use std::{
    collections::HashMap,
    env::{var, var_os},
    fs::{File, create_dir, exists, read_to_string},
    io::{Read, Write},
    os::unix::process::CommandExt,
    process::Command,
};

fn parse(data: &str) -> HashMap<String, String> {
    let mut out = HashMap::new();

    let mut parse_one = |key: &str, value: String, fallback| match key {
        "metadata" => {
            let (left, right) = value
                .split_once('=')
                .expect("missing '=' for cargo::metadata");
            out.insert(left.to_string(), right.to_string());
        }

        _ if fallback => {
            out.insert(key.to_string(), value);
        }

        _ => {}
    };

    for line in data.lines() {
        if let Some(data) = line.strip_prefix("cargo::") {
            let (key, value) = data.split_once('=').expect("missing '=' on cargo:: line");
            parse_one(key, value.to_string(), false);
        } else if let Some(data) = line.strip_prefix("cargo:") {
            let (key, value) = data.split_once('=').expect("missing '=' on cargo: line");
            parse_one(key, value.to_string(), true);
        }
    }

    out
}

fn main() {
    create_dir(var_os("OUT_DIR").unwrap()).unwrap();
    create_dir(var_os("CARGO_TARGET_DIR").unwrap()).unwrap();

    let mut f = File::create(var_os("out").unwrap()).unwrap();
    writeln!(&mut f, "zilch: OUT_DIR={:?}", var("OUT_DIR").unwrap()).unwrap();
    writeln!(
        &mut f,
        "zilch: CARGO_TARGET_DIR={:?}",
        var("CARGO_TARGET_DIR").unwrap()
    )
    .unwrap();

    let mut cmd = Command::new(var_os("script").unwrap());

    cmd.stdout(f).current_dir(var_os("cwd").unwrap());

    if let Ok(inherit) = var("_zilch_links") {
        if !inherit.is_empty() {
            for v in inherit.split('!') {
                let (path, name) = v.split_once(':').unwrap();
                let mut file = File::open(path).unwrap();
                let mut data = String::new();
                file.read_to_string(&mut data).unwrap();

                let data = parse(&data);
                for (k, v) in data {
                    let mut name = format!("DEP_{}_{}", name, k);
                    name.make_ascii_uppercase();
                    cmd.env(name.replace('-', "_"), v);
                }
            }
        }
    }

    let mut pkg_config_path = Vec::new();
    if let Ok(paths) = var("_zilch_pkgconfig") {
        if !paths.is_empty() {
            let mut paths_to_check = Vec::new();
            for path in paths.split(':') {
                paths_to_check.push(path.to_string());
            }

            while let Some(path) = paths_to_check.pop() {
                let pkgconfig_path = format!("{}/lib/pkgconfig", path);
                if exists(&pkgconfig_path).ok() == Some(true)
                    && !pkg_config_path.contains(&pkgconfig_path)
                {
                    pkg_config_path.push(pkgconfig_path);
                }

                let pkgconfig_path = format!("{}/share/pkgconfig", path);
                if exists(&pkgconfig_path).ok() == Some(true)
                    && !pkg_config_path.contains(&pkgconfig_path)
                {
                    pkg_config_path.push(pkgconfig_path);
                }

                if let Ok(file) =
                    read_to_string(format!("{}/nix-support/propagated-build-inputs", path))
                {
                    for path in file.split(' ') {
                        if !path.is_empty() {
                            paths_to_check.push(path.to_string());
                        }
                    }
                }
            }
        }
    }

    cmd.env("PKG_CONFIG_PATH", pkg_config_path.join(":"));
    let status = cmd.status().unwrap();

    if !status.success() {
        panic!(
            "Failed to execute.\nstdout: {}",
            std::fs::read_to_string(var_os("out").unwrap()).unwrap()
        );
    }
}