use std::fs::{metadata, read_dir};
use std::io;
use std::path::{Path, PathBuf};

use eyre::Result;
use git2::Repository;

pub struct State {
    pub root: PathBuf,
    pub data: Vec<Repository>,
}

// TODO figure out how to make this return impl Stream without living in actual hell
// Heartbreaking: E0733
fn find_repos_in(dir: impl AsRef<Path>) -> Result<Vec<Repository>> {
    let dir = dir.as_ref();
    let dir = read_dir(dir);
    let dir = match dir {
        Ok(x) => x,
        Err(err) if err.kind() == io::ErrorKind::PermissionDenied => return Ok(vec![]),
        Err(err) => Err(err)?,
    };
    let mut result = vec![];
    for subdir in dir {
        if let Ok(subdir) = subdir {
            match Repository::open_bare(subdir.path()) {
                Ok(repo) => result.push(repo),
                Err(err) if err.class() == git2::ErrorClass::Repository && err.code() == git2::ErrorCode::NotFound => {
                    let metadata = metadata(subdir.path())?;
                    if metadata.is_dir() {
                        result.extend(find_repos_in(subdir.path())?)
                    }
                }
                // TODO handle in a non-god-awful way
                Err(err) => panic!("{}", err),
            }
        }
    }
    Ok(result)
}

impl State {
    pub async fn discover(root: impl AsRef<Path>) -> Result<Self> {
        let root = root.as_ref();
        let mut data = find_repos_in(root)?;
        data.sort_by_key(|repo| {
            let mut last_update = git2::Time::new(0, 0);
            repo.odb().expect("no object database").foreach(|oid| {
                if let Ok(commit) = repo.find_commit(oid.clone()) {
                    last_update = last_update.max(commit.time());
                }
                true
            }).expect("foreach failed");
            last_update
        });
        data.reverse();
        Ok(Self { root: root.to_owned(), data })
    }

    pub fn relative_path<'a>(&'a self, subdir: &'a Path) -> &'a Path {
        subdir.strip_prefix(&self.root).unwrap_or(subdir)
    }

    pub fn open(&self, path: impl AsRef<Path>) -> Result<Repository> {
        let path = self.root.join(path);
        Ok(Repository::open_bare(path)?)
    }
}