use std::{fmt, str::FromStr};

use evtclib::{EliteSpec, Profession};

use thiserror::Error;

/// An enum containing either a profession or an elite spec.
///
/// This enum provides us with a variety of things:
///
/// Game mechanic wise, a Dragonhunter is also a Guardian, because Dragonhunter is only the elite
/// specialization. However, when outputting that to the user, we usually only write Dragonhunter,
/// and not Guardian, as that is implied. Same when filtering, when we filter for Guardian, we
/// probably don't want any Dragonhunters.
///
/// So this enum unifies the handling between core specs and elite specs, and provides them with a
/// convenient [`Display`][Display] implementation as well.
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
pub enum PlayerClass {
    Profession(Profession),
    EliteSpec(EliteSpec),
}

#[derive(Debug, Clone, Hash, PartialEq, Eq, Error)]
#[error("could not parse the class: {0}")]
pub struct ParsePlayerClassError(String);

impl From<Profession> for PlayerClass {
    fn from(p: Profession) -> Self {
        PlayerClass::Profession(p)
    }
}

impl From<EliteSpec> for PlayerClass {
    fn from(e: EliteSpec) -> Self {
        PlayerClass::EliteSpec(e)
    }
}

impl FromStr for PlayerClass {
    type Err = ParsePlayerClassError;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let err = ParsePlayerClassError(s.to_owned());
        Profession::from_str(s)
            .map(Into::into)
            .map_err(|_| err.clone())
            .or_else(|_| EliteSpec::from_str(s).map(Into::into).map_err(|_| err))
    }
}

impl From<(Profession, Option<EliteSpec>)> for PlayerClass {
    fn from((profession, elite_spec): (Profession, Option<EliteSpec>)) -> Self {
        if let Some(spec) = elite_spec {
            spec.into()
        } else {
            profession.into()
        }
    }
}

impl From<&evtclib::Player> for PlayerClass {
    fn from(player: &evtclib::Player) -> Self {
        (player.profession(), player.elite()).into()
    }
}

impl fmt::Display for PlayerClass {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            PlayerClass::EliteSpec(elite) => elite.fmt(f),
            PlayerClass::Profession(prof) => prof.fmt(f),
        }
    }
}

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

    #[test]
    fn test_player_class_from() {
        let tests: &[(Profession, Option<EliteSpec>, PlayerClass)] = &[
            (
                Profession::Guardian,
                None,
                PlayerClass::Profession(Profession::Guardian),
            ),
            (
                Profession::Guardian,
                Some(EliteSpec::Dragonhunter),
                PlayerClass::EliteSpec(EliteSpec::Dragonhunter),
            ),
        ];

        for (prof, elite_spec, expected) in tests {
            assert_eq!(PlayerClass::from((*prof, *elite_spec)), *expected);
        }
    }

    #[test]
    fn test_parse_player_class() {
        let tests: &[(&'static str, PlayerClass)] = &[
            ("guardian", Profession::Guardian.into()),
            ("dragonhunter", EliteSpec::Dragonhunter.into()),
            ("warrior", Profession::Warrior.into()),
            ("scourge", EliteSpec::Scourge.into()),
        ];

        for (input, expected) in tests {
            assert_eq!(input.parse(), Ok(*expected));
        }
    }
}