use std::{ffi::OsStr, io::Read, os::unix::ffi::OsStrExt, path::PathBuf};

use go_sgf::go::{parse_sgf, GameTree, GameType};
use thiserror::Error;

#[derive(Error, Debug)]
pub enum Error {
    #[error("Database permission denied")]
    PermissionDenied,
    #[error("An IO error occurred: {0}")]
    IOError(std::io::Error),
}

impl From<std::io::Error> for Error {
    fn from(err: std::io::Error) -> Self {
        Error::IOError(err)
    }
}

pub struct Database {
    path: PathBuf,
    games: Vec<GameTree>,
}

impl Database {
    pub fn open_path(path: PathBuf) -> Result<Database, Error> {
        let mut games: Vec<GameTree> = Vec::new();

        let extension = PathBuf::from("sgf").into_os_string();

        let path_iter = std::fs::read_dir(path.clone())?;
        for entry in path_iter {
            match entry {
                Ok(entry) => {
                    if entry.path().extension() == Some(&extension) {
                        let mut buffer = String::new();
                        std::fs::File::open(entry.path())
                            .unwrap()
                            .read_to_string(&mut buffer)
                            .unwrap();
                        let sgf = parse_sgf(&buffer).unwrap();
                        games.extend(sgf);
                    }
                }
                Err(err) => println!("failed entry: {:?}", err),
            }
        }

        Ok(Database { path, games })
    }

    pub fn all_games(&self) -> impl Iterator<Item = &GameTree> {
        self.games.iter()
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn it_reads_empty_database() {
        let db = Database::open_path(PathBuf::from("fixtures/empty_database/"))
            .expect("database to open");
        assert_eq!(db.all_games().count(), 0);
    }

    #[test]
    fn it_reads_five_games_from_database() {
        let db =
            Database::open_path(PathBuf::from("fixtures/five_games/")).expect("database to open");
        assert_eq!(db.all_games().count(), 5);
        for game in db.all_games() {
            assert_eq!(game.game_type, GameType::Go);
        }
    }
}