use std::fmt;
use std::sync::mpsc::{channel, Sender};
use std::thread;

use authenticator::{RegisterResult, StatusUpdate};
use base64::URL_SAFE_NO_PAD;
use rand::Rng;
use rust_util::XResult;
use serde::{Deserialize, Serialize};

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct U2FDeviceInfo {
    pub vendor_name: String,
    pub device_name: String,
    pub version_interface: u8,
    pub version_major: u8,
    pub version_minor: u8,
    pub version_build: u8,
    pub cap_flags: u8,
}

impl U2FDeviceInfo {
    fn from(register_result: &authenticator::RegisterResult) -> Self {
        let i = &register_result.1;
        Self {
            vendor_name: String::from_utf8_lossy(&i.vendor_name).to_string(),
            device_name: String::from_utf8_lossy(&i.device_name).to_string(),
            version_interface: i.version_interface,
            version_major: i.version_major,
            version_minor: i.version_minor,
            version_build: i.version_build,
            cap_flags: i.cap_flags,
        }
    }
}

impl fmt::Display for U2FDeviceInfo {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "Vendor: {}, Device: {}, Interface: {}, Firmware: v{}.{}.{}, Capabilities: {}",
            self.vendor_name,
            self.device_name,
            &self.version_interface,
            &self.version_major,
            &self.version_minor,
            &self.version_build,
            to_hex(&[self.cap_flags], ":"),
        )
    }
}

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct U2fRegistrationData {
    pub app_id: String,
    pub device_info: U2FDeviceInfo,
    pub device_name: Option<String>,
    pub client_data: String,
    pub registration_data: String,
    pub attestation_cert_pem: Option<String>,
    pub pub_key: String,
    pub key_handle: String,
}

impl U2fRegistrationData {
    pub fn from(app_id: &str, client_data: &str, register_result: RegisterResult) -> XResult<Self> {
        let rr = match u2f::register::parse_registration(app_id.to_string(), client_data.as_bytes().to_vec(), register_result.0.to_vec()) {
            Ok(rr) => rr,
            Err(e) => return simple_error!("Parse registration data failed: {}", e),
        };
        Ok(Self {
            app_id: app_id.to_string(),
            device_info: U2FDeviceInfo::from(&register_result),
            device_name: rr.device_name,
            client_data: client_data.into(),
            registration_data: base64::encode(&register_result.0),
            attestation_cert_pem: rr.attestation_cert.map(|c| {
                to_pem(&c, "CERTIFICATE", 64)
            }),
            pub_key: hex::encode(rr.pub_key),
            key_handle: hex::encode(rr.key_handle),
        })
    }
}

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct U2fV2Challenge {
    challenge: String,
    version: String,
    #[serde(rename = "appId")]
    app_id: String,
}

impl U2fV2Challenge {
    pub fn new_random<S>(app_id: S) -> Self where S: Into<String> {
        let mut rng = rand::thread_rng();
        let mut rand_bytes = [0_u8; 32];
        for c in &mut rand_bytes {
            let b: u8 = rng.gen();
            *c = b;
        }

        let challenge = base64::encode_config(&rand_bytes, URL_SAFE_NO_PAD);
        Self::new(challenge, app_id)
    }

    pub fn new<S1, S2>(challenge: S1, app_id: S2) -> Self where S1: Into<String>, S2: Into<String> {
        Self {
            challenge: challenge.into(),
            version: "U2F_V2".into(),
            app_id: app_id.into(),
        }
    }

    pub fn to_json(&self) -> String {
        serde_json::to_string(&self).unwrap()
    }
}

pub fn start_status_updater() -> Sender<StatusUpdate> {
    let (status_tx, status_rx) = channel::<StatusUpdate>();
    thread::spawn(move || loop {
        match status_rx.recv() {
            Ok(StatusUpdate::DeviceAvailable { dev_info }) => {
                debugging!("STATUS: device available: {}", dev_info)
            }
            Ok(StatusUpdate::DeviceUnavailable { dev_info }) => {
                debugging!("STATUS: device unavailable: {}", dev_info)
            }
            Ok(StatusUpdate::Success { dev_info }) => {
                debugging!("STATUS: success using device: {}", dev_info);
            }
            Err(_) => {
                debugging!("STATUS: end");
                return;
            }
        }
    });
    status_tx
}

pub fn to_pem(bs: &[u8], sub: &str, w: usize) -> String {
    let mut s = String::with_capacity(bs.len() * 2);
    s.push_str(&format!("-----BEGIN {}-----", sub));
    let b64 = base64::encode(bs).chars().collect::<Vec<char>>();
    let mut b64 = b64.as_slice();
    while !b64.is_empty() {
        s.push('\n');
        if b64.len() >= w {
            for c in b64.iter().take(w) {
                s.push(*c);
            }
            b64 = &b64[w..];
        } else {
            for c in b64 {
                s.push(*c);
            }
            b64 = &[];
        }
    }
    s.push_str(&format!("\n-----END {}-----", sub));
    s
}

pub fn to_hex(data: &[u8], joiner: &str) -> String {
    let parts: Vec<String> = data.iter().map(|byte| format!("{:02x}", byte)).collect();
    parts.join(joiner)
}