//! Configuration file structure. (TODO, docs)

use std::{
    fmt::Debug,
    fs::File,
    io::{self, Read, Seek},
    net::{Ipv4Addr, SocketAddr, SocketAddrV4},
};

use serde::Deserialize;

use crate::serdes::{DatabasePaths, Group};

#[derive(Debug, Default, Deserialize)]
#[serde(default)]
pub struct Unix {
    pub groups: Vec<Group>,
    pub magic_paths: DatabasePaths,
}

#[derive(Debug, Deserialize)]
#[serde(default)]
pub struct Server {
    pub listen: SocketAddr,
}
impl Default for Server {
    fn default() -> Self {
        Self {
            listen: SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::LOCALHOST, 8080)),
        }
    }
}

#[derive(Debug, Default, Deserialize)]
#[serde(default)]
pub struct Config {
    pub unix: Unix,
    pub server: Server,
}

#[derive(thiserror::Error, Debug)]
pub enum ConfigParseError {
    #[error(transparent)]
    Io(#[from] io::Error),

    #[error(transparent)]
    Parse(#[from] toml::de::Error),
}

impl Config {
    /// # Errors
    ///
    /// For IO errors reading the file or parsing errors.
    ///
    /// # Panics
    ///
    /// If file's u64 length might not fit in memory.
    pub fn from_toml_file(f: &mut File) -> Result<Self, ConfigParseError> {
        let mut buf = Vec::new();
        if let Ok(len) = f.stream_len() {
            buf.reserve_exact(len.try_into().expect("file's u64 len to fit in memory"));
        }
        f.read_to_end(&mut buf)?;

        Ok(toml::from_slice(&buf)?)
    }
}