// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! This module provides a X.509 certificate parser.

#![allow(clippy::unused_unit)]

use std::prelude::v1::*;

use yasna::ASN1Result;
use yasna::{BERReader, BERReaderSeq, BERReaderSet};
use yasna::{DERWriter, DERWriterSeq, DERWriterSet};

pub type Writer<'a> = DERWriter<'a>;
pub type Reader<'a, 'b> = BERReader<'a, 'b>;

pub trait ConsWriter {
    fn next(&mut self) -> Writer<'_>;
}

pub trait ConsReader<'a> {
    fn next(&mut self, tags: &[yasna::Tag]) -> ASN1Result<Reader<'a, '_>>;
}

impl ConsWriter for DERWriterSeq<'_> {
    fn next(&mut self) -> Writer<'_> {
        self.next()
    }
}

impl ConsWriter for DERWriterSet<'_> {
    fn next(&mut self) -> Writer<'_> {
        self.next()
    }
}

impl<'a> ConsReader<'a> for BERReaderSeq<'a, '_> {
    fn next(&mut self, _tags: &[yasna::Tag]) -> ASN1Result<Reader<'a, '_>> {
        Ok(self.next())
    }
}

impl<'a> ConsReader<'a> for BERReaderSet<'a, '_> {
    fn next(&mut self, tags: &[yasna::Tag]) -> ASN1Result<Reader<'a, '_>> {
        self.next(tags)
    }
}

pub trait Asn1Ty {
    type ValueTy;
    const TAG: yasna::Tag;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) -> ();
    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy>;
}

pub trait Asn1ConsTy
where
    Self: std::marker::Sized,
{
    type ValueTy;

    fn dump<W: ConsWriter>(writer: &mut W, value: Self::ValueTy) -> ();
    fn load<'a, R>(reader: &mut R) -> ASN1Result<Self::ValueTy>
    where
        R: ConsReader<'a>;
}

pub trait Asn1Tag {
    const TAG: yasna::Tag;
}

const fn context_tag(tnum: u64) -> yasna::Tag {
    yasna::Tag {
        tag_class: yasna::TagClass::ContextSpecific,
        tag_number: tnum,
    }
}

mod no_instance {
    #![allow(dead_code)]

    use super::{Asn1ConsTy, Asn1Tag, Asn1Ty};
    use std::marker::PhantomData;

    pub(crate) struct CtxT0;
    pub(crate) struct CtxT1;
    pub(crate) struct CtxT3;

    pub(crate) struct Oid;
    pub(crate) struct U8;
    pub(crate) struct I8;
    pub(crate) struct BigUint;
    pub(crate) struct Utf8Str;
    pub(crate) struct UtcTime;
    pub(crate) struct BitVec;
    pub(crate) struct Bytes;
    pub(crate) struct Tagged<T: Asn1Tag, S: Asn1Ty> {
        t: PhantomData<T>,
        s: PhantomData<S>,
    }
    pub(crate) struct Sequence<U: Asn1Ty, V: Asn1ConsTy> {
        u: PhantomData<U>,
        v: PhantomData<V>,
    }
    pub(crate) struct Set<U: Asn1Ty, V: Asn1ConsTy> {
        u: PhantomData<U>,
        v: PhantomData<V>,
    }
    pub(crate) struct Cons<U: Asn1Ty, V: Asn1ConsTy> {
        u: PhantomData<U>,
        v: PhantomData<V>,
    }
    pub(crate) struct Nil;
}

use no_instance::*;

impl Asn1Tag for CtxT0 {
    const TAG: yasna::Tag = context_tag(0);
}

impl Asn1Tag for CtxT1 {
    const TAG: yasna::Tag = context_tag(1);
}

impl Asn1Tag for CtxT3 {
    const TAG: yasna::Tag = context_tag(3);
}

impl<U: Asn1Ty, V: Asn1ConsTy> Asn1ConsTy for Cons<U, V> {
    type ValueTy = (U::ValueTy, V::ValueTy);

    fn dump<W: ConsWriter>(writer: &mut W, value: Self::ValueTy) -> () {
        U::dump(writer.next(), value.0);
        V::dump(writer, value.1);
    }

    fn load<'a, R>(reader: &mut R) -> ASN1Result<Self::ValueTy>
    where
        R: ConsReader<'a>,
    {
        let first = U::load(reader.next(&[U::TAG])?)?;
        let second = V::load(reader)?;
        Ok((first, second))
    }
}

impl Asn1ConsTy for Nil {
    type ValueTy = ();

    fn dump<W: ConsWriter>(_writer: &mut W, _value: Self::ValueTy) -> () {}
    fn load<'a, R>(_reader: &mut R) -> ASN1Result<Self::ValueTy>
    where
        R: ConsReader<'a>,
    {
        Ok(())
    }
}

impl<T: Asn1Tag, S: Asn1Ty> Asn1Ty for Tagged<T, S> {
    type ValueTy = S::ValueTy;
    const TAG: yasna::Tag = T::TAG;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_tagged(T::TAG, |writer| S::dump(writer, value));
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_tagged(T::TAG, S::load)
    }
}

impl<U: Asn1Ty, V: Asn1ConsTy> Asn1Ty for Sequence<U, V> {
    type ValueTy = (U::ValueTy, V::ValueTy);
    const TAG: yasna::Tag = yasna::tags::TAG_SEQUENCE;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_sequence(|writer| {
            U::dump(writer.next(), value.0);
            V::dump(writer, value.1);
        });
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_sequence(|reader| {
            let first = U::load(reader.next())?;
            let second = V::load(reader)?;
            Ok((first, second))
        })
    }
}

impl<U: Asn1Ty, V: Asn1ConsTy> Asn1Ty for Set<U, V> {
    type ValueTy = (U::ValueTy, V::ValueTy);
    const TAG: yasna::Tag = yasna::tags::TAG_SET;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_set(|writer| {
            U::dump(writer.next(), value.0);
            V::dump(writer, value.1);
        });
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_set(|reader| {
            let first = U::load(reader.next(&[U::TAG])?)?;
            let second = V::load(reader)?;
            Ok((first, second))
        })
    }
}

impl Asn1Ty for U8 {
    type ValueTy = u8;
    const TAG: yasna::Tag = yasna::tags::TAG_INTEGER;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_u8(value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_u8()
    }
}

impl Asn1Ty for I8 {
    type ValueTy = i8;
    const TAG: yasna::Tag = yasna::tags::TAG_INTEGER;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_i8(value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_i8()
    }
}

impl Asn1Ty for BigUint {
    type ValueTy = num_bigint::BigUint;
    const TAG: yasna::Tag = yasna::tags::TAG_INTEGER;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_biguint(&value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_biguint()
    }
}

impl Asn1Ty for Utf8Str {
    type ValueTy = String;
    const TAG: yasna::Tag = yasna::tags::TAG_UTF8STRING;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_utf8_string(value.as_str());
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_utf8string()
    }
}

impl Asn1Ty for Oid {
    type ValueTy = yasna::models::ObjectIdentifier;
    const TAG: yasna::Tag = yasna::tags::TAG_OID;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_oid(&value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_oid()
    }
}

impl Asn1Ty for UtcTime {
    type ValueTy = yasna::models::UTCTime;
    const TAG: yasna::Tag = yasna::tags::TAG_UTCTIME;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_utctime(&value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_utctime()
    }
}

impl Asn1Ty for BitVec {
    type ValueTy = bit_vec::BitVec;
    const TAG: yasna::Tag = yasna::tags::TAG_BITSTRING;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_bitvec(&value);
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_bitvec()
    }
}

impl Asn1Ty for Bytes {
    type ValueTy = Vec<u8>;
    const TAG: yasna::Tag = yasna::tags::TAG_OCTETSTRING;

    fn dump(writer: Writer<'_>, value: Self::ValueTy) {
        writer.write_bytes(&value.as_slice());
    }

    fn load<'a>(reader: Reader<'a, '_>) -> ASN1Result<Self::ValueTy> {
        reader.read_bytes()
    }
}

macro_rules! cons {
    () => { Nil };
    ($t: ty) => { Cons<$t, Nil> };
    ($t: ty, $($tt: ty),* $(,)?) => {
        Cons<$t, cons! { $($tt),* }>
    };
}

macro_rules! asn1_seq_ty {
    ($t: ty) => { Sequence<$t, Nil> };
    ($t: ty, $($tt: ty),* $(,)?) => {
        Sequence<$t, cons! { $($tt),* }>
    };
}

macro_rules! asn1_set_ty {
    ($t: ty) => { Set<$t, Nil> };
    ($t: ty, $($tt: ty),* $(,)?) => {
        Set<$t, cons! { $($tt),* }>
    };
}

#[cfg(feature = "mesalock_sgx")]
macro_rules! asn1_seq {
    () => { () };
    ($e: expr) => {
        ($e, ())
    };
    ($e: expr , $($ee: expr),* $(,)?) => {
        ($e, asn1_seq!{ $($ee),* } )
    };
}

pub(crate) type Version = Tagged<CtxT0, I8>;
pub(crate) type Serial = U8;
pub(crate) type CertSignAlgo = asn1_seq_ty!(Oid);
pub(crate) type ValidRange = asn1_seq_ty!(UtcTime, UtcTime);
pub(crate) type Issuer = asn1_seq_ty!(asn1_set_ty!(asn1_seq_ty!(Oid, Utf8Str)));
pub(crate) type Subject = Issuer;
pub(crate) type PubKeyAlgo = asn1_seq_ty!(Oid, Oid);
pub(crate) type PubKey = asn1_seq_ty!(PubKeyAlgo, BitVec);
pub(crate) type SgxRaCertExt = Tagged<CtxT3, asn1_seq_ty!(asn1_seq_ty!(Oid, Bytes))>;
pub(crate) type TbsCert = asn1_seq_ty!(
    Version,
    Serial,
    CertSignAlgo,
    Issuer,
    ValidRange,
    Subject,
    PubKey,
    SgxRaCertExt,
);
pub(crate) type CertSig = BitVec;
pub(crate) type X509 = asn1_seq_ty!(TbsCert, CertSignAlgo, CertSig);