/**
 * Binding service + in-memory link repo tests.
 *
 * Exercises every public surface plus the §4 events the service emits.
 */

import { describe, expect, it } from "vitest";

import type {
  EvidenceLink,
  EvidenceTarget,
} from "@citation-evidence/engine/shared";
import type {
  EvidenceItemId,
  EvidenceLinkId,
} from "@citation-evidence/engine/shared";

import { createEventBus } from "@citation-evidence/engine";
import type { EngineEvent } from "@citation-evidence/engine";

import { createInMemoryLinkRepo } from "../repos/in-memory-links";
import { createBindingService } from "./bindings";

function makeFixture() {
  const bus = createEventBus();
  const repo = createInMemoryLinkRepo();
  const events: EngineEvent[] = [];
  bus.onAny((e) => events.push(e));
  let counter = 0;
  const now = () => `2026-05-25T00:00:0${counter++}.000Z`;
  const service = createBindingService(repo, bus, now);
  return { bus, repo, events, service };
}

const FIELD_A: EvidenceTarget = { targetType: "form-field", targetId: "summary" };
const FIELD_B: EvidenceTarget = { targetType: "form-field", targetId: "amount" };
const EV1 = "ev_test_one" as EvidenceItemId;
const EV2 = "ev_test_two" as EvidenceItemId;

describe("createBindingService", () => {
  it("linkEvidenceToTarget creates a link, emits EvidenceLinkCreated, and persists it", () => {
    const { service, repo, events } = makeFixture();

    const link = service.linkEvidenceToTarget({
      evidenceItemId: EV1,
      target: FIELD_A,
    });

    expect(link.evidenceItemId).toBe(EV1);
    expect(link.targetType).toBe("form-field");
    expect(link.targetId).toBe("summary");
    expect(link.relation).toBe("supports");
    expect(link.status).toBe("candidate");
    expect(link.createdAt).toBe(link.updatedAt);

    expect(repo.get(link.id)).toEqual(link);

    const created = events.filter((e) => e.type === "EvidenceLinkCreated");
    expect(created).toHaveLength(1);
    expect(created[0]).toMatchObject({ linkId: link.id, link });
  });

  it("honours explicit relation/status/confidence", () => {
    const { service } = makeFixture();

    const link = service.linkEvidenceToTarget({
      evidenceItemId: EV1,
      target: FIELD_A,
      relation: "contradicts",
      status: "conflicting",
      confidence: 0.42,
      createdBy: "tegwick",
    });

    expect(link.relation).toBe("contradicts");
    expect(link.status).toBe("conflicting");
    expect(link.confidence).toBe(0.42);
    expect(link.createdBy).toBe("tegwick");
  });

  it("listEvidenceForTarget returns only links for the requested target", () => {
    const { service } = makeFixture();
    const a1 = service.linkEvidenceToTarget({ evidenceItemId: EV1, target: FIELD_A });
    service.linkEvidenceToTarget({ evidenceItemId: EV2, target: FIELD_B });
    const a2 = service.linkEvidenceToTarget({ evidenceItemId: EV2, target: FIELD_A });

    const linksForA = service.listEvidenceForTarget(FIELD_A);
    expect(linksForA.map((l) => l.id).sort()).toEqual([a1.id, a2.id].sort());
  });

  it("listTargetsForEvidence returns all targets an evidence item is linked to", () => {
    const { service } = makeFixture();
    const a = service.linkEvidenceToTarget({ evidenceItemId: EV1, target: FIELD_A });
    const b = service.linkEvidenceToTarget({ evidenceItemId: EV1, target: FIELD_B });
    service.linkEvidenceToTarget({ evidenceItemId: EV2, target: FIELD_A });

    const targets = service.listTargetsForEvidence(EV1);
    expect(targets.map((l) => l.id).sort()).toEqual([a.id, b.id].sort());
  });

  it("unlinkEvidence removes the link and reports success/failure", () => {
    const { service } = makeFixture();
    const link = service.linkEvidenceToTarget({ evidenceItemId: EV1, target: FIELD_A });

    expect(service.unlinkEvidence(link.id)).toBe(true);
    expect(service.getLink(link.id)).toBeNull();
    expect(service.unlinkEvidence(link.id)).toBe(false);
    expect(service.unlinkEvidence("evlink_unknown" as EvidenceLinkId)).toBe(false);
  });

  it("updateLink merges patch, bumps updatedAt, and emits EvidenceLinkUpdated", () => {
    const { service, events } = makeFixture();
    const original = service.linkEvidenceToTarget({
      evidenceItemId: EV1,
      target: FIELD_A,
    });

    const updated = service.updateLink(original.id, {
      status: "confirmed",
      confidence: 0.9,
    });

    expect(updated.status).toBe("confirmed");
    expect(updated.confidence).toBe(0.9);
    expect(updated.relation).toBe(original.relation);
    expect(updated.updatedAt).not.toBe(original.updatedAt);

    const updatedEvents = events.filter((e) => e.type === "EvidenceLinkUpdated");
    expect(updatedEvents).toHaveLength(1);
    expect((updatedEvents[0] as Extract<EngineEvent, { type: "EvidenceLinkUpdated" }>).link).toEqual(updated);
  });

  it("updateLink throws on unknown id", () => {
    const { service } = makeFixture();
    expect(() =>
      service.updateLink("evlink_unknown" as EvidenceLinkId, { status: "verified" }),
    ).toThrow(/unknown id/);
  });

  it("setActiveEvidence emits EvidenceItemActivated with source=form-field", () => {
    const { service, events } = makeFixture();
    service.setActiveEvidence(EV1);
    const activated = events.filter((e) => e.type === "EvidenceItemActivated");
    expect(activated).toHaveLength(1);
    expect(activated[0]).toMatchObject({ evidenceItemId: EV1, source: "form-field" });
  });
});

describe("EvidenceLinkRepository (in-memory)", () => {
  it("rejects duplicate ids on create", () => {
    const repo = createInMemoryLinkRepo();
    const link: EvidenceLink = {
      id: "evlink_x" as EvidenceLinkId,
      evidenceItemId: EV1,
      targetType: "form-field",
      targetId: "f",
      relation: "supports",
      status: "candidate",
      createdAt: "2026-05-25T00:00:00.000Z",
      updatedAt: "2026-05-25T00:00:00.000Z",
    };
    repo.create(link);
    expect(() => repo.create(link)).toThrow(/duplicate/);
  });

  it("update throws on unknown id", () => {
    const repo = createInMemoryLinkRepo();
    const link: EvidenceLink = {
      id: "evlink_unknown" as EvidenceLinkId,
      evidenceItemId: EV1,
      targetType: "form-field",
      targetId: "f",
      relation: "supports",
      status: "candidate",
      createdAt: "2026-05-25T00:00:00.000Z",
      updatedAt: "2026-05-25T00:00:00.000Z",
    };
    expect(() => repo.update(link)).toThrow(/unknown/);
  });
});