// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <string>
#include "common/logging/log.h"
#include "core/hle/ipc_helpers.h"
#include "core/hle/kernel/client_session.h"
#include "core/hle/service/lm/lm.h"

namespace Service {
namespace LM {

class Logger final : public ServiceFramework<Logger> {
public:
    Logger() : ServiceFramework("Logger") {
        static const FunctionInfo functions[] = {
            {0x00000000, &Logger::Log, "Log"},
        };
        RegisterHandlers(functions);
    }

    ~Logger() = default;

private:
    struct MessageHeader {
        enum Flags : u32_le {
            IsHead = 1,
            IsTail = 2,
        };

        u64_le pid;
        u64_le threadContext;
        union {
            BitField<0, 16, Flags> flags;
            BitField<16, 8, u32_le> severity;
            BitField<24, 8, u32_le> verbosity;
        };
        u32_le payload_size;

        /// Returns true if this is part of a single log message
        bool IsSingleMessage() const {
            return (flags & Flags::IsHead) && (flags & Flags::IsTail);
        }
    };
    static_assert(sizeof(MessageHeader) == 0x18, "MessageHeader is incorrect size");

    /// Log field type
    enum class Field : u8 {
        Message = 2,
        Line = 3,
        Filename = 4,
        Function = 5,
        Module = 6,
        Thread = 7,
    };

    /**
     * LM::Initialize service function
     *  Inputs:
     *      0: 0x00000000
     *  Outputs:
     *      0: ResultCode
     */
    void Log(Kernel::HLERequestContext& ctx) {
        // This function only succeeds - Get that out of the way
        IPC::RequestBuilder rb{ctx, 1};
        rb.Push(RESULT_SUCCESS);

        // Read MessageHeader, despite not doing anything with it right now
        MessageHeader header{};
        VAddr addr{ctx.BufferDescriptorX()[0].Address()};
        const VAddr end_addr{addr + ctx.BufferDescriptorX()[0].size};
        Memory::ReadBlock(addr, &header, sizeof(MessageHeader));
        addr += sizeof(MessageHeader);

        if (!header.IsSingleMessage()) {
            UNIMPLEMENTED_MSG("Multi message logs are unimplemeneted");
        }

        // Parse out log metadata
        u32 line{};
        std::string message, filename, function;
        while (addr < end_addr) {
            const Field field{static_cast<Field>(Memory::Read8(addr++))};
            size_t length{Memory::Read8(addr++)};
            switch (field) {
            case Field::Message:
                message = Memory::ReadCString(addr, length);
                break;
            case Field::Line:
                line = Memory::Read32(addr);
                break;
            case Field::Filename:
                filename = Memory::ReadCString(addr, length);
                break;
            case Field::Function:
                function = Memory::ReadCString(addr, length);
                break;
            }
            addr += length;
        }

        // Empty log - nothing to do here
        if (message.size() <= 1) {
            return;
        }

        // Remove trailing new line
        if (message[message.length() - 1] == '\n') {
            message.erase(message.length() - 1);
        }

        // Format a nicely printable string out of the log metadata
        std::string output;
        if (filename.size()) {
            output += filename + ':';
        }
        if (function.size()) {
            output += function + ':';
        }
        if (line) {
            output += std::to_string(line) + ':';
        }
        if (output.back() == ':') {
            output += ' ';
        }
        output += message;

        LOG_DEBUG(Debug_Emulated, "%s", output.c_str());
    }
};

void InstallInterfaces(SM::ServiceManager& service_manager) {
    std::make_shared<LM>()->InstallAsService(service_manager);
}

/**
 * LM::Initialize service function
 *  Inputs:
 *      0: 0x00000000
 *  Outputs:
 *      0: ResultCode
 */
void LM::Initialize(Kernel::HLERequestContext& ctx) {
    auto client_port = std::make_shared<Logger>()->CreatePort();
    auto session = client_port->Connect();
    if (session.Succeeded()) {
        LOG_DEBUG(Service_SM, "called, initialized logger -> session=%u",
                  (*session)->GetObjectId());
        IPC::RequestBuilder rb{ctx, 1, 0, 1};
        rb.Push(RESULT_SUCCESS);
        rb.PushObjects(std::move(session).Unwrap());
        registered_loggers.emplace_back(std::move(client_port));
    } else {
        UNIMPLEMENTED();
    }

    LOG_INFO(Service_SM, "called");
}

LM::LM() : ServiceFramework("lm") {
    static const FunctionInfo functions[] = {
        {0x00000000, &LM::Initialize, "Initialize"},
    };
    RegisterHandlers(functions);
}

} // namespace LM
} // namespace Service
