package org.mvplugins.multiverse.core.world.config;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.dumptruckman.minecraft.util.Logging;
import io.vavr.Tuple2;
import io.vavr.control.Option;
import io.vavr.control.Try;
import jakarta.inject.Inject;
import org.bukkit.configuration.ConfigurationSection;
import org.bukkit.configuration.InvalidConfigurationException;
import org.bukkit.configuration.file.YamlConfiguration;
import org.jetbrains.annotations.NotNull;
import org.jvnet.hk2.annotations.Service;

import org.mvplugins.multiverse.core.MultiverseCore;
import org.mvplugins.multiverse.core.world.helpers.EnforcementHandler;

/**
 * Manages the worlds.yml file.
 */
@Service
public final class WorldsConfigManager {
    // TODO: Rename to worlds.yml
    private static final String CONFIG_FILENAME = "worlds2.yml";

    private final Map<String, WorldConfig> worldConfigMap;
    private final File worldConfigFile;
    private final MultiverseCore multiverseCore;
    private YamlConfiguration worldsConfig;

    @Inject
    WorldsConfigManager(@NotNull MultiverseCore multiverseCore) {
        worldConfigMap = new HashMap<>();
        worldConfigFile = multiverseCore.getDataFolder().toPath().resolve(CONFIG_FILENAME).toFile();
        this.multiverseCore = multiverseCore;
    }

    /**
     * Loads the worlds.yml file and creates a WorldConfig for each world in the file if it doesn't already exist.
     *
     * @return A tuple containing a list of the new WorldConfigs added and a list of the worlds removed from the config.
     */
    public Try<Tuple2<List<WorldConfig>, List<String>>> load() {
        return Try.of(() -> {
            loadWorldYmlFile();
            return parseNewAndRemovedWorlds();
        });
    }

    /**
     * Loads the worlds.yml file.
     *
     * @throws IOException                      If an error occurs while loading the file.
     * @throws InvalidConfigurationException    If the file is not a valid YAML file.
     */
    private void loadWorldYmlFile() throws IOException, InvalidConfigurationException {
        boolean exists = worldConfigFile.exists();
        if (!exists && !worldConfigFile.createNewFile()) {
            throw new IllegalStateException("Could not create worlds.yml config file");
        }
        if (exists) {
            migrateRemoveOldConfigSerializable();
        }
        worldsConfig = new YamlConfiguration();
        worldsConfig.load(worldConfigFile);
    }

    private void migrateRemoveOldConfigSerializable() {
        Try.of(() -> Files.readString(worldConfigFile.toPath()))
                .mapTry(configData -> {
                    if (!configData.contains("==: MVWorld")) {
                        throw new ConfigMigratedException();
                    }
                    return configData.replace("    ==: MVWorld\n", "")
                            .replace("      ==: MVSpawnSettings\n", "")
                            .replace("        ==: MVSpawnSubSettings\n", "")
                            .replace("      ==: MVEntryFee\n", "");
                })
                .andThenTry(configData -> Files.writeString(worldConfigFile.toPath(), configData))
                .andThenTry(() -> {
                    YamlConfiguration config = YamlConfiguration.loadConfiguration(worldConfigFile);
                    List<ConfigurationSection> worlds = config.getConfigurationSection("worlds")
                            .getKeys(false)
                            .stream()
                            .map(worldName -> config.getConfigurationSection("worlds." + worldName))
                            .toList();

                    config.set("worlds", null);

                    for (ConfigurationSection world : worlds) {
                        config.createSection(world.getName(), world.getValues(true));
                    }
                    config.save(worldConfigFile);
                })
                .onFailure(e -> {
                    if (e instanceof ConfigMigratedException) {
                        Logging.fine("Config already migrated");
                        return;
                    }
                    Logging.warning("Failed to migrate old worlds.yml file: %s", e.getMessage());
                    e.printStackTrace();
                });
    }

    /**
     * Parses the worlds.yml file and creates a WorldConfig for each world in the file if it doesn't already exist.
     *
     * @return A tuple containing a list of the new WorldConfigs added and a list of the worlds removed from the config.
     */
    private Tuple2<List<WorldConfig>, List<String>> parseNewAndRemovedWorlds() {
        Set<String> allWorldsInConfig = worldsConfig.getKeys(false);
        List<WorldConfig> newWorldsAdded = new ArrayList<>();

        for (String worldName : allWorldsInConfig) {
            getWorldConfig(worldName)
                    .peek(config -> config.load(getWorldConfigSection(worldName)))
                    .onEmpty(() -> {
                        WorldConfig newWorldConfig = new WorldConfig(
                                worldName,
                                getWorldConfigSection(worldName),
                                multiverseCore);
                        worldConfigMap.put(worldName, newWorldConfig);
                        newWorldsAdded.add(newWorldConfig);
                    });
        }

        List<String> worldsRemoved = worldConfigMap.keySet().stream()
                .filter(worldName -> !allWorldsInConfig.contains(worldName))
                .toList();

        for (String s : worldsRemoved) {
            worldConfigMap.remove(s);
        }

        return new Tuple2<>(newWorldsAdded, worldsRemoved);
    }

    /**
     * Whether the worlds.yml file has been loaded.
     *
     * @return Whether the worlds.yml file has been loaded.
     */
    public boolean isLoaded() {
        return worldsConfig != null;
    }

    /**
     * Saves the worlds.yml file.
     *
     * @return Whether the save was successful or the error that occurred.
     */
    public Try<Void> save() {
        return Try.run(() -> worldsConfig.save(worldConfigFile));
    }

    /**
     * Gets the {@link WorldConfig} instance of all worlds in the worlds.yml file.
     *
     * @param worldName The name of the world to check.
     * @return The {@link WorldConfig} instance of the world, or empty option if it doesn't exist.
     */
    public @NotNull Option<WorldConfig> getWorldConfig(@NotNull String worldName) {
        return Option.of(worldConfigMap.get(worldName));
    }

    /**
     * Add a new world to the worlds.yml file. If a world with the given name already exists, an exception is thrown.
     *
     * @param worldName The name of the world to add.
     * @return The newly created {@link WorldConfig} instance.
     */
    public @NotNull WorldConfig addWorldConfig(@NotNull String worldName) {
        if (worldConfigMap.containsKey(worldName)) {
            throw new IllegalArgumentException("WorldConfig for world " + worldName + " already exists.");
        }
        WorldConfig worldConfig = new WorldConfig(worldName, getWorldConfigSection(worldName), multiverseCore);
        worldConfigMap.put(worldName, worldConfig);
        return worldConfig;
    }

    /**
     * Deletes the world config for the given world.
     *
     * @param worldName The name of the world to delete.
     */
    public void deleteWorldConfig(@NotNull String worldName) {
        worldConfigMap.remove(worldName);
        worldsConfig.set(worldName, null);
    }

    /**
     * Gets the {@link ConfigurationSection} for the given world in the worlds.yml file. If the section doesn't exist,
     * it is created.
     *
     * @param worldName The name of the world.
     * @return The {@link ConfigurationSection} for the given world.
     */
    private ConfigurationSection getWorldConfigSection(String worldName) {
        return worldsConfig.isConfigurationSection(worldName)
                ? worldsConfig.getConfigurationSection(worldName) : worldsConfig.createSection(worldName);
    }

    private static final class ConfigMigratedException extends RuntimeException {
        private ConfigMigratedException() {
            super("Config migrated");
        }
    }
}