//! A local HTTP CGI server for integration tests against native git http-backend.
use std::{
    io::{Read, Write},
    net::TcpListener,
    process::{Command, Stdio},
};
fn main() -> Result<(), Box<dyn std::error::Error>> {
    let args: Vec<_> = std::env::args().collect();
    let listener = TcpListener::bind("127.0.0.1:0")?;
    std::fs::write(&args[2], listener.local_addr()?.port().to_string())?;
    for stream in listener.incoming() {
        let mut stream = stream?;
        if let Err(error) = serve(&mut stream, &args[1]) {
            eprintln!("request failed: {error}");
        }
    }
    Ok(())
}
fn serve(io: &mut (impl Read + Write), root: &str) -> Result<(), Box<dyn std::error::Error>> {
    let mut header = Vec::new();
    while !header.ends_with(b"\r\n\r\n") {
        let mut byte = [0];
        io.read_exact(&mut byte)?;
        header.push(byte[0]);
    }
    let text = std::str::from_utf8(&header)?;
    let mut lines = text.split("\r\n");
    let request: Vec<_> = lines
        .next()
        .ok_or("no request")?
        .split_whitespace()
        .collect();
    let mut length = 0;
    let mut content_type = "";
    for line in lines {
        if let Some((key, value)) = line.split_once(':') {
            if key.eq_ignore_ascii_case("content-length") {
                length = value.trim().parse()?;
            }
            if key.eq_ignore_ascii_case("content-type") {
                content_type = value.trim();
            }
        }
    }
    let mut body = vec![0; length];
    io.read_exact(&mut body)?;
    let (path, query) = request[1].split_once('?').unwrap_or((request[1], ""));
    let mut child = Command::new("git")
        .arg("http-backend")
        .env("GIT_PROJECT_ROOT", root)
        .env("GIT_HTTP_EXPORT_ALL", "1")
        .env("PATH_INFO", path)
        .env("QUERY_STRING", query)
        .env("REQUEST_METHOD", request[0])
        .env("CONTENT_TYPE", content_type)
        .env("CONTENT_LENGTH", length.to_string())
        .stdin(Stdio::piped())
        .stdout(Stdio::piped())
        .spawn()?;
    child.stdin.take().ok_or("no CGI stdin")?.write_all(&body)?;
    let response = child.wait_with_output()?;
    let split = response
        .stdout
        .windows(4)
        .position(|w| w == b"\r\n\r\n")
        .ok_or("invalid CGI response")?;
    let headers = std::str::from_utf8(&response.stdout[..split])?;
    let status = headers
        .lines()
        .find_map(|l| l.strip_prefix("Status: "))
        .unwrap_or("200 OK");
    write!(
        io,
        "HTTP/1.1 {status}\r\nConnection: close\r\nContent-Length: {}\r\n",
        response.stdout.len() - split - 4
    )?;
    for line in headers.split("\r\n") {
        if !line.starts_with("Status:") {
            write!(io, "{line}\r\n")?;
        }
    }
    io.write_all(b"\r\n")?;
    io.write_all(&response.stdout[split + 4..])?;
    io.flush()?;
    Ok(())
}