use params::Args;
use prelude::*;

pub mod feed;
pub mod file;
pub mod history;
pub mod network;
pub mod params;
pub mod prelude;

#[cfg(test)]
mod test_utils;

use file::FileEnv;
use network::NetworkEnv;

pub struct Env {
    pub network: NetworkEnv,
    pub file: FileEnv,
}

pub fn run(site: &str, a: &Args, e: Env) -> Result<()> {
    for channel_name in
        file::read::lines_from(&a.subscriptions, &e.file).context("Reading subscriptions")?
    {
        println!("Channel: {}", channel_name);
        let feed_url = feed::find(site, &channel_name, &e.network).context("Finding channel")?;
        for entry in feed::get(&feed_url, &e.network)
            .context("Fetching channel")?
            .entries()
        {
            if let Some(link) = entry.links().get(0).cloned() {
                if !history::find(&link, &a.history, &e.file).context("Finding history")? {
                    println!("Downloading {}: {}", &channel_name, entry.title().as_str());
                    (e.network.download_as_mp3)(&link.href).context("Downloading as MP3")?;
                    history::add(&link, &a.history, &e.file).context("Adding to history")?;
                }
            }
        }
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use std::{collections::HashMap, sync::mpsc};

    use atom_syndication::{Entry, EntryBuilder, Feed, FeedBuilder, LinkBuilder, Text};

    use crate::test_utils::{
        create_text_file, mock_fetch_as_text_with_rss_url, mock_file_append_line, mock_file_open,
        mock_network_download_as_mp3, mock_network_fetch_as_bytes_with_rss_entries,
    };
    use pretty_assertions::assert_eq;

    use super::*;

    #[test]
    fn downloads_two_items_from_two_feeds_ignoring_existing_items_in_history() -> Result<()> {
        //given

        let site = "http://example.com/";
        let (tx, rx) = mpsc::channel::<String>(); // channel to recieve notice of downloaded urls

        // two channels in subscriptions.txt
        let subs_file_name = "subs";
        let subs_dir =
            create_text_file(subs_file_name, "@channel1\nignore me\n@channel2".as_bytes())?;
        let subs_file_name = format!("{}/{}", subs_dir.path().to_string_lossy(), subs_file_name);

        // one item from each channel is already listed in the downloads.txt file
        let history_file_name = "history";
        let history_dir = create_text_file(history_file_name, "c1-f2\nc2-f3".as_bytes())?;

        let history_file_name = format!(
            "{}/{}",
            history_dir.path().to_string_lossy(),
            history_file_name
        );
        let args = Args {
            downloads: subs_dir.path().to_string_lossy().to_string(),
            history: history_file_name.clone(),
            subscriptions: subs_file_name.clone(),
        };
        let env = Env {
            network: NetworkEnv {
                fetch_as_text: mock_fetch_as_text_with_rss_url(HashMap::from([
                    ("http://example.com/@channel1", "rss-feed-1"),
                    ("http://example.com/@channel2", "rss-feed-2"),
                ])),
                fetch_as_bytes: mock_network_fetch_as_bytes_with_rss_entries(HashMap::from([
                    (
                        "rss-feed-1".into(),
                        feed_with_three_links("c1-f1", "c1-f2", "c1-f3").to_string(),
                    ),
                    (
                        "rss-feed-2".into(),
                        feed_with_three_links("c2-f1", "c2-f2", "c2-f3").to_string(),
                    ),
                ])),
                download_as_mp3: mock_network_download_as_mp3(tx),
            },
            file: FileEnv {
                open: mock_file_open(HashMap::from([
                    (subs_file_name.to_string(), subs_file_name),
                    (history_file_name.to_string(), history_file_name),
                ])),
                append_line: mock_file_append_line(),
            },
        };

        //when
        run(site, &args, env)?;
        //then
        drop(subs_dir);
        drop(history_dir);

        let mut downloads: Vec<String> = vec![];
        for m in rx {
            downloads.push(m);
        }

        assert_eq!(downloads, vec!["c1-f1", "c1-f3", "c2-f1", "c2-f2"]);
        Ok(())
    }

    fn entry_with_link(link: &str, title: &str) -> Entry {
        EntryBuilder::default()
            .links(vec![LinkBuilder::default().href(link.to_string()).build()])
            .title(Text::from(title))
            .build()
    }
    fn feed_with_three_links(l1: &str, l2: &str, l3: &str) -> Feed {
        FeedBuilder::default()
            .entries(vec![
                entry_with_link(l1, "l1"),
                entry_with_link(l2, "l2"),
                entry_with_link(l3, "l3"),
            ])
            .build()
    }
}