#pragma once

#include <xrpl/beast/utility/Journal.h>

#include <boost/beast/core/string.hpp>
#include <boost/filesystem.hpp>

#include <fstream>
#include <map>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <utility>
#include <vector>

namespace xrpl {

/**
 * Manages partitions for logging.
 */
class Logs
{
private:
    class Sink : public beast::Journal::Sink
    {
    private:
        Logs& logs_;
        std::string partition_;

    public:
        Sink(std::string partition, beast::Severity thresh, Logs& logs);

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

        void
        write(beast::Severity level, std::string const& text) override;

        void
        writeAlways(beast::Severity level, std::string const& text) override;
    };

    /**
     * Manages a system file containing logged output.
     * The system file remains open during program execution. Interfaces
     * are provided for interoperating with standard log management
     * tools like logrotate(8):
     *     http://linuxcommand.org/man_pages/logrotate8.html
     * @note None of the listed interfaces are thread-safe.
     */
    class File
    {
    public:
        /**
         * Construct with no associated system file.
         * A system file may be associated later with @ref open.
         * @see open
         */
        File();

        /**
         * Destroy the object.
         * If a system file is associated, it will be flushed and closed.
         */
        ~File() = default;

        /**
         * Determine if a system file is associated with the log.
         * @return `true` if a system file is associated and opened for
         * writing.
         */
        [[nodiscard]] bool
        isOpen() const noexcept;

        /**
         * Associate a system file with the log.
         * If the file does not exist an attempt is made to create it
         * and open it for writing. If the file already exists an attempt is
         * made to open it for appending.
         * If a system file is already associated with the log, it is closed
         * first.
         * @return `true` if the file was opened.
         */
        bool
        open(boost::filesystem::path const& path);

        /**
         * Close and re-open the system file associated with the log
         * This assists in interoperating with external log management tools.
         * @return `true` if the file was opened.
         */
        bool
        closeAndReopen();

        /**
         * Close the system file if it is open.
         */
        void
        close();

        /**
         * write to the log file.
         * Does nothing if there is no associated system file.
         */
        void
        write(char const* text);

        /**
         * write to the log file and append an end of line marker.
         * Does nothing if there is no associated system file.
         */
        void
        writeln(char const* text);

        /**
         * Write to the log file using std::string.
         */
        /** @{ */
        void
        write(std::string const& str)
        {
            write(str.c_str());
        }

        void
        writeln(std::string const& str)
        {
            writeln(str.c_str());
        }
        /** @} */

    private:
        std::unique_ptr<std::ofstream> stream_;
        boost::filesystem::path path_;
    };

    std::mutex mutable mutex_;
    std::map<std::string, std::unique_ptr<beast::Journal::Sink>, boost::beast::iless> sinks_;
    beast::Severity thresh_;
    File file_;
    bool silent_ = false;

public:
    Logs(beast::Severity level);

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

    virtual ~Logs() = default;

    bool
    open(boost::filesystem::path const& pathToLogFile);

    beast::Journal::Sink&
    get(std::string const& name);

    beast::Journal::Sink&
    operator[](std::string const& name);

    beast::Journal
    journal(std::string const& name);

    beast::Severity
    threshold() const;

    void
    threshold(beast::Severity thresh);

    std::vector<std::pair<std::string, std::string>>
    partitionSeverities() const;

    void
    write(
        beast::Severity level,
        std::string const& partition,
        std::string const& text,
        bool console);

    std::string
    rotate();

    /**
     * Set flag to write logs to stderr (false) or not (true).
     *
     * @param bSilent Set flag accordingly.
     */
    void
    silent(bool bSilent)
    {
        silent_ = bSilent;
    }

    virtual std::unique_ptr<beast::Journal::Sink>
    makeSink(std::string const& partition, beast::Severity startingLevel);

public:
    static std::string
    toString(beast::Severity s);

    static std::optional<beast::Severity>
    fromString(std::string const& s);

private:
    // Maximum line length for log messages.
    // If the message exceeds this length it will be truncated with ellipses.
    static constexpr auto kMaximumMessageCharacters = 12 * 1024;

    static void
    format(
        std::string& output,
        std::string const& message,
        beast::Severity severity,
        std::string const& partition);
};

// Wraps a Journal::Stream to skip evaluation of
// expensive argument lists if the stream is not active.
#ifndef JLOG
#define JLOG(x) \
    if (!(x))   \
        ;       \
    else        \
        x
#endif

#ifndef CLOG
#define CLOG(ss) \
    if (!(ss))   \
        ;        \
    else         \
        *ss
#endif

//------------------------------------------------------------------------------
// Debug logging:

/**
 * Set the sink for the debug journal.
 *
 * @param sink unique_ptr to new debug Sink.
 * @return unique_ptr to the previous Sink.  nullptr if there was no Sink.
 */
std::unique_ptr<beast::Journal::Sink>
setDebugLogSink(std::unique_ptr<beast::Journal::Sink> sink);

/**
 * Returns a debug journal.
 * The journal may drain to a null sink, so its output
 * may never be seen. Never use it for critical
 * information.
 */
beast::Journal
debugLog();

}  // namespace xrpl