package com.keuin.kbackupfabric.operation.backup.method;

import com.keuin.kbackupfabric.operation.backup.feedback.IncrementalBackupFeedback;
import com.keuin.kbackupfabric.util.FilesystemUtil;
import com.keuin.kbackupfabric.util.PrintUtil;
import com.keuin.kbackupfabric.util.backup.incremental.ObjectCollection;
import com.keuin.kbackupfabric.util.backup.incremental.ObjectCollectionFactory;
import com.keuin.kbackupfabric.util.backup.incremental.ObjectCollectionSerializer;
import com.keuin.kbackupfabric.util.backup.incremental.identifier.Sha256Identifier;
import com.keuin.kbackupfabric.util.backup.incremental.manager.IncrementalBackupStorageManager;

import java.io.File;
import java.io.IOException;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.HashSet;

public class ConfiguredIncrementalBackupMethod implements ConfiguredBackupMethod {

    private final String backupIndexFileName;
    private final String levelPath;
    private final String backupIndexFileSaveDirectory;
    private final String backupBaseDirectory;

    public ConfiguredIncrementalBackupMethod(String backupIndexFileName, String levelPath, String backupIndexFileSaveDirectory, String backupBaseDirectory) {
        this.backupIndexFileName = backupIndexFileName;
        this.levelPath = levelPath;
        this.backupIndexFileSaveDirectory = backupIndexFileSaveDirectory;
        this.backupBaseDirectory = backupBaseDirectory;
    }

    @Override
    public IncrementalBackupFeedback backup() throws IOException {
        File levelPathFile = new File(levelPath);

        // construct incremental backup index
        PrintUtil.info("Hashing files...");
        ObjectCollection collection = new ObjectCollectionFactory<>(Sha256Identifier.getFactory())
                .fromDirectory(levelPathFile, new HashSet<>(Arrays.asList("session.lock", "kbackup_metadata")));

        // update storage
        PrintUtil.info("Copying files...");
        IncrementalBackupStorageManager storageManager = new IncrementalBackupStorageManager(Paths.get(backupBaseDirectory));
        int filesAdded = storageManager.addObjectCollection(collection, levelPathFile);

        // save index file
        PrintUtil.info("Saving index file...");
        ObjectCollectionSerializer.toFile(collection, new File(backupIndexFileSaveDirectory, backupIndexFileName));

        // return result
        PrintUtil.info("Incremental backup finished.");
        return new IncrementalBackupFeedback(filesAdded >= 0, filesAdded);
    }

    @Override
    public boolean restore() throws IOException {
        // load collection
        PrintUtil.info("Loading file list...");
        ObjectCollection collection = ObjectCollectionSerializer.fromFile(
                new File(backupIndexFileSaveDirectory, backupIndexFileName)
        );

        // delete old level
        File levelPathFile = new File(levelPath);
        PrintUtil.info("Deleting old level...");
        if (!FilesystemUtil.forceDeleteDirectory(levelPathFile)) {
            PrintUtil.info("Failed to delete old level!");
            return false;
        }

        // restore file
        PrintUtil.info("Copying files...");
        IncrementalBackupStorageManager storageManager = new IncrementalBackupStorageManager(Paths.get(backupBaseDirectory));
        int restoreObjectCount = storageManager.restoreObjectCollection(collection, levelPathFile);

        PrintUtil.info(String.format("%d file(s) restored.", restoreObjectCount));
        return true;
    }

    @Override
    public boolean touch() {
        File baseDirectoryFile = new File(backupBaseDirectory);
        return baseDirectoryFile.isDirectory() || baseDirectoryFile.mkdir();
    }

    @Override
    public String getBackupFileName() {
        return backupIndexFileName;
    }


}