use clap::{CommandFactory, ValueEnum};
use clap_complete::{Shell, generate_to};
use std::{env, ffi::OsString, fs, io::Error, path::PathBuf};

include!("src/cli/mod.rs");

fn shell_name(shell: Shell) -> String {
    shell
        .to_possible_value()
        .map(|v| v.get_name().to_owned())
        .unwrap_or_default()
}

fn non_empty(name: &str) -> Option<OsString> {
    env::var_os(name).filter(|v| !v.is_empty())
}

fn install_dir(shell: Shell) -> Option<(PathBuf, bool)> {
    let per_shell = format!("SHELL_COMPLETIONS_DIR_{}", shell_name(shell).to_uppercase());

    if let Some(dir) = non_empty(&per_shell).or_else(|| non_empty("SHELL_COMPLETIONS_DIR")) {
        return Some((PathBuf::from(dir), true));
    }
    non_empty("OUT_DIR").map(|dir| (PathBuf::from(dir), false))
}

fn main() -> Result<(), Error> {
    println!("cargo::rerun-if-env-changed=SHELL_COMPLETIONS_DIR");
    for shell in Shell::value_variants() {
        println!(
            "cargo::rerun-if-env-changed=SHELL_COMPLETIONS_DIR_{}",
            shell_name(*shell).to_uppercase()
        );
    }

    let mut cmd = ahab::Ahab::command();

    for shell in Shell::value_variants() {
        let Some((dir, requested)) = install_dir(*shell) else {
            continue;
        };

        fs::create_dir_all(&dir)?;
        let path = generate_to(*shell, &mut cmd, env!("CARGO_PKG_NAME"), &dir)?;

        if requested {
            println!(
                "cargo::warning=installed {} completion: {}",
                shell_name(*shell),
                path.display()
            );
        }
    }

    Ok(())
}