import type { CinemaSha256 } from './cinema-types.js';

export interface CinemaArtifactDependencyNode {
  artifactId: string;
  artifactType: 'identity-portrait' | 'character-sheet' | 'reference-pack' | 'shot-manifest' | 'provider-payload';
  contentHash: CinemaSha256;
  characterVersionId: string;
  dependencies: Array<{ artifactId: string; contentHash: CinemaSha256 }>;
}

export interface CinemaInvalidationRecord {
  artifactId: string;
  artifactType: CinemaArtifactDependencyNode['artifactType'];
  reason: string;
  invalidatedByArtifactId: string;
}

export function planCinemaIdentityReplacement(input: {
  priorIdentityArtifactId: string;
  priorIdentityHash: CinemaSha256;
  nextIdentityArtifactId: string;
  nextIdentityHash: CinemaSha256;
  priorCharacterVersionId: string;
  nextCharacterVersionId: string;
  graph: CinemaArtifactDependencyNode[];
}): { nextCharacterVersionId: string; invalidations: CinemaInvalidationRecord[] } {
  if (input.priorIdentityArtifactId === input.nextIdentityArtifactId) throw new Error('Identity replacement requires a new immutable portrait artifact ID');
  if (input.priorIdentityHash === input.nextIdentityHash) throw new Error('Identity replacement requires changed portrait bytes');
  if (input.priorCharacterVersionId === input.nextCharacterVersionId) throw new Error('Identity replacement requires a new character version');
  const invalidated = new Map<string, CinemaInvalidationRecord>();
  let frontier = new Set([input.priorIdentityArtifactId]);
  while (frontier.size > 0) {
    const next = new Set<string>();
    for (const node of input.graph) {
      if (invalidated.has(node.artifactId)) continue;
      const dependency = node.dependencies.find((entry) => frontier.has(entry.artifactId));
      if (!dependency) continue;
      if (dependency.artifactId === input.priorIdentityArtifactId && dependency.contentHash !== input.priorIdentityHash) continue;
      invalidated.set(node.artifactId, {
        artifactId: node.artifactId,
        artifactType: node.artifactType,
        reason: `Dependency ${dependency.artifactId}@${dependency.contentHash} was superseded by ${input.nextIdentityArtifactId}@${input.nextIdentityHash}`,
        invalidatedByArtifactId: dependency.artifactId,
      });
      next.add(node.artifactId);
    }
    frontier = next;
  }
  return { nextCharacterVersionId: input.nextCharacterVersionId, invalidations: [...invalidated.values()] };
}