refactor: rename 'ecs' submodule to 'systems'

src/systems/components.rs

@@ -0,0 +1,138 @@
+use bevy_ecs::{bundle::Bundle, component::Component, resource::Resource};
+use glam::Vec2;
+
+use crate::{
+    entity::{direction::Direction, graph::Graph},
+    error::{EntityError, GameResult},
+    texture::{animated::AnimatedTexture, sprite::AtlasTile},
+};
+
+/// A tag component for entities that are controlled by the player.
+#[derive(Default, Component)]
+pub struct PlayerControlled;
+
+/// A component for entities that have a sprite, with a layer for ordering.
+///
+/// This is intended to be modified by other entities allowing animation.
+#[derive(Component)]
+pub struct Renderable {
+    pub sprite: AtlasTile,
+    pub layer: u8,
+}
+
+/// A component for entities that have a directional animated texture.
+#[derive(Component)]
+pub struct DirectionalAnimated {
+    pub textures: [Option<AnimatedTexture>; 4],
+    pub stopped_textures: [Option<AnimatedTexture>; 4],
+}
+
+/// A unique identifier for a node, represented by its index in the graph's storage.
+pub type NodeId = usize;
+
+/// Represents the current position of an entity traversing the graph.
+///
+/// This enum allows for precise tracking of whether an entity is exactly at a node
+/// or moving along an edge between two nodes.
+#[derive(Component, Debug, Copy, Clone, PartialEq)]
+pub enum Position {
+    /// The traverser is located exactly at a node.
+    AtNode(NodeId),
+    /// The traverser is on an edge between two nodes.
+    BetweenNodes {
+        from: NodeId,
+        to: NodeId,
+        /// The floating-point distance traversed along the edge from the `from` node.
+        traversed: f32,
+    },
+}
+
+impl Position {
+    /// Calculates the current pixel position in the game world.
+    ///
+    /// Converts the graph position to screen coordinates, accounting for
+    /// the board offset and centering the sprite.
+    pub fn get_pixel_pos(&self, graph: &Graph) -> GameResult<Vec2> {
+        let pos = match self {
+            Position::AtNode(node_id) => {
+                let node = graph.get_node(*node_id).ok_or(EntityError::NodeNotFound(*node_id))?;
+                node.position
+            }
+            Position::BetweenNodes { from, to, traversed } => {
+                let from_node = graph.get_node(*from).ok_or(EntityError::NodeNotFound(*from))?;
+                let to_node = graph.get_node(*to).ok_or(EntityError::NodeNotFound(*to))?;
+                let edge = graph
+                    .find_edge(*from, *to)
+                    .ok_or(EntityError::EdgeNotFound { from: *from, to: *to })?;
+                from_node.position + (to_node.position - from_node.position) * (traversed / edge.distance)
+            }
+        };
+
+        Ok(Vec2::new(
+            pos.x + crate::constants::BOARD_PIXEL_OFFSET.x as f32,
+            pos.y + crate::constants::BOARD_PIXEL_OFFSET.y as f32,
+        ))
+    }
+}
+
+impl Default for Position {
+    fn default() -> Self {
+        Position::AtNode(0)
+    }
+}
+
+#[allow(dead_code)]
+impl Position {
+    /// Returns `true` if the position is exactly at a node.
+    pub fn is_at_node(&self) -> bool {
+        matches!(self, Position::AtNode(_))
+    }
+
+    /// Returns the `NodeId` of the current or most recently departed node.
+    #[allow(clippy::wrong_self_convention)]
+    pub fn from_node_id(&self) -> NodeId {
+        match self {
+            Position::AtNode(id) => *id,
+            Position::BetweenNodes { from, .. } => *from,
+        }
+    }
+
+    /// Returns the `NodeId` of the destination node, if currently on an edge.
+    #[allow(clippy::wrong_self_convention)]
+    pub fn to_node_id(&self) -> Option<NodeId> {
+        match self {
+            Position::AtNode(_) => None,
+            Position::BetweenNodes { to, .. } => Some(*to),
+        }
+    }
+
+    /// Returns `true` if the traverser is stopped at a node.
+    pub fn is_stopped(&self) -> bool {
+        matches!(self, Position::AtNode(_))
+    }
+}
+
+/// A component for entities that have a velocity, with a direction and speed.
+#[derive(Default, Component)]
+pub struct Velocity {
+    pub direction: Direction,
+    pub next_direction: Option<(Direction, u8)>,
+    pub speed: f32,
+}
+
+#[derive(Bundle)]
+pub struct PlayerBundle {
+    pub player: PlayerControlled,
+    pub position: Position,
+    pub velocity: Velocity,
+    pub sprite: Renderable,
+    pub directional_animated: DirectionalAnimated,
+}
+
+#[derive(Resource)]
+pub struct GlobalState {
+    pub exit: bool,
+}
+
+#[derive(Resource)]
+pub struct DeltaTime(pub f32);

src/systems/interact.rs

@@ -0,0 +1,43 @@
+use bevy_ecs::{
+    event::{EventReader, EventWriter},
+    system::{Query, ResMut},
+};
+
+use crate::{
+    error::GameError,
+    game::events::GameEvent,
+    input::commands::GameCommand,
+    systems::components::{GlobalState, PlayerControlled, Velocity},
+};
+
+// Handles
+pub fn interact_system(
+    mut events: EventReader<GameEvent>,
+    mut state: ResMut<GlobalState>,
+    mut players: Query<(&PlayerControlled, &mut Velocity)>,
+    mut errors: EventWriter<GameError>,
+) {
+    // Get the player's velocity (handling to ensure there is only one player)
+    let mut velocity = match players.single_mut() {
+        Ok((_, velocity)) => velocity,
+        Err(e) => {
+            errors.write(GameError::InvalidState(format!("Player not found: {}", e)).into());
+            return;
+        }
+    };
+
+    // Handle events
+    for event in events.read() {
+        match event {
+            GameEvent::Command(command) => match command {
+                GameCommand::MovePlayer(direction) => {
+                    velocity.next_direction = Some((*direction, 90));
+                }
+                GameCommand::Exit => {
+                    state.exit = true;
+                }
+                _ => {}
+            },
+        }
+    }
+}

src/systems/mod.rs

@@ -0,0 +1,9 @@
+//! The Entity-Component-System (ECS) module.
+//!
+//! This module contains all the ECS-related logic, including components, systems,
+//! and resources.
+
+pub mod components;
+pub mod interact;
+pub mod movement;
+pub mod render;

src/systems/movement.rs

@@ -0,0 +1,129 @@
+use crate::entity::graph::EdgePermissions;
+use crate::error::{EntityError, GameError};
+use crate::map::builder::Map;
+use crate::systems::components::{DeltaTime, PlayerControlled, Position, Velocity};
+use bevy_ecs::event::EventWriter;
+use bevy_ecs::system::{Query, Res};
+
+fn can_traverse(_player: &mut PlayerControlled, edge: crate::entity::graph::Edge) -> bool {
+    matches!(edge.permissions, EdgePermissions::All)
+}
+
+pub fn movement_system(
+    map: Res<Map>,
+    delta_time: Res<DeltaTime>,
+    mut entities: Query<(&mut PlayerControlled, &mut Velocity, &mut Position)>,
+    mut errors: EventWriter<GameError>,
+) {
+    for (mut player, mut velocity, mut position) in entities.iter_mut() {
+        let distance = velocity.speed * 60.0 * delta_time.0;
+
+        // Decrement the remaining frames for the next direction
+        if let Some((direction, remaining)) = velocity.next_direction {
+            if remaining > 0 {
+                velocity.next_direction = Some((direction, remaining - 1));
+            } else {
+                velocity.next_direction = None;
+            }
+        }
+
+        match *position {
+            Position::AtNode(node_id) => {
+                // We're not moving, but a buffered direction is available.
+                if let Some((next_direction, _)) = velocity.next_direction {
+                    if let Some(edge) = map.graph.find_edge_in_direction(node_id, next_direction) {
+                        if can_traverse(&mut player, edge) {
+                            // Start moving in that direction
+                            *position = Position::BetweenNodes {
+                                from: node_id,
+                                to: edge.target,
+                                traversed: distance,
+                            };
+                            velocity.direction = next_direction;
+                            velocity.next_direction = None;
+                        }
+                    } else {
+                        errors.write(
+                            EntityError::InvalidMovement(format!(
+                                "No edge found in direction {:?} from node {}",
+                                next_direction, node_id
+                            ))
+                            .into(),
+                        );
+                    }
+                }
+            }
+            Position::BetweenNodes { from, to, traversed } => {
+                // There is no point in any of the next logic if we don't travel at all
+                if distance <= 0.0 {
+                    return;
+                }
+
+                let edge = map
+                    .graph
+                    .find_edge(from, to)
+                    .ok_or_else(|| {
+                        errors.write(
+                            EntityError::InvalidMovement(format!(
+                                "Inconsistent state: Traverser is on a non-existent edge from {} to {}.",
+                                from, to
+                            ))
+                            .into(),
+                        );
+                        return;
+                    })
+                    .unwrap();
+
+                let new_traversed = traversed + distance;
+
+                if new_traversed < edge.distance {
+                    // Still on the same edge, just update the distance.
+                    *position = Position::BetweenNodes {
+                        from,
+                        to,
+                        traversed: new_traversed,
+                    };
+                } else {
+                    let overflow = new_traversed - edge.distance;
+                    let mut moved = false;
+
+                    // If we buffered a direction, try to find an edge in that direction
+                    if let Some((next_dir, _)) = velocity.next_direction {
+                        if let Some(edge) = map.graph.find_edge_in_direction(to, next_dir) {
+                            if can_traverse(&mut player, edge) {
+                                *position = Position::BetweenNodes {
+                                    from: to,
+                                    to: edge.target,
+                                    traversed: overflow,
+                                };
+
+                                velocity.direction = next_dir; // Remember our new direction
+                                velocity.next_direction = None; // Consume the buffered direction
+                                moved = true;
+                            }
+                        }
+                    }
+
+                    // If we didn't move, try to continue in the current direction
+                    if !moved {
+                        if let Some(edge) = map.graph.find_edge_in_direction(to, velocity.direction) {
+                            if can_traverse(&mut player, edge) {
+                                *position = Position::BetweenNodes {
+                                    from: to,
+                                    to: edge.target,
+                                    traversed: overflow,
+                                };
+                            } else {
+                                *position = Position::AtNode(to);
+                                velocity.next_direction = None;
+                            }
+                        } else {
+                            *position = Position::AtNode(to);
+                            velocity.next_direction = None;
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/systems/render.rs

@@ -0,0 +1,98 @@
+use crate::error::{GameError, TextureError};
+use crate::map::builder::Map;
+use crate::systems::components::{DeltaTime, DirectionalAnimated, Position, Renderable, Velocity};
+use crate::texture::sprite::SpriteAtlas;
+use bevy_ecs::entity::Entity;
+use bevy_ecs::event::EventWriter;
+use bevy_ecs::system::{NonSendMut, Query, Res};
+use sdl2::render::{Canvas, Texture};
+use sdl2::video::Window;
+
+/// Updates the directional animated texture of an entity.
+pub fn directional_render_system(
+    dt: Res<DeltaTime>,
+    mut renderables: Query<(&Velocity, &mut DirectionalAnimated, &mut Renderable, &Position)>,
+    mut errors: EventWriter<GameError>,
+) {
+    for (velocity, mut texture, mut renderable, position) in renderables.iter_mut() {
+        let stopped = matches!(position, Position::AtNode(_));
+        let texture = if stopped {
+            texture.stopped_textures[velocity.direction.as_usize()].as_mut()
+        } else {
+            texture.textures[velocity.direction.as_usize()].as_mut()
+        };
+
+        if let Some(texture) = texture {
+            if !stopped {
+                texture.tick(dt.0);
+            }
+            renderable.sprite = *texture.current_tile();
+        } else {
+            errors.write(TextureError::RenderFailed(format!("Entity has no texture")).into());
+            continue;
+        }
+    }
+}
+
+pub struct MapTextureResource(pub Texture<'static>);
+pub struct BackbufferResource(pub Texture<'static>);
+
+pub fn render_system(
+    mut canvas: NonSendMut<&mut Canvas<Window>>,
+    map_texture: NonSendMut<MapTextureResource>,
+    mut backbuffer: NonSendMut<BackbufferResource>,
+    mut atlas: NonSendMut<SpriteAtlas>,
+    map: Res<Map>,
+    mut renderables: Query<(Entity, &mut Renderable, &Position)>,
+    mut errors: EventWriter<GameError>,
+) {
+    // Clear the main canvas first
+    canvas.set_draw_color(sdl2::pixels::Color::BLACK);
+    canvas.clear();
+
+    // Render to backbuffer
+    canvas
+        .with_texture_canvas(&mut backbuffer.0, |backbuffer_canvas| {
+            // Clear the backbuffer
+            backbuffer_canvas.set_draw_color(sdl2::pixels::Color::BLACK);
+            backbuffer_canvas.clear();
+
+            // Copy the pre-rendered map texture to the backbuffer
+            backbuffer_canvas
+                .copy(&map_texture.0, None, None)
+                .err()
+                .map(|e| errors.write(TextureError::RenderFailed(e.to_string()).into()));
+
+            // Render all entities to the backbuffer
+            for (_, mut renderable, position) in renderables.iter_mut() {
+                let pos = position.get_pixel_pos(&map.graph);
+                match pos {
+                    Ok(pos) => {
+                        let dest = crate::helpers::centered_with_size(
+                            glam::IVec2::new(pos.x as i32, pos.y as i32),
+                            glam::UVec2::new(renderable.sprite.size.x as u32, renderable.sprite.size.y as u32),
+                        );
+
+                        renderable
+                            .sprite
+                            .render(backbuffer_canvas, &mut atlas, dest)
+                            .err()
+                            .map(|e| errors.write(TextureError::RenderFailed(e.to_string()).into()));
+                    }
+                    Err(e) => {
+                        errors.write(e.into());
+                    }
+                }
+            }
+        })
+        .err()
+        .map(|e| errors.write(TextureError::RenderFailed(e.to_string()).into()));
+
+    // Copy backbuffer to main canvas and present
+    canvas
+        .copy(&backbuffer.0, None, None)
+        .err()
+        .map(|e| errors.write(TextureError::RenderFailed(e.to_string()).into()));
+
+    canvas.present();
+}