use std::fmt::{Display, Error, Formatter};
use std::num::NonZeroUsize;
use std::path::Path;

#[derive(Clone, Debug, PartialEq, Hash, Eq)]
pub struct FpmPoolConfig {
  max_children: NonZeroUsize,
  custom: Option<Box<str>>,
}

impl Display for FpmPoolConfig {
  fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
    match &self.custom {
      None => write!(f, "pm.max_children = {}", self.max_children),
      Some(custom) => write!(f, "pm.max_children = {}\n{}", self.max_children, custom),
    }
  }
}

impl From<usize> for FpmPoolConfig {
  fn from(max_children: usize) -> Self {
    Self {
      max_children: NonZeroUsize::try_from(max_children).unwrap(),
      custom: None,
    }
  }
}

impl FpmPoolConfig {
  pub fn new(max_children: NonZeroUsize, custom: impl Into<Box<str>>) -> Self {
    Self {
      max_children,
      custom: Some(custom.into()),
    }
  }
}

pub fn fpm_pool_config<U: AsRef<str>, S: AsRef<Path>>(
  user_name: U,
  socket_path: S,
  config: &FpmPoolConfig,
) -> String {
  format!(
    "[{0}]

user = {0}
group = www-data
listen = {1}
listen.owner = www-data
pm = ondemand
catch_workers_output = yes
env[PATH] = /usr/local/bin:/usr/bin:/bin
{2}
",
    user_name.as_ref(),
    socket_path.as_ref().to_str().unwrap(),
    config
  )
}

#[cfg(test)]
mod test {
  use super::fpm_pool_config;
  #[test]
  fn test_fpm_pool_config() {
    assert_eq!(
      fpm_pool_config("user", "socket", &5.into()),
      r"[user]

user = user
group = www-data
listen = socket
listen.owner = www-data
pm = ondemand
catch_workers_output = yes
env[PATH] = /usr/local/bin:/usr/bin:/bin
pm.max_children = 5
"
    );
  }
}