use std::{error::Error as StdError, sync::Arc};
use std::io::{self, IsTerminal};
use std::path::Path;
use std::process::ExitCode;


use append_override::source::SourceFile;
use clap::{ColorChoice, Parser as _};
use fs_err::File;
use fs_err::os::unix::fs::OpenOptionsExt;

fn main_wrapped() -> Result<(), Box<dyn StdError + Send + Sync + 'static>> {
    let args = append_override::Parser::parse();

    let success = append_override::CLI_ENABLE_COLOR.set(match args.color {
        ColorChoice::Always => true,
        ColorChoice::Auto => io::stdin().is_terminal(),
        ColorChoice::Never => false,
    });
    if cfg!(debug_assertions) {
        success.expect("logic error in CLI_ENABLE_COLOR");
    }

    // FIXME: handle relative paths without leading ./
    let filepath = Path::new(&args.file);

    // Get what file that thing is defined in.
    let def_path = append_override::get_where(&args.name, filepath)?;
    let def_path = Arc::from(def_path);
    let mut opts = File::options();
    opts
        .read(true)
        .write(true)
        .create(false)
        .custom_flags(libc::O_CLOEXEC);
    let source_file = SourceFile::open_from(Arc::clone(&def_path), opts)?;

    let last_def_line = append_override::get_highest_prio(&args.name, source_file.clone())?;
    let pri: i64 = {
        let text = last_def_line.text();
        let pat = "lib.mkOverride (";
        let start = text.find(pat).unwrap();
        let substr = &text[start..];
        let substr = substr.strip_prefix(pat).unwrap();
        let end_paren = substr.find(")").unwrap();
        let final_num = &substr[..end_paren];

        final_num.parse().unwrap()
    };

    eprintln!("{last_def_line}");

    dbg!(&pri);

    append_override::write_next_prio(source_file, last_def_line, pri, pri - 1)?;

    Ok(())
}

fn main() -> ExitCode {
    match main_wrapped() {
        Ok(_) => ExitCode::SUCCESS,
        Err(e) => {
            eprintln!("append-override: error: {}", e);
            ExitCode::FAILURE
        }
    }
}