/**
 * Deterministic verification of the CU synthesis experiment helper.
 *
 * Proves:
 *   - A fixed compatible input reaches synthesizeCurrentUnderstanding()
 *   - The expected structured output is captured
 *   - The production synthesis prompt includes Rule 2 boundary text
 *   - Exactly one synthesis invocation occurs
 *   - Input fixture is not mutated
 *   - No persistence operation occurs
 */

import { describe, expect, it, vi } from "vitest";
import {
  synthesizeCurrentUnderstanding,
  buildSynthesisPrompt,
} from "@/lib/graph/current-understanding-synthesis.js";

// ── Fixtures ──────────────────────────────────────────────────────

const situationGraph = {
  centralStatement: "Manufacturing complaints increased while production output rose.",
  nodes: [
    { id: "g1", label: "Complaint volume up 35%", description: "Primary complaint metric", kind: "metric", status: "known", value: 35, unit: "%" },
    { id: "g2", label: "Production output up 40%", description: "Secondary production metric", kind: "metric", status: "supported", value: 40, unit: "%" },
    { id: "g3", label: "Baseline period unclear", description: "Uncertain time window for the data", kind: "question", status: "unknown", confidence: "low" },
    { id: "g4", label: "Shift pattern change", description: "Resolved hypothesis about shift changes", kind: "hypothesis", status: "resolved", confidence: "high" },
  ],
  edges: [
    { fromNodeId: "g1", toNodeId: "g2", relationship: "correlates_with", confidence: "medium", description: "Complaints and production trends" },
  ],
  activeUnknownNodeId: "g3",
  resolvedNodeIds: ["g4"],
};

const findings = [
  { id: "f1", proposition: "Quality process breakdown during Q3 shift transition.", evaluation: "considered", userDisposition: "agree", sourceObservation: "obs-q3", contributionId: "contrib-q1" },
  { id: "f2", proposition: "Raw material supplier changed without notification.", evaluation: "considered", userDisposition: null, sourceObservation: "obs-supply", contributionId: "contrib-q2" },
];

// Deep-clone helper for immutability checks
function deepClone(obj) { return JSON.parse(JSON.stringify(obj)); }

// ── Inline test double provider (mirrors the production test pattern) ──

function makeFakeProvider(defaultResponse) {
  let callCount = 0;
  let capturedArgs = null;

  return {
    generateReconstruction: async function (prompt, modelName, schema) {
      callCount += 1;
      capturedArgs = { prompt: prompt, modelName: modelName, schema: schema };
      const response = typeof defaultResponse === "function" ? JSON.stringify(defaultResponse()) : JSON.stringify(defaultResponse || { currentUnderstanding: "Synthesized output" });
      return {
        response: response,
        providerApiPath: "/test-provider",
      };
    },
    getCallCount: function () { return callCount; },
    getCapturedArgs: function () { return capturedArgs; },
  };
}

// ── Test Suite ────────────────────────────────────────────────────

describe("CU synthesis experiment helper — deterministic verification", function () {

  // ── A. Input reaches synthesizeCurrentUnderstanding() ───────

  it("accepts a fixed compatible situationGraph and findings without error", async function () {
    const fixture = deepClone(situationGraph);
    const fixFindings = deepClone(findings);
    const fake = makeFakeProvider();

    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: fixture, findings: fixFindings },
        { provider: fake }
      )
    ).resolves.toBeDefined();

    // Verify output contract
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: fixture, findings: fixFindings },
      { provider: makeFakeProvider({ currentUnderstanding: "Verified structure" }) }
    );
    expect(result).toHaveProperty("currentUnderstanding");
    expect(typeof result.currentUnderstanding).toBe("string");
  });

  // ── B. Exactly one synthesis invocation ───────────────────────

  it("invokes production synthesizeCurrentUnderstanding exactly once", async function () {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: findings },
      { provider: fake }
    );
    expect(fake.getCallCount()).toBe(1);
  });

  // ── C. Provider receives the structured evidence projection ───

  it("provider receives an evidence projection with Known Facts and Supported Inferences headers", async function () {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: findings },
      { provider: fake }
    );
    const prompt = fake.getCapturedArgs().prompt;
    expect(prompt).toContain("Known Facts:");
    expect(prompt).toContain("Supported Inferences:");
  });

  // ── D. Rule 2 boundary text in prompt ────────────────────────

  it("production synthesis prompt includes the revised Rule 2 text about open questions and uncertainty", async function () {
    const expected = buildSynthesisPrompt(situationGraph, findings);
    expect(expected).toContain(
      "Do not introduce or describe open questions, unresolved uncertainties, assumptions, provisional hypotheses"
    );
    expect(expected.toLowerCase()).toContain("speculative explanations");
  });

  it("Rule 2 text includes the allowed exception for acknowledged knowledge gaps", async function () {
    const expected = buildSynthesisPrompt(situationGraph, findings);
    expect(expected).toContain("acknowledge a specific gap in established evidence");
  });

  // ── E. Output is captured correctly ──────────────────────────

  it("captured currentUnderstanding string matches provider output", async function () {
    const expectedText = "Deterministic CU result for apparatus verification";
    const fake = makeFakeProvider({ currentUnderstanding: expectedText });
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: findings },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe(expectedText);
  });

  it("output is the validated JSON unwrapped from provider envelope", async function () {
    const fake = makeFakeProvider(function () { return { currentUnderstanding: "envelope-tested" }; });
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: [] },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe("envelope-tested");
  });

  // ── F. Input immutability ────────────────────────────────────

  it("situationGraph is not mutated by synthesizeCurrentUnderstanding", async function () {
    const graphBefore = deepClone(situationGraph);
    const fake = makeFakeProvider();

    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: [] },
      { provider: fake }
    );

    expect(JSON.stringify(situationGraph)).toBe(JSON.stringify(graphBefore));
  });

  it("findings array is not mutated by synthesizeCurrentUnderstanding", async function () {
    const fixBefore = deepClone(findings);
    const fake = makeFakeProvider();

    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: findings },
      { provider: fake }
    );

    expect(JSON.stringify(findings)).toBe(JSON.stringify(fixBefore));
  });

  // ── G. No persistence operations ─────────────────────────────

  it("synthesizeCurrentUnderstanding does not invoke Supabase or DB write — only calls generateReconstruction", async function () {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: [] },
      { provider: fake }
    );

    // The only side effect should be the single generateReconstruction call.
    expect(fake.getCallCount()).toBe(1);

    // Verify the method called matches what we expect from the domain seam.
    const args = fake.getCapturedArgs();
    expect(typeof args.prompt).toBe("string");
    expect(args.schema).toBeDefined();
  });

  // ── H. Schema passed to provider ─────────────────────────────

  it("provider receives synthesisOutputSchema as third argument", async function () {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: [] },
      { provider: fake }
    );
    const args = fake.getCapturedArgs();
    expect(args.schema).toEqual({
      type: "object",
      properties: { currentUnderstanding: { type: "string" } },
      required: ["currentUnderstanding"],
      additionalProperties: false,
    });
  });

  // ── I. Input validation still enforced ───────────────────────

  it("missing situationGraph throws with statusCode 400", async function () {
    const fake = makeFakeProvider();
    await expect(
      synthesizeCurrentUnderstanding({}, { provider: fake })
    ).rejects.toThrow(/situationGraph is required/);
  });

  it("findings as non-array throws with statusCode 400", async function () {
    const fake = makeFakeProvider();
    await expect(
      synthesizeCurrentUnderstanding({ situationGraph: situationGraph, findings: "not-array" }, { provider: fake })
    ).rejects.toThrow(/findings must be an array/);
  });

  // ── J. Full apparatus integration test (mirrors the helper output) ─

  it("apparatus captures all required fields in deterministic mode", async function () {
    const graphBefore = deepClone(situationGraph);
    const fixBefore = deepClone(findings);
    const fake = makeFakeProvider();

    const startMs = Date.now();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: situationGraph, findings: findings },
      { provider: fake }
    );
    const elapsedMs = Date.now() - startMs;

    // Reproduce the helper's output shape
    const apparatusOutput = {
      success: true,
      mode: "deterministic-no-network",
      fixtureNodes: situationGraph.nodes.length,
      fixtureEdges: situationGraph.edges ? situationGraph.edges.length : 0,
      findingsCount: findings.length,
      elapsedMs: elapsedMs,
      currentUnderstandingLength: result.currentUnderstanding ? result.currentUnderstanding.length : 0,
      synthesisInvocations: fake.getCallCount(),
      rule2Present: buildSynthesisPrompt(situationGraph, findings).indexOf("Do not introduce or describe open questions") !== -1,
      outputValidated: true,
    };

    // Core apparatus invariants
    expect(apparatusOutput.success).toBe(true);
    expect(apparatusOutput.mode).toBe("deterministic-no-network");
    expect(apparatusOutput.fixtureNodes).toBeGreaterThan(0);
    expect(apparatusOutput.findingsCount).toBe(findings.length);
    expect(apparatusOutput.elapsedMs).toBeGreaterThanOrEqual(0);
    expect(typeof apparatusOutput.currentUnderstandingLength).toBe("number");
    expect(apparatusOutput.synthesisInvocations).toBe(1);
    expect(apparatusOutput.rule2Present).toBe(true);
    expect(apparatusOutput.outputValidated).toBe(true);

    // Immutability post-run
    expect(JSON.stringify(situationGraph)).toBe(JSON.stringify(graphBefore));
    expect(JSON.stringify(findings)).toBe(JSON.stringify(fixBefore));
  });
});