kiln/kiln-core/src/object_def.rs

use crate::glyph::Glyph;
use crate::utils::ObjectId;
use color::Rgba8;
use std::collections::HashSet;

/// A scripted object placed on the board, loaded from a map file.
///
/// `ObjectDef` represents a tile that has Rhai script attached to it.
/// Scripts can respond to events like the player touching or shooting the
/// tile. Objects are parsed from `[[objects]]` entries in `.toml` map files
/// and stored on [`Board`].
///
/// Objects are rendered as an overlay on top of the board grid — the grid
/// cell at `(x, y)` holds the background (floor) that is revealed if the
/// object moves away. `glyph` is owned by the object itself and may be
/// mutated by its Rhai script at runtime.
///
/// Script text lives in [`Board::scripts`]; this struct holds only the name
/// used to look it up. Two `ObjectDef`s with the same `script_name` share
/// source text but run with independent Rhai scopes (see [`crate::script`]).
///
/// Scripts are executed by [`crate::script::ScriptHost`]: an object's optional
/// `init()` and `tick(dt)` functions are called via [`GameState::run_init`] and
/// [`GameState::tick`]. Other event hooks (touch, shoot, …) are future work.
pub struct ObjectDef {
    /// Stable identity assigned by [`crate::board::Board::add_object`].
    /// `0` is the sentinel meaning "not yet inserted into a board".
    /// Real ids start at 1 and never change after assignment.
    /// Not serialized — the id is stamped on insert, not stored in map files.
    pub id: ObjectId,
    /// Column of this object on the board (0-indexed).
    pub x: usize,
    /// Row of this object on the board (0-indexed).
    pub y: usize,
    /// Index of the layer this object belongs to (0 = bottom). Determines its
    /// draw order: objects on higher layers render above lower-layer terrain and
    /// objects. Set at load from the layer the object's palette char appeared in.
    pub z: usize,
    /// Visual representation of this object. Owned by the object (not derived
    /// from the grid cell), so scripts can change tile, fg, and bg at runtime.
    pub glyph: Glyph,
    /// Whether the object blocks / participates in movement. A solid object stops
    /// a mover walking into it; at most one solid (object or grid archetype) may
    /// occupy a cell. Inverse of the old `passable` flag.
    pub solid: bool,
    /// Whether the object blocks line of sight / FOV for the player
    pub opaque: bool,
    /// Whether the object can be shoved by a mover. Unused for now (no push
    /// mechanic yet); defaults to `false`.
    pub pushable: bool,
    /// Name of the Rhai script in [`Board::scripts`] that drives this object.
    /// `None` means this object has no script yet.
    pub script_name: Option<String>,
    /// Embedded built-in script source, set when a script-backed archetype (e.g. a
    /// `pusher_*`) is expanded into an object at load time (see
    /// [`crate::builtin_scripts`]). Takes precedence over [`script_name`](ObjectDef::script_name)
    /// and is not part of the map file (it is regenerated from the archetype on load).
    pub builtin_script: Option<&'static str>,
    /// Open-ended string labels for this object. Serialized as a TOML array;
    /// not subject to any rate limit — mutations take effect immediately after
    /// the frame's action queue is drained.
    pub tags: HashSet<String>,
    /// Optional unique human-readable name for this object. `None` if unnamed.
    /// Names are validated for uniqueness at map-load time; a duplicate name is
    /// cleared to `None` (the object survives but becomes anonymous).
    pub name: Option<String>,
}

impl ObjectDef {
    /// Returns the default glyph for a newly placed object: tile 63 (`?`) in yellow on black.
    #[rustfmt::skip]
    pub fn default_glyph() -> Glyph {
        Glyph {
            tile: 63,
            fg: Rgba8 { r: 255, g: 255, b: 0, a: 255 }, // yellow
            bg: Rgba8 { r: 0, g: 0, b: 0, a: 255 },
        }
    }

    /// Creates a new object at `(x, y)` with default glyph and blocking behavior.
    ///
    /// Defaults: `solid = true`, `opaque = true`, `pushable = false`, no script.
    /// These match the serde defaults in the map file format so new objects
    /// round-trip correctly.
    pub fn new(x: usize, y: usize) -> Self {
        Self {
            id: 0,
            x,
            y,
            z: 0,
            glyph: Self::default_glyph(),
            solid: true,
            opaque: true,
            pushable: false,
            script_name: None,
            builtin_script: None,
            tags: HashSet::new(),
            name: None,
        }
    }
}