import { describe, expect, it } from "vitest";
import {
  isCompleteJson,
  salvageTruncatedPayload,
} from "../src/llm/truncation.js";

describe("isCompleteJson", () => {
  it("accepts complete objects and empty", () => {
    expect(isCompleteJson('{"content":"x"}')).toBe(true);
    expect(isCompleteJson("")).toBe(true);
  });

  it("rejects truncated objects", () => {
    expect(isCompleteJson('{"content":"第一章')).toBe(false);
  });
});

describe("salvageTruncatedPayload", () => {
  it("returns null when the field never started", () => {
    expect(salvageTruncatedPayload('{"content', ["content"])).toBeNull();
    expect(salvageTruncatedPayload('{"other":"x"}', ["content"])).toBeNull();
  });

  it("keeps the generated text before the cut", () => {
    const raw = '{"content":"第一章\\n她推开门';
    expect(salvageTruncatedPayload(raw, ["content"])).toEqual({
      field: "content",
      text: "第一章\n她推开门",
    });
  });

  it("stops at the closing quote when the value is complete", () => {
    const raw = '{"content":"正文","outputTags":["a"';
    expect(salvageTruncatedPayload(raw, ["content"])?.text).toBe("正文");
  });

  it("tries fields in order", () => {
    const raw = '{"display_stream":"走了","content":"没到"';
    expect(salvageTruncatedPayload(raw, ["content", "display_stream"])?.field).toBe(
      "content",
    );
    expect(
      salvageTruncatedPayload('{"display_stream":"走了', [
        "content",
        "display_stream",
      ])?.field,
    ).toBe("display_stream");
  });

  it("decodes unicode escapes and skips dangling escapes", () => {
    expect(
      salvageTruncatedPayload('{"content":"\\u7b2c\\u4e00\\u7ae0', [
        "content",
      ])?.text,
    ).toBe("第一章");
    expect(
      salvageTruncatedPayload('{"content":"收尾\\', ["content"])?.text,
    ).toBe("收尾");
  });
});