use std::time::SystemTime;

use clap::{App, Arg, ArgMatches, SubCommand};
use rust_util::{util_msg, XResult};
use rust_util::util_clap::{Command, CommandError};
use serde::{Deserialize, Serialize};
use spki::der::Encode;
use x509_parser::nom::AsBytes;
use yubikey::{Key, YubiKey};
use yubikey::piv::{sign_data, SlotId};

use crate::{argsutil, pivutil};
use crate::digest::sha256_bytes;
use crate::util::base64_encode;

pub const SIMPLE_SIG_V1: &str = "v1";
pub const SIMPLE_SIG_SPECIFICATION: &str = "https://openwebstandard.org/simple-sign-file/v1";
pub const HASH_ALGORITHM_SHA256: &str = "sha256";
pub const SIGNATURE_ALGORITHM_SHA256_WITH_ECDSA: &str = "SHA256withECDSA";
pub const CERTIFICATES_SEARCH_URL: &str = "https://hatter.ink/ca/fetch_certificates.json?fingerprint=";

pub struct SignFileRequest {
    pub filename: Option<String>,
    pub digest: Vec<u8>,
    pub timestamp: i64,
    pub attributes: Option<String>,
    pub comment: Option<String>,
}

impl SignFileRequest {
    pub fn get_tobe_signed(&self) -> Vec<u8> {
        let mut tobe_signed = vec![];
        // "v1"||TLV(filename)||TLV(timestamp)||TLV(attributes)||TLV(comment)||TLV(digest)
        debugging!("Tobe signed version: {}", SIMPLE_SIG_V1);
        tobe_signed.extend_from_slice(SIMPLE_SIG_V1.as_bytes());
        let tobe_signed_filename = SignFileTlv::Filename(self.filename.clone()).to_byes();
        debugging!("Tobe signed filename: {} ({:?})", hex::encode(&tobe_signed_filename), &self.filename);
        tobe_signed.extend_from_slice(&tobe_signed_filename);
        let tobe_signed_timestamp = SignFileTlv::Timestamp(self.timestamp.clone()).to_byes();
        debugging!("Tobe signed timestamp: {} ({})", hex::encode(&tobe_signed_timestamp), &self.timestamp);
        tobe_signed.extend_from_slice(&tobe_signed_timestamp);
        let tobe_signed_attributes = SignFileTlv::Attributes(self.attributes.clone()).to_byes();
        debugging!("Tobe signed attributes: {} ({:?})", hex::encode(&tobe_signed_attributes), &self.attributes);
        tobe_signed.extend_from_slice(&tobe_signed_attributes);
        let tobe_signed_comment = SignFileTlv::Comment(self.comment.clone()).to_byes();
        debugging!("Tobe signed comment: {} ({:?})", hex::encode(&tobe_signed_comment), &self.comment);
        tobe_signed.extend_from_slice(&tobe_signed_comment);
        let tobe_signed_digest = SignFileTlv::Digest(self.digest.clone()).to_byes();
        debugging!("Tobe signed digest: {}", hex::encode(&tobe_signed_digest));
        tobe_signed.extend_from_slice(&tobe_signed_digest);
        tobe_signed
    }
}

pub enum SignFileTlv {
    Filename(Option<String>),
    Timestamp(i64),
    Attributes(Option<String>),
    Comment(Option<String>),
    Digest(Vec<u8>),
}

impl SignFileTlv {
    pub fn tag(&self) -> u8 {
        match self {
            SignFileTlv::Filename(_) => 0,
            SignFileTlv::Timestamp(_) => 1,
            SignFileTlv::Attributes(_) => 2,
            SignFileTlv::Comment(_) => 3,
            SignFileTlv::Digest(_) => 254,
        }
    }

    pub fn to_byes(&self) -> Vec<u8> {
        let mut bytes = vec![];
        bytes.push(self.tag());
        match self {
            SignFileTlv::Timestamp(timestamp) => {
                bytes.extend_from_slice(&timestamp.to_be_bytes());
            }
            SignFileTlv::Filename(value)
            | SignFileTlv::Attributes(value)
            | SignFileTlv::Comment(value) => {
                Self::extends_bytes(&mut bytes, match value {
                    None => &[],
                    Some(value) => value.as_bytes(),
                });
            }
            SignFileTlv::Digest(digest) => {
                Self::extends_bytes(&mut bytes, digest);
            }
        }
        bytes
    }

    fn extends_bytes(bytes: &mut Vec<u8>, b: &[u8]) {
        if b.len() > u16::MAX as usize {
            panic!("Cannot more than: {}", u16::MAX);
        }
        bytes.extend_from_slice(&(b.len() as u16).to_be_bytes());
        bytes.extend_from_slice(b);
    }
}

#[derive(Serialize)]
pub struct SimpleSignFileSignature {
    pub algorithm: String,
    pub signature: String,
    pub certificates: Vec<String>,
}

#[derive(Serialize)]
pub struct SimpleSignFile {
    pub specification: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub filename: Option<String>,
    pub digest: String,
    pub timestamp: i64,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub attributes: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub comment: Option<String>,
    pub signatures: Vec<SimpleSignFileSignature>,
}

pub struct CommandImpl;

// Format:
// {
//   "specification": "https://openwebstandard.org/simple-sign-file/v1",
//   "version": "v1",
//   "filename": "example.zip",
//   "digest": "HEX(SHA256(filename-content))",
//   "timestamp": 1700964163340,
//   "attributes": "****",
//   "comment": "***",
//   "signatures": [{
//     "algorithm": "SHA256withECDSA",
//     "signature": "Base64(Sign(SHA256("v1"||TLV(filename)||TLV(timestamp)||TLV(attributes)||TLV(comment)||TLV(digest))))",
//     "certificates": ["-----BEGIN CERTIFICATE-----\n*****\n-----END CERTIFICATE-----", ...]
//   }]
// }
// v1 only support SHA256
// all hex is in lower case default
// file ext: *.simple-sig
impl Command for CommandImpl {
    fn name(&self) -> &str { "sign-file" }

    fn subcommand<'a>(&self) -> App<'a, 'a> {
        SubCommand::with_name(self.name()).about("PIV Sign(with SHA256) subcommand")
            .arg(Arg::with_name("pin").short("p").long("pin").takes_value(true).help("PIV card user pin"))
            .arg(Arg::with_name("slot").short("s").long("slot").takes_value(true).required(true).help("PIV slot, e.g. 82, 83 ... 95, 9a, 9c, 9d, 9e"))
            .arg(Arg::with_name("file").short("f").long("file").takes_value(true).required(true).help("Input file"))
            .arg(Arg::with_name("filename").short("n").long("filename").takes_value(true).help("Filename"))
            .arg(Arg::with_name("comment").short("c").long("comment").takes_value(true).help("Comment"))
            .arg(Arg::with_name("attributes").short("a").long("attributes").takes_value(true).help("Attributes"))
    }

    fn run(&self, _arg_matches: &ArgMatches, sub_arg_matches: &ArgMatches) -> CommandError {
        util_msg::set_logger_std_out(false);

        let filename_opt = sub_arg_matches.value_of("filename").map(ToString::to_string);
        let comment_opt = sub_arg_matches.value_of("comment").map(ToString::to_string);
        let attributes_opt = sub_arg_matches.value_of("attributes").map(ToString::to_string);

        let pin_opt = sub_arg_matches.value_of("pin");

        let slot = opt_value_result!(sub_arg_matches.value_of("slot"), "--slot must assigned, e.g. 82, 83 ... 95, 9a, 9c, 9d, 9e");
        // TODO read from stream not in memory
        let file_digest = argsutil::get_sha256_digest_or_hash(sub_arg_matches)?;
        debugging!("File digest: {}", hex::encode(&file_digest));

        let mut yk = opt_result!(YubiKey::open(), "YubiKey not found: {}");

        let slot_id = pivutil::get_slot_id(slot)?;
        let key = find_key(&mut yk, &slot_id)?;
        let key = opt_value_result!(key, "Cannot find key in slot: {}", slot_id);

        let certificate = key.certificate();
        let tbs_certificate = &certificate.cert.tbs_certificate;
        let spki_der = opt_result!(tbs_certificate.subject_public_key_info.to_der(), "SPKI to DER failed: {}");
        debugging!("Slot public DER: {}", hex::encode(&spki_der));
        let spki_der_fingerprint = hex::encode(sha256_bytes(&spki_der));
        debugging!("Slot public fingerprint: {}", &spki_der_fingerprint);
        let certificates = fetch_certificates(&spki_der_fingerprint)?;

        let algorithm_id = opt_result!(
            pivutil::get_algorithm_id_by_certificate(certificate), "Get slot key algorithm failed: {}");
        debugging!("PIV algorithm: {:?}", algorithm_id);
        if let Some(pin) = pin_opt {
            debugging!("PIN is assigned.");
            opt_result!(yk.verify_pin(pin.as_bytes()), "YubiKey verify pin failed: {}");
        }

        let sign_file_request = SignFileRequest {
            filename: filename_opt,
            digest: file_digest.clone(),
            timestamp: SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_millis() as i64,
            attributes: attributes_opt,
            comment: comment_opt,
        };
        let tobe_signed = sign_file_request.get_tobe_signed();
        debugging!("Tobe signed: {}", hex::encode(&tobe_signed));
        let tobe_signed_digest = sha256_bytes(&tobe_signed);
        debugging!("Tobe signed digest: {}", hex::encode(&tobe_signed_digest));

        let signed_data = opt_result!(sign_data(&mut yk, &tobe_signed_digest, algorithm_id, slot_id), "Sign PIV failed: {}");
        let signature_bytes = signed_data.as_slice();
        debugging!("Tobe signed signature: {}", hex::encode(&signature_bytes));

        let signature = SimpleSignFileSignature {
            algorithm: SIGNATURE_ALGORITHM_SHA256_WITH_ECDSA.to_string(),
            signature: format!("{}", base64_encode(&signature_bytes)),
            certificates,
        };
        let simple_sig = SimpleSignFile {
            specification: SIMPLE_SIG_SPECIFICATION.to_string(),
            filename: sign_file_request.filename.clone(),
            digest: format!("{}-{}", HASH_ALGORITHM_SHA256, hex::encode(&sign_file_request.digest)),
            timestamp: sign_file_request.timestamp,
            attributes: sign_file_request.attributes.clone(),
            comment: sign_file_request.comment.clone(),
            signatures: vec![signature],
        };

        println!("{}", serde_json::to_string_pretty(&simple_sig).unwrap());
        Ok(None)
    }
}

#[derive(Deserialize)]
struct FetchCertificateResponseData {
    pub certificates: Vec<String>,
}

#[derive(Deserialize)]
struct FetchCertificateResponse {
    pub status: i32,
    pub message: String,
    pub data: Option<FetchCertificateResponseData>,
}

fn fetch_certificates(fingerprint: &str) -> XResult<Vec<String>> {
    let url = format!("{}{}", CERTIFICATES_SEARCH_URL, fingerprint);
    let certificates_response = opt_result!( reqwest::blocking::get(&url), "Fetch certificates failed: {}");
    let certificates_response_bytes = opt_result!(certificates_response.bytes(), "Fetch certificates failed: {}");
    let response = opt_result!(
        serde_json::from_slice::<FetchCertificateResponse>(certificates_response_bytes.as_bytes()),
        "Parse fetch certificates response failed: {}");
    if response.status != 200 {
        return simple_error!("Fetch certificates failed, status: {}, message: {}", response.status, response.message);
    }
    match response.data {
        None => simple_error!("Fetch certificates failed, empty."),
        Some(data) => Ok(data.certificates),
    }
}

fn find_key(yk: &mut YubiKey, slot_id: &SlotId) -> XResult<Option<Key>> {
    match Key::list(yk) {
        Err(e) => warning!("List keys failed: {}", e),
        Ok(keys) => for k in keys {
            let slot_str = format!("{:x}", Into::<u8>::into(k.slot()));
            if pivutil::slot_equals(slot_id, &slot_str) {
                return Ok(Some(k));
            }
        }
    }
    Ok(None)
}