use ffi;
use std::fmt;
use ssl::error::{SslError, StreamError};
use std::ptr;
use std::io::{self, Read, Write};
use libc::c_int;

use bn::BigNum;
use bio::MemBio;
use crypto::HashTypeInternals;
use crypto::hash;

pub struct RSA(*mut ffi::RSA);

impl Drop for RSA {
    fn drop(&mut self) {
        unsafe {
            ffi::RSA_free(self.0);
        }
    }
}

impl RSA {
    /// only useful for associating the key material directly with the key, it's safer to use
    /// the supplied load and save methods for DER formatted keys.
    pub fn from_public_components(n: BigNum, e: BigNum) -> Result<RSA, SslError> {
        unsafe {
            let rsa = try_ssl_null!(ffi::RSA_new());
            (*rsa).n = n.into_raw();
            (*rsa).e = e.into_raw();
            Ok(RSA(rsa))
        }
    }

    pub fn from_private_components(n: BigNum,
                                   e: BigNum,
                                   d: BigNum,
                                   p: BigNum,
                                   q: BigNum,
                                   dp: BigNum,
                                   dq: BigNum,
                                   qi: BigNum)
                                   -> Result<RSA, SslError> {
        unsafe {
            let rsa = try_ssl_null!(ffi::RSA_new());
            (*rsa).n = n.into_raw();
            (*rsa).e = e.into_raw();
            (*rsa).d = d.into_raw();
            (*rsa).p = p.into_raw();
            (*rsa).q = q.into_raw();
            (*rsa).dmp1 = dp.into_raw();
            (*rsa).dmq1 = dq.into_raw();
            (*rsa).iqmp = qi.into_raw();
            Ok(RSA(rsa))
        }
    }

    /// the caller should assert that the rsa pointer is valid.
    pub unsafe fn from_raw(rsa: *mut ffi::RSA) -> RSA {
        RSA(rsa)
    }

    /// Reads an RSA private key from PEM formatted data.
    pub fn private_key_from_pem<R>(reader: &mut R) -> Result<RSA, SslError>
        where R: Read
    {
        let mut mem_bio = try!(MemBio::new());
        try!(io::copy(reader, &mut mem_bio).map_err(StreamError));

        unsafe {
            let rsa = try_ssl_null!(ffi::PEM_read_bio_RSAPrivateKey(mem_bio.get_handle(),
                                                                    ptr::null_mut(),
                                                                    None,
                                                                    ptr::null_mut()));
            Ok(RSA(rsa))
        }
    }

    /// Writes an RSA private key as unencrypted PEM formatted data
    pub fn private_key_to_pem<W>(&self, writer: &mut W) -> Result<(), SslError>
        where W: Write
    {
        let mut mem_bio = try!(MemBio::new());

        let result = unsafe {
            ffi::PEM_write_bio_RSAPrivateKey(mem_bio.get_handle(),
                                             self.0,
                                             ptr::null(),
                                             ptr::null_mut(),
                                             0,
                                             None,
                                             ptr::null_mut())
        };

        if result == 1 {
            try!(io::copy(&mut mem_bio, writer).map_err(StreamError));

            Ok(())
        } else {
            Err(SslError::OpenSslErrors(vec![]))
        }
    }

    /// Reads an RSA public key from PEM formatted data.
    pub fn public_key_from_pem<R>(reader: &mut R) -> Result<RSA, SslError>
        where R: Read
    {
        let mut mem_bio = try!(MemBio::new());
        try!(io::copy(reader, &mut mem_bio).map_err(StreamError));

        unsafe {
            let rsa = try_ssl_null!(ffi::PEM_read_bio_RSA_PUBKEY(mem_bio.get_handle(),
                                                                 ptr::null_mut(),
                                                                 None,
                                                                 ptr::null_mut()));
            Ok(RSA(rsa))
        }
    }

    /// Writes an RSA public key as PEM formatted data
    pub fn public_key_to_pem<W>(&self, writer: &mut W) -> Result<(), SslError>
        where W: Write
    {
        let mut mem_bio = try!(MemBio::new());

        let result = unsafe { ffi::PEM_write_bio_RSA_PUBKEY(mem_bio.get_handle(), self.0) };

        if result == 1 {
            try!(io::copy(&mut mem_bio, writer).map_err(StreamError));

            Ok(())
        } else {
            Err(SslError::OpenSslErrors(vec![]))
        }
    }

    pub fn size(&self) -> Result<u32, SslError> {
        if self.has_n() {
            unsafe { Ok(ffi::RSA_size(self.0) as u32) }
        } else {
            Err(SslError::OpenSslErrors(vec![]))
        }
    }

    pub fn sign(&self, hash: hash::Type, message: &[u8]) -> Result<Vec<u8>, SslError> {
        let k_len = try!(self.size());
        let mut sig = vec![0;k_len as usize];
        let mut sig_len = k_len;

        unsafe {
            let result = ffi::RSA_sign(hash.as_nid() as c_int,
                                       message.as_ptr(),
                                       message.len() as u32,
                                       sig.as_mut_ptr(),
                                       &mut sig_len,
                                       self.0);
            assert!(sig_len == k_len);

            if result == 1 {
                Ok(sig)
            } else {
                Err(SslError::OpenSslErrors(vec![]))
            }
        }
    }

    pub fn verify(&self, hash: hash::Type, message: &[u8], sig: &[u8]) -> Result<bool, SslError> {
        unsafe {
            let result = ffi::RSA_verify(hash.as_nid() as c_int,
                                         message.as_ptr(),
                                         message.len() as u32,
                                         sig.as_ptr(),
                                         sig.len() as u32,
                                         self.0);

            Ok(result == 1)
        }
    }

    pub fn as_ptr(&self) -> *mut ffi::RSA {
        self.0
    }

    // The following getters are unsafe, since BigNum::new_from_ffi fails upon null pointers
    pub fn n(&self) -> Result<BigNum, SslError> {
        unsafe { BigNum::new_from_ffi((*self.0).n) }
    }

    pub fn has_n(&self) -> bool {
        unsafe { !(*self.0).n.is_null() }
    }

    pub fn d(&self) -> Result<BigNum, SslError> {
        unsafe { BigNum::new_from_ffi((*self.0).d) }
    }

    pub fn e(&self) -> Result<BigNum, SslError> {
        unsafe { BigNum::new_from_ffi((*self.0).e) }
    }

    pub fn has_e(&self) -> bool {
        unsafe { !(*self.0).e.is_null() }
    }

    pub fn p(&self) -> Result<BigNum, SslError> {
        unsafe { BigNum::new_from_ffi((*self.0).p) }
    }

    pub fn q(&self) -> Result<BigNum, SslError> {
        unsafe { BigNum::new_from_ffi((*self.0).q) }
    }
}

impl fmt::Debug for RSA {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "RSA")
    }
}

#[cfg(test)]
mod test {
    use std::fs::File;
    use std::io::Write;
    use super::*;
    use crypto::hash::*;

    fn signing_input_rs256() -> Vec<u8> {
        vec![101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 122, 73, 49, 78, 105, 74, 57,
             46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48,
             75, 73, 67, 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107,
             122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76, 121,
             57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118, 98, 83, 57, 112, 99,
             49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48, 99, 110, 86, 108, 102, 81]
    }

    fn signature_rs256() -> Vec<u8> {
        vec![112, 46, 33, 137, 67, 232, 143, 209, 30, 181, 216, 45, 191, 120, 69, 243, 65, 6, 174,
             27, 129, 255, 247, 115, 17, 22, 173, 209, 113, 125, 131, 101, 109, 66, 10, 253, 60,
             150, 238, 221, 115, 162, 102, 62, 81, 102, 104, 123, 0, 11, 135, 34, 110, 1, 135, 237,
             16, 115, 249, 69, 229, 130, 173, 252, 239, 22, 216, 90, 121, 142, 232, 198, 109, 219,
             61, 184, 151, 91, 23, 208, 148, 2, 190, 237, 213, 217, 217, 112, 7, 16, 141, 178, 129,
             96, 213, 248, 4, 12, 167, 68, 87, 98, 184, 31, 190, 127, 249, 217, 46, 10, 231, 111,
             36, 242, 91, 51, 187, 230, 244, 74, 230, 30, 177, 4, 10, 203, 32, 4, 77, 62, 249, 18,
             142, 212, 1, 48, 121, 91, 212, 189, 59, 65, 238, 202, 208, 102, 171, 101, 25, 129,
             253, 228, 141, 247, 127, 55, 45, 195, 139, 159, 175, 221, 59, 239, 177, 139, 93, 163,
             204, 60, 46, 176, 47, 158, 58, 65, 214, 18, 202, 173, 21, 145, 18, 115, 160, 95, 35,
             185, 232, 56, 250, 175, 132, 157, 105, 132, 41, 239, 90, 30, 136, 121, 130, 54, 195,
             212, 14, 96, 69, 34, 165, 68, 200, 242, 122, 122, 45, 184, 6, 99, 209, 108, 247, 202,
             234, 86, 222, 64, 92, 178, 33, 90, 69, 178, 194, 85, 102, 181, 90, 193, 167, 72, 160,
             112, 223, 200, 163, 42, 70, 149, 67, 208, 25, 238, 251, 71]
    }

    #[test]
    pub fn test_sign() {
        let mut buffer = File::open("test/rsa.pem").unwrap();
        let private_key = RSA::private_key_from_pem(&mut buffer).unwrap();

        let mut sha = Hasher::new(Type::SHA256);
        sha.write_all(&signing_input_rs256()).unwrap();
        let digest = sha.finish();

        let result = private_key.sign(Type::SHA256, &digest).unwrap();

        assert_eq!(result, signature_rs256());
    }

    #[test]
    pub fn test_verify() {
        let mut buffer = File::open("test/rsa.pem.pub").unwrap();
        let public_key = RSA::public_key_from_pem(&mut buffer).unwrap();

        let mut sha = Hasher::new(Type::SHA256);
        sha.write_all(&signing_input_rs256()).unwrap();
        let digest = sha.finish();

        let result = public_key.verify(Type::SHA256, &digest, &signature_rs256()).unwrap();

        assert!(result);
    }
}