// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0

package sop.external.operation;

import sop.MicAlg;
import sop.ReadyWithResult;
import sop.SigningResult;
import sop.enums.SignAs;
import sop.exception.SOPGPException;
import sop.external.ExternalSOP;
import sop.operation.DetachedSign;

import javax.annotation.Nonnull;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

/**
 * Implementation of the {@link DetachedSign} operation using an external SOP binary.
 */
public class DetachedSignExternal implements DetachedSign {

    private final ExternalSOP.TempDirProvider tempDirProvider;
    private final List<String> commandList = new ArrayList<>();
    private final List<String> envList;

    private int withKeyPasswordCounter = 0;
    private int keyCounter = 0;

    public DetachedSignExternal(String binary, Properties properties, ExternalSOP.TempDirProvider tempDirProvider) {
        this.tempDirProvider = tempDirProvider;
        commandList.add(binary);
        commandList.add("sign");
        envList = ExternalSOP.propertiesToEnv(properties);
    }

    @Override
    @Nonnull
    public DetachedSign noArmor() {
        commandList.add("--no-armor");
        return this;
    }

    @Override
    @Nonnull
    public DetachedSign key(@Nonnull InputStream key) throws SOPGPException.KeyCannotSign, SOPGPException.BadData, SOPGPException.UnsupportedAsymmetricAlgo, IOException {
        String envVar = "KEY_" + keyCounter++;
        commandList.add("@ENV:" + envVar);
        envList.add(envVar + "=" + ExternalSOP.readString(key));
        return this;
    }

    @Override
    @Nonnull
    public DetachedSign withKeyPassword(@Nonnull byte[] password) throws SOPGPException.UnsupportedOption, SOPGPException.PasswordNotHumanReadable {
        String envVar = "WITH_KEY_PASSWORD_" + withKeyPasswordCounter++;
        commandList.add("--with-key-password=@ENV:" + envVar);
        envList.add(envVar + "=" + new String(password));
        return this;
    }

    @Override
    @Nonnull
    public DetachedSign mode(@Nonnull SignAs mode) throws SOPGPException.UnsupportedOption {
        commandList.add("--as=" + mode);
        return this;
    }

    @Override
    @Nonnull
    public ReadyWithResult<SigningResult> data(@Nonnull InputStream data)
            throws IOException, SOPGPException.KeyIsProtected, SOPGPException.ExpectedText {

        File tempDir = tempDirProvider.provideTempDirectory();
        File micAlgOut = new File(tempDir, "micAlgOut");
        micAlgOut.delete();
        commandList.add("--micalg-out=" + micAlgOut.getAbsolutePath());

        String[] command = commandList.toArray(new String[0]);
        String[] env = envList.toArray(new String[0]);
        try {
            Process process = Runtime.getRuntime().exec(command, env);
            OutputStream processOut = process.getOutputStream();
            InputStream processIn = process.getInputStream();

            return new ReadyWithResult<SigningResult>() {
                @Override
                public SigningResult writeTo(@Nonnull OutputStream outputStream) throws IOException {
                    byte[] buf = new byte[4096];
                    int r;
                    while ((r = data.read(buf)) > 0) {
                        processOut.write(buf, 0, r);
                    }

                    data.close();
                    try {
                        processOut.close();
                    } catch (IOException e) {
                        // Ignore Stream closed
                        if (!"Stream closed".equals(e.getMessage())) {
                            throw e;
                        }
                    }

                    while ((r = processIn.read(buf)) > 0) {
                        outputStream.write(buf, 0 , r);
                    }

                    processIn.close();
                    outputStream.close();

                    ExternalSOP.finish(process);

                    SigningResult.Builder builder = SigningResult.builder();
                    if (micAlgOut.exists()) {
                        BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(micAlgOut)));
                        String line = reader.readLine();
                        if (line != null && !line.trim().isEmpty()) {
                            MicAlg micAlg = new MicAlg(line.trim());
                            builder.setMicAlg(micAlg);
                        }
                        reader.close();
                        micAlgOut.delete();
                    }

                    return builder.build();
                }
            };
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}