import { type PropertyBag, textOf } from '../model/Properties';
import { isTaggedKind } from '../properties/kinds';
import { flatDef, isValidFieldName, type PropertyDef } from '../properties/PropertySchema';
import {
  type DeclaredPort,
  declaredPortType,
  edgesInto,
  findNode,
  type Graph,
  type GraphEdge,
  type GraphNode,
  type PortType,
} from './Graph';
import type { GraphLookup } from './lookup';
import { nodeDef, type NodeDef, type PortDef } from './NodeRegistry';
import { lerpProblem } from './nodes/data/Lerp';
import { withSplits } from './portSplits';
import { agreedType, type SharedPortGroup } from './portTypes';

export const BEHAVIOR_START = 'BehaviorStart';
export const BEHAVIOR_END = 'BehaviorEnd';
export const RUN_BEHAVIOR = 'RunBehavior';
export const ON_BEHAVIOR = 'OnBehavior';
export const VARIABLES = 'Variables';
export const PROPERTIES = 'Properties';
const ON_START = 'OnStart';

export const BEHAVIOR_PARAM = 'behavior';
export const VARIABLES_PARAM = 'variablesAsset';

/** Whose declarations a `Variables` node reads; empty is the behavior the node sits in. */
export const VARIABLES_SETTING: PropertyDef = {
  key: VARIABLES_PARAM,
  label: 'Variables',
  kind: 'asset',
  default: '',
  assetTypes: ['variables'],
};

export const STRUCT_TYPE_PARAM = 'structType';

/** The Struct asset whose fields a `Pack` or `Expand` takes as its ports (#253); empty is by hand. */
export const STRUCT_TYPE_SETTING: PropertyDef = {
  key: STRUCT_TYPE_PARAM,
  label: 'Type',
  kind: 'asset',
  default: '',
  assetTypes: ['struct'],
};

export function variablesSourceOf(params: PropertyBag): string {
  return textOf(params[VARIABLES_PARAM] ?? '');
}

/**
 * Nodes whose declared ports are not names of their own but variables of the behavior around them.
 * Renaming a variable therefore has to reach them, and the inspector picks their ports from a list
 * instead of letting them be typed.
 */
export function declaresVariablePorts(type: string): boolean {
  return type === VARIABLES;
}

/** Nodes whose declared ports are properties of the object they are handed. */
export function declaresPropertyPorts(type: string): boolean {
  return type === PROPERTIES;
}

/** Identifier-like, and not `exec`: that key belongs to the fixed flow port of every terminal node. */
export function isValidPortName(name: string): boolean {
  return isValidFieldName(name) && name !== 'exec';
}

/**
 * Keys a declared port cannot take: the node's fixed ports on the side it declares (`object`), and
 * its settings, which share the params bag with the typed-in values of its inputs.
 */
export function fixedPortKeys(def: NodeDef): string[] {
  const side = def.declaresPorts;
  const fixed =
    side === 'inputs' ? def.inputs : side === 'outputs' ? def.outputs : [...def.inputs, ...def.outputs];
  return [...fixed.map((p) => p.key), ...def.params.map((p) => p.key)];
}

function declaredOn(
  def: NodeDef,
  ports: readonly DeclaredPort[],
  side: 'inputs' | 'outputs',
): DeclaredPort[] {
  if (def.declaresPorts === 'both') return side === 'outputs' ? [...ports] : ports.filter((p) => p.write);
  return def.declaresPorts === side ? [...ports] : [];
}

/** What a collapsed Variables or Properties node does, since its ports are out of sight. */
export function collapsedTitle(ports: readonly DeclaredPort[], noun: string): string {
  const set = ports.filter((p) => p.write);
  const get = ports.filter((p) => !p.write);
  if (set.length > 1) return `Set ${set.length} ${noun}`;
  if (get.length > 1) return `Get ${get.length} ${noun}`;
  if (set[0]) return `Set ${set[0].key}`;
  if (get[0]) return `Get ${get[0].key}`;
  return `No ${noun}`;
}

/** The single start (or end) node of a graph; a second one is ignored. */
export function terminalNode(graph: Graph, type: string): GraphNode | undefined {
  return graph.nodes.find((n) => n.type === type);
}

/**
 * Where a call into `graph` begins: its start node, or – for a behavior that has none – every
 * `On start` in it, in graph order, as when the behavior starts on its own (#230).
 */
export function callEntries(graph: Graph): GraphNode[] {
  const start = terminalNode(graph, BEHAVIOR_START);
  return start ? [start] : graph.nodes.filter((n) => n.type === ON_START);
}

export function isTerminalType(type: string): boolean {
  return type === BEHAVIOR_START || type === BEHAVIOR_END;
}

export function isTerminalNode(node: GraphNode): boolean {
  return isTerminalType(node.type);
}

/** The two nodes that stand for another behavior: the one running it, the one listening to it (#294). */
export function namesBehavior(type: string): boolean {
  return type === RUN_BEHAVIOR || type === ON_BEHAVIOR;
}

/** A further flow port of a start or end node, next to its fixed `exec` (#294). */
export function isFlowPort(port: DeclaredPort): boolean {
  return port.kind === 'flow';
}

/**
 * A tagged kind is one the value cannot show, so its port carries the field that edits it – except
 * an object, which nothing can type in.
 */
export function portDefOf(port: DeclaredPort): PortDef {
  const def: PortDef = { key: port.key, label: port.key, type: declaredPortType(port.kind) };
  return isTaggedKind(port.kind) && port.kind !== 'object'
    ? { ...def, field: flatDef(port.key, port.kind) }
    : def;
}

/** The ports the start (or end) node of `graph` declares, as seen from a node calling it. */
export function declaredPorts(graph: Graph | undefined, type: string): PortDef[] {
  const node = graph && terminalNode(graph, type);
  return (node?.ports ?? []).map(portDefOf);
}

/**
 * The node definition as it applies to *this* node: identical to the registered one, unless the
 * type declares ports per node (`declaresPorts`) or computes them (`derivePorts`).
 */
export function resolveDef(node: GraphNode, graph: Graph, lookup: GraphLookup): NodeDef | undefined {
  const def = shapedDef(node, graph, lookup, newTrail());
  return def && splitDef(def, node);
}

function splitDef(def: NodeDef, node: GraphNode): NodeDef {
  return withSplits(def, node, (key, field) => ({ ...portDefOf(field), key, label: key }));
}

/**
 * The definition a run works with: `resolveDef` without the field ports of split outputs. The node
 * produces its wholes as always; reading a field port picks the field out of one (`splitField`).
 */
export function runDef(node: GraphNode, graph: Graph, lookup: GraphLookup): NodeDef | undefined {
  return shapedDef(node, graph, lookup, newTrail());
}

/**
 * One question about a shared group, followed through the nodes of that kind in front of it (#210).
 * `open` holds the nodes still being asked: reaching one again is a data cycle, and it then reports
 * the `any` it was registered with, which ends the circle. `done` keeps each answer, so a node
 * feeding both inputs of the next is asked once and not once per path.
 */
interface Trail {
  open: Set<string>;
  done: Map<string, NodeDef>;
}

function newTrail(): Trail {
  return { open: new Set(), done: new Map() };
}

function shapedDef(node: GraphNode, graph: Graph, lookup: GraphLookup, trail: Trail): NodeDef | undefined {
  const def = nodeDef(node.type);
  if (!def) return undefined;
  const shared = def.sharedType;
  if (!shared || trail.open.has(node.id)) return ownShape(def, node, graph, lookup);
  const known = trail.done.get(node.id);
  if (known) return known;
  trail.open.add(node.id);
  const typed = withSharedType(ownShape(def, node, graph, lookup), shared, node, graph, lookup, trail);
  trail.open.delete(node.id);
  trail.done.set(node.id, typed);
  return typed;
}

/** The ports of this node before any shared group has its say. */
function ownShape(def: NodeDef, node: GraphNode, graph: Graph, lookup: GraphLookup): NodeDef {
  if (!def.declaresPorts && !def.derivePorts) return def;
  const own = (side: 'inputs' | 'outputs') =>
    declaredOn(def, node.ports ?? [], side).map((p) =>
      def.declaredPort ? def.declaredPort(p, node, graph, lookup) : portDefOf(p),
    );
  const grown = def.derivePorts?.({ node, graph, lookup }) ?? {};
  const side = (key: 'inputs' | 'outputs') => {
    const ports = [...def[key], ...(grown[key] ?? []), ...own(key)];
    return grown.inOrder ? ports : execFirst(ports);
  };
  return {
    ...def,
    label: grown.label ?? def.label,
    inputs: side('inputs'),
    outputs: side('outputs'),
  };
}

/** The group's outputs, retyped to what its inputs agree on; `any` leaves the definition alone. */
function withSharedType(
  def: NodeDef,
  group: SharedPortGroup,
  node: GraphNode,
  graph: Graph,
  lookup: GraphLookup,
  trail: Trail,
): NodeDef {
  const agree = group.agree ?? agreedType;
  const type = agree(group.inputs.map((key) => feedingType(node, key, graph, lookup, trail)));
  if (type === 'any') return def;
  return {
    ...def,
    outputs: def.outputs.map((p) => (group.outputs.includes(p.key) ? { ...p, type } : p)),
  };
}

/**
 * What the edge into that input carries, or undefined while nothing is connected to it: the type
 * the feeding node resolves to, which is what the edge itself is drawn in.
 */
function feedingType(
  node: GraphNode,
  key: string,
  graph: Graph,
  lookup: GraphLookup,
  trail: Trail,
): PortType | undefined {
  const edge = edgesInto(graph, node.id, key)[0];
  if (!edge) return undefined;
  const from = findNode(graph, edge.from.node);
  const def = from && shapedDef(from, graph, lookup, trail);
  return def && splitDef(def, from).outputs.find((p) => p.key === edge.from.port)?.type;
}

/**
 * `any` inputs painted as what flows into them: an unconnected one stays grey, a connected one takes
 * the colour of its own edge, so a group feeding two different types is visible as two colours.
 * Only `paintType` is set – the port's `type` stays `any`, so `canConnect` keeps taking everything.
 */
function paintedInputs(node: GraphNode, graph: Graph, def: NodeDef, lookup: GraphLookup): PortDef[] | null {
  if (!def.inputs.some((port) => port.type === 'any' && !port.ghost)) return null;
  const trail = newTrail();
  return def.inputs.map((port) => {
    if (port.type !== 'any' || port.ghost) return port;
    const fed = feedingType(node, port.key, graph, lookup, trail);
    return fed === undefined || fed === 'any' || fed === 'exec' ? port : { ...port, paintType: fed };
  });
}

/** A derived exec pin belongs at the top, above the fixed data ports too. */
function execFirst(ports: PortDef[]): PortDef[] {
  return [...ports.filter((p) => p.type === 'exec'), ...ports.filter((p) => p.type !== 'exec')];
}

/** One end of an edge naming a key its node no longer has. */
interface GhostEnd {
  edge: GraphEdge;
  key: string;
  isOutput: boolean;
}

/** Read from the edge list, not from the ports: what is looked for is exactly what has no port. */
function ghostEnds(node: GraphNode, graph: Graph, def: NodeDef): GhostEnd[] {
  const inputs = new Set(def.inputs.map((p) => p.key));
  const outputs = new Set(def.outputs.map((p) => p.key));
  const ends: GhostEnd[] = [];
  for (const edge of graph.edges) {
    if (edge.to.node === node.id && !inputs.has(edge.to.port))
      ends.push({ edge, key: edge.to.port, isOutput: false });
    if (edge.from.node === node.id && !outputs.has(edge.from.port))
      ends.push({ edge, key: edge.from.port, isOutput: true });
  }
  return ends;
}

/** `any` because the type the key once had is exactly what is no longer known. */
function ghostPort(key: string): PortDef {
  return { key, label: key, type: 'any', inline: false, ghost: true };
}

/**
 * The definition as the canvas draws it: the real ports with their pin colours (`paintedInputs`),
 * then the keys only edges still name. The ghosts go last and skip `execFirst`, so no real row moves
 * because of one – and none of this reaches `resolveDef`, which the interpreter, the compilers and
 * `ConnectCommand` read as the truth.
 */
export function drawnDef(node: GraphNode, graph: Graph, def: NodeDef, lookup: GraphLookup): NodeDef {
  const painted = paintedInputs(node, graph, def, lookup);
  const ends = ghostEnds(node, graph, def);
  if (ends.length === 0) return painted ? { ...def, inputs: painted } : def;
  const side = (isOutput: boolean) =>
    [...new Set(ends.filter((e) => e.isOutput === isOutput).map((e) => e.key))].map(ghostPort);
  return {
    ...def,
    inputs: [...(painted ?? def.inputs), ...side(false)],
    outputs: [...def.outputs, ...side(true)],
  };
}

/** Why a node warns although its own settings are sound: edges left hanging on keys that are gone. */
export function ghostProblem(node: GraphNode, graph: Graph, def: NodeDef): string | null {
  const count = ghostEnds(node, graph, def).length;
  if (count === 0) return null;
  return count === 1 ? '1 edge on a port that is gone' : `${count} edges on ports that are gone`;
}

/**
 * Why this call cannot do anything, or null if it can. A call is the one node that depends on a
 * *different* graph, so it is the one node that can look perfectly healthy and still be dead. A
 * `Lerp` depends on another asset as well, the curve it eases along (#247), and says so here too.
 */
export function callProblem(node: GraphNode, lookup: GraphLookup, ownerId = ''): string | null {
  if (node.type === ON_BEHAVIOR) return listenProblem(node, lookup, ownerId);
  if (node.type !== RUN_BEHAVIOR) return lerpProblem(node, lookup);
  const id = textOf(node.params[BEHAVIOR_PARAM] ?? '');
  if (!id) return 'No behavior picked';
  if (id === ownerId) return 'A behavior cannot run itself';
  const program = lookup.behavior(id);
  if (!program) return 'That behavior is gone';
  if (callEntries(program.graph).length === 0) return 'No start or On start node – does nothing';
  return null;
}

/** Why an `On behavior` never fires: it hears nothing, itself, or a graph without an end to reach. */
function listenProblem(node: GraphNode, lookup: GraphLookup, ownerId: string): string | null {
  const id = textOf(node.params[BEHAVIOR_PARAM] ?? '');
  if (!id) return 'No behavior picked';
  const program = lookup.behavior(id);
  if (!program) return 'That behavior is gone';
  if (ownerId && listensTo(lookup, id, ownerId)) return 'A behavior cannot listen to itself';
  if (!terminalNode(program.graph, BEHAVIOR_END)) return 'No End node – never fires';
  return null;
}

/** The behaviors the `On behavior` nodes of that graph name, picked or not found alike. */
export function heardBehaviors(graph: Graph): string[] {
  return graph.nodes
    .filter((n) => n.type === ON_BEHAVIOR)
    .map((n) => textOf(n.params[BEHAVIOR_PARAM] ?? ''))
    .filter((id) => id !== '');
}

/** Whether `from` is `target` or hears it, however many behaviors lie between. */
export function listensTo(
  lookup: GraphLookup,
  from: string,
  target: string,
  seen: Set<string> = new Set(),
): boolean {
  if (from === target) return true;
  if (seen.has(from)) return false;
  seen.add(from);
  const program = lookup.behavior(from);
  return program ? heardBehaviors(program.graph).some((id) => listensTo(lookup, id, target, seen)) : false;
}

/**
 * Everything that changes how a node looks, as one string. Views and the inspector rebuild when it
 * changes – a port list that is derived rather than fixed has no other way of being noticed.
 */
export function portSignature(node: GraphNode, graph: Graph, lookup: GraphLookup, ownerId = ''): string {
  const def = resolveDef(node, graph, lookup);
  if (!def) return 'missing';
  const list = (ports: PortDef[]) => ports.map((p) => `${p.key}:${p.type}`).join(',');
  return `${node.type}|${def.label}|${list(def.inputs)}|${list(def.outputs)}|${
    callProblem(node, lookup, ownerId) ?? ''
  }`;
}