/**
 * Annotation service — creates technical marks on document ranges and
 * emits `AnnotationCreated`. Resolution-status updates emit
 * `AnnotationResolved` / `AnnotationResolutionFailed`.
 *
 * Annotation creation is the engine's response to a user action in the
 * viewer (T07). The viewer adapter has already turned the selection into
 * `Selector[]`; this service stamps an ID, normalize-version, timestamps,
 * persists, and broadcasts.
 */

import type {
  Annotation,
  AnnotationResolutionStatus,
} from "@shared/annotation";
import type { DocumentId, RepresentationId, AnnotationId } from "@shared/ids";
import type { Selector } from "@shared/selector";
import { newId } from "@shared/ids";
import { NORMALIZE_VERSION } from "@shared/text/normalize";

import type { EventBus } from "../events";
import type { AnnotationRepository } from "../repos";

export interface CreateAnnotationInput {
  readonly documentId: DocumentId;
  readonly representationId?: RepresentationId;
  readonly selectors: readonly Selector[];
  readonly quote?: string;
  readonly note?: string;
  readonly createdBy?: string;
}

export interface AnnotationService {
  create(input: CreateAnnotationInput): Annotation;
  get(id: AnnotationId): Annotation | null;
  listByDocument(documentId: DocumentId): readonly Annotation[];
  setResolutionStatus(
    id: AnnotationId,
    status: AnnotationResolutionStatus,
    opts: { readonly confidence: number; readonly reason?: string },
  ): Annotation;
  /**
   * Edit the human-facing `quote` text on an annotation without touching
   * the underlying selectors. Selectors stay the source of truth for
   * locating the passage; the quote is the user's editable display copy.
   */
  updateQuote(id: AnnotationId, quote: string): Annotation;
}

export function createAnnotationService(
  annotations: AnnotationRepository,
  bus: EventBus,
  now: () => string = () => new Date().toISOString(),
): AnnotationService {
  return {
    create(input) {
      const ts = now();
      const annotation: Annotation = {
        id: newId("annotation"),
        documentId: input.documentId,
        ...(input.representationId !== undefined ? { representationId: input.representationId } : {}),
        selectors: input.selectors,
        ...(input.quote !== undefined ? { quote: input.quote } : {}),
        ...(input.note !== undefined ? { note: input.note } : {}),
        normalizeVersion: NORMALIZE_VERSION,
        ...(input.createdBy !== undefined ? { createdBy: input.createdBy } : {}),
        createdAt: ts,
        updatedAt: ts,
      };
      const stored = annotations.create(annotation);
      bus.emit({ type: "AnnotationCreated", annotationId: stored.id, annotation: stored });
      return stored;
    },
    get(id) {
      return annotations.get(id);
    },
    listByDocument(documentId) {
      return annotations.listByDocument(documentId);
    },
    setResolutionStatus(id, status, opts) {
      const existing = annotations.get(id);
      if (!existing) {
        throw new Error(`AnnotationService.setResolutionStatus: unknown id ${id}`);
      }
      const updated: Annotation = {
        ...existing,
        resolutionStatus: status,
        updatedAt: now(),
      };
      const stored = annotations.update(updated);
      if (status === "unresolved" || status === "stale") {
        bus.emit({
          type: "AnnotationResolutionFailed",
          annotationId: stored.id,
          reason: opts.reason ?? status,
        });
      } else {
        bus.emit({
          type: "AnnotationResolved",
          annotationId: stored.id,
          status,
          confidence: opts.confidence,
        });
      }
      return stored;
    },
    updateQuote(id, quote) {
      const existing = annotations.get(id);
      if (!existing) {
        throw new Error(`AnnotationService.updateQuote: unknown id ${id}`);
      }
      const trimmed = quote.length === 0 ? undefined : quote;
      const updated: Annotation = {
        ...existing,
        // exactOptionalPropertyTypes: drop `quote` when empty rather
        // than setting it to undefined.
        ...(trimmed !== undefined ? { quote: trimmed } : {}),
        updatedAt: now(),
      };
      if (trimmed === undefined && "quote" in updated) {
        // Remove the field outright when clearing.
        delete (updated as { quote?: string }).quote;
      }
      const stored = annotations.update(updated);
      bus.emit({ type: "AnnotationUpdated", annotationId: stored.id, annotation: stored });
      return stored;
    },
  };
}