/**
 * Experiment 21 — Question Relevance to Decision Target.
 *
 * Tests assessQuestionRelevanceToDecision against explicit decision targets
 * and the long-investigation scenario fixture.
 */

import { describe, expect, it } from "vitest";
import { assessQuestionRelevanceToDecision } from "@/lib/graph/question-decision-relevance.js";
import { buildScenarioFixture } from "@/lib/mocks/scenarios.js";

/* ── Helpers ─────────────────────────────────────────────────── */

const DECISION_TARGET = "Should we enter the European market with our SaaS analytics platform?";

function makeUnknown(id, label) {
  return {
    id, label: label || `Unknown ${id}`, description: label || `Unknown ${id}`,
    kind: "unknown", status: "unknown", confidence: "low",
    value: null, unit: null, evidenceIds: [], dependsOn: [], affects: [], childIds: [],
  };
}

function makeGraphFor(nodes) {
  return {
    nodes, edges: [], resolvedNodeIds: [], activeUnknownNodeId: null,
    centralStatement: "Test", currentSummary: "Test", reasoningState: null,
  };
}

/* ── Could change decision ───────────────────────────────────── */

describe("assessQuestionRelevanceToDecision — could_change_decision", () => {
  it("classifies a direct go/no-go question against the decision target", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("g1", "Whether to proceed with European market entry"),
    });

    expect(result.relevance).toBe("could_change_decision");
    expect(typeof result.reason).toBe("string");
    expect(result.reason.length).toBeGreaterThan(0);
  });

  it("classifies a 'whether we should enter' question as could_change_decision", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("g2", "Whether we should enter the European market"),
    });

    expect(result.relevance).toBe("could_change_decision");
  });

  it("is deterministic for identical inputs", () => {
    const node = makeUnknown("g3", "Whether to proceed with expansion into Europe");
    const input = { decisionTarget: DECISION_TARGET, unknown: node };
    const r1 = assessQuestionRelevanceToDecision(input);
    const r2 = assessQuestionRelevanceToDecision(input);
    expect(r1).toEqual(r2);
  });
});

/* ── Supports decision ───────────────────────────────────────── */

describe("assessQuestionRelevanceToDecision — supports_decision", () => {
  it("classifies a compliance question as supports_decision (necessary precondition)", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("c1", "Whether our product is suitable for European compliance requirements"),
    });

    expect(result.relevance).toBe("supports_decision");
  });

  it("classifies a cost justification question as supports_decision (feasibility)", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("c2", "Whether the cost of achieving compliance is justified by the market size"),
    });

    expect(result.relevance).toBe("supports_decision");
  });

  it("classifies a differentiation question as supports_decision (supporting context)", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("c3", "Whether we have competitive differentiation against existing European players"),
    });

    expect(result.relevance).toBe("supports_decision");
  });

  it("classifies a feasibility question as supports_decision even without precondition keywords", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("c4", "Is the investment of $500K and six months justified by potential returns"),
    });

    expect(result.relevance).toBe("supports_decision");
  });
});

/* ── Unlikely to change decision ─────────────────────────────── */

describe("assessQuestionRelevanceToDecision — unlikely_to_change_decision", () => {
  it("classifies a background comparison as unlikely_to_change_decision", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: makeUnknown("b1", "What benchmarks do other SaaS companies use for market sizing"),
    });

    expect(result.relevance).toBe("unlikely_to_change_decision");
  });
});

/* ── Cannot determine — missing input ────────────────────────── */

describe("assessQuestionRelevanceToDecision — cannot_determine (missing input)", () => {
  it("returns cannot_determine when decisionTarget is missing", () => {
    const result = assessQuestionRelevanceToDecision({
      unknown: makeUnknown("m1", "Whether to enter Europe"),
    });

    expect(result.relevance).toBe("cannot_determine");
  });

  it("returns cannot_determine when decisionTarget is empty string", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: "",
      unknown: makeUnknown("m2", "Whether to enter Europe"),
    });

    expect(result.relevance).toBe("cannot_determine");
  });

  it("returns cannot_determine when unknown is missing", () => {
    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
    });

    expect(result.relevance).toBe("cannot_determine");
  });

  it("returns cannot_determine when unknown has empty label and description", () => {
    const node = makeUnknown("m3", "");
    node.label = "";
    node.description = "";

    const result = assessQuestionRelevanceToDecision({
      decisionTarget: DECISION_TARGET,
      unknown: node,
    });

    expect(result.relevance).toBe("cannot_determine");
  });

  it("returns cannot_determine when no input object is provided", () => {
    const result = assessQuestionRelevanceToDecision(null);
    expect(result.relevance).toBe("cannot_determine");
  });
});

/* ── Input immutability ──────────────────────────────────────── */

describe("assessQuestionRelevanceToDecision — input immutability", () => {
  it("does not mutate the unknown node", () => {
    const node = makeUnknown("i1", "Whether to proceed with European market entry");
    const snapshot = JSON.parse(JSON.stringify(node));
    assessQuestionRelevanceToDecision({ decisionTarget: DECISION_TARGET, unknown: node });
    expect(node).toEqual(snapshot);
  });

  it("does not mutate the graph (when provided)", () => {
    const node = makeUnknown("i2", "Whether to proceed with European market entry");
    const graph = makeGraphFor([node]);
    const originalNodesJSON = JSON.stringify(graph.nodes);
    assessQuestionRelevanceToDecision({ decisionTarget: DECISION_TARGET, unknown: node, graph });
    expect(JSON.stringify(graph.nodes)).toBe(originalNodesJSON);
  });

  it("does not mutate the decisionTarget string", () => {
    const dt = "Should we enter the European market with our SaaS analytics platform?";
    assessQuestionRelevanceToDecision({ decisionTarget: dt, unknown: makeUnknown("i3", "test") });
    expect(dt).toBe("Should we enter the European market with our SaaS analytics platform?");
  });
});

/* ── Complete long-investigation sequence ─────────────────────── */

describe("assessQuestionRelevanceToDecision — long investigation sequence", () => {
  const scenarioName = "long";
  const turnCount = 5;

  const allResults = [];

  for (let t = 0; t < turnCount; t++) {
    const fixture = buildScenarioFixture(scenarioName, t);
    expect(fixture).not.toBeNull(`Turn ${t} should have a valid fixture`);

    // Use the centralStatement as decision target (present in every turn)
    const decisionTarget = fixture.situationGraph.centralStatement;
    const resolvedIds = new Set(fixture.situationGraph.resolvedNodeIds || []);

    for (const node of fixture.situationGraph.nodes) {
      if (node.kind !== "unknown") continue;
      if (resolvedIds.has(node.id)) continue;

      const result = assessQuestionRelevanceToDecision({
        decisionTarget,
        unknown: node,
        graph: fixture.situationGraph,
      });

      allResults.push({ turn: t, nodeId: node.id, label: node.label, relevance: result.relevance, reason: result.reason });
    }
  }

  it("every unresolved unknown across all turns receives a valid relevance classification", () => {
    const validCategories = ["could_change_decision", "supports_decision", "unlikely_to_change_decision", "cannot_determine"];
    for (const r of allResults) {
      expect(validCategories).toContain(r.relevance);
    }
  });

  it("the complete long-investigation sequence runs without error and produces results", () => {
    expect(allResults.length).toBeGreaterThan(0);
  });

  it("produces more than one distinct relevance category across the sequence", () => {
    const distinct = new Set(allResults.map((r) => r.relevance));
    expect(distinct.size).toBeGreaterThanOrEqual(2);
  });

  it("category distribution across the full sequence", () => {
    const categories = {};
    for (const r of allResults) {
      categories[r.relevance] = (categories[r.relevance] || 0) + 1;
    }
    console.log("\n=== Experiment 21 — Classification Results ===");
    console.log(`Total unresolved unknowns classified: ${allResults.length}`);
    console.log("Category distribution:", JSON.stringify(categories, null, 2));
    expect(allResults.length).toBeGreaterThan(0);
  });

  it("detailed per-turn classifications", () => {
    const byTurn = {};
    for (const r of allResults) {
      if (!byTurn[r.turn]) byTurn[r.turn] = [];
      byTurn[r.turn].push(r);
    }
    for (const [turn, results] of Object.entries(byTurn)) {
      console.log(`\n--- Turn ${turn} (${results.length} unresolved unknowns) ---`);
      for (const r of results) {
        const shortLabel = r.label?.length > 60 ? r.label.slice(0, 60) + "..." : r.label;
        console.log(`  [${r.relevance}] ${shortLabel}`);
      }
    }
    expect(allResults.length).toBeGreaterThan(0);
  });

  it("Turn 0 (market demand question) is classified as could_change_decision", () => {
    const turn0 = allResults.find((r) => r.turn === 0);
    expect(turn0).toBeDefined();
    expect(turn0.relevance).toBe("could_change_decision");
  });

  it("Turns 1-3 (compliance, cost, differentiation) are classified as supports_decision", () => {
    const turns1to3 = allResults.filter((r) => r.turn >= 1 && r.turn <= 3);
    for (const r of turns1to3) {
      expect(r.relevance).toBe("supports_decision");
    }
  });

  it("all classified questions include a non-empty reason", () => {
    for (const r of allResults) {
      if (r.relevance !== "cannot_determine") {
        expect(typeof r.reason).toBe("string");
        expect(r.reason.length).toBeGreaterThan(0);
      }
    }
  });
});

/* ── Comparison with Experiment 20: different categories produced ─ */

describe("assessQuestionRelevanceToDecision — comparison with Experiment 20 collapse", () => {
  it("does not collapse entirely to one category across the long investigation", () => {
    const scenarioName = "long";
    const results = [];

    for (let t = 0; t < 5; t++) {
      const fixture = buildScenarioFixture(scenarioName, t);
      if (!fixture) continue;
      const decisionTarget = fixture.situationGraph.centralStatement;
      const resolvedIds = new Set(fixture.situationGraph.resolvedNodeIds || []);

      for (const node of fixture.situationGraph.nodes) {
        if (node.kind !== "unknown") continue;
        if (resolvedIds.has(node.id)) continue;

        results.push(assessQuestionRelevanceToDecision({ decisionTarget, unknown: node }));
      }
    }

    const distinct = new Set(results.map((r) => r.relevance));
    expect(distinct.size).toBeGreaterThan(1);
  });
});