import { describe, it, expect } from "vitest";
import { createHash } from "node:crypto";

/**
 * TEST-ONLY helper. Not exported into production.
 *
 * Creates a deterministic source record from raw user input.
 * This exists only to test whether trustworthy source identity
 * can be established before any LLM interpretation occurs.
 */
function createSourceRecord(rawInput) {
  // Defensive clone so the caller's original string is never mutated
  const verbatimText = String(rawInput);

  const record = {
    sourceId: createHash("sha256")
      .update(verbatimText, "utf8")
      .digest("hex"),
    sourceType: "user_input",
    verbatimText,
  };

  return record;
}

// ──────────────────────────────────────────────
// Four fixed inputs (Experiment 54H)
// ──────────────────────────────────────────────

const CASE_1 = "The business has lost three major customers this year.";
const CASE_2 = "Three major customers have left the business this year.";
const CASE_3 = "Revenue is down. I think pricing may be part of the problem, but I am not sure.";
const CASE_4 = "The business has lost three major customers this year."; // identical to Case 1

describe("Deterministic source record (Exp 54H — test-only)", () => {
  it("Case 1: verbatimText equals the exact input string", () => {
    const record = createSourceRecord(CASE_1);
    expect(record.verbatimText).toBe(CASE_1);
  });

  it("Case 2 (paraphrase): sourceType is always user_input", () => {
    const record2 = createSourceRecord(CASE_2);
    const record3 = createSourceRecord(CASE_3);
    expect(record2.sourceType).toBe("user_input");
    expect(record3.sourceType).toBe("user_input");
  });

  it("Case 1 and Case 4 produce identical sourceId", () => {
    const r1 = createSourceRecord(CASE_1);
    const r4 = createSourceRecord(CASE_4);
    expect(r1.sourceId).toBe(r4.sourceId);
  });

  it("Case 1 and Case 2 produce different sourceIds despite similar meaning", () => {
    const r1 = createSourceRecord(CASE_1);
    const r2 = createSourceRecord(CASE_2);
    expect(r1.sourceId).not.toBe(r2.sourceId);
  });

  it("Case 3: multi-sentence verbatim text is preserved unchanged", () => {
    const record = createSourceRecord(CASE_3);
    expect(record.verbatimText).toBe(CASE_3);
  });

  it("Input string is not mutated by createSourceRecord", () => {
    let originalLength = CASE_1.length;
    createSourceRecord(CASE_1);
    expect(CASE_1.length).toBe(originalLength);
    // Also verify no characters were altered (strings are immutable in JS,
    // but be explicit about the contract)
    const r = createSourceRecord(CASE_1);
    expect(r.verbatimText).toBe(CASE_1);
  });

  it("Helper output is deterministic across repeated calls", () => {
    const rA = createSourceRecord(CASE_1);
    const rB = createSourceRecord(CASE_1);
    const rC = createSourceRecord(CASE_2);
    expect(rA).toEqual(rB);
    expect(rA.sourceId).not.toBe(rC.sourceId);
  });

  it("No interpretation or summarisation occurs in the source record", () => {
    // The record must contain only source identity fields, never
    // evidence type, confidence, relevance, summary, etc.
    const record = createSourceRecord(CASE_3);
    const keys = Object.keys(record);
    expect(keys).toEqual(expect.arrayContaining(["sourceId", "sourceType", "verbatimText"]));
    expect(keys.length).toBe(3);
    // No extra fields that would imply interpretation
    expect(keys).not.toContain("evidenceType");
    expect(keys).not.toContain("confidence");
    expect(keys).not.toContain("relevance");
    expect(keys).not.toContain("summary");
    expect(keys).not.toContain("interpretation");
  });

  it("Different inputs produce different IDs (distinct text)", () => {
    const r1 = createSourceRecord(CASE_1);
    const r2 = createSourceRecord(CASE_2);
    const r3 = createSourceRecord(CASE_3);
    expect(r1.sourceId).not.toBe(r2.sourceId);
    expect(r1.sourceId).not.toBe(r3.sourceId);
    expect(r2.sourceId).not.toBe(r3.sourceId);
  });
});