use std::fs::File;
use std::io::Read;
use std::time::Duration;

use anyhow::{anyhow, bail, Result};

use crate::config::{ConfigOpts, ConfigOptsAcme, ConfigOptsBase, ConfigOptsConsul};

// This code is inspired by the Trunk crate (https://github.com/thedodd/trunk)

// In this file, we take ConfigOpts and transform them into ready-to-use
// RuntimeConfig. We apply default values and business logic.

#[derive(Debug)]
pub struct RuntimeConfigAcme {
  pub email: String,
}

#[derive(Debug)]
pub struct RuntimeConfigConsul {
  pub node_name: String,
  pub url: String,
  pub tls: Option<(reqwest::Certificate, reqwest::Identity)>,
}

#[derive(Debug)]
pub struct RuntimeConfigFirewall {
  pub refresh_time: Duration,
}

#[derive(Debug)]
pub struct RuntimeConfigIgd {
  pub private_ip: Option<String>,
  pub expiration_time: Duration,
  pub refresh_time: Duration,
}

#[derive(Debug)]
pub struct RuntimeConfig {
  pub acme: Option<RuntimeConfigAcme>,
  pub consul: RuntimeConfigConsul,
  pub firewall: RuntimeConfigFirewall,
  pub igd: RuntimeConfigIgd,
}

impl RuntimeConfig {
  pub fn new(opts: ConfigOpts) -> Result<Self> {
    let acme = RuntimeConfigAcme::new(opts.acme.clone())?;
    let consul = RuntimeConfigConsul::new(opts.consul.clone())?;
    let firewall = RuntimeConfigFirewall::new(opts.base.clone())?;
    let igd = RuntimeConfigIgd::new(opts.base.clone())?;

    Ok(Self {
      acme,
      consul,
      firewall,
      igd,
    })
  }
}

impl RuntimeConfigAcme {
  pub fn new(opts: ConfigOptsAcme) -> Result<Option<Self>> {
    if !opts.enable {
      return Ok(None);
    }

    let email = opts.email.expect(
      "'DIPLONAT_ACME_EMAIL' environment variable is required if 'DIPLONAT_ACME_ENABLE' == 'true'",
    );

    Ok(Some(Self { email }))
  }
}

impl RuntimeConfigConsul {
  pub(super) fn new(opts: ConfigOptsConsul) -> Result<Self> {
    let node_name = opts
      .node_name
      .expect("'DIPLONAT_CONSUL_NODE_NAME' environment variable is required");
    let url = opts.url.unwrap_or(super::CONSUL_URL.to_string());

    let tls = match (&opts.ca_cert, &opts.client_cert, &opts.client_key) {
      (Some(ca_cert), Some(client_cert), Some(client_key)) => {
        let mut ca_cert_buf = vec![];
        File::open(ca_cert)?.read_to_end(&mut ca_cert_buf)?;
        let cert = reqwest::Certificate::from_pem(&ca_cert_buf[..])?;

        let mut client_cert_buf = vec![];
        File::open(client_cert)?.read_to_end(&mut client_cert_buf)?;

        let mut client_key_buf = vec![];
        File::open(client_key)?.read_to_end(&mut client_key_buf)?;

        let ident =
          reqwest::Identity::from_pem(&[&client_cert_buf[..], &client_key_buf[..]].concat()[..])?;

        Some((cert, ident))
      }
      (None, None, None) => None,
      _ => bail!("Incomplete TLS configuration parameters"),
    };

    Ok(Self {
      node_name,
      url,
      tls,
    })
  }
}

impl RuntimeConfigFirewall {
  pub(super) fn new(opts: ConfigOptsBase) -> Result<Self> {
    let refresh_time = Duration::from_secs(opts.refresh_time.unwrap_or(super::REFRESH_TIME).into());

    Ok(Self { refresh_time })
  }
}

impl RuntimeConfigIgd {
  pub(super) fn new(opts: ConfigOptsBase) -> Result<Self> {
    let private_ip = opts.private_ip;
    let expiration_time = Duration::from_secs(
      opts
        .expiration_time
        .unwrap_or(super::EXPIRATION_TIME)
        .into(),
    );
    let refresh_time = Duration::from_secs(opts.refresh_time.unwrap_or(super::REFRESH_TIME).into());

    if refresh_time.as_secs() * 2 > expiration_time.as_secs() {
      return Err(anyhow!(
        "IGD expiration time (currently: {}s) must be at least twice bigger than refresh time \
         (currently: {}s)",
        expiration_time.as_secs(),
        refresh_time.as_secs()
      ));
    }

    Ok(Self {
      private_ip,
      expiration_time,
      refresh_time,
    })
  }
}