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

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

const canonicalGraph = {
  centralStatement: "Revenue dropped 30% in Q2 due to supply chain disruption.",
  nodes: [
    { id: "n1", proposition: "Q1 revenue was stable", description: "Baseline metric", status: "confirmed", confidence: 0.95 },
    { id: "n2", proposition: "Supplier A failed deliveries in May", description: "Primary cause", status: "active", confidence: 0.85 },
    { id: "n3", proposition: "Customer churn increased by 12%", description: "Secondary effect", status: "active", confidence: 0.7 },
  ],
  edges: [
    { from: "n2", to: "n3", type: "causal", context: "Supply failure led to customer dissatisfaction" },
    { from: "n1", to: "n2", type: "temporal", context: "Preceding event in causal chain" },
  ],
};

const makeFinding = (overrides = {}) => ({
  id: `find-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
  proposition: "Supplier delays caused production halts",
  evaluation: "considered",
  userDisposition: null,
  sourceObservation: "obs-1",
  contributionId: "contrib-001",
  ...overrides,
});

// Fake provider factory for tests — always has generateReconstruction
// If defaultResponse is passed, use it; otherwise default to success.
const makeFakeProvider = (defaultResponse) => ({
  generateReconstruction: vi.fn(async () => {
    return typeof defaultResponse === "function"
      ? defaultResponse()
      : JSON.stringify({ currentUnderstanding: "Synthesized output" });
  }),
});

// ── Eligibility tests ───────────────────────────────────────

describe("filterEligibleFindings — eligibility contract", () => {
  it("includes null disposition → eligible", () => {
    const findings = [makeFinding({ userDisposition: null })];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(1);
    expect(result[0].userDisposition).toBeNull();
  });

  it("includes agree disposition → eligible", () => {
    const findings = [makeFinding({ userDisposition: "agree" })];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(1);
    expect(result[0].userDisposition).toBe("agree");
  });

  it("excludes not_quite disposition → ineligible", () => {
    const findings = [makeFinding({ userDisposition: "not_quite" })];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(0);
  });

  it("excludes not_relevant disposition → ineligible", () => {
    const findings = [makeFinding({ userDisposition: "not_relevant" })];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(0);
  });

  it("excludes rejected evaluation → excluded", () => {
    const findings = [makeFinding({ evaluation: "rejected" })];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(0);
  });

  it("mixed dispositions — only eligible pass through", () => {
    const findings = [
      makeFinding({ userDisposition: null, id: "f1" }),
      makeFinding({ userDisposition: "agree", id: "f2" }),
      makeFinding({ userDisposition: "not_quite", id: "f3" }),
      makeFinding({ userDisposition: "not_relevant", id: "f4" }),
      makeFinding({ evaluation: "rejected", id: "f5" }),
    ];
    const result = filterEligibleFindings(findings);
    expect(result).toHaveLength(2);
    expect(result.map((f) => f.id)).toEqual(["f1", "f2"]);
  });

  it("null input returns empty array", () => {
    expect(filterEligibleFindings(null)).toEqual([]);
    expect(filterEligibleFindings(undefined)).toEqual([]);
    expect(filterEligibleFindings([])).toEqual([]);
  });
});

// ── Prompt content tests ────────────────────────────────────

describe("buildSynthesisPrompt — full graph input", () => {
  it("includes full canonical graph: nodes, edges, centralStatement (not just centralStatement)", () => {
    const prompt = buildSynthesisPrompt(canonicalGraph, []);
    expect(prompt).toContain("Canonical Situation Graph");
    expect(prompt).toContain("Revenue dropped 30%");

    // Verify nodes are included with content beyond centralStatement
    expect(prompt).toContain('Node(n1)');
    expect(prompt).toContain("Q1 revenue was stable");
    expect(prompt).toContain('Node(n2)');
    expect(prompt).toContain("Supplier A failed deliveries in May");

    // Verify edges are included
    expect(prompt).toContain("Edge(n2 → n3");
    expect(prompt).toContain("causal");
    expect(prompt).toContain("Edge(n1 → n2");
    expect(prompt).toContain("temporal");

    // Verify centralStatement value is present (not just the key name)
    expect(prompt).toContain("supply chain disruption");
  });

  it("includes eligible Finding propositions in prompt", () => {
    const findings = [makeFinding({ userDisposition: "agree" })];
    const prompt = buildSynthesisPrompt(canonicalGraph, findings);
    expect(prompt).toContain("Supplier delays caused production halts");
  });

  it("excludes non-eligible Finding propositions from prompt", () => {
    const ineligibleFindings = [makeFinding({ userDisposition: "not_quite" })];
    const eligibleFindings = filterEligibleFindings(ineligibleFindings);
    const prompt = buildSynthesisPrompt(canonicalGraph, eligibleFindings);
    expect(prompt).toContain("Eligible Findings");
    // The excluded proposition must not appear because eligible findings is empty
    expect(eligibleFindings).toHaveLength(0);
  });

  it("includes provisional (null disposition) findings", () => {
    const findings = [makeFinding({ userDisposition: null })];
    const prompt = buildSynthesisPrompt(canonicalGraph, findings);
    expect(prompt).toContain("Provisional Findings");
    expect(prompt).toContain("Supplier delays caused production halts");
  });

  it("includes confirmed (agree) findings", () => {
    const findings = [makeFinding({ userDisposition: "agree" })];
    const prompt = buildSynthesisPrompt(canonicalGraph, findings);
    expect(prompt).toContain("Confirmed Evidence");
  });

  it("handles zero eligible Findings — synthesis still proceeds from graph alone", () => {
    const prompt = buildSynthesisPrompt(canonicalGraph, []);
    expect(prompt).toContain("(none)");
    // Must still contain graph content
    expect(prompt).toContain("Canonical Situation Graph");
  });

  it("prompt contains fresh-synthesis instructions (not append semantics)", () => {
    const prompt = buildSynthesisPrompt(canonicalGraph, []);
    expect(prompt).toContain("FRESH synthesis");
    expect(prompt).toContain("Do NOT treat any previous Current Understanding as input");
    expect(prompt).toContain("Do NOT append to prior summaries");
  });

  it("prompt does NOT request graph mutations or Finding mutations", () => {
    const prompt = buildSynthesisPrompt(canonicalGraph, []);
    expect(prompt).not.toMatch(/change\s+selectedQuestion/i);
  });
});

// ── Output validation tests ─────────────────────────────────

describe("validateSynthesisResponse", () => {
  it("accepts valid narrative JSON object", () => {
    const result = validateSynthesisResponse({ currentUnderstanding: "The data shows X" });
    expect(result.valid).toBe(true);
    expect(result.data.currentUnderstanding).toBe("The data shows X");
  });

  it("accepts valid narrative JSON string", () => {
    const result = validateSynthesisResponse('{"currentUnderstanding": "parsed"}');
    expect(result.valid).toBe(true);
    expect(result.data.currentUnderstanding).toBe("parsed");
  });

  it("rejects missing currentUnderstanding field", () => {
    const result = validateSynthesisResponse({ summary: "wrong field" });
    expect(result.valid).toBe(false);
  });

  it("rejects empty string narrative", () => {
    const result = validateSynthesisResponse({ currentUnderstanding: "" });
    expect(result.valid).toBe(false);
  });

  it("rejects malformed JSON string", () => {
    const result = validateSynthesisResponse("not json at all [[[");
    expect(result.valid).toBe(false);
  });

  it("rejects null input", () => {
    const result = validateSynthesisResponse(null);
    expect(result.valid).toBe(false);
  });

  it("rejects undefined input", () => {
    const result = validateSynthesisResponse(undefined);
    expect(result.valid).toBe(false);
  });
});

// ── Domain function tests ───────────────────────────────────

describe("synthesizeCurrentUnderstanding — full seam", () => {
  it("null disposition finding → included in synthesis", async () => {
    const fake = makeFakeProvider();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ userDisposition: null })] },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe("Synthesized output");
    expect(fake.generateReconstruction).toHaveBeenCalledTimes(1);
    const prompt = fake.generateReconstruction.mock.calls[0][0];
    expect(prompt).toContain("Supplier delays caused production halts");
  });

  it("agree disposition finding → included in synthesis", async () => {
    const fake = makeFakeProvider();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ userDisposition: "agree" })] },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe("Synthesized output");
  });

  it("not_quite disposition finding → excluded from synthesis", async () => {
    const fake = makeFakeProvider();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ userDisposition: "not_quite" })] },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe("Synthesized output");
    const prompt = fake.generateReconstruction.mock.calls[0][0];
    // The not_quite proposition must NOT appear because it was excluded by eligibility
    expect(prompt).toContain("(none)");
    expect(prompt).not.toContain("Supplier delays caused production halts");
  });

  it("not_relevant disposition finding → excluded from synthesis", async () => {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ userDisposition: "not_relevant" })] },
      { provider: fake }
    );
    const prompt = fake.generateReconstruction.mock.calls[0][0];
    expect(prompt).toContain("(none)");
  });

  it("rejected evaluation → excluded from synthesis", async () => {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ evaluation: "rejected" })] },
      { provider: fake }
    );
    const prompt = fake.generateReconstruction.mock.calls[0][0];
    expect(prompt).toContain("(none)");
  });

  it("zero eligible Findings → synthesis succeeds from graph alone", async () => {
    const fake = makeFakeProvider();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [] },
      { provider: fake }
    );
    expect(result.currentUnderstanding).toBe("Synthesized output");
    const prompt = fake.generateReconstruction.mock.calls[0][0];
    // Must still contain graph content
    expect(prompt).toContain("Canonical Situation Graph");
    expect(prompt).toContain("Node(n1)");
  });

  it("fake provider returns valid narrative → { currentUnderstanding }", async () => {
    const fake = makeFakeProvider();
    const result = await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [makeFinding({ userDisposition: "agree" })] },
      { provider: fake }
    );
    expect(result).toEqual({ currentUnderstanding: "Synthesized output" });
  });

  it("fake provider returns empty narrative → rejected", async () => {
    const fake = makeFakeProvider(async () => JSON.stringify({ currentUnderstanding: "" }));
    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        { provider: fake }
      )
    ).rejects.toThrow(/Synthesis validation failed/);
  });

  it("fake provider returns malformed JSON → rejected", async () => {
    const fake = makeFakeProvider(async () => "{ not valid json");
    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        { provider: fake }
      )
    ).rejects.toThrow(/Synthesis validation failed/);
  });

  it("fake provider returns object without currentUnderstanding → rejected", async () => {
    const fake = makeFakeProvider(async () => JSON.stringify({ wrongField: "value" }));
    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        { provider: fake }
      )
    ).rejects.toThrow(/Synthesis validation failed/);
  });

  // ── Immutability tests ────────────────────────────────────

  it("graph structurally unchanged after synthesis", async () => {
    const graphSnapshot = JSON.parse(JSON.stringify(canonicalGraph));
    const fake = makeFakeProvider();

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

    expect(JSON.stringify(canonicalGraph)).toBe(JSON.stringify(graphSnapshot));
  });

  it("findings structurally unchanged after synthesis", async () => {
    const findings = [makeFinding({ userDisposition: "agree" })];
    const findingsSnapshot = JSON.parse(JSON.stringify(findings));
    const fake = makeFakeProvider();

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

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

  // ── Input validation tests ────────────────────────────────

  it("missing situationGraph → throws 400", async () => {
    await expect(
      synthesizeCurrentUnderstanding({}, { provider: makeFakeProvider() })
    ).rejects.toThrow(/situationGraph is required/);
  });

  it("non-object situationGraph → throws 400", async () => {
    await expect(
      synthesizeCurrentUnderstanding({ situationGraph: "not an object" }, { provider: makeFakeProvider() })
    ).rejects.toThrow(/situationGraph is required/);
  });

  it("findings as non-array → throws 400", async () => {
    await expect(
      synthesizeCurrentUnderstanding({ situationGraph: canonicalGraph, findings: "string" }, { provider: makeFakeProvider() })
    ).rejects.toThrow(/findings must be an array/);
  });

  it("provider generateReconstruction throws → statusCode 502", async () => {
    const fake = makeFakeProvider(async () => { throw new Error("provider down"); });
    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        { provider: fake }
      )
    ).rejects.toThrow(/Synthesis provider call failed|provider down/);
  });

  it("no provider provided — falls through to getProvider() which needs env vars", async () => {
    await expect(
      synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        {}
      )
    ).rejects.toThrow(/OLLAMA_BASE_URL/);
  });


  // ── Configured model resolution ──────────────────────────

  it("default synthesis path resolves configured modelName — provider receives non-null", async () => {
    const fake = makeFakeProvider();

    // Stub the configured model so test does not depend on dev-machine .env.local
    const savedModel = process.env.OLLAMA_MODEL;
    process.env.OLLAMA_MODEL = "configured-model-v0.50";

    try {
      const result = await synthesizeCurrentUnderstanding(
        { situationGraph: canonicalGraph, findings: [] },
        { provider: fake }
      );

      expect(result.currentUnderstanding).toBe("Synthesized output");

      // KEY ASSERTION: configured model must flow to provider
      const receivedModel = fake.generateReconstruction.mock.calls[0][1];
      expect(receivedModel).toBeDefined();
      expect(receivedModel).not.toBeNull();
      expect(typeof receivedModel).toBe("string");
      expect(receivedModel.length).toBeGreaterThan(0);
    } finally {
      // Restore original env value (may be undefined)
      if (savedModel == null) {
        delete process.env.OLLAMA_MODEL;
      } else {
        process.env.OLLAMA_MODEL = savedModel;
      }
    }
  });

  it("explicit modelName dependency overrides default — provider receives injected model", async () => {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [] },
      { provider: fake, modelName: "test-model-v0.50" }
    );

    expect(fake.generateReconstruction.mock.calls[0][1]).toBe("test-model-v0.50");
  });

  // ── Provider sees full graph, not just centralStatement ───

  it("provider receives full canonical graph content (nodes + edges + centralStatement)", async () => {
    const fake = makeFakeProvider();
    await synthesizeCurrentUnderstanding(
      { situationGraph: canonicalGraph, findings: [] },
      { provider: fake }
    );

    const prompt = fake.generateReconstruction.mock.calls[0][0];
    // Must contain node content (not just centralStatement)
    expect(prompt).toContain("Node(n1)");
    expect(prompt).toContain("Q1 revenue was stable");
    expect(prompt).toContain("Node(n2)");
    expect(prompt).toContain("Supplier A failed deliveries in May");
    // Must contain edge content
    expect(prompt).toContain("Edge(n2 → n3");
    expect(prompt).toContain("causal");
    // Must contain centralStatement value
    expect(prompt).toContain("Revenue dropped 30%");
    // Must instruct about fresh synthesis (not previous CU)
    expect(prompt).toContain("Do NOT treat any previous Current Understanding as input");
  });
});