kiln/kiln-core/src/action.rs

//! The [`Action`] enum and its Rhai-facing conversions.
//!
//! This module owns the `Action` type (which scripts enqueue via write host
//! functions), the rate-limiting delay constant, and [`action_to_map`] which
//! converts an `Action` to a Rhai map for `Queue.peek()` / `Queue.pop()`.

use crate::log::LogLine;
use crate::map_file::color_to_hex;
use crate::utils::{Direction, ObjectId, ScriptArg};
use color::Rgba8;
use rhai::Dynamic;

/// How long a move occupies an object before it can act again, in seconds.
pub(crate) const MOVE_COST: f64 = 0.25;

/// One line of content in a [`Action::Scroll`] overlay.
///
/// Each element of the array passed to the `scroll()` Rhai function becomes a
/// `ScrollLine`: a plain string becomes [`Text`](ScrollLine::Text); a two-element
/// array `[choice, display]` becomes a [`Choice`](ScrollLine::Choice).
pub enum ScrollLine {
    /// Plain text, word-wrapped to the scroll window width.
    Text(String),
    /// A selectable option: `choice` is the event name sent back to the source
    /// object via `send`, and `display` is the label shown to the player.
    Choice { choice: String, display: String },
}

/// One deferred mutation emitted by a script, applied by [`crate::game::GameState`]
/// after it is promoted onto the board queue.
///
/// [`Action::Delay`] is the exception: it is **never** promoted to the board queue.
/// It lives only in the per-object output queue and is consumed by `ScriptHost::drain`
/// to pace how quickly other actions are released.
pub(crate) enum Action {
    /// Move the source object one cell in a direction (subject to passability).
    Move(Direction),
    /// Set the source object's glyph tile index.
    SetTile(u32),
    /// Append a styled line to the game log.
    Log(LogLine),
    /// Add (`present = true`) or remove (`present = false`) `tag` on `target`.
    SetTag { target: ObjectId, tag: String, present: bool },
    /// Display a speech bubble above the source object for [`crate::game::SAY_DURATION`] seconds.
    Say(String),
    /// Pause draining this object's queue for `secs` seconds. Never reaches the board queue.
    Delay(f64),
    /// Set the source object's foreground and/or background color.
    SetColor { fg: Option<Rgba8>, bg: Option<Rgba8> },
    /// Call `fn_name` on `target` object, optionally passing `arg`.
    Send { target: ObjectId, fn_name: String, arg: Option<ScriptArg> },
    /// Open a scrollable text overlay. Pauses game ticks while shown; a choice
    /// selection dispatches [`Send`](Action::Send) to the source object.
    Scroll(Vec<ScrollLine>),
}

// ── Direction helper ──────────────────────────────────────────────────────────

fn dir_to_str(d: Direction) -> &'static str {
    match d {
        Direction::North => "North",
        Direction::South => "South",
        Direction::East  => "East",
        Direction::West  => "West",
    }
}

// ── action_to_map ─────────────────────────────────────────────────────────────

/// Converts an [`Action`] to a Rhai map for `Queue.peek()` / `Queue.pop()`.
///
/// The map always has a `"type"` key naming the variant; other keys carry the
/// payload. [`Action::Log`] is flattened to its first span's text.
pub(crate) fn action_to_map(action: &Action) -> rhai::Map {
    // Dynamic::from(String) avoids rhai 1.x's From<&str> lifetime restriction.
    let ds = |v: &'static str| Dynamic::from(v.to_string());
    let mut m = rhai::Map::new();
    match action {
        Action::Move(dir) => {
            m.insert("type".into(), ds("Move"));
            m.insert("dir".into(),  ds(dir_to_str(*dir)));
        }
        Action::SetTile(n) => {
            m.insert("type".into(), ds("SetTile"));
            m.insert("tile".into(), Dynamic::from(*n as i64));
        }
        Action::Log(line) => {
            let text = line.spans.first().map(|s| s.text.as_str()).unwrap_or("").to_string();
            m.insert("type".into(), ds("Log"));
            m.insert("msg".into(),  Dynamic::from(text));
        }
        Action::SetTag { target, tag, present } => {
            m.insert("type".into(),    ds("SetTag"));
            m.insert("target".into(),  Dynamic::from(*target as i64));
            m.insert("tag".into(),     Dynamic::from(tag.clone()));
            m.insert("present".into(), Dynamic::from(*present));
        }
        Action::Say(text) => {
            m.insert("type".into(), ds("Say"));
            m.insert("msg".into(),  Dynamic::from(text.clone()));
        }
        Action::Delay(secs) => {
            m.insert("type".into(), ds("Delay"));
            m.insert("secs".into(), Dynamic::from(*secs));
        }
        Action::SetColor { fg, bg } => {
            m.insert("type".into(), ds("SetColor"));
            if let Some(c) = fg { m.insert("fg".into(), Dynamic::from(color_to_hex(*c))); }
            if let Some(c) = bg { m.insert("bg".into(), Dynamic::from(color_to_hex(*c))); }
        }
        Action::Send { target, fn_name, arg } => {
            m.insert("type".into(),   ds("Send"));
            m.insert("target".into(), Dynamic::from(*target as i64));
            m.insert("name".into(),   Dynamic::from(fn_name.clone()));
            if let Some(a) = arg {
                let dyn_arg = match a {
                    ScriptArg::Str(s) => Dynamic::from(s.clone()),
                    ScriptArg::Num(n) => Dynamic::from(*n),
                };
                m.insert("arg".into(), dyn_arg);
            }
        }
        // Scroll lines are not inspectable via the queue map API; emit type only.
        Action::Scroll(_) => {
            m.insert("type".into(), ds("Scroll"));
        }
    }
    m
}