import type {
  InjectionPacket,
  InjectionScoreDetails,
  InjectionSnippet,
} from "../../agent-contract/dto.js";

export interface RetrievalLogCandidate {
  tier: 1 | 2 | 3;
  refKind: string;
  refId: string;
  score: number;
  snippet: string;
  scoreDetails?: InjectionScoreDetails;
}

export interface LocalRetrievalLogStages {
  /** Mechanical/ranked candidates before the local LLM relevance pass. */
  candidates: RetrievalLogCandidate[];
  /** Candidates retained by the local LLM relevance pass. */
  filtered: RetrievalLogCandidate[];
  /** Candidates rejected by the local LLM relevance pass. */
  dropped: RetrievalLogCandidate[];
}

/**
 * `InjectionPacket.snippets` is already post-LLM-filter. Reconstruct the
 * Logs-page funnel from the kept and explicitly surfaced dropped snippets
 * instead of trying to remove dropped ids from an already-filtered list.
 * The LLM may reorder its kept subset, so restore the mechanical ranker's
 * score-descending order only for the complete pre-filter candidate view.
 */
export function buildLocalRetrievalLogStages(
  packet:
    | Pick<InjectionPacket, "snippets" | "droppedByLlm">
    | null
    | undefined,
): LocalRetrievalLogStages {
  const filtered = (packet?.snippets ?? []).map(toLogCandidate);
  const dropped = (packet?.droppedByLlm ?? []).map(toLogCandidate);
  return {
    candidates: [...filtered, ...dropped].sort(
      (left, right) => right.score - left.score,
    ),
    filtered,
    dropped,
  };
}

function toLogCandidate(snippet: InjectionSnippet): RetrievalLogCandidate {
  return {
    tier: inferSnippetTier(snippet.refKind),
    refKind: snippet.refKind,
    refId: snippet.refId,
    score: snippet.score ?? 0,
    snippet: snippet.body,
    scoreDetails: snippet.scoreDetails,
  };
}

function inferSnippetTier(refKind: InjectionSnippet["refKind"]): 1 | 2 | 3 {
  if (refKind === "skill") return 1;
  if (refKind === "world-model") return 3;
  return 2;
}