import { NameTransitionCommand } from '../../core/commands/graphCommands';
import { findNode, type GraphEdge, isStateNode, resolveDef, stateName } from '../../core/graph';
import { graphLookup } from '../../core/model/graphLookup';
import { findGraphAsset, type Project } from '../../core/model/Project';
import { textOf } from '../../core/model/Properties';
import { Button, Label } from '../../ui';
import { hideLinks, linkNoun, removeGraphSelection } from '../actions';
import { createFieldRow, labelledRow } from './fieldFactory';
import { addGap, addNote, addTitle, type InspectorHost } from './host';

const NAME_KEY = 'transition-name';

/** What the panel says about one link: the two ends by the names drawn on them. */
export interface EdgeDescription {
  transition: boolean;
  from: string;
  output: string;
  to: string;
  input: string;
  /** What flows through it, as the output names it. */
  type: string;
  name: string;
}

/** Null when the link is gone. An end whose node or port is gone reads `?`. */
export function describeEdge(project: Project, assetId: string, edgeId: string): EdgeDescription | null {
  const graph = findGraphAsset(project, assetId)?.graph;
  const edge = graph?.edges.find((e) => e.id === edgeId);
  if (!graph || !edge) return null;
  const lookup = graphLookup(project);
  const end = (side: GraphEdge['from'], ports: 'inputs' | 'outputs') => {
    const node = findNode(graph, side.node);
    const def = node && resolveDef(node, graph, lookup);
    const port = def?.[ports].find((p) => p.key === side.port);
    return {
      state: node !== undefined && isStateNode(node),
      node: node ? (isStateNode(node) ? stateName(node) : (def?.label ?? node.type)) : '?',
      port: port ? port.label || port.key : '?',
      type: port?.type ?? '?',
    };
  };
  const from = end(edge.from, 'outputs');
  const to = end(edge.to, 'inputs');
  return {
    transition: from.state && to.state,
    from: from.node,
    output: from.port,
    to: to.node,
    input: to.port,
    type: from.type,
    name: edge.label ?? '',
  };
}

/** Structure of a link selection: how many, and for one of them what it joins. */
export function edgeSignature(
  project: Project,
  assetId: string,
  edgeId: string,
  edgeIds: readonly string[],
): string {
  if (edgeIds.length > 1) return `many:${edgeIds.length}`;
  const d = describeEdge(project, assetId, edgeId);
  return d ? [d.transition, d.from, d.output, d.to, d.input, d.type].join('|') : 'missing';
}

/** One link: where it comes from and goes to. Several: how many, and the way to delete them. */
export function buildEdgeSection(
  host: InspectorHost,
  assetId: string,
  edgeId: string,
  edgeIds: readonly string[],
): void {
  const noun = linkNoun(host.state, assetId);
  const remove = (label: string) =>
    host.body.add(
      new Button(label, {
        variant: 'danger',
        onClick: () => removeGraphSelection(host.state, assetId, [], [], edgeIds),
      }),
    );
  if (edgeIds.length > 1) {
    addTitle(host, `${edgeIds.length} ${noun.toUpperCase()}S`);
    addNote(host, 'Delete removes all of them in one step.');
    addGap(host);
    remove(`Delete ${edgeIds.length} ${noun}s`);
    return;
  }
  const d = describeEdge(host.state.project, assetId, edgeId);
  if (!d) return;
  addTitle(host, noun.toUpperCase());
  const fact = (label: string, value: string) => {
    const { row } = labelledRow(label);
    row.add(new Label(value), 1);
    host.body.add(row);
  };
  fact('From', d.from);
  if (!d.transition) fact('Output', d.output);
  fact('To', d.to);
  if (d.transition) {
    const name = createFieldRow(host, { key: NAME_KEY, label: 'Name', kind: 'text', default: '' }, d.name, {
      onInput: () => {},
      onChange: (next) => void host.state.execute(new NameTransitionCommand(assetId, edgeId, textOf(next))),
    });
    host.fields.set(NAME_KEY, name);
    host.body.add(name.row);
    addNote(host, 'A State transition node takes it by this name.', 'small');
  } else {
    fact('Input', d.input);
    fact('Type', d.type);
  }
  addGap(host);
  if (!d.transition)
    host.body.add(new Button('Hide link', { onClick: () => hideLinks(host.state, assetId, [edgeId]) }));
  remove(`Delete ${noun}`);
}

/** Pushes the current name into its row. False when the link is gone (rebuild). */
export function refreshEdgeSection(host: InspectorHost, assetId: string, edgeId: string): boolean {
  const d = describeEdge(host.state.project, assetId, edgeId);
  if (!d) return false;
  host.fields.get(NAME_KEY)?.setValue(d.name);
  return true;
}