use anyhow::{anyhow, Result};
use clap::Parser;
use reqwest::Url;

use crate::api::ApiClient;
use crate::cache::CacheRef;
use crate::cli::Opts;
use crate::config::Config;
use crate::nix_config::NixConfig;
use crate::nix_netrc::NixNetrc;

/// Configure Nix to use a binary cache.
#[derive(Debug, Parser)]
pub struct Use {
    /// The cache to configure.
    ///
    /// This can be either `servername:cachename` or `cachename`
    /// when using the default server.
    cache: CacheRef,
}

pub async fn run(opts: Opts) -> Result<()> {
    let sub = opts.command.as_use().unwrap();
    let config = Config::load()?;

    let (server_name, server, cache) = config.resolve_cache(&sub.cache)?;

    let api = ApiClient::from_server_config(server.clone())?;
    let cache_config = api.get_cache_config(cache).await?;

    let substituter = cache_config
        .substituter_endpoint
        .ok_or_else(|| anyhow!("The server did not tell us where the binary cache endpoint is."))?;
    let public_key = cache_config.public_key
        .ok_or_else(|| anyhow!("The server did not tell us which public key it uses. Is signing managed by the client?"))?;

    eprintln!(
        "Configuring Nix to use \"{cache}\" on \"{server_name}\":",
        cache = cache.as_str(),
        server_name = server_name.as_str(),
    );

    // Modify nix.conf
    eprintln!("+ Substituter: {}", substituter);
    eprintln!("+ Trusted Public Key: {}", public_key);

    let mut nix_config = NixConfig::load().await?;
    nix_config.add_substituter(&substituter);
    nix_config.add_trusted_public_key(&public_key);

    // Modify netrc
    if let Some(token) = server.token()? {
        eprintln!("+ Access Token");

        let mut nix_netrc = NixNetrc::load().await?;
        let host = Url::parse(&substituter)?
            .host()
            .map(|h| h.to_string())
            .unwrap();
        nix_netrc.add_token(host, token.to_string());
        nix_netrc.save().await?;

        let netrc_path = nix_netrc.path().unwrap().to_str().unwrap();

        nix_config.set_netrc_file(netrc_path);
    }

    nix_config.save().await?;

    Ok(())
}