use std::ffi::OsString;
use std::io;
use std::path::Path;

use crate::{Child, Endpoint, Executable, MAX_DESCRIPTOR};

pub struct Launch<'a> {
    pub executable: Executable,
    pub program: &'a Path,
    pub args: &'a [String],
    pub env: Vec<(OsString, OsString)>,
    pub cwd: &'a Path,
    pub group: bool,
    pub join: Option<&'a crate::Group>,
    pub terminal: bool,
    pub endpoints: Vec<(u32, Endpoint)>,
}

pub fn spawn(launch: Launch<'_>) -> io::Result<Child> {
    let mut descriptors = std::collections::BTreeSet::new();
    if launch
        .endpoints
        .iter()
        .any(|(fd, _)| *fd > MAX_DESCRIPTOR || !descriptors.insert(*fd))
    {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "Invalid or duplicate subprocess descriptor",
        ));
    }
    if launch.args.iter().any(|arg| arg.contains('\0'))
        || launch.env.iter().any(|(name, value)| {
            name.is_empty()
                || name
                    .as_encoded_bytes()
                    .iter()
                    .enumerate()
                    .any(|(index, byte)| {
                        *byte == 0 || (*byte == b'=' && !(cfg!(windows) && index == 0))
                    })
                || value.as_encoded_bytes().contains(&0)
        })
        || launch.program.as_os_str().as_encoded_bytes().contains(&0)
        || launch.cwd.as_os_str().as_encoded_bytes().contains(&0)
    {
        return Err(io::Error::new(
            io::ErrorKind::InvalidInput,
            "Invalid subprocess argument, environment, or path",
        ));
    }
    crate::sys::spawn(launch)
}