// -*- coding: utf-8 -*-
//
// pwman-f2e
//
// Copyright 2023 Michael Büsch <m@bues.ch>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//

use anyhow::{self as ah, Context as _};
use std::collections::HashMap;

use crate::hid::MAX_MSG_PAYLOAD_SIZE;

// CTAP commands:
const CTAP_AUTHENTICATOR_MAKE_CREDENTIAL: u8 = 0x01;
const CTAP_AUTHENTICATOR_GET_ASSERTION: u8 = 0x02;
const CTAP_AUTHENTICATOR_GET_INFO: u8 = 0x04;
const CTAP_AUTHENTICATOR_CLIENT_PIN: u8 = 0x06;
const CTAP_AUTHENTICATOR_RESET: u8 = 0x07;
const CTAP_AUTHENTICATOR_GET_NEXT_ASSERTION: u8 = 0x08;
const CTAP_AUTHENTICATOR_VENDOR_FIRST: u8 = 0x40;
const CTAP_AUTHENTICATOR_VENDOR_LAST: u8 = 0xBF;

// CTAP errors:
const CTAP2_OK: u8 = 0x00;
const CTAP1_ERR_INVALID_COMMAND: u8 = 0x01;
const CTAP2_ERR_INVALID_CBOR: u8 = 0x12;
const CTAP1_ERR_OTHER: u8 = 0x7F;

#[allow(clippy::large_enum_variant)]
pub enum CtapCmd {
    MakeCredential {
        client_data_hash: Vec<u8>,
        rp: HashMap<String, String>,
        user: HashMap<String, String>,
        pub_key_cred_param: Vec<(String, i32)>,
        exclude_list: Vec<(String, String, Vec<String>)>,
        extensions: HashMap<String, String>,
        options: HashMap<String, bool>,
        pin_auth: Vec<u8>,
        pin_protocol: u8,
    },
    GetAssertion, //TODO
    NextAssertion,
    GetInfo,
    ClientPin, //TODO
    Reset,
    ParseError(u8),
}

impl CtapCmd {
    fn parse_cbor_make_credential(params: &[u8]) -> ah::Result<Self> {
        let mut cmd = CtapCmd::MakeCredential {
            client_data_hash: vec![],   //TODO
            rp: HashMap::new(),         //TODO
            user: HashMap::new(),       //TODO
            pub_key_cred_param: vec![], //TODO
            exclude_list: vec![],       //TODO
            extensions: HashMap::new(), //TODO
            options: HashMap::new(),    //TODO
            pin_auth: vec![],           //TODO
            pin_protocol: 1,            //TODO
        };
        let mut decoder = minicbor::Decoder::new(params);
        let Some(num_main) = decoder.map()
            .context("Main map not found.")? else {
            return Err(ah::format_err!("Indefinite map not supported."));
        };
        for _ in 0..num_main {
            let param_id = decoder.u8().context("Parameter ID is not u8.")?;
            #[rustfmt::skip]
            match param_id {
                0x01 => { // clientDataHash
                    let h = decoder.array();
                    //TODO
                }
                0x02 => { // rp
                    let rp = decoder.map();
                    //TODO
                }
                0x03 => { // user
                    let user = decoder.map();
                    //TODO
                }
                0x04 => { // pubKeyCredParams
                }
                0x05 => { // excludeList
                }
                0x06 => { // extensions
                }
                0x07 => { // options
                }
                0x08 => { // pinAuth
                }
                0x09 => { // pinProtocol
                }
                param_id => {
                    return Err(ah::format_err!("Unknown parameter ID {param_id}."));
                }
            };
        }
        Ok(cmd)
    }

    pub fn parse_cbor(cmd_id: u8, params: &[u8]) -> ah::Result<Self> {
        #[rustfmt::skip]
        let cmd = match cmd_id {
            CTAP_AUTHENTICATOR_MAKE_CREDENTIAL => {
                match Self::parse_cbor_make_credential(params) {
                    Ok(cmd) => cmd,
                    Err(e) => {
                        println!("Failed to parse CTAP_AUTHENTICATOR_MAKE_CREDENTIAL: {}", e);
                        CtapCmd::ParseError(CTAP2_ERR_INVALID_CBOR)
                    }
                }
            }
            CTAP_AUTHENTICATOR_GET_ASSERTION => {
                //TODO params
                CtapCmd::GetAssertion
            }
            CTAP_AUTHENTICATOR_GET_INFO => {
                CtapCmd::GetInfo
            }
            CTAP_AUTHENTICATOR_CLIENT_PIN => {
                //TODO params
                CtapCmd::ClientPin
            }
            CTAP_AUTHENTICATOR_RESET => {
                CtapCmd::Reset
            }
            CTAP_AUTHENTICATOR_GET_NEXT_ASSERTION => {
                CtapCmd::NextAssertion
            }
            CTAP_AUTHENTICATOR_VENDOR_FIRST..=CTAP_AUTHENTICATOR_VENDOR_LAST => {
                println!("CTAP_AUTHENTICATOR_VENDOR commands are not supported,");
                CtapCmd::ParseError(CTAP1_ERR_INVALID_COMMAND)
            }
            _ => {
                println!("Unsupported CTAP command: {cmd_id}");
                CtapCmd::ParseError(CTAP1_ERR_INVALID_COMMAND)
            }
        };
        Ok(cmd)
    }
}

#[non_exhaustive]
pub struct CtapResp {
    pub status: u8,
    pub cbor: Vec<u8>,
}

impl CtapResp {
    fn new() -> Self {
        Self {
            status: CTAP2_OK,
            cbor: vec![],
        }
    }
}

pub struct Ctap {}

impl Ctap {
    pub fn new() -> Self {
        Self {}
    }

    pub fn handle_command(&mut self, cmd: CtapCmd) -> ah::Result<CtapResp> {
        let mut resp = CtapResp::new();
        match cmd {
            CtapCmd::MakeCredential {
                client_data_hash,
                rp,
                user,
                pub_key_cred_param,
                exclude_list,
                extensions,
                options,
                pin_auth,
                pin_protocol,
            } => {
                println!("TODO: CtapCmd::MakeCredential");
                //TODO
                resp.status = CTAP1_ERR_OTHER;
            }
            CtapCmd::GetAssertion => {
                println!("TODO: CtapCmd::GetAssertion");
                //TODO
                resp.status = CTAP1_ERR_OTHER;
            }
            CtapCmd::NextAssertion => {
                println!("TODO: CtapCmd::NextAssertion");
                //TODO
                resp.status = CTAP1_ERR_OTHER;
            }
            CtapCmd::GetInfo => {
                let mut encoder = minicbor::Encoder::new(&mut resp.cbor);
                #[rustfmt::skip]
                encoder.map(5)?
                    .u8(0x01)?.array(1)?.str("FIDO_2_0")? // versions
                    //TODO .u8(0x02)?.array(1)?.str("")? // extensions
                    .u8(0x03)?.bytes(&[42; 16])? // aaguid //TODO
                    .u8(0x04)?.map(3)? // options
                        .str("rk")?.bool(true)?
                        .str("up")?.bool(true)?
                        .str("plat")?.bool(true)?
                    .u8(0x05)?.u16(MAX_MSG_PAYLOAD_SIZE as u16)? // maxMsgSize
                    .u8(0x06)?.array(1)?.u8(1)?; // pinProtocols
            }
            CtapCmd::ClientPin => {
                println!("CTAP command 'authenticatorClientPIN' not supported.");
                resp.status = CTAP1_ERR_OTHER;
            }
            CtapCmd::Reset => {
                println!("CTAP command 'authenticatorReset' not supported.");
                resp.status = CTAP1_ERR_OTHER;
            }
            CtapCmd::ParseError(status) => {
                resp.status = status;
            }
        };
        Ok(resp)
    }
}

// vim: ts=4 sw=4 expandtab