ALogger.h

/*
 * AUI Framework - Declarative UI toolkit for modern C++20
 * Copyright (C) 2020-2024 Alex2772 and Contributors
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
#pragma once
 
#include <AUI/Core.h>
#include <AUI/IO/APath.h>
#include <AUI/IO/IOutputStream.h>
#include <AUI/Reflect/AReflect.h>
#include <AUI/Util/ARaiiHelper.h>
#include "AUI/Thread/AMutex.h"
#include "AUI/IO/AFileOutputStream.h"
#include <fmt/format.h>
#include <fmt/chrono.h>
#include <AUI/Thread/AMutexWrapper.h>
 
class AString;

class API_AUI_CORE ALogger final
{
public:
    enum Level
    {
        INFO,
        WARN,
        ERR,
        DEBUG,
    };
 
    struct LogWriter {
        private:
            ALogger& mLogger;
            Level mLevel;
            AString mPrefix;
            struct Buffer {
            private:
                struct StackBuffer {
                    char buffer[2048];
                    char* currentIterator;
                };
                using HeapBuffer = AVector<char>;
                std::variant<StackBuffer, HeapBuffer> mBuffer;
 
                void switchToHeap() {
                    HeapBuffer h;
                    h.reserve(16384);
                    auto& stack = std::get<StackBuffer>(mBuffer);
                    h.insert(h.end(), stack.buffer, stack.currentIterator);
                    mBuffer = std::move(h);
                }
            public:
                using value_type = char;
 
                Buffer() noexcept: mBuffer({}) {
                    auto& sb = std::get<StackBuffer>(mBuffer);
                    sb.currentIterator = sb.buffer;
                }
                size_t write(const char* t, size_t s) {
                    if (std::holds_alternative<StackBuffer>(mBuffer)) {
                        auto& stack = std::get<StackBuffer>(mBuffer);
                        if (stack.currentIterator + s <= stack.buffer + sizeof(stack.buffer)) {
                            std::memcpy(stack.currentIterator, t, s);
                            stack.currentIterator += s;
                            return s;
                        }
                        switchToHeap();
                    }
                    auto& h = std::get<HeapBuffer>(mBuffer);
                    h.insert(h.end(), t, t + s);
                    return s;
                }
                void write(char c) {
                    if (std::holds_alternative<StackBuffer>(mBuffer)) {
                        auto& stack = std::get<StackBuffer>(mBuffer);
                        if (stack.currentIterator + sizeof(c) <= stack.buffer + sizeof(stack.buffer)) {
                            *stack.currentIterator = c;
                            stack.currentIterator += 1;
                            return;
                        }
                        switchToHeap();
                    }
                    std::get<HeapBuffer>(mBuffer).push_back(c);
                }
 
                void push_back(char c) { // for std::back_inserter
                    write(c);
                }
 
                [[nodiscard]]
                std::string_view str() const {
                    // assuming there's a null terminator
                    if (std::holds_alternative<StackBuffer>(mBuffer)) {
                        auto& stack = std::get<StackBuffer>(mBuffer);
                        return {stack.buffer, static_cast<std::string_view::size_type>(stack.currentIterator - stack.buffer) - 1};
                    }
                    auto& h = std::get<HeapBuffer>(mBuffer);
                    return {h.data(), h.size()};
                }
            };
 
            struct LazyStreamBuf final: std::streambuf {
            private:
                Buffer& stackBuffer;
            public:
                std::ostream stream;
                LazyStreamBuf(Buffer& stackBuffer) : stackBuffer(stackBuffer), stream(this) {}
 
            protected:
                std::streamsize xsputn(const char_type* s, std::streamsize n) override {
                    return stackBuffer.write(s, n);
                }
 
                int overflow(int_type __c) override {
                    stackBuffer.write(__c);
                    return 1;
                }
            };
            AOptional<LazyStreamBuf> mStreamBuf;
 
            Buffer mBuffer;
 
            void writeTimestamp(const char* fmt, std::chrono::system_clock::time_point t) noexcept {
                fmt::format_to(std::back_inserter(mBuffer), "{}", t);
            }
 
        public:
            LogWriter(ALogger& logger, Level level, AString prefix) :
                mLogger(logger),
                mLevel(level),
                mPrefix(std::move(prefix)) {
 
            }
 
            ~LogWriter() {
                mBuffer.write(0); // null terminator
                auto s = mBuffer.str();
                mLogger.log(mLevel, mPrefix.toStdString().c_str(), s);
            }
 
            template<typename T>
            LogWriter& operator<<(const T& t) noexcept {
                // avoid usage of std::ostream because it's expensive
                if constexpr(std::is_constructible_v<std::string_view, T>) {
                    std::string_view stringView(t);
                    mBuffer.write(stringView.data(), stringView.size());
                } else if constexpr(std::is_base_of_v<AString, T>) {
                    *this << t.toStdString();
                } else if constexpr(std::is_base_of_v<std::exception, T> && !std::is_base_of_v<AException, T>) {
                    *this << "(" << AReflect::name(&t) << ") " << t.what();
                } else if constexpr(std::is_same_v<std::chrono::seconds, T>) {
                    writeTimestamp("%D %T", std::chrono::system_clock::time_point(t));
                } else if constexpr(std::is_same_v<std::chrono::minutes, T> || std::is_same_v<std::chrono::hours, T>) {
                    writeTimestamp("%D %R", std::chrono::system_clock::time_point(t));
                } else {
                    if (!mStreamBuf) {
                        mStreamBuf.emplace(mBuffer);
                    }
                    mStreamBuf->stream << t;
                }
                return *this;
            }
    };
 

    ALogger(AString filename) {
        setLogFileImpl(std::move(filename));
    }
    ALogger();
    ~ALogger();
 
    static ALogger& global();
 
    void setDebugMode(bool debug) {
        global().mDebug = debug;
    }
    bool isDebug() {
        return global().mDebug;
    }

    void setLogFile(APath path) {
        setLogFileImpl(std::move(path));
    }

    static void setLogFileForGlobal(APath path);
 
    [[nodiscard]]
    APath logFile() {
        return mLogFile.valueOrException().path();
    }
 
    void onLogged(std::function<void(const AString& prefix, const AString& message, Level level)> callback) {
        std::unique_lock lock(mOnLogged);
        mOnLogged = std::move(callback);
    }
    template <aui::invocable Callable>
    void doLogFileAccessSafe(Callable action) {
        std::unique_lock lock(mLogSync);
        ARaiiHelper opener = [&] {
            if (!mLogFile) return;
            try {
                mLogFile->open(true);
            } catch (const AException& e) {
                auto path = mLogFile->path();
                mLogFile.reset();
                lock.unlock();
                log(WARN, "Logger", fmt::format("Unable to reopen file {}: {}", path, e.getMessage()));
            }
        };
        if (!mLogFile || !mLogFile->nativeHandle()) {
            action();
            return;
        }
 
        mLogFile->close();
        action();
    }
 
    static LogWriter info(const AString& str)
    {
        return {global(), INFO, str};
    }
    static LogWriter warn(const AString& str)
    {
        return {global(), WARN, str};
    }
    static LogWriter err(const AString& str)
    {
        return {global(), ERR, str};
    }
    static LogWriter debug(const AString& str)
    {
        return {global(), DEBUG, str};
    }

    LogWriter log(Level level, const AString& prefix)
    {
        return {*this, level, prefix};
    }
 
 
private:
 
    AOptional<AFileOutputStream> mLogFile;
    AMutex mLogSync;
    AMutexWrapper<std::function<void(const AString& prefix, const AString& message, Level level)>> mOnLogged;
 
    bool mDebug = AUI_DEBUG;
 
    void setLogFileImpl(AString path);
 

    void log(Level level, std::string_view prefix, std::string_view message);
 
};
namespace glm {
    template<glm::length_t L, typename T, glm::qualifier Q>
    inline std::ostream& operator<<(std::ostream& o, vec<L, T, Q> vec) {
        o << "{ ";
        for (std::size_t i = 0; i < L; ++i) {
            if (i != 0) o << ", ";
            o << vec[i];
        }
        o << " }";
 
        return o;
    }
 
}
 
template<glm::length_t L, typename T, glm::qualifier Q>
struct fmt::formatter<glm::vec<L, T, Q>> {
    constexpr auto parse (format_parse_context& ctx) { return ctx.begin(); }
 
    template <typename Context>
    constexpr auto format(glm::vec<L, T, Q> vec, Context& ctx) const {
        auto out = ctx.out();
        out = format_to(out, FMT_STRING("{{ "));
        for (glm::length_t i = 0; i < L; ++i) {
            if (i == 0) {
                out = format_to(out, FMT_STRING("{}"), vec[i]);
            } else {
                out = format_to(out, FMT_STRING(", {}"), vec[i]);
            }
        }
        out = format_to(out, FMT_STRING(" }}"));
        return out;
    }
 
private:
};
 
#define ALOG_DEBUG(str) if (ALogger::global().isDebug()) ALogger::debug(str)
 
#include <AUI/Traits/strings.h>