use cosmwasm_std::ensure_eq;
use num_bigint::BigUint;
use sha2::{Digest, Sha256};

use crate::intel_sgx::{
    epid::{types::IASReport, Error as EpidError, INTEL_ROOT_EXPONENT, INTEL_ROOT_MODULUS},
    Error,
};

/// Given an RSA signature and the signer's exponent + modulus we recover the digest that was signed by the signature.
pub fn recover_signature_digest(signature: &[u8], exponent: &[u8], modulus: &[u8]) -> Vec<u8> {
    let sig_as_bignum_be = BigUint::from_bytes_be(signature);
    let intel_modulus_be = BigUint::from_bytes_be(modulus);
    let intel_exponent_be = BigUint::from_bytes_be(exponent);

    let digest_be = sig_as_bignum_be.modpow(&intel_exponent_be, &intel_modulus_be);

    // last 32 bytes contain the digest
    let digest_bytes = digest_be.to_bytes_be();
    let n = digest_bytes.len();
    digest_bytes[n - 32..n].to_vec()
}

pub fn verify(
    ias_report: IASReport,
    mrenclave: impl AsRef<[u8]>,
    user_data: impl AsRef<[u8]>,
) -> Result<(), Error> {
    // Extract the payload from the quote body
    let user_data_in_quote = ias_report.report.isv_enclave_quote_body.user_data();

    // check user_report_data
    ensure_eq!(
        user_data_in_quote,
        user_data.as_ref(),
        Error::UserDataMismatch
    );

    // Extract the mrenclave from the quote body
    let mrenclave_in_quote = ias_report.report.isv_enclave_quote_body.mrenclave();

    // check mrenclave
    ensure_eq!(
        mrenclave_in_quote,
        mrenclave.as_ref(),
        Error::MrEnclaveMismatch
    );

    // Recover the RSA signature's digest
    let recovered_digest = recover_signature_digest(
        ias_report.report_sig.as_slice(),
        INTEL_ROOT_EXPONENT,
        INTEL_ROOT_MODULUS,
    );
    // Convert the recovered digest into a byte slice
    let recovered_digest = recovered_digest.as_slice();

    // Convert the ias report as a json string, removing all the backslashes to escape stuff
    let ias_report_asjson = serde_json::to_string(&ias_report.report)
        .expect("infallible serializer for IASReport")
        .replace('\\', "");
    // Convert the ias report without the back slashes to bytes
    let ias_report_asbytes = ias_report_asjson.as_bytes();
    // We are going to calculate our own digest of the ias report
    let mut hasher = Sha256::default();
    // Update the hasher contents with that of the ias report json
    hasher.update(ias_report_asbytes);
    // finalize the sha256 hasher so that it produces a byte slice of the digest, should be 32 bytes
    let ias_report_digest = &hasher.finalize()[..];

    // ensure that the recovered digest from the signature matches the digest of the report
    ensure_eq!(
        ias_report_digest,
        recovered_digest,
        EpidError::RecoveredDigestMismatch
    );

    Ok(())
}

#[cfg(test)]
mod tests {
    use cosmwasm_schema::cw_serde;
    use cosmwasm_std::HexBinary;

    use super::*;

    #[cw_serde]
    pub enum QueryMsg {
        /// Verify an attestation
        VerifyEpidAttestation {
            // The report that is generated by an enclave
            report: IASReport,
            // The MRENCLAVE of this enclave (as hex string)
            mrenclave: HexBinary,
            // User data - whose commitment is in the `user_report_data` (as hex string)
            user_data: HexBinary,
        },
    }

    fn parse_attestation(query_verifier: &str) -> (IASReport, HexBinary, HexBinary) {
        let query_verifier: QueryMsg =
            serde_json::from_str(query_verifier).expect("deserialize query");
        match query_verifier {
            QueryMsg::VerifyEpidAttestation {
                report,
                mrenclave,
                user_data,
            } => (report, mrenclave, user_data),
        }
    }

    fn verify_attestation(query_verifier: &str) {
        let (report, mrenclave, user_data) = parse_attestation(query_verifier);
        verify(report, mrenclave, user_data).expect("RA verification failure");
    }

    #[test]
    fn test_verifier_ok() {
        verify_attestation(
            r#"{
                "verify_epid_attestation": {
                    "report": {"report":{"id":"5246688123689513540899231107533660789","timestamp":"2024-02-07T17:06:23.913745","version":4,"epidPseudonym":"+CUyIi74LPqS6M0NF7YrSxLqPdX3MKs6D6LIPqRG/ZEB4WmxZVvxAJwdwg/0m9cYnUUQguLnJotthX645lAogfJgO8Xg5/91lSegwyUKvHmKgtjOHX/YTbVe/wmgWiBdaL+KmarY0Je459Px/FqGLWLsAF7egPAJRd1Xn88Znrs=","advisoryURL":"https://security-center.intel.com","advisoryIDs":["INTEL-SA-00161","INTEL-SA-00219","INTEL-SA-00289","INTEL-SA-00334","INTEL-SA-00615"],"isvEnclaveQuoteStatus":"CONFIGURATION_AND_SW_HARDENING_NEEDED","platformInfoBlob":"150200650000080000141402040180070000000000000000000D00000C000000020000000000000CB0F08115F3DE71AE97980FE5E10B042054930ACE356C79EC44603D3F890756EC6ED73927A7C58CDE9AF1E754AEC77E335E8D80294407936BEB6404F27669FF7BB1","isvEnclaveQuoteBody":"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"},"reportsig":"YcY4SPvkfR4P2E8A5huutCeS+vY/ir+xq6disalNfNtAcUyOIOqTPVXhAZgY1M5B47Hjj1oYWf2qC2w+dnj7VcZjzO9oR0pJYdA+A7jaVrNzH2eXA79yICkuU8WE/x58I0j5vjXLoHXahaKlpZkMeTphqBY8u+FTVSdP3cWPho4viPapTfQRuEWmYq4KIq2zSr6wLg3Pz+yQ+G3e9BASVkLYxdYGTDFH1pMmfas9SEI7V4I+j8DaXmL8bucSRakmcQdmDMPGiA7mvIhSAlprzCrdxM7CHeUC6MPLN1fmFFcc9kyO/ved69j/651MWC83GgxSJ15L80U+DQzmrSW8xg=="},
                    "mrenclave": "e3c2f2a5b840d89e069acaffcadb6510ef866a73d3a9ee57100ed5f8646ee4bb",
                    "user_data": "9113b0be77ed5d0d68680ec77206b8d587ed40679b71321ccdd5405e4d54a6820000000000000000000000000000000000000000000000000000000000000000"
                }
            }"#,
        )
    }

    #[test]
    #[should_panic]
    fn test_verifier_bad_mrenclave() {
        verify_attestation(
            r#"{
                "verify_epid_attestation": {
                    "report": {"report":{"id":"5246688123689513540899231107533660789","timestamp":"2024-02-07T17:06:23.913745","version":4,"epidPseudonym":"+CUyIi74LPqS6M0NF7YrSxLqPdX3MKs6D6LIPqRG/ZEB4WmxZVvxAJwdwg/0m9cYnUUQguLnJotthX645lAogfJgO8Xg5/91lSegwyUKvHmKgtjOHX/YTbVe/wmgWiBdaL+KmarY0Je459Px/FqGLWLsAF7egPAJRd1Xn88Znrs=","advisoryURL":"https://security-center.intel.com","advisoryIDs":["INTEL-SA-00161","INTEL-SA-00219","INTEL-SA-00289","INTEL-SA-00334","INTEL-SA-00615"],"isvEnclaveQuoteStatus":"CONFIGURATION_AND_SW_HARDENING_NEEDED","platformInfoBlob":"150200650000080000141402040180070000000000000000000D00000C000000020000000000000CB0F08115F3DE71AE97980FE5E10B042054930ACE356C79EC44603D3F890756EC6ED73927A7C58CDE9AF1E754AEC77E335E8D80294407936BEB6404F27669FF7BB1","isvEnclaveQuoteBody":"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"},"reportsig":"YcY4SPvkfR4P2E8A5huutCeS+vY/ir+xq6disalNfNtAcUyOIOqTPVXhAZgY1M5B47Hjj1oYWf2qC2w+dnj7VcZjzO9oR0pJYdA+A7jaVrNzH2eXA79yICkuU8WE/x58I0j5vjXLoHXahaKlpZkMeTphqBY8u+FTVSdP3cWPho4viPapTfQRuEWmYq4KIq2zSr6wLg3Pz+yQ+G3e9BASVkLYxdYGTDFH1pMmfas9SEI7V4I+j8DaXmL8bucSRakmcQdmDMPGiA7mvIhSAlprzCrdxM7CHeUC6MPLN1fmFFcc9kyO/ved69j/651MWC83GgxSJ15L80U+DQzmrSW8xg=="},
                    "mrenclave": "f3c2f2a5b840d89e069acaffcadb6510ef866a73d3a9ee57100ed5f8646ee4bb",
                    "user_data": "9113b0be77ed5d0d68680ec77206b8d587ed40679b71321ccdd5405e4d54a6820000000000000000000000000000000000000000000000000000000000000000"
                }
            }"#,
        )
    }

    #[test]
    #[should_panic]
    fn test_verifier_bad_user_data() {
        verify_attestation(
            r#"{
                "verify_epid_attestation": {
                    "report": {"report":{"id":"5246688123689513540899231107533660789","timestamp":"2024-02-07T17:06:23.913745","version":4,"epidPseudonym":"+CUyIi74LPqS6M0NF7YrSxLqPdX3MKs6D6LIPqRG/ZEB4WmxZVvxAJwdwg/0m9cYnUUQguLnJotthX645lAogfJgO8Xg5/91lSegwyUKvHmKgtjOHX/YTbVe/wmgWiBdaL+KmarY0Je459Px/FqGLWLsAF7egPAJRd1Xn88Znrs=","advisoryURL":"https://security-center.intel.com","advisoryIDs":["INTEL-SA-00161","INTEL-SA-00219","INTEL-SA-00289","INTEL-SA-00334","INTEL-SA-00615"],"isvEnclaveQuoteStatus":"CONFIGURATION_AND_SW_HARDENING_NEEDED","platformInfoBlob":"150200650000080000141402040180070000000000000000000D00000C000000020000000000000CB0F08115F3DE71AE97980FE5E10B042054930ACE356C79EC44603D3F890756EC6ED73927A7C58CDE9AF1E754AEC77E335E8D80294407936BEB6404F27669FF7BB1","isvEnclaveQuoteBody":"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"},"reportsig":"YcY4SPvkfR4P2E8A5huutCeS+vY/ir+xq6disalNfNtAcUyOIOqTPVXhAZgY1M5B47Hjj1oYWf2qC2w+dnj7VcZjzO9oR0pJYdA+A7jaVrNzH2eXA79yICkuU8WE/x58I0j5vjXLoHXahaKlpZkMeTphqBY8u+FTVSdP3cWPho4viPapTfQRuEWmYq4KIq2zSr6wLg3Pz+yQ+G3e9BASVkLYxdYGTDFH1pMmfas9SEI7V4I+j8DaXmL8bucSRakmcQdmDMPGiA7mvIhSAlprzCrdxM7CHeUC6MPLN1fmFFcc9kyO/ved69j/651MWC83GgxSJ15L80U+DQzmrSW8xg=="},
                    "mrenclave": "e3c2f2a5b840d89e069acaffcadb6510ef866a73d3a9ee57100ed5f8646ee4bb",
                    "user_data": "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
                }
            }"#,
        )
    }

    #[test]
    #[should_panic]
    fn test_verifier_bad_platform_info_blob() {
        verify_attestation(
            r#"{
                "verify_epid_attestation": {
                    "report": {"report":{"id":"5246688123689513540899231107533660789","timestamp":"2024-02-07T17:06:23.913745","version":4,"epidPseudonym":"+CUyIi74LPqS6M0NF7YrSxLqPdX3MKs6D6LIPqRG/ZEB4WmxZVvxAJwdwg/0m9cYnUUQguLnJotthX645lAogfJgO8Xg5/91lSegwyUKvHmKgtjOHX/YTbVe/wmgWiBdaL+KmarY0Je459Px/FqGLWLsAF7egPAJRd1Xn88Znrs=","advisoryURL":"https://security-center.intel.com","advisoryIDs":["INTEL-SA-00161","INTEL-SA-00219","INTEL-SA-00289","INTEL-SA-00334","INTEL-SA-00615"],"isvEnclaveQuoteStatus":"CONFIGURATION_AND_SW_HARDENING_NEEDED","platformInfoBlob":"150200650000080000141402040180070000000000000000000D00000C000000020000000000000CB0F08115F3DE71AE97980FE5E10B042054930ACE356C79EC44603D3F890756EC6ED73927A7C58CDE9AF1E754AEC77E335E8D80294407936BEB6404F27669FF7BB1","isvEnclaveQuoteBody":"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"},"reportsig":"YaY4SPvkfR4P2E8A5huutCeS+vY/ir+xq6disalNfNtAcUyOIOqTPVXhAZgY1M5B47Hjj1oYWf2qC2w+dnj7VcZjzO9oR0pJYdA+A7jaVrNzH2eXA79yICkuU8WE/x58I0j5vjXLoHXahaKlpZkMeTphqBY8u+FTVSdP3cWPho4viPapTfQRuEWmYq4KIq2zSr6wLg3Pz+yQ+G3e9BASVkLYxdYGTDFH1pMmfas9SEI7V4I+j8DaXmL8bucSRakmcQdmDMPGiA7mvIhSAlprzCrdxM7CHeUC6MPLN1fmFFcc9kyO/ved69j/651MWC83GgxSJ15L80U+DQzmrSW8xg=="},
                    "mrenclave": "e3c2f2a5b840d89e069acaffcadb6510ef866a73d3a9ee57100ed5f8646ee4bb",
                    "user_data": "9113b0be77ed5d0d68680ec77206b8d587ed40679b71321ccdd5405e4d54a6820000000000000000000000000000000000000000000000000000000000000000"
                }
            }"#,
        )
    }
}