pub enum StandardSkills {
    Acrobatics,
    AnimalHandling,
    Arcana,
    Athletics,
    Deception,
    History,
    Insight,
    Intimidation,
    Investigation,
    Medicine,
    Nature,
    Perception,
    Performance,
    Persuasion,
    Religion,
    SleightOfHand,
    Stealth,
    Survival,
    StrengthSave,
    DexteritySave,
    ConstitutionSave,
    IntelligenceSave,
    WisdomSave,
    CharismaSave
}

#[derive(PartialEq, Clone, Copy)]
pub enum SkillProficiency {
    None,
    Proficient,
    Expert,
}

impl Default for SkillProficiency {
    fn default() -> Self { SkillProficiency::None }
}

pub trait Stat {
    fn score(&self) -> u8;

    fn modifier(&self) -> i8 {
        return (self.score() as i8 / 2) - 5;
    }

    fn skill_modifier(&self, proficiency_modifier: u8, proficiency: SkillProficiency) -> i8 {
        let modifier : i8 = self.modifier();
        let expert = proficiency == SkillProficiency::Expert; // are they an expert?
        let proficient = expert || proficiency == SkillProficiency::Proficient; // are they at least proficient?
        let proficiency_boost : u8 = proficiency_modifier * proficient as u8;
        let expertise_boost : u8 = proficiency_modifier * expert as u8;
        return modifier + (proficiency_boost as i8) + (expertise_boost as i8);
    }
}

pub trait StatSet {
    fn strength(&self) -> &impl Stat;
    fn dexterity(&self) -> &impl Stat;
    fn constitution(&self) -> &impl Stat;
    fn intelligence(&self) -> &impl Stat;
    fn wisdom(&self) -> &impl Stat;
    fn charisma(&self) -> &impl Stat;
}

pub trait ProficiencySet {
    fn get_proficiency(&self, skill: StandardSkills) -> SkillProficiency;

    fn get_proficiency_modifier(&self) -> u8;
}

pub trait Skill {
    fn select_stat<'a>(&self, set: &'a impl StatSet) -> &'a dyn Stat;

    fn get_modifier(&self, set: &impl StatSet, proficiency: SkillProficiency, proficiency_modifier: u8) -> i8 {
        return self.select_stat(set).skill_modifier(proficiency_modifier, proficiency);
    }

    fn is_save(&self) -> bool;
}

impl Skill for StandardSkills {
    fn select_stat<'a>(&self, set: &'a impl StatSet) -> &'a dyn Stat {
        match self {
            StandardSkills::DexteritySave | StandardSkills::Acrobatics | StandardSkills::SleightOfHand | StandardSkills::Stealth => set.dexterity(),
            StandardSkills::StrengthSave | StandardSkills::Athletics => set.strength(),
            StandardSkills::ConstitutionSave => set.constitution(),
            StandardSkills::IntelligenceSave | StandardSkills::Arcana | StandardSkills::History | StandardSkills::Investigation | StandardSkills::Nature | StandardSkills::Religion => set.intelligence(),
            StandardSkills::WisdomSave | StandardSkills::AnimalHandling | StandardSkills::Insight | StandardSkills::Medicine | StandardSkills::Perception | StandardSkills::Survival => set.wisdom(),
            StandardSkills::CharismaSave | StandardSkills::Deception | StandardSkills::Intimidation | StandardSkills::Performance | StandardSkills::Persuasion => set.charisma(),
        }
    }

    fn is_save(&self) -> bool {
        return matches!(self, StandardSkills::StrengthSave | StandardSkills::DexteritySave | StandardSkills::ConstitutionSave | StandardSkills::IntelligenceSave | StandardSkills::WisdomSave | StandardSkills::CharismaSave);
    }
}

impl Stat for u8 {
    fn score(&self) -> u8 {
        return *self;
    }
}