endpoints;

    auto assert_specific = [&](char ch) {
        if (lexer.peek() != ch)
            warnln("assert_specific: wanted '{}', but got '{}' at index {}", ch, lexer.peek(), lexer.tell());
        bool saw_expected = lexer.consume_specific(ch);
        ASSERT(saw_expected);
    };

    auto consume_whitespace = [&] {
        lexer.ignore_while([](char ch) { return isspace(ch); });
        if (lexer.peek() == '/' && lexer.peek(1) == '/')
            lexer.ignore_until([](char ch) { return ch == '\n'; });
    };

    auto parse_parameter = [&](Vector<Parameter>& storage) {
        for (;;) {
            Parameter parameter;
            consume_whitespace();
            if (lexer.peek() == ')')
                break;
            if (lexer.consume_specific('[')) {
                for (;;) {
                    if (lexer.consume_specific(']')) {
                        consume_whitespace();
                        break;
                    }
                    if (lexer.consume_specific(',')) {
                        consume_whitespace();
                    }
                    auto attribute = lexer.consume_until([](char ch) { return ch == ']' || ch == ','; });
                    parameter.attributes.append(attribute);
                    consume_whitespace();
                }
            }
            parameter.type = lexer.consume_until([](char ch) { return isspace(ch); });
            consume_whitespace();
            parameter.name = lexer.consume_until([](char ch) { return isspace(ch) || ch == ',' || ch == ')'; });
            consume_whitespace();
            storage.append(move(parameter));
            if (lexer.consume_specific(','))
                continue;
            if (lexer.peek() == ')')
                break;
        }
    };

    auto parse_parameters = [&](Vector<Parameter>& storage) {
        for (;;) {
            consume_whitespace();
            parse_parameter(storage);
            consume_whitespace();
            if (lexer.consume_specific(','))
                continue;
            if (lexer.peek() == ')')
                break;
        }
    };

    auto parse_message = [&] {
        Message message;
        consume_whitespace();
        message.name = lexer.consume_until([](char ch) { return isspace(ch) || ch == '('; });
        consume_whitespace();
        assert_specific('(');
        parse_parameters(message.inputs);
        assert_specific(')');
        consume_whitespace();
        assert_specific('=');

        auto type = lexer.consume();
        if (type == '>')
            message.is_synchronous = true;
        else if (type == '|')
            message.is_synchronous = false;
        else
            ASSERT_NOT_REACHED();

        consume_whitespace();

        if (message.is_synchronous) {
            assert_specific('(');
            parse_parameters(message.outputs);
            assert_specific(')');
        }

        consume_whitespace();

        endpoints.last().messages.append(move(message));
    };

    auto parse_messages = [&] {
        for (;;) {
            consume_whitespace();
            parse_message();
            consume_whitespace();
            if (lexer.peek() == '}')
                break;
        }
    };

    auto parse_endpoint = [&] {
        endpoints.empend();
        consume_whitespace();
        lexer.consume_specific("endpoint");
        consume_whitespace();
        endpoints.last().name = lexer.consume_while([](char ch) { return !isspace(ch); });
        consume_whitespace();
        assert_specific('=');
        consume_whitespace();
        auto magic_string = lexer.consume_while([](char ch) { return !isspace(ch) && ch != '{'; });
        endpoints.last().magic = magic_string.to_int().value();
        consume_whitespace();
        assert_specific('{');
        parse_messages();
        assert_specific('}');
        consume_whitespace();
    };

    while (lexer.tell() < file_contents.size())
        parse_endpoint();

    StringBuilder builder;
    SourceGenerator generator { builder };

    generator.append(R"~~~(
#pragma once
#include <AK/MemoryStream.h>
#include <AK/OwnPtr.h>
#include <AK/URL.h>
#include <AK/Utf8View.h>
#include <LibGfx/Color.h>
#include <LibGfx/Rect.h>
#include <LibGfx/ShareableBitmap.h>
#include <LibIPC/Decoder.h>
#include <LibIPC/Dictionary.h>
#include <LibIPC/Encoder.h>
#include <LibIPC/Endpoint.h>
#include <LibIPC/File.h>
#include <LibIPC/Message.h>
)~~~");

    for (auto& endpoint : endpoints) {
        auto endpoint_generator = generator.fork();

        endpoint_generator.set("endpoint.name", endpoint.name);
        endpoint_generator.set("endpoint.magic", String::number(endpoint.magic));

        endpoint_generator.append(R"~~~(
namespace Messages::@endpoint.name@ {
)~~~");

        HashMap<String, int> message_ids;

        endpoint_generator.append(R"~~~(
enum class MessageID : i32 {
)~~~");
        for (auto& message : endpoint.messages) {
            auto message_generator = endpoint_generator.fork();

            message_ids.set(message.name, message_ids.size() + 1);
            message_generator.set("message.name", message.name);
            message_generator.set("message.id", String::number(message_ids.size()));

            message_generator.append(R"~~~(
    @message.name@ = @message.id@,
)~~~");
            if (message.is_synchronous) {
                message_ids.set(message.response_name(), message_ids.size() + 1);
                message_generator.set("message.name", message.response_name());
                message_generator.set("message.id", String::number(message_ids.size()));

                message_generator.append(R"~~~(
    @message.name@ = @message.id@,
)~~~");
            }
        }
        endpoint_generator.append(R"~~~(
};
)~~~");

        auto constructor_for_message = [&](const String& name, const Vector<Parameter>& parameters) {
            StringBuilder builder;
            builder.append(name);

            if (parameters.is_empty()) {
                builder.append("() {}");
                return builder.to_string();
            }

            builder.append('(');
            for (size_t i = 0; i < parameters.size(); ++i) {
                auto& parameter = parameters[i];
                builder.append("const ");
                builder.append(parameter.type);
                builder.append("& ");
                builder.append(parameter.name);
                if (i != parameters.size() - 1)
                    builder.append(", ");
            }
            builder.append(") : ");
            for (size_t i = 0; i < parameters.size(); ++i) {
                auto& parameter = parameters[i];
                builder.append("m_");
                builder.append(parameter.name);
                builder.append("(");
                builder.append(parameter.name);
                builder.append(")");
                if (i != parameters.size() - 1)
                    builder.append(", ");
            }
            builder.append(" {}");
            return builder.to_string();
        };

        auto do_message = [&](const String& name, const Vector<Parameter>& parameters, const String& response_type = {}) {
            auto message_generator = endpoint_generator.fork();
            message_generator.set("message.name", name);
            message_generator.set("message.response_type", response_type);
            message_generator.set("message.constructor", constructor_for_message(name, parameters));

            message_generator.append(R"~~~(
class @message.name@ final : public IPC::Message {
public:
)~~~");

            if (!response_type.is_null())
                message_generator.append(R"~~~(
   typedef class @message.response_type@ ResponseType;
)~~~");

            message_generator.append(R"~~~(
    @message.constructor@
    virtual ~@message.name@() override {}

    virtual i32 endpoint_magic() const override { return @endpoint.magic@; }
    virtual i32 message_id() const override { return (int)MessageID::@message.name@; }
    static i32 static_message_id() { return (int)MessageID::@message.name@; }
    virtual const char* message_name() const override { return "@endpoint.name@::@message.name@"; }

    static OwnPtr<@message.name@> decode(InputMemoryStream& stream, int sockfd)
    {
        IPC::Decoder decoder { stream, sockfd };
)~~~");

            for (auto& parameter : parameters) {
                auto parameter_generator = message_generator.fork();

                parameter_generator.set("parameter.type", parameter.type);
                parameter_generator.set("parameter.name", parameter.name);

                if (parameter.type == "bool")
                    parameter_generator.set("parameter.initial_value", "false");
                else
                    parameter_generator.set("parameter.initial_value", "{}");

                parameter_generator.append(R"~~~(
        @parameter.type@ @parameter.name@ = @parameter.initial_value@;
        if (!decoder.decode(@parameter.name@))
            return nullptr;
)~~~");

                if (parameter.attributes.contains_slow("UTF8")) {
                    parameter_generator.append(R"~~~(
        if (!Utf8View(@parameter.name@).validate())
            return nullptr;
)~~~");
                }
            }

            StringBuilder builder;
            for (size_t i = 0; i < parameters.size(); ++i) {
                auto& parameter = parameters[i];
                builder.append(parameter.name);
                if (i != parameters.size() - 1)
                    builder.append(", ");
            }

            message_generator.set("message.constructor_call_parameters", builder.build());

            message_generator.append(R"~~~(
        return make<@message.name@>(@message.constructor_call_parameters@);
    }
)~~~");

            message_generator.append(R"~~~(
    virtual IPC::MessageBuffer encode() const override
    {
        IPC::MessageBuffer buffer;
        IPC::Encoder stream(buffer);
        stream << endpoint_magic();
        stream << (int)MessageID::@message.name@;
)~~~");

            for (auto& parameter : parameters) {
                auto parameter_generator = message_generator.fork();

                parameter_generator.set("parameter.name", parameter.name);
                parameter_generator.append(R"~~~(
        stream << m_@parameter.name@;
)~~~");
            }

            message_generator.append(R"~~~(
        return buffer;
    }
)~~~");

            for (auto& parameter : parameters) {
                auto parameter_generator = message_generator.fork();
                parameter_generator.set("parameter.type", parameter.type);
                parameter_generator.set("parameter.name", parameter.name);
                parameter_generator.append(R"~~~(
    const @parameter.type@& @parameter.name@() const { return m_@parameter.name@; }
)~~~");
            }

            message_generator.append(R"~~~(
private:
            )~~~");

            for (auto& parameter : parameters) {
                auto parameter_generator = message_generator.fork();
                parameter_generator.set("parameter.type", parameter.type);
                parameter_generator.set("parameter.name", parameter.name);
                parameter_generator.append(R"~~~(
    @parameter.type@ m_@parameter.name@;
)~~~");
            }

            message_generator.append(R"~~~(
};
            )~~~");
        };
        for (auto& message : endpoint.messages) {
            String response_name;
            if (message.is_synchronous) {
                response_name = message.response_name();
                do_message(response_name, message.outputs);
            }
            do_message(message.name, message.inputs, response_name);
        }

        endpoint_generator.append(R"~~~(
} // namespace Messages::@endpoint.name@
        )~~~");

        endpoint_generator.append(R"~~~(
class @endpoint.name@Endpoint : public IPC::Endpoint {
public:
    @endpoint.name@Endpoint() { }
    virtual ~@endpoint.name@Endpoint() override { }

    static int static_magic() { return @endpoint.magic@; }
    virtual int magic() const override { return @endpoint.magic@; }
    static String static_name() { return "@endpoint.name@"; }
    virtual String name() const override { return "@endpoint.name@"; }

    static OwnPtr<IPC::Message> decode_message(ReadonlyBytes buffer, int sockfd)
    {
        InputMemoryStream stream { buffer };
        i32 message_endpoint_magic = 0;
        stream >> message_endpoint_magic;
        if (stream.handle_any_error()) {
)~~~");
#ifdef GENERATE_DEBUG_CODE
        endpoint_generator.append(R"~~~(
            dbgln("Failed to read message endpoint magic");
)~~~");
#endif
        endpoint_generator.append(R"~~~(
            return nullptr;
        }

        if (message_endpoint_magic != @endpoint.magic@) {
)~~~");
#ifdef GENERATE_DEBUG_CODE
        endpoint_generator.append(R"~~~(
            dbgln("Endpoint magic number message_endpoint_magic != @endpoint.magic@");
)~~~");
#endif
        endpoint_generator.append(R"~~~(
            return nullptr;
        }

        i32 message_id = 0;
        stream >> message_id;
        if (stream.handle_any_error()) {
)~~~");
#ifdef GENERATE_DEBUG_CODE
        endpoint_generator.append(R"~~~(
            dbgln("Failed to read message ID");
)~~~");
#endif
        endpoint_generator.append(R"~~~(
            return nullptr;
        }

        OwnPtr<IPC::Message> message;
        switch (message_id) {
)~~~");

        for (auto& message : endpoint.messages) {
            auto do_decode_message = [&](const String& name) {
                auto message_generator = endpoint_generator.fork();

                message_generator.set("message.name", name);

                message_generator.append(R"~~~(
        case (int)Messages::@endpoint.name@::MessageID::@message.name@:
            message = Messages::@endpoint.name@::@message.name@::decode(stream, sockfd);
            break;
)~~~");
            };

            do_decode_message(message.name);
            if (message.is_synchronous)
                do_decode_message(message.response_name());
        }

        endpoint_generator.append(R"~~~(
        default:
)~~~");
#ifdef GENERATE_DEBUG_CODE
        endpoint_generator.append(R"~~~(
            dbgln("Failed to decode @endpoint.name@.({})", message_id);
)~~~");
#endif
        endpoint_generator.append(R"~~~(
            return nullptr;
        }

        if (stream.handle_any_error()) {
)~~~");
#ifdef GENERATE_DEBUG_CODE
        endpoint_generator.append(R"~~~(
            dbgln("Failed to read the message");
)~~~");
#endif
        endpoint_generator.append(R"~~~(
            return nullptr;
        }

        return message;
    }

    virtual OwnPtr<IPC::Message> handle(const IPC::Message& message) override
    {
        switch (message.message_id()) {
)~~~");
        for (auto& message : endpoint.messages) {
            auto do_decode_message = [&](const String& name, bool returns_something) {
                auto message_generator = endpoint_generator.fork();

                message_generator.set("message.name", name);
                message_generator.append(R"~~~(
        case (int)Messages::@endpoint.name@::MessageID::@message.name@:
)~~~");
                if (returns_something) {
                    message_generator.append(R"~~~(
            return handle(static_cast<const Messages::@endpoint.name@::@message.name@&>(message));
)~~~");
                } else {
                    message_generator.append(R"~~~(
            handle(static_cast<const Messages::@endpoint.name@::@message.name@&>(message));
            return nullptr;
)~~~");
                }
            };
            do_decode_message(message.name, message.is_synchronous);
            if (message.is_synchronous)
                do_decode_message(message.response_name(), false);
        }
        endpoint_generator.append(R"~~~(
        default:
            return nullptr;
        }
    }
)~~~");

        for (auto& message : endpoint.messages) {
            auto message_generator = endpoint_generator.fork();

            message_generator.set("message.name", message.name);

            String return_type = "void";
            if (message.is_synchronous) {
                StringBuilder builder;
                builder.append("OwnPtr<Messages::");
                builder.append(endpoint.name);
                builder.append("::");
                builder.append(message.name);
                builder.append("Response");
                builder.append(">");
                return_type = builder.to_string();
            }
            message_generator.set("message.complex_return_type", return_type);

            message_generator.append(R"~~~(
    virtual @message.complex_return_type@ handle(const Messages::@endpoint.name@::@message.name@&) = 0;
)~~~");
        }

        endpoint_generator.append(R"~~~(
private:
};
)~~~");
    }

    outln("{}", generator.as_string_view());

#ifdef DEBUG
    for (auto& endpoint : endpoints) {
        warnln("Endpoint '{}' (magic: {})", endpoint.name, endpoint.magic);
        for (auto& message : endpoint.messages) {
            warnln("  Message: '{}'", message.name);
            warnln("    Sync: {}", message.is_synchronous);
            warnln("    Inputs:");
            for (auto& parameter : message.inputs)
                warnln("      Parameter: {} ({})", parameter.name, parameter.type);
            if (message.inputs.is_empty())
                warnln("      (none)");
            if (message.is_synchronous) {
                warnln("    Outputs:");
                for (auto& parameter : message.outputs)
                    warnln("      Parameter: {} ({})", parameter.name, parameter.type);
                if (message.outputs.is_empty())
                    warnln("      (none)");
            }
        }
    }
#endif
}