// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <algorithm>
#include <array>
#include <chrono>
#include <cstdio>
#include <future>
#include <memory>
#include <thread>
#ifdef _WIN32
#include <share.h> // For _SH_DENYWR
#else
#define _SH_DENYWR 0
#endif
#include "common/assert.h"
#include "common/common_funcs.h" // snprintf compatibility define
#include "common/logging/backend.h"
#include "common/logging/log.h"
#include "common/logging/text_formatter.h"
#include "common/string_util.h"
#include "common/threadsafe_queue.h"

namespace Log {

/**
 * Static state as a singleton.
 */
class Impl {
public:
    static Impl& Instance() {
        static Impl backend;
        return backend;
    }

    Impl(Impl const&) = delete;
    const Impl& operator=(Impl const&) = delete;

    void PushEntry(Entry e) {
        message_queue.Push(std::move(e));
    }

    void AddBackend(std::unique_ptr<Backend> backend) {
        backends.push_back(std::move(backend));
    }

    void RemoveBackend(const std::string& backend_name) {
        std::remove_if(backends.begin(), backends.end(),
                       [&backend_name](const auto& i) { return i->GetName() == backend_name; });
    }

    const Filter& GetGlobalFilter() const {
        return filter;
    }

    void SetGlobalFilter(const Filter& f) {
        filter = f;
    }

    boost::optional<Backend*> GetBackend(const std::string& backend_name) {
        auto it = std::find_if(backends.begin(), backends.end(), [&backend_name](const auto& i) {
            return i->GetName() == backend_name;
        });
        if (it == backends.end())
            return boost::none;
        return it->get();
    }

private:
    Impl() {
        backend_thread = std::async(std::launch::async, [&] {
            using namespace std::chrono_literals;
            Entry entry;
            while (running) {
                if (!message_queue.PopWait(entry)) {
                    continue;
                }
                for (const auto& backend : backends) {
                    backend->Write(entry);
                }
            }
        });
    }
    ~Impl() {
        running = false;
    }

    std::atomic_bool running{true};
    std::future<void> backend_thread;
    std::vector<std::unique_ptr<Backend>> backends;
    Common::MPSCQueue<Log::Entry> message_queue;
    Filter filter;
};

void ConsoleBackend::Write(const Entry& entry) {
    PrintMessage(entry);
}

void ColorConsoleBackend::Write(const Entry& entry) {
    PrintColoredMessage(entry);
}

// _SH_DENYWR allows read only access to the file for other programs.
// It is #defined to 0 on other platforms
FileBackend::FileBackend(const std::string& filename) : file(filename, "w", _SH_DENYWR) {}

void FileBackend::Write(const Entry& entry) {
    if (!file.IsOpen()) {
        return;
    }
    file.WriteString(FormatLogMessage(entry) + '\n');
    if (entry.log_level >= Level::Error) {
        file.Flush();
    }
}

/// Macro listing all log classes. Code should define CLS and SUB as desired before invoking this.
#define ALL_LOG_CLASSES()                                                                          \
    CLS(Log)                                                                                       \
    CLS(Common)                                                                                    \
    SUB(Common, Filesystem)                                                                        \
    SUB(Common, Memory)                                                                            \
    CLS(Core)                                                                                      \
    SUB(Core, ARM11)                                                                               \
    SUB(Core, Timing)                                                                              \
    CLS(Config)                                                                                    \
    CLS(Debug)                                                                                     \
    SUB(Debug, Emulated)                                                                           \
    SUB(Debug, GPU)                                                                                \
    SUB(Debug, Breakpoint)                                                                         \
    SUB(Debug, GDBStub)                                                                            \
    CLS(Kernel)                                                                                    \
    SUB(Kernel, SVC)                                                                               \
    CLS(Service)                                                                                   \
    SUB(Service, SRV)                                                                              \
    SUB(Service, FRD)                                                                              \
    SUB(Service, FS)                                                                               \
    SUB(Service, ERR)                                                                              \
    SUB(Service, APT)                                                                              \
    SUB(Service, BOSS)                                                                             \
    SUB(Service, GSP)                                                                              \
    SUB(Service, AC)                                                                               \
    SUB(Service, AM)                                                                               \
    SUB(Service, PTM)                                                                              \
    SUB(Service, LDR)                                                                              \
    SUB(Service, MIC)                                                                              \
    SUB(Service, NDM)                                                                              \
    SUB(Service, NFC)                                                                              \
    SUB(Service, NIM)                                                                              \
    SUB(Service, NS)                                                                               \
    SUB(Service, NWM)                                                                              \
    SUB(Service, CAM)                                                                              \
    SUB(Service, CECD)                                                                             \
    SUB(Service, CFG)                                                                              \
    SUB(Service, CSND)                                                                             \
    SUB(Service, DSP)                                                                              \
    SUB(Service, DLP)                                                                              \
    SUB(Service, HID)                                                                              \
    SUB(Service, HTTP)                                                                             \
    SUB(Service, SOC)                                                                              \
    SUB(Service, IR)                                                                               \
    SUB(Service, Y2R)                                                                              \
    CLS(HW)                                                                                        \
    SUB(HW, Memory)                                                                                \
    SUB(HW, LCD)                                                                                   \
    SUB(HW, GPU)                                                                                   \
    SUB(HW, AES)                                                                                   \
    CLS(Frontend)                                                                                  \
    CLS(Render)                                                                                    \
    SUB(Render, Software)                                                                          \
    SUB(Render, OpenGL)                                                                            \
    CLS(Audio)                                                                                     \
    SUB(Audio, DSP)                                                                                \
    SUB(Audio, Sink)                                                                               \
    CLS(Input)                                                                                     \
    CLS(Network)                                                                                   \
    CLS(Movie)                                                                                     \
    CLS(Loader)                                                                                    \
    CLS(WebService)

// GetClassName is a macro defined by Windows.h, grrr...
const char* GetLogClassName(Class log_class) {
    switch (log_class) {
#define CLS(x)                                                                                     \
    case Class::x:                                                                                 \
        return #x;
#define SUB(x, y)                                                                                  \
    case Class::x##_##y:                                                                           \
        return #x "." #y;
        ALL_LOG_CLASSES()
#undef CLS
#undef SUB
    case Class::Count:
        UNREACHABLE();
    }
}

const char* GetLevelName(Level log_level) {
#define LVL(x)                                                                                     \
    case Level::x:                                                                                 \
        return #x
    switch (log_level) {
        LVL(Trace);
        LVL(Debug);
        LVL(Info);
        LVL(Warning);
        LVL(Error);
        LVL(Critical);
    case Level::Count:
        UNREACHABLE();
    }
#undef LVL
}

Entry CreateEntry(Class log_class, Level log_level, const char* filename, unsigned int line_nr,
                  const char* function, std::string message) {
    using std::chrono::duration_cast;
    using std::chrono::steady_clock;

    static steady_clock::time_point time_origin = steady_clock::now();

    Entry entry;
    entry.timestamp = duration_cast<std::chrono::microseconds>(steady_clock::now() - time_origin);
    entry.log_class = log_class;
    entry.log_level = log_level;
    entry.filename = Common::TrimSourcePath(filename);
    entry.line_num = line_nr;
    entry.function = function;
    entry.message = std::move(message);

    return entry;
}

void SetGlobalFilter(const Filter& filter) {
    Impl::Instance().SetGlobalFilter(filter);
}

void AddBackend(std::unique_ptr<Backend> backend) {
    Impl::Instance().AddBackend(std::move(backend));
}

void RemoveBackend(const std::string& backend_name) {
    Impl::Instance().RemoveBackend(backend_name);
}

boost::optional<Backend*> GetBackend(const std::string& backend_name) {
    return Impl::Instance().GetBackend(backend_name);
}

void LogMessage(Class log_class, Level log_level, const char* filename, unsigned int line_num,
                const char* function, const char* format, ...) {
    auto filter = Impl::Instance().GetGlobalFilter();
    if (!filter.CheckMessage(log_class, log_level))
        return;
    std::array<char, 4 * 1024> formatting_buffer;
    va_list args;
    va_start(args, format);
    vsnprintf(formatting_buffer.data(), formatting_buffer.size(), format, args);
    va_end(args);
    Entry entry = CreateEntry(log_class, log_level, filename, line_num, function,
                              std::string(formatting_buffer.data()));

    Impl::Instance().PushEntry(std::move(entry));
}

void FmtLogMessage(Class log_class, Level log_level, const char* filename, unsigned int line_num,
                   const char* function, const char* format, fmt::ArgList args) {
    auto filter = Impl::Instance().GetGlobalFilter();
    if (!filter.CheckMessage(log_class, log_level))
        return;

    Entry entry =
        CreateEntry(log_class, log_level, filename, line_num, function, fmt::format(format, args));

    Impl::Instance().PushEntry(std::move(entry));
}
} // namespace Log