use std::io::Write;
use std::net::ToSocketAddrs;
use std::process;

use log::debug;

use clap::Clap;
use serde::{Deserialize, Serialize};

const BASE_URL: &str = "https://api.azirevpn.com/v1";

#[derive(Clap, Debug)]
struct Opts {
    #[clap(short, long)]
    json: bool,

    #[clap(subcommand)]
    command: Command,
}

#[derive(Clap, Debug)]
struct ConfigOpts {
    location: String,
    username: String,
    token: String,
}

#[derive(Clap, Debug)]
enum Command {
    Endpoints,
    Config(ConfigOpts),
    Check,
}

#[derive(Serialize, Deserialize, Debug)]
struct Endpoints {
    wireguard: String,
}

#[derive(Serialize, Deserialize, Debug)]
struct Location {
    name: String,
    city: String,
    country: String,
    iso: String,
    endpoints: Endpoints,
}

#[derive(Serialize, Deserialize, Debug)]
struct Locations {
    locations: Vec<Location>,
}

#[derive(Serialize, Deserialize, Debug)]
struct CheckResult {
    connected: bool,
    ip: String, // XXX
    location: String,
}

#[derive(Serialize, Deserialize, Debug)]
struct WireguardConfig {
    status: String,
    data: WireguardConfigData,
}

#[derive(Serialize, Deserialize, Debug)]
#[serde(rename_all = "PascalCase")]
struct WireguardConfigData {
    public_key: String,
    address: String,
    endpoint: String,
}

#[derive(Debug)]
struct WireguardKeyPair {
    public_key: String,
    private_key: String,
}

fn main() -> Result<(), anyhow::Error> {
    env_logger::init();
    let opts = Opts::parse();
    match &opts.command {
        Command::Endpoints => list_endpoints(&opts)?,
        Command::Config(get_config_opts) => get_config(&opts, &get_config_opts)?,
        Command::Check => check(&opts)?,
    }
    Ok(())
}

fn list_endpoints(opts: &Opts) -> Result<(), anyhow::Error> {
    let locations: Locations = get_locations()?;
    if opts.json {
        println!("{}", serde_json::to_string(&locations)?);
    } else {
        for (i, location) in locations.locations.iter().enumerate() {
            if i > 0 {
                println!()
            };
            println!("Name: {}", location.name);
            println!("City: {}", location.city);
            println!("Country: {}", location.country);
            println!("Country code: {}", location.iso);
            println!("WireGuard endpoint: {}", location.endpoints.wireguard);
        }
    }
    Ok(())
}

fn get_config(_opts: &Opts, config_opts: &ConfigOpts) -> Result<(), anyhow::Error> {
    let locations = get_locations()?;
    let location = locations
        .locations
        .iter()
        .find(|location| location.name == config_opts.location)
        .ok_or_else(|| anyhow::anyhow!("no such location: {}", config_opts.location))?;
    debug!("location = {:?}", &location);
    let keys = generage_keys()?;
    debug!("keys = {:?}", &keys);
    let config: WireguardConfig = ureq::post(&location.endpoints.wireguard)
        .send_form(&[
            ("username", &config_opts.username),
            ("token", &config_opts.token),
            ("pubkey", &keys.public_key),
        ])?
        .into_json()?;
    debug!("config = {:?}", &config);
    let mut endpoint_addrs = config.data.endpoint.to_socket_addrs()?;
    let endpoint_addr = endpoint_addrs
        .next()
        .ok_or_else(|| anyhow::anyhow!("no endpoint address received"))?;
    debug!("endpoint_addr = {:?}", &endpoint_addr);
    println!(
        r"[Interface]
PrivateKey = {}
Address = {}

[Peer]
PublicKey = {}
Endpoint = {}
AllowedIPs = 0.0.0.0/0 #, ::/0",
        &keys.private_key, &config.data.address, &config.data.public_key, &endpoint_addr
    );
    Ok(())
}

fn check(opts: &Opts) -> Result<(), anyhow::Error> {
    let url = format!("{}/check", BASE_URL);
    let result: CheckResult = ureq::get(&url).call()?.into_json()?;
    if opts.json {
        println!("{}", serde_json::to_string(&result)?);
    } else {
        println!("Connected: {:?}", result.connected);
        println!("IP: {}", result.ip);
        println!("Location: {}", result.location);
    }
    Ok(())
}

fn get_locations() -> Result<Locations, anyhow::Error> {
    let url = format!("{}/locations", BASE_URL);
    let locations: Locations = ureq::get(&url).call()?.into_json()?;
    Ok(locations)
}

fn generage_keys() -> Result<WireguardKeyPair, anyhow::Error> {
    let privkey = process::Command::new("wg").arg("genkey").output()?.stdout;
    let mut pubkey_cmd = process::Command::new("wg")
        .arg("pubkey")
        .stdin(process::Stdio::piped())
        .stdout(process::Stdio::piped())
        .spawn()?;
    pubkey_cmd
        .stdin
        .as_mut()
        .expect("no stdin")
        .write_all(&privkey)?;
    let pubkey = pubkey_cmd.wait_with_output()?.stdout;
    Ok(WireguardKeyPair {
        private_key: String::from_utf8(privkey)?.trim_end().to_string(),
        public_key: String::from_utf8(pubkey)?.trim_end().to_string(),
    })
}