// https://www.phind.com/agent?cache=clke9xk39001cmj085upzho1t

use std::fs::File;

use atom_syndication::{Entry, Feed, Link};

mod errors;
mod feed;
pub mod prelude;

use prelude::*;

pub fn run(subscriptions: &str, history: &str, site: &str) -> Result<()> {
    for channel_name in lines_from(subscriptions)? {
        let channel_name = channel_name?;
        println!("Channel: {}", channel_name);
        let feed_url = feed::get_feed_url(site, &channel_name)?;
        for entry in get_feed(feed_url)?.entries() {
            if let Some(link) = get_link(entry) {
                if !is_already_downloaded(&link, history)? {
                    println!("Downloading {}: {}", &channel_name, entry.title().as_str());
                    download_audio(&link)?;
                    mark_as_downloaded(&link, history)?;
                }
            }
        }
    }
    Ok(())
}

fn get_link(item: &Entry) -> Option<Link> {
    item.links().get(0).cloned()
}

// read list of rss feed URLs from file 'feeds.txt'
fn lines_from(file_name: &str) -> Result<std::io::Lines<std::io::BufReader<std::fs::File>>> {
    use std::io::{BufRead, BufReader};

    let file = File::open(file_name)?;
    let reader = BufReader::new(file);
    Ok(reader.lines())
}

// fetch the RSS feed
fn get_feed(url: String) -> Result<Feed> {
    let content = reqwest::blocking::get(url)?.bytes()?;
    let channel = Feed::read_from(&content[..])?;
    Ok(channel)
}

fn is_already_downloaded(link: &Link, file_name: &str) -> Result<bool> {
    use std::io::{BufRead, BufReader};

    if let Ok(file) = File::open(file_name) {
        let reader = BufReader::new(file);
        for line in reader.lines() {
            if line? == link.href {
                return Ok(true); // is already downloaded
            }
        }
    }
    Ok(false) // is not already downloaded
}

fn download_audio(link: &Link) -> Result<()> {
    use std::process::Command;

    let cmd = "yt-dlp";
    // println!("{} --extract-audio --audio-format mp3 {}", cmd, &link.href);
    let output = Command::new(cmd)
        .arg("--extract-audio")
        .arg("--audio-format")
        .arg("mp3")
        .arg(&link.href)
        .output()?;
    if !output.stderr.is_empty() {
        eprintln!("Error: {}", String::from_utf8(output.stderr)?);
        println!("{}", String::from_utf8(output.stdout)?);
    }
    Ok(())
}

fn mark_as_downloaded(link: &Link, file_name: &str) -> Result<()> {
    use std::fs::OpenOptions;
    use std::io::prelude::*;

    let mut file = OpenOptions::new()
        .write(true)
        .append(true)
        .create(true)
        .open(file_name)
        .unwrap();

    writeln!(file, "{}", link.href)?;
    Ok(())
}