package io.gitlab.jfronny.resclone.fetchers;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import io.gitlab.jfronny.resclone.Resclone;
import io.gitlab.jfronny.resclone.data.RescloneException;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Scanner;
import java.util.Set;

public abstract class PackFetcher {
    abstract public String getSourceTypeName(); // The name for users to specify in the config
    abstract String getDownloadUrl(String baseUrl) throws RescloneException; // Return the actual download URL for the file based on the provided string
    protected final Gson gson = Resclone.gson;
    protected boolean urlValid(String url) {
        try {
            HttpURLConnection connection = (HttpURLConnection)new URL(url).toURI().toURL().openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            return connection.getResponseCode() == 200;
        }
        catch (Throwable e) {
            return false;
        }
    }

    protected String readStringFromURL(String requestURL) throws IOException {
        try (Scanner scanner = new Scanner(new URL(requestURL).openStream(), StandardCharsets.UTF_8.toString()))
        {
            scanner.useDelimiter("\\A");
            return scanner.hasNext() ? scanner.next() : "";
        }
    }

    public <T> T readJsonFromURL(String requestUrl, Class<T> classOfT) throws IOException {
        return gson.fromJson(readStringFromURL(requestUrl), classOfT);
    }

    public <T> Set<T> readJsonFromURLSet(String requestUrl, Class<T> classOfT) throws IOException {
        return gson.fromJson(readStringFromURL(requestUrl), TypeToken.getParameterized(Set.class, classOfT).getType());
    }

    public Result get(String baseUrl, Path targetDir, boolean forceDownload) throws RescloneException {
        String url;
        try {
            url = getDownloadUrl(baseUrl);
            Resclone.urlCache.set(baseUrl, url);
        }
        catch (RescloneException e) {
            if (Resclone.urlCache.containsKey(baseUrl)) {
                e.printStackTrace();
                url = Resclone.urlCache.get(baseUrl);
            }
            else {
                throw e;
            }
        }
        Path p = targetDir.resolve(Integer.toHexString(url.hashCode()));
        if (!forceDownload && Files.exists(p))
            return new Result(p, false);
        System.out.println("Downloading pack " + url);
        try (InputStream is = new URL(url).openStream()) {
            FileOutputStream os = new FileOutputStream(p.toFile());
            byte[] dataBuffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = is.read(dataBuffer, 0, 1024)) != -1) {
                os.write(dataBuffer, 0, bytesRead);
            }
            System.out.println("Completed download");
        }
        catch (Throwable e) {
            throw new RescloneException("Could not download pack", e);
        }
        return new Result(p, true);
    }

    public class Result {
        public final Path downloadPath;
        public final boolean freshDownload;

        public Result(Path downloadPath, boolean freshDownload) {
            this.downloadPath = downloadPath;
            this.freshDownload = freshDownload;
        }
    }
}