shinespark/src/fighter/state/hitstun.rs

use crate::{
    fighter::{
        FighterVelocity, animation::AnimKind, attack::{self, FighterHitReaction}, state::{
            CollisionContext, EnterContext, ExitContext, FighterState, FighterStateImpl,
            InterruptContext, UpdateContext,
            air::{self, AirborneStateCommon},
            fall::FallState,
            ground::collision_interrupt,
            land::LandingType,
            wait::WaitState,
        },
    }, math::{int::FGi32, vec::FGVec2},
};

#[derive(Clone, Debug, Hash)]
pub enum HitstopStateKind {
    Grounded,
    Airborne,
}

#[derive(Clone, Debug, Hash)]
pub struct HitstunState {
    pub hit_reaction: FighterHitReaction,
    pub hitstop_kind: HitstopStateKind,
    knockback_applied: bool,
}

impl HitstunState {
    pub fn new(hit_reaction: FighterHitReaction, hitstop_kind: HitstopStateKind) -> Self {
        Self {
            hit_reaction,
            hitstop_kind,
            knockback_applied: false,
        }
    }
}

impl FighterStateImpl for HitstunState {
    const NAME: &'static str = "Hitstun";

    fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
        if state_context.get_current_animation_frame() > self.hit_reaction.hitstun_frames {
            match &self.hitstop_kind {
                HitstopStateKind::Grounded => Some(FighterState::Wait(WaitState)),
                HitstopStateKind::Airborne => Some(FighterState::Fall(FallState::new(
                    AirborneStateCommon::default(),
                ))),
            }
        } else {
            None
        }
    }

    fn on_enter(&mut self, state_context: &mut EnterContext) {
        let animation = match self.hitstop_kind {
            HitstopStateKind::Grounded => AnimKind::FlinchGround,
            HitstopStateKind::Airborne => AnimKind::FlinchAir,
        };
        state_context.play_animation(animation, false);
        state_context.velocity.0 = FGVec2::ZERO;
    }

    fn on_exit(&mut self, _state_context: &mut ExitContext) {}

    fn name(&self) -> String {
        let hitstop_kind = match self.hitstop_kind {
            HitstopStateKind::Grounded => "Grounded",
            HitstopStateKind::Airborne => "Airborne",
        };

        let hit_reaction_type = match &self.hit_reaction.kind {
            crate::fighter::attack::HitReactionKind::Flinch => "Flinch",
            crate::fighter::attack::HitReactionKind::Tumble => "Tumble",
        };

        format!("Hitstun ({hitstop_kind}, {hit_reaction_type})")
    }

    fn update(&mut self, ctx: &mut UpdateContext) {
        if !self.knockback_applied {
            let launch_direction = attack::directional_influence::apply_directional_influence(
                ctx.input.get_last_frame().movement,
                self.hit_reaction.launch_angle,
                ctx.game_settings.fighter_common.di_max_angle,
            );

            ctx.knockback_velocity.0 = launch_direction * self.hit_reaction.launch_velocity;
            self.knockback_applied = true;
        }

        match self.hitstop_kind {
            HitstopStateKind::Grounded => {}
            HitstopStateKind::Airborne => {
                air::integrate_gravity(ctx.velocity, ctx.fighter_attributes, false);
                let vel_with_kb = FighterVelocity(ctx.velocity.0 + ctx.knockback_velocity.0);
                air::apply_air_motion(&vel_with_kb, ctx.translation, ctx.prev_translation);
            }
        }

        let speed = ctx.knockback_velocity.length();
        let next_speed = speed
            .saturating_sub(ctx.game_settings.fighter_common.knockback_decay_per_frame)
            .max(FGi32::ZERO);

        ctx.knockback_velocity.0 = ctx.knockback_velocity.normalize_or_zero() * next_speed;
    }

    fn check_collision_interrupt(
        &mut self,
        state_context: &mut CollisionContext,
    ) -> Option<FighterState> {
        match &mut self.hitstop_kind {
            HitstopStateKind::Grounded => collision_interrupt(state_context, true),
            HitstopStateKind::Airborne => {
                air::collision_interrupt(state_context, LandingType::Normal, Default::default())
            }
        }
    }

    fn is_visually_grounded<'a>(&'a self) -> bool {
        match self.hitstop_kind {
            HitstopStateKind::Grounded => true,
            HitstopStateKind::Airborne => false,
        }
    }

    fn surface_policy(&self) -> super::SurfacePolicy {
        match self.hitstop_kind {
            HitstopStateKind::Grounded => super::SurfacePolicy::Grounded,
            HitstopStateKind::Airborne => super::SurfacePolicy::Airborne(
                crate::fighter::surface::EcbLockPolicy::StartOnDetach,
            ),
        }
    }
}