/**
 * Art-historical movement lineage (predecessor → successor).
 * Defaults match museum essays; live data comes from GET /api/movement-links.
 * Multiple parents are allowed (e.g. Post-Impressionism feeding several modern paths).
 */

export type MovementLineageEdge = readonly [parent: string, child: string];

export const FALLBACK_MOVEMENT_LINEAGE: ReadonlyArray<MovementLineageEdge> = [
  // Classical & medieval
  ['Ancient Greek & Roman', 'Byzantine'],
  ['Byzantine', 'Gothic'],

  // Renaissance chain
  ['Gothic', 'Early Renaissance'],
  ['Early Renaissance', 'High Renaissance'],
  ['Northern Renaissance', 'Early Renaissance'],
  ['High Renaissance', 'Mannerism'],
  ['Mannerism', 'Baroque'],

  // 17th–19th century
  ['Baroque', 'Rococo'],
  ['Rococo', 'Neoclassicism'],
  ['Neoclassicism', 'Romanticism'],
  ['Romanticism', 'Realism'],
  ['Romanticism', 'Impressionism'],
  ['Realism', 'Impressionism'],

  // Modern origins
  ['Impressionism', 'Post-Impressionism'],
  ['Post-Impressionism', 'Symbolism'],
  ['Post-Impressionism', 'Fauvism'],
  ['Post-Impressionism', 'Expressionism'],
  ['Post-Impressionism', 'Cubism'],
  ['Symbolism', 'Art Nouveau'],
  ['Fauvism', 'Cubism'],
  ['Cubism', 'Futurism'],
  ['Cubism', 'Suprematism'],
  ['Cubism', 'Constructivism'],
  ['Expressionism', 'Abstract Expressionism'],

  // Avant-garde 20th century
  ['Dada', 'Surrealism'],
  ['Surrealism', 'Abstract Expressionism'],
  ['Abstract Expressionism', 'Pop Art'],
];

let activeLineage: ReadonlyArray<MovementLineageEdge> = FALLBACK_MOVEMENT_LINEAGE;

/** Active edges for timeline / tree layout (API-backed when loaded). */
export function getMovementLineage(): ReadonlyArray<MovementLineageEdge> {
  return activeLineage;
}

/** Apply curator DB rows; empty list keeps the static fallback. */
export function setMovementLineageFromApi(
  items: ReadonlyArray<{ source_name: string; target_name: string }>
): void {
  if (!items.length) {
    activeLineage = FALLBACK_MOVEMENT_LINEAGE;
    return;
  }
  activeLineage = items.map((row) => [row.source_name, row.target_name] as const);
}

/** @deprecated Use getMovementLineage() — alias for older imports. */
export const MOVEMENT_LINEAGE = FALLBACK_MOVEMENT_LINEAGE;

export function lineageParentsByName(childName: string): string[] {
  return getMovementLineage()
    .filter(([, child]) => child === childName)
    .map(([parent]) => parent);
}

export function lineageChildrenByName(parentName: string): string[] {
  return getMovementLineage()
    .filter(([parent]) => parent === parentName)
    .map(([, child]) => child);
}