import * as vscode from 'vscode';
import { DiagramSource, readDiagramSource } from '../sources/detect';
import { ModelProblem, Registry, resolveRefs } from './format';
import { ModelService } from './service';

/**
 * A diagram ready for Archify: the source as written, plus the resolved JSON
 * with registry references expanded, the model problems found on the way,
 * and the diagram links the viewer should offer.
 */
export interface PreparedDiagram {
  source: DiagramSource;
  /** Model root when the file is inside a model. */
  root?: vscode.Uri;
  registry?: Registry;
  problems: ModelProblem[];
  /** Node id → diagram path relative to the model root. */
  links: Map<string, string>;
}

/**
 * Reads a diagram and resolves it against its model, if any. Every place
 * that hands a diagram to Archify (preview, Problems, render, browser) goes
 * through here, so they all see the same resolved diagram.
 */
export async function prepareDiagram(models: ModelService, uri: vscode.Uri, text: string): Promise<PreparedDiagram | undefined> {
  const source = readDiagramSource(text, uri.path);
  if (!source) return undefined;
  const found = await models.registryFor(uri);
  const resolved = resolveRefs(source.diagram, { registry: found?.registry, fileName: uri.path });
  // Only diagrams that use refs (or carry a model block) need the resolved form.
  const changed = resolved.refs.size > 0 || resolved.problems.length > 0 || 'model' in source.diagram || resolved.links.size > 0;
  const prepared: DiagramSource = changed
    ? { ...source, diagram: resolved.diagram, json: JSON.stringify(resolved.diagram, null, 2) }
    : source;
  return { source: prepared, root: found?.root, registry: found?.registry, problems: resolved.problems, links: resolved.links };
}