//! Utility functions for user interaction.
use std::{
    fmt::Display,
    io::{self, Write},
};

use anyhow::{bail, Result};
use termcolor::{Color, ColorSpec, StandardStream, WriteColor};

/// Presents the user with a choice of items and awaits a selection.
pub fn user_choice<'i, L: Display, I>(
    items: &'i [(L, I)],
    output: &mut StandardStream,
) -> Result<&'i I> {
    for (i, (label, _)) in items.iter().enumerate() {
        output.set_color(ColorSpec::new().set_fg(Some(Color::Blue)))?;
        write!(output, "[{}]", i)?;
        output.reset()?;
        writeln!(output, " {}", label)?;
    }

    let stdin = io::stdin();
    loop {
        write!(output, "Enter a number: ")?;
        output.flush()?;
        let mut buffer = String::new();
        stdin.read_line(&mut buffer)?;
        if let Ok(number) = buffer.trim().parse::<usize>() {
            if number < items.len() {
                return Ok(&items[number].1);
            }
        }
    }
}

/// Ask the user whether they want to continue.
///
/// Returns `Ok(())` if the program should continue, and an error otherwise.
pub fn ask_continue(output: &mut StandardStream) -> Result<()> {
    let stdin = io::stdin();
    loop {
        output.set_color(ColorSpec::new().set_fg(Some(Color::Yellow)))?;
        write!(output, "Continue? [Y/n] ")?;
        output.reset()?;
        output.flush()?;

        let mut buffer = String::new();
        stdin.read_line(&mut buffer)?;
        if buffer == "\n" || buffer == "Y\n" || buffer == "y\n" {
            return Ok(());
        } else if buffer == "N\n" || buffer == "n\n" {
            bail!("Cancelled by user");
        }
    }
}