package com.example.pdfsigner.service;

import org.apache.pdfbox.pdmodel.interactive.digitalsignature.SignatureInterface;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSTypedData;
import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
import org.bouncycastle.cert.jcajce.JcaCertStore;
import org.bouncycastle.operator.ContentSigner;

import java.io.InputStream;
import java.security.PrivateKey;
import java.security.cert.Certificate;
import java.util.Arrays;
import java.util.List;

public class CreateSignature implements SignatureInterface {

    private PrivateKey privateKey;
    private Certificate[] certificateChain;

    public CreateSignature(PrivateKey privateKey, Certificate[] certificateChain) {
        this.privateKey = privateKey;
        this.certificateChain = certificateChain;
    }

    @Override
    public byte[] sign(InputStream content) {
        try {
            byte[] contentBytes = content.readAllBytes();
            List<Certificate> certList = Arrays.asList(certificateChain);
            JcaCertStore certStore = new JcaCertStore(certList);
            ContentSigner sha256Signer = new JcaContentSignerBuilder("SHA256withRSA").build(privateKey);
            CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
            gen.addSignerInfoGenerator(
                    new org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder(
                            new org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder().build())
                            .build(sha256Signer, (java.security.cert.X509Certificate) certificateChain[0])
            );
            gen.addCertificates(certStore);
            CMSTypedData cmsData = new CMSProcessableByteArray(contentBytes);
            CMSSignedData signedData = gen.generate(cmsData, false);
            return signedData.getEncoded();
        } catch (Exception e) {
            throw new RuntimeException("Error al firmar el PDF", e);
        }
    }
}