// SPDX-License-Identifier: BSD-2-Clause

/*

 * Copyright © The libcoap-rs Contributors, all rights reserved.

 * This file is part of the libcoap-rs project, see the README file for

 * general information on this project and the NOTICE.md and LICENSE files

 * for information regarding copyright ownership and terms of use.

 *

 * crypto/pki_rpk/rpk.rs - Interfaces and types for RPK support in libcoap-rs.

 */

use std::{ffi::CString, fmt::Debug};

use libcoap_sys::{

    coap_const_char_ptr_t, coap_dtls_key_t, coap_dtls_key_t__bindgen_ty_1, coap_dtls_pki_t, coap_pki_define_t,

    coap_pki_define_t_COAP_PKI_KEY_DEF_PEM, coap_pki_define_t_COAP_PKI_KEY_DEF_PKCS11_RPK,

    coap_pki_define_t_COAP_PKI_KEY_DEF_RPK_BUF, coap_pki_key_define_t, coap_pki_key_t_COAP_PKI_KEY_DEFINE,

};

use crate::{

    crypto::{

        pki_rpk,

        pki_rpk::{

            key::{KeyComponentSealed, KeyTypeSealed},

            Asn1PrivateKeyType, CnCallback, KeyComponent, KeyDef, KeyDefSealed, NonCertVerifying,

            PemMemoryKeyComponent, Pkcs11KeyComponent, PkiRpkContext, PkiRpkContextBuilder, ServerPkiRpkCryptoContext,

        },

        ClientCryptoContext,

    },

    session::CoapSession,

};

/// (Marker) key type for asymmetric DTLS keys not signed by a CA (raw public keys).

#[derive(Debug, Clone, Copy)]

pub struct Rpk {}

impl KeyTypeSealed for Rpk {

}

// If PKI is enabled, implement conversions for PKI contexts to RPK-supporting server/client-side

// cryptographic contexts.

impl<'a> From<PkiRpkContext<'a, Rpk>> for ClientCryptoContext<'a> {

}

impl<'a> From<PkiRpkContext<'a, Rpk>> for ServerPkiRpkCryptoContext<'a> {

}

impl<'a> PkiRpkContextBuilder<'a, Rpk, NonCertVerifying> {

    /// Sets the raw public key validator for this encryption context.

    ///

    /// The raw public key validator's [`validate_rpk`](RpkValidator::validate_rpk) function will be

    /// called after the TLS-level validation checks have been completed in order to check whether

    /// the RPK provided by the peer is allowed/as expected.

    ///

    /// # Implementation details (informative, not covered by semver guarantees)

    ///

    /// Setting an RPK validator will set the `validate_cn_call_back` of the underlying

    /// [`coap_dtls_pki_t`] to a wrapper function, which will then call the RPK validator.

}

/// Trait for types that can validate that a raw public key is the one expected for a given peer.

pub trait RpkValidator {

    /// Validates the raw public key of a peer.

    ///

    /// This function is provided with the public key (`asn1_public_key`), the respective `session`,

    /// and the TLS library's `validated` status, and should return `true` if the connection is to

    /// be accepted and `false` if the connection should be aborted.

    ///

    /// `asn1_encoded_key` should be the certificate structure defined in

    /// [RFC 7250, section 3](https://datatracker.ietf.org/doc/html/rfc7250#section-3), which you

    /// might be able to parse with crates like

    /// [x509-cert](https://docs.rs/x509-cert/latest/x509_cert/index.html) and

    /// [spki](https://docs.rs/spki/0.7.3/spki/index.html) to obtain and match the

    /// SubjectPublicKeyInformation encoded within.

    ///

    /// See [the libcoap documentation](https://libcoap.net/doc/reference/4.3.5/group__dtls.html#gaef7a2800757a4922102311c94c3fa529)

    /// for more information.

    fn validate_rpk(&self, asn1_public_key: &[u8], session: &CoapSession, validated: bool) -> bool;

}

impl<T: Fn(&[u8], &CoapSession, bool) -> bool> RpkValidator for T {

}

/// Key definition for a DTLS key consisting of a private and public key component without a signed

/// certificate.

///

/// # Note on key construction

///

/// For maximum compatibility, you should stick to the `with_*` constructors defined for this type.

/// While in theory you could use an arbitrary combination of key component types for a key

/// definition, those defined using `with_*` match explicit key types provided in libcoap and should

/// therefore always be supported.

#[derive(Clone, Debug)]

pub struct RpkKeyDef<PK: KeyComponent<Rpk>, SK: KeyComponent<Rpk>> {

    public_key: PK,

    private_key: SK,

    user_pin: Option<CString>,

    asn1_private_key_type: Asn1PrivateKeyType,

}

impl<PK: KeyComponent<Rpk>, SK: KeyComponent<Rpk>> RpkKeyDef<PK, SK> {

    /// Creates a new key definition using the given components.

    ///

    /// # Parameters

    ///

    /// - `public_key`:  The public key component of this key.

    /// - `private_key`: The private key.

    /// - `user_pin`:    The PIN that should be used when unlocking a token (for PKCS11 keys stored

    ///                  on a token, ignored otherwise)

    /// - `asn1_private_key_type`: The type of the private key (only used for DER/ASN.1 encoded

    ///                  keys).

}

impl RpkKeyDef<PemMemoryKeyComponent, PemMemoryKeyComponent> {

    /// Creates a new key definition using PEM-encoded byte sequences in memory as components.

    ///

    /// See the documentation of [`RpkKeyDef::new`] for more information on the parameters.

}

impl RpkKeyDef<Pkcs11KeyComponent, Pkcs11KeyComponent> {

    /// Creates a new key definition using PKCS11 URIs as components.

    ///

    /// See the documentation of [`RpkKeyDef::new`] for more information on the parameters.

}

impl<PK: KeyComponent<Rpk>, SK: KeyComponent<Rpk>> KeyDefSealed for RpkKeyDef<PK, SK> {

}

impl<PK: KeyComponent<Rpk>, SK: KeyComponent<Rpk>> KeyDef for RpkKeyDef<PK, SK> {

    type KeyType = Rpk;

}

impl KeyComponentSealed<Rpk> for PemMemoryKeyComponent {

    const DEFINE_TYPE: coap_pki_define_t = coap_pki_define_t_COAP_PKI_KEY_DEF_RPK_BUF;

}

impl KeyComponentSealed<Rpk> for Pkcs11KeyComponent {

    const DEFINE_TYPE: coap_pki_define_t = coap_pki_define_t_COAP_PKI_KEY_DEF_PKCS11_RPK;

}