sculkr 0.1.1

use std::{
    cell::{RefCell, RefMut},
    collections::{HashMap, HashSet},
    io::{BufWriter, Write},
};

use crate::{
    Cache, Error, Mod,
    args::Cli,
    cache::CacheId,
    format::Formatter,
    get_curseforge_mods, get_modrinth_mods,
    parser::{ParsedCurseForgeId, ParsedModrinthId, Parser},
    request::{CurseForgeId, ModrinthId},
};

/// Warns about ids that were requested but never came back.
///
/// A deleted or renamed project will just vanishes from the list, leaving
/// an incorrect mod count, compared to what packwiz found on disk.
fn warn_missing(source: &str, requested: &HashMap<String, CacheId>, returned: &HashSet<String>) {
    for id in requested.keys() {
        if !returned.contains(id) {
            log::warn!(
                "{source} returned no result for \"{id}\" -- it will be missing from the list"
            );
        }
    }
}

pub struct App {
    cache: RefCell<Cache>,
    modrinth_mods: Vec<ParsedModrinthId>,
    curseforge_mods: Vec<ParsedCurseForgeId>,
}

impl App {
    pub fn new<P>(cache: Cache, parser: P) -> Self
    where
        P: Parser,
    {
        let (modrinth_mods, curseforge_mods) = parser.get_mods_owned();

        Self {
            cache: RefCell::new(cache),
            modrinth_mods,
            curseforge_mods,
        }
    }

    fn get_mods(&self) -> Result<Vec<Mod>, Error> {
        let mut cache = self.cache.borrow_mut();
        let mut mods =
            Vec::<Mod>::with_capacity(self.modrinth_mods.len() + self.curseforge_mods.len());
        let mut mr_mods_ids = Vec::<ModrinthId>::with_capacity(self.modrinth_mods.len());
        let mut cf_mods_ids = Vec::<CurseForgeId>::with_capacity(self.curseforge_mods.len());
        let mut mr_id_map = HashMap::<String, CacheId>::with_capacity(mr_mods_ids.capacity());
        let mut cf_id_map = HashMap::<String, CacheId>::with_capacity(cf_mods_ids.capacity());

        for id in self.modrinth_mods.iter().cloned() {
            match cache.get_mod(id.clone()).cloned() {
                None => {
                    mr_id_map.insert(id.id.clone(), id.clone().into());
                    mr_mods_ids.push(id.into());
                }
                Some(m) => mods.push(m),
            }
        }

        for id in self.curseforge_mods.iter().cloned() {
            match cache.get_mod(id.clone()).cloned() {
                None => {
                    cf_id_map.insert(id.id.to_string(), id.clone().into());
                    cf_mods_ids.push(id.into());
                }
                Some(m) => mods.push(m),
            }
        }

        if !mr_mods_ids.is_empty() {
            let fetched = get_modrinth_mods(mr_mods_ids)?;
            let mut returned = HashSet::<String>::with_capacity(fetched.len());

            for m in fetched {
                returned.insert(m.id.clone());

                match mr_id_map.get(&m.id).cloned() {
                    Some(id) => {
                        cache.set_mod(id, m.clone());
                        mods.push(m);
                    }
                    // An id we never asked for should not take the whole run down.
                    None => {
                        log::warn!(
                            "Modrinth returned unrequested project \"{}\"; ignoring",
                            m.id
                        )
                    }
                }
            }

            warn_missing("Modrinth", &mr_id_map, &returned);
        }

        if !cf_mods_ids.is_empty() {
            let fetched = get_curseforge_mods(cf_mods_ids)?;
            let mut returned = HashSet::<String>::with_capacity(fetched.len());

            for m in fetched.into_iter().map(Mod::from) {
                returned.insert(m.id.clone());

                match cf_id_map.get(&m.id).cloned() {
                    Some(id) => {
                        cache.set_mod(id, m.clone());
                        mods.push(m);
                    }
                    None => {
                        log::warn!(
                            "CurseForge returned unrequested project \"{}\"; ignoring",
                            m.id
                        )
                    }
                }
            }

            warn_missing("CurseForge", &cf_id_map, &returned);
        }

        Ok(mods)
    }

    /// Every mod in the pack in alphabetical order by title, then id.
    pub fn sorted_mods(&self) -> Result<Vec<Mod>, Error> {
        let mut mods = self.get_mods()?;

        // Tie-break on id so mods sharing a title still land in a fixed order.
        mods.sort_by(|a, b| {
            a.title
                .to_lowercase()
                .cmp(&b.title.to_lowercase())
                .then_with(|| a.id.cmp(&b.id))
        });

        Ok(mods)
    }

    pub fn run(&self, cli: Cli) -> Result<(), Error> {
        // Parsed before anything is fetched, so a typo in the template costs a
        // message instead of a round of API calls.
        let formatter = Formatter::new(&cli.format)?;
        let mods = self.sorted_mods()?;

        // One locked, buffered handle: a few hundred mods would otherwise be a few
        // hundred lock-and-flush cycles.
        let stdout = std::io::stdout();
        let mut out = BufWriter::new(stdout.lock());

        formatter.write_all(&mut out, &mods)?;

        out.flush()?;

        log::info!("listed {} mod(s)", mods.len());
        Ok(())
    }

    /// Persists the cache, pruning anything no longer in the pack first.
    pub fn close(&self) -> Result<(), Error> {
        let mut cache = self.cache.borrow_mut();

        let installed: HashSet<String> = self
            .modrinth_mods
            .iter()
            .map(|m| m.id.clone())
            .chain(self.curseforge_mods.iter().map(|m| m.id.to_string()))
            .collect();

        let pruned = cache.retain_only(&installed);

        if pruned > 0 {
            log::debug!("pruned {pruned} cached mod(s) no longer in the pack");
        }

        cache.save()
    }
}