//! Tiny stderr logger. We use a consistent `==> <action>: <details>` prefix
//! so progress messages are easy to scan during long builds.

use std::io::{IsTerminal, Write};

const ARROW: &str = "==>";

fn paint(color: &str, text: &str) -> String {
    if std::io::stderr().is_terminal() {
        format!("\x1b[{color}m{text}\x1b[0m")
    } else {
        text.to_owned()
    }
}

fn emit(color: &str, action: &str, details: &str) {
    let arrow = paint(color, ARROW);
    let action = paint("1", action);
    let _ = writeln!(std::io::stderr(), "{arrow} {action} {details}");
}

/// Major step, e.g. starting a build or packaging an output.
pub fn step(action: &str, details: &str) {
    emit("1;34", action, details); // bold blue
}

/// Cache hit / skipped work.
pub fn skip(action: &str, details: &str) {
    emit("1;33", action, details); // bold yellow
}

/// Sub-step inside a larger action.
pub fn info(action: &str, details: &str) {
    emit("1;32", action, details); // bold green
}