free-rusty-maker/src/engine/character/mod.rs

use std::time::{Duration, Instant};

use sfml::graphics::{FloatRect, IntRect, View};
use sfml::system::Vector2;
use sfml::window::Event;

use crate::engine::controls::{Action, Controls};
use crate::engine::math::{clamp, duration_as_f32, duration_as_frame};
use crate::engine::physics;
use crate::engine::renderer::Drawable;
use crate::engine::scene::Updatable;
use crate::engine::texture::Texture;

/// The different sides a character can face.
pub enum Side {
    /// The character looks to the left.
    Left,

    /// The character looks to the right.
    Right,
}

/// This enum represents the type of damages that the character can get.
#[derive(Copy, Clone)]
pub enum Damage {
    /// No damage were made
    None,

    /// A single point of life has been taken from the character.
    One,

    /// The character died.
    Death,
}

impl Side {
    /// Returns the side corresponding to the force.
    ///
    /// Returns None if the force is null.
    pub fn from_force(force: Vector2<f32>) -> Option<Side> {
        if force.x > 0.0 {
            Some(Side::Right)
        } else if force.x < 0.0 {
            Some(Side::Left)
        } else {
            None
        }
    }

    /// Returns the offset in the texture.
    pub fn offset(&self) -> i32 {
        match *self {
            Side::Left => 32,
            Side::Right => 0,
        }
    }
}

/// A character, enemy or controllable.
pub struct Character {
    /// The position of the character.
    pub position: Vector2<f32>,

    /// The speed of the character.
    pub speed: Vector2<f32>,

    /// If the player is controlling a character.
    controls: Option<Controls>,

    /// The side of the character.
    side: Side,

    /// The number of hp of the character.
    hp: u32,

    /// The counter of jumps.
    ///
    /// When it's 0, the character can no longer jump.
    jump_counter: usize,

    /// The maximum number of jumps a character can do.
    ///
    /// It's reset when the character hits the ground.
    max_jump: usize,

    /// The timer of the character's animation.
    animation_timer: Instant,

    /// Whether the character is walking or not.
    walking: bool,

    /// Indicates that the player has released the jump button.
    can_jump: bool,
}

impl Character {
    /// Creates a character in (0, 0).
    fn generic(controls: Option<Controls>) -> Character {
        Character {
            position: Vector2::new(0.0, 0.0),
            speed: Vector2::new(0.0, 0.0),
            controls,
            side: Side::Right,
            hp: 1,
            jump_counter: 1,
            max_jump: 1,
            animation_timer: Instant::now(),
            can_jump: true,
            walking: false,
        }
    }

    /// Creates a character in (0, 0).
    pub fn new() -> Character {
        Character::generic(None)
    }

    /// Creates a character with the specified controls.
    pub fn with_controls(controls: Controls) -> Character {
        Character::generic(Some(controls))
    }

    /// Sets the position of the character.
    pub fn set_position<S: Into<Vector2<f32>>>(&mut self, position: S) {
        self.position = position.into();
    }

    /// Makes the character jump.
    pub fn jump(&mut self) {
        if self.can_jump && self.jump_counter > 0 {
            self.jump_counter -= 1;
            self.speed.y = physics::JUMP_SPEED.y;
        }
    }

    /// Resets the jump counter.
    pub fn ground_collision(&mut self) {
        self.jump_counter = self.max_jump;
    }

    /// Make the player fall.
    pub fn fall_off(&mut self) {
        if self.jump_counter == self.max_jump {
            self.jump_counter -= 1;
        }
    }

    /// Returns a reference to the controls.
    pub fn controls(&self) -> &Option<Controls> {
        &self.controls
    }

    /// Returns a view that looks at the character.
    pub fn view(&self) -> View {
        View::new(self.position, Vector2::new(24.0 * 16.0, 24.0 * 9.0))
    }

    /// Returns the collision bounding box of the character.
    pub fn bbox(&self) -> FloatRect {
        FloatRect::new(self.position.x + 8.0, self.position.y, 16.0, 32.0)
    }

    /// Returns the number of hp of the character.
    pub fn hp(&self) -> u32 {
        self.hp
    }

    /// Returns true if the character is alive.
    pub fn is_alive(&self) -> bool {
        self.hp > 0
    }

    /// Returns true if the character is dead.
    pub fn is_dead(&self) -> bool {
        self.hp == 0
    }

    /// Takes the corresponding damage.
    pub fn take_damage(&mut self, damage: Damage) {
        match damage {
            Damage::None => (),
            Damage::One => self.hp -= 1,
            Damage::Death => self.hp = 0,
        }
    }
}

impl Updatable for Character {
    fn update(&mut self, duration: &Duration) {
        let mut force: Vector2<f32> = Vector2::new(0.0, 0.0);

        if let Some(ref controls) = self.controls {
            force += controls.direction();
        }

        if let Some(side) = Side::from_force(force) {
            if !self.walking {
                self.animation_timer = Instant::now();
            }
            self.walking = true;
            self.side = side;
        } else {
            if self.walking {
                self.animation_timer = Instant::now();
            }
            self.walking = false;
        }

        let duration = duration_as_f32(duration);

        // Compute acceleration
        let accel = physics::G + force * 64.0 * 64.0;

        // Compute speed
        self.speed.x *= physics::GROUND_FRICTION.x;
        self.speed += accel * duration;

        if self.speed.y > physics::MAXIMUM_VERTICAL_SPEED {
            self.speed.y = physics::MAXIMUM_VERTICAL_SPEED;
        }

        let limit = match self.controls {
            Some(controls) if controls.is_running() => physics::MAXIMUM_RUNNING_SPEED,
            _ => physics::MAXIMUM_WALKING_SPEED,
        };

        self.speed.x = clamp(self.speed.x, -limit, limit);

        // Compute position
        self.position += self.speed * duration;
    }

    fn manage_event(&mut self, event: &Event) {
        let action = if let Some(ref controls) = self.controls {
            controls.convert(event)
        } else {
            None
        };

        match action {
            Some(Action::Jump(true)) => {
                self.jump();
                self.can_jump = false;
            }

            Some(Action::Jump(false)) => {
                self.can_jump = true;
            }

            _ => (),
        }
    }
}

impl Drawable for Character {
    fn texture(&self) -> Texture {
        Texture::Rusty
    }

    fn texture_rect(&self) -> IntRect {
        let frame = duration_as_frame(&Instant::now().duration_since(self.animation_timer), 4);
        let offset = if self.walking { 64 } else { 0 };
        IntRect::new(self.side.offset() + offset, frame * 32, 32, 32)
    }

    fn position(&self) -> Vector2<f32> {
        self.position
    }
}