/**
 * Copyright 2013-2021 Software Radio Systems Limited
 *
 * This file is part of srsRAN.
 *
 * srsRAN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsRAN is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#ifndef SRSLOG_LOG_CHANNEL_H
#define SRSLOG_LOG_CHANNEL_H

#include "srsran/srslog/detail/log_backend.h"
#include "srsran/srslog/detail/log_entry.h"
#include "srsran/srslog/sink.h"
#include <atomic>

namespace srslog {

/// Log channel configuration settings.
struct log_channel_config {
  log_channel_config() = default;
  log_channel_config(std::string n, char tag, bool should_print_context) :
    name(std::move(n)), tag(tag), should_print_context(should_print_context)
  {}

  /// Optional log channel name. If set, will get printed for each log entry.
  /// Disabled by default.
  std::string name;
  /// Optional log channel tag. If set, will get printed for each log entry.
  /// Disabled by default.
  char tag = '\0';
  /// When set to true, each log entry will get printed with the context value.
  /// Disabled by default.
  bool should_print_context = false;
};

/// A log channel is the entity used for logging messages.
///
/// It can deliver a log entry to one or more different sinks, for example a
/// file or a console.
/// Generated log entries by the application will be ignored by the channel when
/// set to disabled.
/// NOTE: Thread safe class.
class log_channel
{
public:
  log_channel(std::string id, sink& s, detail::log_backend& backend) : log_channel(std::move(id), s, backend, {}) {}

  log_channel(std::string id, sink& s, detail::log_backend& backend, log_channel_config config) :
    log_id(std::move(id)),
    log_sink(s),
    backend(backend),
    log_name(std::move(config.name)),
    log_tag(config.tag),
    should_print_context(config.should_print_context),
    ctx_value(0),
    hex_max_size(0),
    is_enabled(true)
  {}

  log_channel(const log_channel& other) = delete;
  log_channel& operator=(const log_channel& other) = delete;

  /// Controls when the channel accepts incoming log entries.
  void set_enabled(bool enabled) { is_enabled.store(enabled, std::memory_order_relaxed); }

  /// Returns true if the channel is accepting incoming log entries, otherwise
  /// false.
  bool enabled() const { return is_enabled.load(std::memory_order_relaxed); }

  /// Returns the id string of the channel.
  const std::string& id() const { return log_id; }

  /// Set the log channel context to the specified value.
  void set_context(uint32_t x) { ctx_value = x; }

  /// Set the maximum number of bytes to can be printed in a hex dump.
  /// Set to -1 to indicate no hex dump limit.
  void set_hex_dump_max_size(int size) { hex_max_size = size; }

  /// Builds the provided log entry and passes it to the backend. When the
  /// channel is disabled the log entry will be discarded.
  template <typename... Args>
  void operator()(const char* fmtstr, Args&&... args)
  {
    if (!enabled()) {
      return;
    }

    // Populate the store with all incoming arguments.
    auto* store = backend.alloc_arg_store();
    if (!store) {
      return;
    }
    (void)std::initializer_list<int>{(store->push_back(std::forward<Args>(args)), 0)...};

    // Send the log entry to the backend.
    log_formatter&    formatter = log_sink.get_formatter();
    detail::log_entry entry     = {&log_sink,
                               [&formatter](detail::log_entry_metadata&& metadata, fmt::memory_buffer& buffer) {
                                 formatter.format(std::move(metadata), buffer);
                               },
                               {std::chrono::high_resolution_clock::now(),
                                {ctx_value, should_print_context},
                                fmtstr,
                                store,
                                log_name,
                                log_tag}};
    backend.push(std::move(entry));
  }

  /// Builds the provided log entry and passes it to the backend. When the
  /// channel is disabled the log entry will be discarded.
  template <typename... Args>
  void operator()(const uint8_t* buffer, size_t len, const char* fmtstr, Args&&... args)
  {
    if (!enabled()) {
      return;
    }

    // Populate the store with all incoming arguments.
    auto* store = backend.alloc_arg_store();
    if (!store) {
      return;
    }
    (void)std::initializer_list<int>{(store->push_back(std::forward<Args>(args)), 0)...};

    // Calculate the length to capture in the buffer.
    if (hex_max_size >= 0) {
      len = std::min<size_t>(len, hex_max_size);
    }

    // Send the log entry to the backend.
    log_formatter&    formatter = log_sink.get_formatter();
    detail::log_entry entry     = {&log_sink,
                               [&formatter](detail::log_entry_metadata&& metadata, fmt::memory_buffer& buffer) {
                                 formatter.format(std::move(metadata), buffer);
                               },
                               {std::chrono::high_resolution_clock::now(),
                                {ctx_value, should_print_context},
                                fmtstr,
                                store,
                                log_name,
                                log_tag,
                                std::vector<uint8_t>(buffer, buffer + len)}};
    backend.push(std::move(entry));
  }

  /// Builds the provided log entry and passes it to the backend. When the
  /// channel is disabled the log entry will be discarded.
  template <typename... Ts>
  void operator()(const context<Ts...>& ctx)
  {
    if (!enabled()) {
      return;
    }

    // Send the log entry to the backend.
    log_formatter&    formatter = log_sink.get_formatter();
    detail::log_entry entry     = {&log_sink,
                               [&formatter, ctx](detail::log_entry_metadata&& metadata, fmt::memory_buffer& buffer) {
                                 formatter.format_ctx(ctx, std::move(metadata), buffer);
                               },
                               {std::chrono::high_resolution_clock::now(),
                                {ctx_value, should_print_context},
                                nullptr,
                                nullptr,
                                log_name,
                                log_tag}};
    backend.push(std::move(entry));
  }

  /// Builds the provided log entry and passes it to the backend. When the
  /// channel is disabled the log entry will be discarded.
  template <typename... Ts, typename... Args>
  void operator()(const context<Ts...>& ctx, const char* fmtstr, Args&&... args)
  {
    if (!enabled()) {
      return;
    }

    // Populate the store with all incoming arguments.
    auto* store = backend.alloc_arg_store();
    if (!store) {
      return;
    }
    (void)std::initializer_list<int>{(store->push_back(std::forward<Args>(args)), 0)...};

    // Send the log entry to the backend.
    log_formatter&    formatter = log_sink.get_formatter();
    detail::log_entry entry     = {&log_sink,
                               [&formatter, ctx](detail::log_entry_metadata&& metadata, fmt::memory_buffer& buffer) {
                                 formatter.format_ctx(ctx, std::move(metadata), buffer);
                               },
                               {std::chrono::high_resolution_clock::now(),
                                {ctx_value, should_print_context},
                                fmtstr,
                                store,
                                log_name,
                                log_tag}};
    backend.push(std::move(entry));
  }

private:
  const std::string     log_id;
  sink&                 log_sink;
  detail::log_backend&  backend;
  const std::string     log_name;
  const char            log_tag;
  const bool            should_print_context;
  std::atomic<uint32_t> ctx_value;
  std::atomic<int>      hex_max_size;
  std::atomic<bool>     is_enabled;
};

} // namespace srslog

#endif // SRSLOG_LOG_CHANNEL_H