figcraft/plugins/examples/counter/src/lib.rs

//! Counter: a widget on the canvas with − and + buttons around a count, a label you can edit on the
//! canvas, and a property menu (reset, steps of ten, a colour). Each click, edit or menu choice
//! calls the plugin back with the widget's state; it hands back the new state and the redrawn
//! widget.

use figcraft_plugin_sdk::{Input, Result, Value, Widget, entry, json, render_widget};

/// The count stays within ± this.
const LIMIT: i64 = 999_999;
/// The colours the menu offers for the count (the first is the default).
const COLORS: [&str; 4] = ["#1E1E1E", "#0D99FF", "#14AE5C", "#F24822"];
/// Shown in the label field while it's empty.
const PLACEHOLDER: &str = "Add a label";

/// What the widget shows.
#[derive(Debug, PartialEq)]
struct Counter {
    count: i64,
    big: bool,
    color: String,
}

impl Counter {
    fn from_state(state: &Value) -> Counter {
        let color = state.get("color").and_then(Value::as_str).filter(|c| COLORS.contains(c)).unwrap_or(COLORS[0]);
        Counter {
            count: state.get("count").and_then(Value::as_i64).unwrap_or(0),
            big: state.get("big").and_then(Value::as_bool).unwrap_or(false),
            color: color.into(),
        }
    }

    /// After the click, edit or menu choice `w` brings (nothing: the widget was just inserted).
    fn next(mut self, w: &Widget) -> Counter {
        let step = if self.big { 10 } else { 1 };
        match (w.target.as_deref(), w.menu.as_deref()) {
            (Some("increment"), _) => self.count = self.count.saturating_add(step),
            (Some("decrement"), _) => self.count = self.count.saturating_sub(step),
            (_, Some("reset")) => self.count = 0,
            (_, Some("big")) => self.big = w.value.as_bool().unwrap_or(!self.big),
            (_, Some("color")) => {
                if let Some(c) = w.value.as_str().filter(|c| COLORS.contains(c)) {
                    self.color = c.into();
                }
            }
            _ => {}
        }
        self.count = self.count.clamp(-LIMIT, LIMIT);
        self
    }
}

/// A square button that calls back with `target`, darker while the pointer is over it.
fn button(target: &str, name: &str, label: &str) -> Value {
    json!({"type": "frame", "name": name, "target": target, "layout": "horizontal", "justify": "center", "width": 32, "height": 32, "radius": 8, "fill": "#F0F0F0",
           "hover": {"fill": "#E0E0E0"},
           "children": [{"type": "text", "text": label, "size": 16, "bold": true, "color": "#1E1E1E"}]})
}

/// The widget showing `c` under `label`.
fn view(c: &Counter, label: &str) -> Value {
    let (text, ink) = if label.trim().is_empty() { (PLACEHOLDER, "#B3B3B3") } else { (label, "#757575") };
    let (minus, plus) = if c.big { ("−10", "+10") } else { ("−", "+") };
    json!({"type": "frame", "name": "Counter", "layout": "vertical", "gap": 6, "padding": 12, "radius": 12, "align": "min",
           "fill": "#FFFFFF", "stroke": "#D9D9D9", "children": [
        {"type": "text", "name": "Label", "field": "label", "text": text, "size": 12, "color": ink},
        {"type": "frame", "name": "Row", "layout": "horizontal", "gap": 12, "children": [
            button("decrement", "Decrease", minus),
            {"type": "text", "name": "Count", "text": c.count.to_string(), "size": 24, "bold": true, "color": c.color},
            button("increment", "Increase", plus),
        ]},
    ]})
}

/// The property menu for `c`.
fn menu(c: &Counter) -> Value {
    json!([
        {"item": "reset", "label": "Reset", "type": "action"},
        {"item": "big", "label": "Steps of 10", "type": "toggle", "checked": c.big},
        {"item": "color", "label": "Colour", "type": "color", "options": COLORS, "value": c.color},
    ])
}

fn run(input: Input) -> Result<Value> {
    let w = input.widget.ok_or("Insert the counter from Plugins ▸ Widgets")?;
    let c = Counter::from_state(&w.state).next(&w);
    // An edited label is in the state already, under its field's name.
    let label = w.state.get("label").and_then(Value::as_str).unwrap_or("Counter").to_string();
    let state = json!({"count": c.count, "big": c.big, "color": c.color, "label": label});
    render_widget(&json!({"state": state, "root": view(&c, &label), "menu": menu(&c)}))?;
    Ok(json!({"count": c.count}))
}

entry!(run);

#[cfg(test)]
mod tests {
    use super::*;

    fn widget(target: Option<&str>, menu: Option<&str>, value: Value) -> Widget {
        Widget { target: target.map(Into::into), menu: menu.map(Into::into), value, ..Widget::default() }
    }

    #[test]
    fn counts_within_its_limit_and_follows_its_menu() {
        let c = |count: i64| Counter { count, big: false, color: COLORS[0].into() };
        let at = |n: i64, t: &str| c(n).next(&widget(Some(t), None, Value::Null)).count;
        assert_eq!(c(0).next(&Widget::default()).count, 0);
        assert_eq!((at(4, "increment"), at(4, "decrement")), (5, 3));
        assert_eq!((at(LIMIT, "increment"), at(i64::MIN, "decrement"), at(2, "other")), (LIMIT, -LIMIT, 2));
        assert_eq!(c(7).next(&widget(None, Some("reset"), Value::Null)).count, 0);
        let big = c(1).next(&widget(None, Some("big"), json!(true)));
        assert!(big.big);
        assert_eq!(big.next(&widget(Some("increment"), None, Value::Null)).count, 11, "steps of ten");
        assert_eq!(c(1).next(&widget(None, Some("color"), json!("#14AE5C"))).color, "#14AE5C");
        assert_eq!(c(1).next(&widget(None, Some("color"), json!("#123456"))).color, COLORS[0], "only the colours offered");
        assert_eq!(Counter::from_state(&json!({"count": 3, "color": "junk"})), c(3));
        let v = view(&c(3), "Score");
        assert_eq!((v["children"][0]["text"].clone(), v["children"][1]["children"][1]["text"].clone()), (json!("Score"), json!("3")));
        assert_eq!(view(&c(3), " ")["children"][0]["text"], PLACEHOLDER);
        assert_eq!(menu(&c(0))[1]["checked"], false);
        assert_eq!(v["children"][1]["children"][0]["hover"], json!({"fill": "#E0E0E0"}), "buttons darken under the pointer");
        assert!(run(Input::default()).is_err(), "it only runs as a widget");
    }
}