feuerwerk/src/core/graph/NodeRegistry.ts

import { isList, type ListValue, type PropertyBag, type PropertyValue } from '../model/Properties';
import { isKindWith, plainKindOf } from '../properties/kinds';
import { flatDef, type PropertyDef } from '../properties/PropertySchema';
import type { DeclaredPort, Graph, GraphNode, PortType } from './Graph';
import type { GraphLookup } from './lookup';
import type { NodeContext } from './NodeContext';
import type { SharedPortGroup } from './portTypes';
import { asList, namedValue, type Value } from './values';

export interface PortDef {
  key: string;
  label: string;
  type: PortType;
  /** Inline value used while the input is unconnected and the node has no own value (else 0/''/false). */
  default?: PropertyValue;
  /** The property this port carries; its typed-in value is edited as that property (color, enum, …). */
  field?: PropertyDef;
  /** `false`: nothing to type in even for a number – unconnected, the node's own rule applies. */
  inline?: boolean;
  /** Not a port of the definition: a key only an edge still names, drawn so that edge can be seen. */
  ghost?: true;
  /**
   * Drawing only: the colour an `any` input is painted in, taken from the edge that feeds it (#207).
   * Its `type` stays `any`, so the port keeps taking everything and can be swapped at any time –
   * only the pin says what currently flows in. Set by `drawnDef`, read by `NodeView`, nowhere else.
   */
  paintType?: PortType;
}

/**
 * `state`, `shader` and `particles` are the categories no behavior graph offers: their nodes are the
 * states of a state machine, the GLSL of a shader asset and the motion of one particle.
 */
export type NodeCategory =
  'event' | 'flow' | 'data' | 'variable' | 'action' | 'state' | 'shader' | 'particles';

/**
 * How a loop node asks for one of its exec outputs to be run repeatedly: `port` carries the body,
 * `index` is the number output seeded with the round number.
 */
export interface RepeatResult {
  port: string;
  index: string;
  times: number;
  /** Round i also sets output `port` to `values[i]` – the element a `For each` is at. */
  items?: { port: string; values: readonly Value[] };
  /**
   * Boolean input read anew before every round, after the round's outputs are set. True ends the
   * loop there: that round's body does not run, and its outputs stay for what follows.
   */
  stopWhen?: string;
  /** Boolean output telling whether `stopWhen` ended the loop. */
  stopped?: string;
  /** Outputs standing after a loop that ran through all rounds without being stopped. */
  exhausted?: Record<string, Value>;
}

/** How a node asks for another behavior's graph to be run in place, `inputs` seeding its start node. */
export interface CallResult {
  behaviorId: string;
  inputs: Record<string, Value>;
}

export interface RunResult {
  /** Cached for the rest of the pulse. */
  outputs?: Record<string, Value>;
  /** Exec output(s) to continue along; omitted = the node ends the flow. */
  next?: string | string[];
  /** Runs `port` that many times before continuing along `next`. */
  repeat?: RepeatResult;
  /** Runs another behavior before continuing along `next`; its results join `outputs`. */
  call?: CallResult;
  /**
   * The elements a `Find` tests one by one against the `Match` closing its block. The flow goes on
   * from that Match, not from the Find.
   */
  find?: readonly Value[];
}

/** What a node may compute its ports from: itself, the graph it sits in, and the project around it. */
export interface PortSource {
  node: GraphNode;
  graph: Graph;
  lookup: GraphLookup;
}

/** Ports a single node has on top of the fixed ones of its type, and a label naming what it does. */
export interface DerivedShape {
  label?: string;
  inputs?: PortDef[];
  outputs?: PortDef[];
}

/** Palette, port rendering, connection validation and inspector fields are all derived from this. */
export interface NodeDef {
  type: string;
  label: string;
  category: NodeCategory;
  description: string;
  inputs: PortDef[];
  outputs: PortDef[];
  /** Node settings that are not ports (key name, operator, variable). */
  params: PropertyDef[];
  /**
   * Settings that say nothing at this value set, so the node body leaves them off; the inspector
   * still offers them. Without it a switched-off repeat is two rows of "0" on every key node.
   */
  hiddenParams?(params: PropertyBag): string[];
  /**
   * Which side the ports this node declares for itself (`GraphNode.ports`) appear on. Setting it
   * is what gives a node the port editor in the inspector. `both`: every port is an output, and an
   * input as well where it is marked `write`.
   */
  declaresPorts?: 'inputs' | 'outputs' | 'both';
  /** How a declared port becomes a port; without it, named after its key and typed by its kind. */
  declaredPort?(port: DeclaredPort, node: GraphNode): PortDef;
  /**
   * Edges between two such nodes are transitions: drawn as a straight arrow instead of the usual
   * curve, and hung on ports that are never shown. A transition graph is read as directed steps
   * between whole states, not as signal flowing left to right into a particular socket.
   */
  transitionEdges?: true;
  /** The node that comes along when this one is added, `dx` to the right: the end of its block. */
  opens?: { type: string; dx: number };
  /**
   * Ports this node computes beyond the fixed and the declared ones – how many outputs a Sequence
   * offers, which values the behavior a call node names takes. `resolveDef` applies it.
   */
  derivePorts?(source: PortSource): DerivedShape;
  /**
   * Ports carrying one and the same value: the outputs take the type the inputs agree on, so an
   * `any` output is drawn, validated and edited as what actually flows through it (#207).
   * `resolveDef` applies it; only the outputs change, the inputs stay `any` and take everything.
   */
  sharedType?: SharedPortGroup;
  /**
   * Outputs readable at any moment, even while the node's exec input has not fired in this pulse.
   * Never cached, so a read after a write sees the new value. `input` pulls one input on demand:
   * pulling all of them would loop through an edge that feeds the node's own output back in.
   * `def` and `lookup` are as in `run`: the definition resolved for this very node, and the project
   * around it – what a reader with one output per state needs to answer for all of them.
   */
  read?(
    ctx: NodeContext,
    params: PropertyBag,
    input: (key: string) => Value,
    def: NodeDef,
    lookup: GraphLookup,
  ): Record<string, Value>;
  /**
   * Event nodes have no `run` – the interpreter seeds their outputs. `def` is resolved for the node at
   * hand, the only way a node with derived ports knows how many it has. `entry` is the exec input
   * the pulse arrived through – what a node with one exec input per meaning reads. `lookup` is the
   * project around the graph, for a node whose step is written in another asset.
   */
  run?(
    ctx: NodeContext,
    inputs: Record<string, Value>,
    params: PropertyBag,
    def: NodeDef,
    entry: string,
    lookup: GraphLookup,
  ): RunResult;
}

const defs = new Map<string, NodeDef>();

export function registerNode(def: NodeDef): NodeDef {
  if (defs.has(def.type)) throw new Error(`Node type "${def.type}" registered twice`);
  defs.set(def.type, def);
  return def;
}

export function nodeDef(type: string): NodeDef | undefined {
  return defs.get(type);
}

export function allNodeDefs(): NodeDef[] {
  return [...defs.values()];
}

export function isEventNode(def: NodeDef): boolean {
  return def.category === 'event';
}

export function hasExecInput(def: NodeDef): boolean {
  return def.inputs.some((p) => p.type === 'exec');
}

/**
 * Data inputs that may carry an inline value while unconnected. An object is a live handle and a
 * struct is assembled from its parts, so neither has a value that could be typed on one line; a
 * shader colour has one only where the node gives it a colour field.
 */
export function inlineInputs(def: NodeDef): PortDef[] {
  return def.inputs.filter(isInlinePort);
}

function isInlinePort(port: PortDef): boolean {
  if (port.inline === false) return false;
  if (port.type === 'vec3') return port.field !== undefined;
  return port.type !== 'exec' && port.type !== 'object' && port.type !== 'struct';
}

/** Untyped, an input writes the zero of its kind; as its default the node body shows it, not just the name. */
export function withInlineDefault(port: PortDef): PortDef {
  return isInlinePort(port) ? { ...port, default: inlineInputDef(port).default } : port;
}

export function inlineInputDef(port: PortDef): PropertyDef {
  if (port.field) return { ...port.field, key: port.key, label: port.label };
  const kind = port.type === 'any' ? 'text' : plainKindOf(port.type);
  // A declared default is a stored value, never a live handle.
  if (kind === 'list')
    return { key: port.key, label: port.label, kind, default: namedValue(asList(port.default)) as ListValue };
  const flat = kind !== undefined && isKindWith('field', kind) ? kind : 'number';
  const def = flatDef(port.key, flat, { label: port.label, value: port.default });
  return def.kind === 'number' ? { ...def, step: 1 } : def;
}

/**
 * The value an unconnected input carries: the node's own inline value, else the default the
 * inspector shows for it – `false`, `0`, `""`, an empty list –, so what the node reads is what the
 * editor says it reads. Only an input with nothing to type in (object, struct, exec) is `null`.
 */
export function inlineValue(node: { params: PropertyBag }, port: PortDef): Value {
  return node.params[port.key] ?? port.default ?? shownDefault(port);
}

/** Cached per port: the interpreter asks for it on every read of an unconnected input. */
const shownDefaults = new WeakMap<PortDef, PropertyValue | null>();

function shownDefault(port: PortDef): Value {
  let value = shownDefaults.get(port);
  if (value === undefined) {
    value = isInlinePort(port) ? inlineInputDef(port).default : null;
    shownDefaults.set(port, value);
  }
  // A list is handed out fresh: a node that edits its input in place must not edit every other one.
  return isList(value) ? [...value] : value;
}