use libc::{c_char, c_int, c_long, c_ulong, c_uint};
use std::io;
use std::io::prelude::*;
use std::cmp::Ordering;
use std::ffi::CString;
use std::iter::repeat;
use std::mem;
use std::ptr;

use asn1::{Asn1Time};
use bio::{MemBio};
use crypto::hash;
use crypto::hash::Type as HashType;
use crypto::pkey::{PKey,Parts};
use crypto::rand::rand_bytes;
use ffi;
use ssl::error::{SslError, StreamError};


#[cfg(test)]
mod tests;

#[derive(Copy, Clone)]
#[repr(i32)]
pub enum X509FileType {
    PEM = ffi::X509_FILETYPE_PEM,
    ASN1 = ffi::X509_FILETYPE_ASN1,
    Default = ffi::X509_FILETYPE_DEFAULT
}

#[allow(missing_copy_implementations)]
pub struct X509StoreContext {
    ctx: *mut ffi::X509_STORE_CTX
}

impl X509StoreContext {
    pub fn new(ctx: *mut ffi::X509_STORE_CTX) -> X509StoreContext {
        X509StoreContext {
            ctx: ctx
        }
    }

    pub fn get_error(&self) -> Option<X509ValidationError> {
        let err = unsafe { ffi::X509_STORE_CTX_get_error(self.ctx) };
        X509ValidationError::from_raw(err)
    }

    pub fn get_current_cert<'a>(&'a self) -> Option<X509<'a>> {
        let ptr = unsafe { ffi::X509_STORE_CTX_get_current_cert(self.ctx) };

        if ptr.is_null() {
            None
        } else {
            Some(X509 { ctx: Some(self), handle: ptr, owned: false })
        }
    }
}

#[doc(hidden)]
trait AsStr<'a> {
    fn as_str(&self) -> &'a str;
}

#[derive(Clone, Copy)]
pub enum KeyUsage {
    DigitalSignature,
    NonRepudiation,
    KeyEncipherment,
    DataEncipherment,
    KeyAgreement,
    KeyCertSign,
    CRLSign,
    EncipherOnly,
    DecipherOnly
}

impl AsStr<'static> for KeyUsage {
    fn as_str(&self) -> &'static str {
        match self {
            &KeyUsage::DigitalSignature => "digitalSignature",
            &KeyUsage::NonRepudiation => "nonRepudiation",
            &KeyUsage::KeyEncipherment => "keyEncipherment",
            &KeyUsage::DataEncipherment => "dataEncipherment",
            &KeyUsage::KeyAgreement => "keyAgreement",
            &KeyUsage::KeyCertSign => "keyCertSign",
            &KeyUsage::CRLSign => "cRLSign",
            &KeyUsage::EncipherOnly => "encipherOnly",
            &KeyUsage::DecipherOnly => "decipherOnly"
        }
    }
}


#[derive(Clone, Copy)]
pub enum ExtKeyUsage {
    ServerAuth,
    ClientAuth,
    CodeSigning,
    EmailProtection,
    TimeStamping,
    MsCodeInd,
    MsCodeCom,
    MsCtlSign,
    MsSgc,
    MsEfs,
    NsSgc
}

impl AsStr<'static> for ExtKeyUsage {
    fn as_str(&self) -> &'static str {
        match self {
            &ExtKeyUsage::ServerAuth => "serverAuth",
            &ExtKeyUsage::ClientAuth => "clientAuth",
            &ExtKeyUsage::CodeSigning => "codeSigning",
            &ExtKeyUsage::EmailProtection => "emailProtection",
            &ExtKeyUsage::TimeStamping => "timeStamping",
            &ExtKeyUsage::MsCodeInd => "msCodeInd",
            &ExtKeyUsage::MsCodeCom => "msCodeCom",
            &ExtKeyUsage::MsCtlSign => "msCTLSign",
            &ExtKeyUsage::MsSgc => "msSGC",
            &ExtKeyUsage::MsEfs => "msEFS",
            &ExtKeyUsage::NsSgc =>"nsSGC"
        }
    }
}


// FIXME: a dirty hack as there is no way to
// implement ToString for Vec as both are defined
// in another crate
#[doc(hidden)]
trait ToStr {
    fn to_str(&self) -> String;
}

impl<'a, T: AsStr<'a>> ToStr for Vec<T> {
    fn to_str(&self) -> String {
        self.iter().enumerate().fold(String::new(), |mut acc, (idx, v)| {
            if idx > 0 { acc.push(',') };
            acc.push_str(v.as_str());
            acc
        })
    }
}

#[allow(non_snake_case)]
/// Generator of private key/certificate pairs
///
/// # Example
///
/// ```
/// # #[allow(unstable)]
/// # fn main() {
/// use std::fs;
/// use std::fs::File;
/// use std::io::prelude::*;
/// use std::path::Path;
///
/// use openssl::crypto::hash::Type;
/// use openssl::x509::{KeyUsage, X509Generator};
///
/// let gen = X509Generator::new()
///        .set_bitlength(2048)
///        .set_valid_period(365*2)
///        .set_CN("SuperMegaCorp Inc.")
///        .set_sign_hash(Type::SHA256)
///        .set_usage(&[KeyUsage::DigitalSignature]);
///
/// let (cert, pkey) = gen.generate().unwrap();
///
/// let cert_path = "doc_cert.pem";
/// let mut file = File::create(cert_path).unwrap();
/// assert!(cert.write_pem(&mut file).is_ok());
/// # let _ = fs::remove_file(cert_path);
///
/// let pkey_path = "doc_key.pem";
/// let mut file = File::create(pkey_path).unwrap();
/// assert!(pkey.write_pem(&mut file).is_ok());
/// # let _ = fs::remove_file(pkey_path);
/// # }
/// ```
pub struct X509Generator {
    bits: u32,
    days: u32,
    CN: String,
    key_usage: Vec<KeyUsage>,
    ext_key_usage: Vec<ExtKeyUsage>,
    hash_type: HashType,
}

impl X509Generator {
    /// Creates a new generator with the following defaults:
    ///
    /// bit length: 1024
    ///
    /// validity period: 365 days
    ///
    /// CN: "rust-openssl"
    ///
    /// hash: SHA1
    pub fn new() -> X509Generator {
        X509Generator {
            bits: 1024,
            days: 365,
            CN: "rust-openssl".to_string(),
            key_usage: Vec::new(),
            ext_key_usage: Vec::new(),
            hash_type: HashType::SHA1
        }
    }

    /// Sets desired bit length
    pub fn set_bitlength(mut self, bits: u32) -> X509Generator {
        self.bits = bits;
        self
    }

    /// Sets certificate validity period in days since today
    pub fn set_valid_period(mut self, days: u32) -> X509Generator {
        self.days = days;
        self
    }

    #[allow(non_snake_case)]
    /// Sets Common Name of certificate
    pub fn set_CN(mut self, CN: &str) -> X509Generator {
        self.CN = CN.to_string();
        self
    }

    /// Sets what for certificate could be used
    pub fn set_usage(mut self, purposes: &[KeyUsage]) -> X509Generator {
        self.key_usage = purposes.to_vec();
        self
    }

    /// Sets allowed extended usage of certificate
    pub fn set_ext_usage(mut self, purposes: &[ExtKeyUsage]) -> X509Generator {
        self.ext_key_usage = purposes.to_vec();
        self
    }

    pub fn set_sign_hash(mut self, hash_type: hash::Type) -> X509Generator {
        self.hash_type = hash_type;
        self
    }

    fn add_extension(x509: *mut ffi::X509, extension: c_int, value: &str) -> Result<(), SslError> {
        unsafe {
            let mut ctx: ffi::X509V3_CTX = mem::zeroed();
            ffi::X509V3_set_ctx(&mut ctx, x509, x509,
                                ptr::null_mut(), ptr::null_mut(), 0);
            let value = CString::new(value.as_bytes()).unwrap();
            let ext = ffi::X509V3_EXT_conf_nid(ptr::null_mut(),
                                               mem::transmute(&ctx),
                                               extension,
                                               value.as_ptr() as *mut c_char);

            let mut success = false;
            if ext != ptr::null_mut() {
                success = ffi::X509_add_ext(x509, ext, -1) != 0;
                ffi::X509_EXTENSION_free(ext);
            }
            lift_ssl_if!(!success)
        }
    }

    fn add_name(name: *mut ffi::X509_NAME, key: &str, value: &str) -> Result<(), SslError> {
        let value_len = value.len() as c_int;
        lift_ssl!(unsafe {
            let key = CString::new(key.as_bytes()).unwrap();
            let value = CString::new(value.as_bytes()).unwrap();
            ffi::X509_NAME_add_entry_by_txt(name, key.as_ptr(), ffi::MBSTRING_UTF8,
                                            value.as_ptr(), value_len, -1, 0)
        })
    }

    fn random_serial() -> c_long {
        let len = mem::size_of::<c_long>();
        let bytes = rand_bytes(len);
        let mut res = 0;
        for b in bytes.iter() {
            res = res << 8;
            res |= (*b as c_long) & 0xff;
        }

        // While OpenSSL is actually OK to have negative serials
        // other libraries (for example, Go crypto) can drop
        // such certificates as invalid, so we clear the high bit
        ((res as c_ulong) >> 1) as c_long
    }

    /// Generates a private key and a signed certificate and returns them
    pub fn generate<'a>(&self) -> Result<(X509<'a>, PKey), SslError> {
        ffi::init();

        let mut p_key = PKey::new();
        p_key.gen(self.bits as usize);

        let x509 = try!(self.sign(&p_key));
        Ok((x509, p_key))
    }

    /// Signs certificate with a private key and returns it
    /// Note: That the bit-length of the private key is used (set_bitlength is ignored)
    pub fn sign<'a>(&self, p_key: &PKey) -> Result<X509<'a>, SslError> {
        ffi::init();

        unsafe {
            let x509 = ffi::X509_new();
            try_ssl_null!(x509);

            let x509 = X509 { handle: x509, ctx: None, owned: true};

            try_ssl!(ffi::X509_set_version(x509.handle, 2));
            try_ssl!(ffi::ASN1_INTEGER_set(ffi::X509_get_serialNumber(x509.handle), X509Generator::random_serial()));

            let not_before = try!(Asn1Time::days_from_now(0));
            let not_after = try!(Asn1Time::days_from_now(self.days));

            try_ssl!(ffi::X509_set_notBefore(x509.handle, mem::transmute(not_before.get_handle())));
            // If prev line succeded - ownership should go to cert
            mem::forget(not_before);

            try_ssl!(ffi::X509_set_notAfter(x509.handle, mem::transmute(not_after.get_handle())));
            // If prev line succeded - ownership should go to cert
            mem::forget(not_after);

            try_ssl!(ffi::X509_set_pubkey(x509.handle, p_key.get_handle()));

            let name = ffi::X509_get_subject_name(x509.handle);
            try_ssl_null!(name);

            try!(X509Generator::add_name(name, "CN", &self.CN));
            ffi::X509_set_issuer_name(x509.handle, name);

            if self.key_usage.len() > 0 {
                try!(X509Generator::add_extension(x509.handle, ffi::NID_key_usage,
                                                  &self.key_usage.to_str()));
            }

            if self.ext_key_usage.len() > 0 {
                try!(X509Generator::add_extension(x509.handle, ffi::NID_ext_key_usage,
                                                  &self.ext_key_usage.to_str()));
            }

            let hash_fn = self.hash_type.evp_md();
            try_ssl!(ffi::X509_sign(x509.handle, p_key.get_handle(), hash_fn));
            Ok(x509)
        }
    }
}


#[allow(dead_code)]
/// A public key certificate
pub struct X509<'ctx> {
    ctx: Option<&'ctx X509StoreContext>,
    handle: *mut ffi::X509,
    owned: bool
}

impl<'ctx> X509<'ctx> {
    /// Creates new from handle with desired ownership.
    pub fn new(handle: *mut ffi::X509, owned: bool) -> X509<'ctx> {
        X509 {
            ctx: None,
            handle: handle,
            owned: owned,
        }
    }

    /// Creates a new certificate from context. Doesn't take ownership
    /// of handle.
    pub fn new_in_ctx(handle: *mut ffi::X509, ctx: &'ctx X509StoreContext) -> X509<'ctx> {
        X509 {
            ctx: Some(ctx),
            handle: handle,
            owned: false
        }
    }

    /// Reads certificate from PEM, takes ownership of handle
    pub fn from_pem<R>(reader: &mut R) -> Result<X509<'ctx>, SslError> where R: Read {
        let mut mem_bio = try!(MemBio::new());
        try!(io::copy(reader, &mut mem_bio).map_err(StreamError));

        unsafe {
            let handle = try_ssl_null!(ffi::PEM_read_bio_X509(mem_bio.get_handle(),
                                                              ptr::null_mut(),
                                                              None, ptr::null_mut()));
            Ok(X509::new(handle, true))
        }
    }

    pub fn get_handle(&self) -> *mut ffi::X509 {
        self.handle
    }

    pub fn subject_name<'a>(&'a self) -> X509Name<'a> {
        let name = unsafe { ffi::X509_get_subject_name(self.handle) };
        X509Name { x509: self, name: name }
    }

    pub fn public_key(&self) -> PKey {
        let pkey = unsafe { ffi::X509_get_pubkey(self.handle) };
        assert!(!pkey.is_null());

        PKey::from_handle(pkey, Parts::Public)
    }

    /// Returns certificate fingerprint calculated using provided hash
    pub fn fingerprint(&self, hash_type: hash::Type) -> Option<Vec<u8>> {
        let evp = hash_type.evp_md();
        let len = hash_type.md_len();
        let v: Vec<u8> = repeat(0).take(len as usize).collect();
        let act_len: c_uint = 0;
        let res = unsafe {
            ffi::X509_digest(self.handle, evp, mem::transmute(v.as_ptr()),
                             mem::transmute(&act_len))
        };

        match res {
            0 => None,
            _ => {
                let act_len = act_len as usize;
                match len.cmp(&act_len) {
                    Ordering::Greater => None,
                    Ordering::Equal => Some(v),
                    Ordering::Less => panic!("Fingerprint buffer was corrupted!")
                }
            }
        }
    }

    /// Writes certificate as PEM
    pub fn write_pem<W>(&self, writer: &mut W) -> Result<(), SslError> where W: Write {
        let mut mem_bio = try!(MemBio::new());
        unsafe {
            try_ssl!(ffi::PEM_write_bio_X509(mem_bio.get_handle(),
                                             self.handle));
        }
        io::copy(&mut mem_bio, writer).map_err(StreamError).map(|_| ())
    }
}

impl<'ctx> Drop for X509<'ctx> {
    fn drop(&mut self) {
        if self.owned {
            unsafe { ffi::X509_free(self.handle) };
        }
    }
}

#[allow(dead_code)]
pub struct X509Name<'x> {
    x509: &'x X509<'x>,
    name: *mut ffi::X509_NAME
}

macro_rules! make_validation_error(
    ($ok_val:ident, $($name:ident = $val:ident,)+) => (
        #[derive(Copy, Clone)]
        pub enum X509ValidationError {
            $($name,)+
            X509UnknownError(c_int)
        }

        impl X509ValidationError {
            #[doc(hidden)]
            pub fn from_raw(err: c_int) -> Option<X509ValidationError> {
                match err {
                    ffi::$ok_val => None,
                    $(ffi::$val => Some(X509ValidationError::$name),)+
                    err => Some(X509ValidationError::X509UnknownError(err))
                }
            }
        }
    )
);

make_validation_error!(X509_V_OK,
    X509UnableToGetIssuerCert = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT,
    X509UnableToGetCrl = X509_V_ERR_UNABLE_TO_GET_CRL,
    X509UnableToDecryptCertSignature = X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE,
    X509UnableToDecryptCrlSignature = X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE,
    X509UnableToDecodeIssuerPublicKey = X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY,
    X509CertSignatureFailure = X509_V_ERR_CERT_SIGNATURE_FAILURE,
    X509CrlSignatureFailure = X509_V_ERR_CRL_SIGNATURE_FAILURE,
    X509CertNotYetValid = X509_V_ERR_CERT_NOT_YET_VALID,
    X509CertHasExpired = X509_V_ERR_CERT_HAS_EXPIRED,
    X509CrlNotYetValid = X509_V_ERR_CRL_NOT_YET_VALID,
    X509CrlHasExpired = X509_V_ERR_CRL_HAS_EXPIRED,
    X509ErrorInCertNotBeforeField = X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD,
    X509ErrorInCertNotAfterField = X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD,
    X509ErrorInCrlLastUpdateField = X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD,
    X509ErrorInCrlNextUpdateField = X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD,
    X509OutOfMem = X509_V_ERR_OUT_OF_MEM,
    X509DepthZeroSelfSignedCert = X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT,
    X509SelfSignedCertInChain = X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN,
    X509UnableToGetIssuerCertLocally = X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY,
    X509UnableToVerifyLeafSignature = X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE,
    X509CertChainTooLong = X509_V_ERR_CERT_CHAIN_TOO_LONG,
    X509CertRevoked = X509_V_ERR_CERT_REVOKED,
    X509InvalidCA = X509_V_ERR_INVALID_CA,
    X509PathLengthExceeded = X509_V_ERR_PATH_LENGTH_EXCEEDED,
    X509InvalidPurpose = X509_V_ERR_INVALID_PURPOSE,
    X509CertUntrusted = X509_V_ERR_CERT_UNTRUSTED,
    X509CertRejected = X509_V_ERR_CERT_REJECTED,
    X509SubjectIssuerMismatch = X509_V_ERR_SUBJECT_ISSUER_MISMATCH,
    X509AkidSkidMismatch = X509_V_ERR_AKID_SKID_MISMATCH,
    X509AkidIssuerSerialMismatch = X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH,
    X509KeyusageNoCertsign = X509_V_ERR_KEYUSAGE_NO_CERTSIGN,
    X509UnableToGetCrlIssuer = X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER,
    X509UnhandledCriticalExtension = X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION,
    X509KeyusageNoCrlSign = X509_V_ERR_KEYUSAGE_NO_CRL_SIGN,
    X509UnhandledCriticalCrlExtension = X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION,
    X509InvalidNonCA = X509_V_ERR_INVALID_NON_CA,
    X509ProxyPathLengthExceeded = X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED,
    X509KeyusageNoDigitalSignature = X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE,
    X509ProxyCertificatesNotAllowed = X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED,
    X509InvalidExtension = X509_V_ERR_INVALID_EXTENSION,
    X509InavlidPolicyExtension = X509_V_ERR_INVALID_POLICY_EXTENSION,
    X509NoExplicitPolicy = X509_V_ERR_NO_EXPLICIT_POLICY,
    X509DifferentCrlScope = X509_V_ERR_DIFFERENT_CRL_SCOPE,
    X509UnsupportedExtensionFeature = X509_V_ERR_UNSUPPORTED_EXTENSION_FEATURE,
    X509UnnestedResource = X509_V_ERR_UNNESTED_RESOURCE,
    X509PermittedVolation = X509_V_ERR_PERMITTED_VIOLATION,
    X509ExcludedViolation = X509_V_ERR_EXCLUDED_VIOLATION,
    X509SubtreeMinmax = X509_V_ERR_SUBTREE_MINMAX,
    X509UnsupportedConstraintType = X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE,
    X509UnsupportedConstraintSyntax = X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX,
    X509UnsupportedNameSyntax = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX,
    X509CrlPathValidationError= X509_V_ERR_CRL_PATH_VALIDATION_ERROR,
    X509ApplicationVerification = X509_V_ERR_APPLICATION_VERIFICATION,
);


#[test]
fn test_negative_serial() {
    // I guess that's enough to get a random negative number
    for _ in 0..1000 {
        assert!(X509Generator::random_serial() > 0, "All serials should be positive");
    }
}