// yabridge: a Wine VST bridge
// Copyright (C) 2020  Robbert van der Helm
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

#pragma once

#include <boost/filesystem.hpp>
#include <optional>

/**
 * An object that's used to provide plugin-specific configuration. Right now
 * this is only used to declare plugin groups. A plugin group is a set of
 * plugins that will be hosted in the same process rather than individually so
 * they can share resources. Configuration file loading works as follows:
 *
 * 1. `Configuration::load_for(path)` gets called with a path to the copy of or
 *    symlink to `libyabridge.so` that the plugin host has tried to load.
 * 2. We start looking for a file named `yabridge.toml` in the same directory as
 *    that `.so` file, iteratively continuing to search one directory higher
 *    until we either find the file or we reach the filesystem root.
 * 3. If the file is found, then parse it as a TOML file and look for the first
 *    table whose key is a glob pattern that (partially) matches the relative
 *    path between the found `yabridge.toml` and the `.so` file. As a rule of
 *    thumb, if the `find <pattern> -type f` command executed in Bash would list
 *    the `.so` file, then the following table in `yabridge.tmol` would also
 *    match the same `.so` file:
 *
 *    ```toml
 *    ["<patern>"]
 *    group = "..."
 *    ```
 * 4. If one of these glob patterns could be matched with the relative path of
 *    the `.so` file then we'll use the settings specified in that section.
 *    Otherwise the default settings will be used.
 */
class Configuration {
   public:
    /**
     * Create an empty configuration object with default settings.
     */
    Configuration();

    /**
     * Load the configuration for an instance of yabridge from a configuration
     * file by matching the plugin's relative path to the glob patterns in that
     * configuration file. Will leave the object empty if the plugin cannot be
     * matched to any of the patterns. Not meant to be used directly.
     *
     * @throw toml::parsing_error If the file could not be parsed.
     *
     * @see Configuration::load_for
     */
    Configuration(const boost::filesystem::path& config_path,
                  const boost::filesystem::path& yabridge_path);

    /**
     * Load the configuration that belongs to a copy of or symlink to
     * `libyabridge.so`. If no configuration file could be found then this will
     * return an empty configuration object with default settings.
     *
     * This function will take any optional compile-time features that have not
     * been enabled into account.
     *
     * @param yabridge_path The path to the .so file that's being loaded.by the
     *   VST host. This will be used both for the starting location of the
     *   search and to determine which section in the config file to use.
     *
     * @return Either a configuration object populated with values from matched
     *   glob pattern within the found configuration file, or an empty
     *   configuration object if no configuration file could be found or if the
     *   plugin could not be matched to any of the glob patterns in the
     *   configuration file.
     */
    static Configuration load_for(const boost::filesystem::path& yabridge_path);

    /**
     * The name of the plugin group that should be used for the plugin this
     * configuration object was created for. If not set, then the plugin should
     * be hosted individually instead.
     */
    std::optional<std::string> group;

    /**
     * The path to the configuration file that was parsed.
     */
    std::optional<boost::filesystem::path> matched_file;

    /**
     * The matched glob pattern in the above configuration file.
     */
    std::optional<std::string> matched_pattern;
};