use crate::config::{update_config, update_episode, Config};
use crate::initialization::init_config;
use crate::result::{AppError, AppResult};
use crate::{generate_completion, Opt, RunMode};
use std::process::Command;

pub fn run(opts: Opt) -> AppResult<()> {
    let mode = opts.mode.unwrap_or_else(|| RunMode::Play);
    match mode {
        RunMode::Init => init_config(),
        RunMode::Play => play(),
        RunMode::Prev => update_episode(prev_episode),
        RunMode::Next => update_episode(next_episode),
        RunMode::Update => update_config(),
        RunMode::Reset => update_episode(|_| Ok(0)),
        RunMode::Completion { shell } => generate_completion(shell),
    }
}

pub fn prev_episode(current: usize) -> AppResult<usize> {
    if let Some(episode) = current.checked_sub(1) {
        Ok(episode)
    } else {
        Err(AppError::RuntimeError(String::from(
            "Episode can't be less than zero.",
        )))
    }
}

pub fn next_episode(current: usize) -> AppResult<usize> {
    if let Some(episode) = current.checked_add(1) {
        Ok(episode)
    } else {
        Err(AppError::RuntimeError(String::from(
            "Reached usize limit. Sorry.",
        )))
    }
}

fn add_leading_zero(n: usize) -> String {
    if n < 10 {
        format!("0{}", n)
    } else {
        format!("{}", n)
    }
}

fn prepare_command(conf: Config) -> AppResult<String> {
    let index = conf.current_episode_count;
    Ok(conf
        .command
        .replace("{}", conf.get_current_episode()?.as_str())
        .replace("{n}", format!("{}", index).as_str())
        .replace("{n+}", format!("{}", index + 1).as_str())
        .replace("{zn}", add_leading_zero(index).as_str())
        .replace("{zn+}", add_leading_zero(index + 1).as_str()))
}

pub fn play() -> AppResult<()> {
    let mut conf = Config::read()?;
    let mut episode = conf.get_current_episode()?;
    while !episode.is_empty() {
        let mut child = Command::new("sh")
            .arg("-c")
            .arg(prepare_command(conf.clone())?)
            .spawn()?;
        child.wait()?;
        update_episode(next_episode)?;
        conf = Config::read()?;
        episode = conf.get_current_episode()?;
    }
    Ok(())
}