//! Certificate support.

use core_foundation::base::TCFType;
use core_foundation::data::CFData;
use core_foundation::string::CFString;
use core_foundation_sys::base::kCFAllocatorDefault;
use security_framework_sys::base::{errSecParam, SecCertificateRef};
use security_framework_sys::certificate::*;
use std::fmt;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use std::ptr;

use crate::base::{Error, Result};
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use core_foundation::base::FromVoid;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use core_foundation::number::CFNumber;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use core_foundation_sys::base::CFRelease;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use security_framework_sys::base::SecPolicyRef;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use security_framework_sys::item::*;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use security_framework_sys::policy::SecPolicyCreateBasicX509;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use security_framework_sys::trust::{
    SecTrustCopyPublicKey, SecTrustCreateWithCertificates, SecTrustEvaluate, SecTrustRef,
    SecTrustResultType,
};
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use std::ops::Deref;
#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
use crate::{cvt, key};

declare_TCFType! {
    /// A type representing a certificate.
    SecCertificate, SecCertificateRef
}
impl_TCFType!(SecCertificate, SecCertificateRef, SecCertificateGetTypeID);

unsafe impl Sync for SecCertificate {}
unsafe impl Send for SecCertificate {}

impl fmt::Debug for SecCertificate {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("SecCertificate")
            .field("subject", &self.subject_summary())
            .finish()
    }
}

impl SecCertificate {
    /// Creates a `SecCertificate` from DER encoded certificate data.
    pub fn from_der(der_data: &[u8]) -> Result<Self> {
        let der_data = CFData::from_buffer(der_data);
        unsafe {
            let certificate =
                SecCertificateCreateWithData(kCFAllocatorDefault, der_data.as_concrete_TypeRef());
            if certificate.is_null() {
                Err(Error::from_code(errSecParam))
            } else {
                Ok(Self::wrap_under_create_rule(certificate))
            }
        }
    }

    /// Returns DER encoded data describing this certificate.
    pub fn to_der(&self) -> Vec<u8> {
        unsafe {
            let der_data = SecCertificateCopyData(self.0);
            CFData::wrap_under_create_rule(der_data).to_vec()
        }
    }

    /// Returns a human readable summary of this certificate.
    pub fn subject_summary(&self) -> String {
        unsafe {
            let summary = SecCertificateCopySubjectSummary(self.0);
            CFString::wrap_under_create_rule(summary).to_string()
        }
    }

    #[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
    /// Returns DER encoded subjectPublicKeyInfo of certificate if available. This can be used
    /// for certificate pinning.
    pub fn public_key_info_der(&self) -> Result<Option<Vec<u8>>> {
        // Imported from TrustKit
        // https://github.com/datatheorem/TrustKit/blob/master/TrustKit/Pinning/TSKSPKIHashCache.m
        let public_key = self.public_key()?;
        Ok(self.pk_to_der(public_key))
    }

    #[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
    fn pk_to_der(&self, public_key: key::SecKey) -> Option<Vec<u8>> {
        let public_key_attributes = public_key.attributes();
        let public_key_type = public_key_attributes
            .find(unsafe { kSecAttrKeyType } as *const ::std::os::raw::c_void)?;
        let public_keysize = public_key_attributes
            .find(unsafe { kSecAttrKeySizeInBits } as *const ::std::os::raw::c_void)?;
        let public_keysize = unsafe { CFNumber::from_void(*public_keysize.deref()) };
        let public_keysize_val = public_keysize.to_i64()? as u32;
        let hdr_bytes = get_asn1_header_bytes(
            unsafe { CFString::wrap_under_get_rule(*public_key_type.deref() as _) },
            public_keysize_val,
        )?;
        let public_key_data = public_key.external_representation()?;
        let mut out = Vec::with_capacity(hdr_bytes.len() + public_key_data.len() as usize);
        out.extend_from_slice(hdr_bytes);
        out.extend_from_slice(public_key_data.bytes());
        Some(out)
    }

    #[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
    /// Get public key from certificate
    pub fn public_key(&self) -> Result<key::SecKey> {
        unsafe {
            // Create an X509 trust using the using the certificate
            let mut trust: SecTrustRef = ptr::null_mut();
            let policy: SecPolicyRef = SecPolicyCreateBasicX509();
            cvt(SecTrustCreateWithCertificates(
                self.as_concrete_TypeRef() as _,
                policy as _,
                &mut trust,
            ))?;

            // Get a public key reference for the certificate from the trust
            let mut result: SecTrustResultType = 0;
            cvt(SecTrustEvaluate(trust, &mut result))?;
            let public_key = SecTrustCopyPublicKey(trust);
            CFRelease(policy as _);
            CFRelease(trust as _);

            Ok(key::SecKey::wrap_under_create_rule(public_key))
        }
    }
}

#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
fn get_asn1_header_bytes(pkt: CFString, ksz: u32) -> Option<&'static [u8]> {
    if pkt == unsafe { CFString::wrap_under_get_rule(kSecAttrKeyTypeRSA) } && ksz == 2048 {
        return Some(&RSA_2048_ASN1_HEADER);
    }
    if pkt == unsafe { CFString::wrap_under_get_rule(kSecAttrKeyTypeRSA) } && ksz == 4096 {
        return Some(&RSA_4096_ASN1_HEADER);
    }
    if pkt == unsafe { CFString::wrap_under_get_rule(kSecAttrKeyTypeECSECPrimeRandom) }
        && ksz == 256
    {
        return Some(&EC_DSA_SECP_256_R1_ASN1_HEADER);
    }
    if pkt == unsafe { CFString::wrap_under_get_rule(kSecAttrKeyTypeECSECPrimeRandom) }
        && ksz == 384
    {
        return Some(&EC_DSA_SECP_384_R1_ASN1_HEADER);
    }
    None
}

#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
const RSA_2048_ASN1_HEADER: [u8; 24] = [
    0x30, 0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
    0x01, 0x05, 0x00, 0x03, 0x82, 0x01, 0x0f, 0x00,
];

#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
const RSA_4096_ASN1_HEADER: [u8; 24] = [
    0x30, 0x82, 0x02, 0x22, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
    0x01, 0x05, 0x00, 0x03, 0x82, 0x02, 0x0f, 0x00,
];

#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
const EC_DSA_SECP_256_R1_ASN1_HEADER: [u8; 26] = [
    0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0x03, 0x42, 0x00,
];

#[cfg(any(feature = "OSX_10_12", target_os = "ios"))]
const EC_DSA_SECP_384_R1_ASN1_HEADER: [u8; 23] = [
    0x30, 0x76, 0x30, 0x10, 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x05, 0x2b,
    0x81, 0x04, 0x00, 0x22, 0x03, 0x62, 0x00,
];

#[cfg(test)]
mod test {
    use crate::test::certificate;

    #[test]
    fn subject_summary() {
        let cert = certificate();
        assert_eq!("foobar.com", cert.subject_summary());
    }
}