//! MusicHoard - a music collection manager.

pub mod database;
pub mod library;

use std::fmt;

use database::IDatabase;
use library::{ILibrary, Query};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// [MusicBrainz Identifier](https://musicbrainz.org/doc/MusicBrainz_Identifier) (MBID).
pub type Mbid = Uuid;

/// The track file format.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub enum TrackFormat {
    Flac,
    Mp3,
}

/// A single track on an album.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct Track {
    pub number: u32,
    pub title: String,
    pub artist: Vec<String>,
    pub format: TrackFormat,
}

/// The album identifier.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq, Hash)]
pub struct AlbumId {
    pub year: u32,
    pub title: String,
}

/// An album is a collection of tracks that were released together.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct Album {
    pub id: AlbumId,
    pub tracks: Vec<Track>,
}

/// The artist identifier.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq, Hash)]
pub struct ArtistId {
    pub name: String,
}

/// An artist.
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct Artist {
    pub id: ArtistId,
    pub albums: Vec<Album>,
}

/// The collection type. Currently, a collection is a list of artists.
pub type Collection = Vec<Artist>;

/// Error type for `musichoard`.
#[derive(Debug, PartialEq, Eq)]
pub enum Error {
    /// The [`MusicHoard`] failed to read/write from/to the library.
    LibraryError(String),
    /// The [`MusicHoard`] failed to read/write from/to the database.
    DatabaseError(String),
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Self::LibraryError(ref s) => write!(f, "failed to read/write from/to the library: {s}"),
            Self::DatabaseError(ref s) => {
                write!(f, "failed to read/write from/to the database: {s}")
            }
        }
    }
}

impl From<library::Error> for Error {
    fn from(err: library::Error) -> Error {
        Error::LibraryError(err.to_string())
    }
}

impl From<database::Error> for Error {
    fn from(err: database::Error) -> Error {
        Error::DatabaseError(err.to_string())
    }
}

/// The Music Hoard. It is responsible for pulling information from both the library and the
/// database, ensuring its consistent and writing back any changes.
pub struct MusicHoard<LIB, DB> {
    library: LIB,
    database: DB,
    collection: Collection,
}

impl<LIB: ILibrary, DB: IDatabase> MusicHoard<LIB, DB> {
    /// Create a new [`MusicHoard`] with the provided [`ILibrary`] and [`IDatabase`].
    pub fn new(library: LIB, database: DB) -> Self {
        MusicHoard {
            library,
            database,
            collection: vec![],
        }
    }

    pub fn rescan_library(&mut self) -> Result<(), Error> {
        self.collection = self.library.list(&Query::new())?;
        Ok(())
    }

    pub fn save_to_database(&mut self) -> Result<(), Error> {
        self.database.write(&self.collection)?;
        Ok(())
    }

    pub fn get_collection(&self) -> &Collection {
        &self.collection
    }
}

#[cfg(test)]
#[macro_use]
mod testlib;

#[cfg(test)]
mod tests {
    use mockall::predicate;
    use once_cell::sync::Lazy;

    use crate::{database::MockIDatabase, library::MockILibrary};

    use super::*;

    pub static COLLECTION: Lazy<Vec<Artist>> = Lazy::new(|| collection!());

    #[test]
    fn read_get_write() {
        let mut library = MockILibrary::new();
        let mut database = MockIDatabase::new();

        let library_input = Query::new();
        let library_result = Ok(COLLECTION.to_owned());

        let database_input = COLLECTION.to_owned();
        let database_result = Ok(());

        library
            .expect_list()
            .with(predicate::eq(library_input))
            .times(1)
            .return_once(|_| library_result);

        database
            .expect_write()
            .with(predicate::eq(database_input))
            .times(1)
            .return_once(|_: &Collection| database_result);

        let mut music_hoard = MusicHoard::new(library, database);

        music_hoard.rescan_library().unwrap();
        assert_eq!(music_hoard.get_collection(), &*COLLECTION);
        music_hoard.save_to_database().unwrap();
    }

    #[test]
    fn library_error() {
        let mut library = MockILibrary::new();
        let database = MockIDatabase::new();

        let library_result = Err(library::Error::Invalid(String::from("invalid data")));

        library
            .expect_list()
            .times(1)
            .return_once(|_| library_result);

        let mut music_hoard = MusicHoard::new(library, database);

        let actual_err = music_hoard.rescan_library().unwrap_err();
        let expected_err =
            Error::LibraryError(library::Error::Invalid(String::from("invalid data")).to_string());

        assert_eq!(actual_err, expected_err);
        assert_eq!(actual_err.to_string(), expected_err.to_string());
    }

    #[test]
    fn database_error() {
        let library = MockILibrary::new();
        let mut database = MockIDatabase::new();

        let database_result = Err(database::Error::IoError(String::from("I/O error")));

        database
            .expect_write()
            .times(1)
            .return_once(|_: &Collection| database_result);

        let mut music_hoard = MusicHoard::new(library, database);

        let actual_err = music_hoard.save_to_database().unwrap_err();
        let expected_err =
            Error::DatabaseError(database::Error::IoError(String::from("I/O error")).to_string());

        assert_eq!(actual_err, expected_err);
        assert_eq!(actual_err.to_string(), expected_err.to_string());
    }
}