oauth-fabric/src/main/java/dev/lilyvex/oauthfabric/OAuthFabricConfig.java

package dev.lilyvex.oauthfabric;

import com.electronwill.nightconfig.core.CommentedConfig;
import com.electronwill.nightconfig.core.io.ParsingException;
import com.electronwill.nightconfig.core.io.ParsingMode;
import com.electronwill.nightconfig.toml.TomlParser;
import com.electronwill.nightconfig.toml.TomlWriter;

import net.fabricmc.loader.api.FabricLoader;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class OAuthFabricConfig {
    private static final Logger LOGGER = LoggerFactory.getLogger("oauth-fabric");
    private static final String DEFAULT_PROVIDER = "auth.lilyvex.dev";
    private static final String DEFAULT_CLIENT_ID = "minecraft";
    private static final String DEFAULT_CLIENT_SECRET = "<No default secret>";
    private static final String DEFAULT_REDIRECT_URI = "mc.lilyvex.dev/oauth2";
    private static final String DEFAULT_DATABASE = "sqlite";
    
    public static final Path CONFIG_FILE_PATH = FabricLoader.getInstance().getConfigDir()
        .resolve("oauth-fabric.toml")
        .normalize();

    private final CommentedConfig config = CommentedConfig.inMemory();

    // URL to the OAuth provider (e.g. accounts.google.com, discord.com/oauth2)
    private String provider;

    // ID of the OAuth client. This is usually defined when creating the OAuth application.
    private String client_id;

    // Client secret
    private String client_secret;

    // URI to redirect to. Ensure that this URI is listed in the allowed redirect URIs section
    // of your OAuth provider.
    private String redirect_uri;

    // Which database to use (SQLite is currently the only supported database).
    private String database;

    public void load() {
        this.config.getOrElse("provider", DEFAULT_PROVIDER);
        this.config.getOrElse("client_id", DEFAULT_CLIENT_ID);
        this.config.getOrElse("client_secret", DEFAULT_CLIENT_SECRET);
        this.config.getOrElse("redirect_uri", DEFAULT_REDIRECT_URI);
        this.config.getOrElse("database", DEFAULT_DATABASE);

        try {
            this.loadFromFile(true);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        LOGGER.info("oauth-fabric: Configuration loaded.");
    }

    private void loadFromFile(boolean firstAttempt) throws IOException {
        try (var reader = Files.newBufferedReader(CONFIG_FILE_PATH)) {
            new TomlParser().parse(reader, this.config, ParsingMode.REPLACE);
        } catch (NoSuchFileException | FileNotFoundException e) {
            if (!firstAttempt) {
                throw e;
            }

            this.copyDefaultFile();
            this.loadFromFile(true);
        } catch (ParsingException e) {
            if (!firstAttempt) {
                throw e;
            }

            var backupPath = CONFIG_FILE_PATH.resolveSibling("oauth-fabric.toml.old").toAbsolutePath().normalize();

			LOGGER.error("oauth-fabric: Failed to parse configuration file, THIS IS BAD.", e);
			LOGGER.error("oauth-fabric: Copying the corrupt file to \"{}\".", backupPath);
			Files.copy(CONFIG_FILE_PATH, backupPath, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);
			this.copyDefaultFile();
			this.loadFromFile(false);
        }
    }

    private void copyDefaultFile() throws IOException {
        Files.createDirectories(CONFIG_FILE_PATH.getParent());

        try (var writer = Files.newBufferedWriter(CONFIG_FILE_PATH, StandardCharsets.UTF_8)) {
            new TomlWriter().write(this.config.unmodifiable(), writer);
        } catch (NoSuchFileException | FileNotFoundException e) {
            LOGGER.error("oauth-fabric: Failed to write default configuration file.");
        }
    }
}