/**
 * Regression: Reopen a Done-for-now thread should resume from accumulated
 * contribution history instead of restarting from the original focused question.
 *
 * Invariants verified by these simulations (mirroring reasoning-workspace.jsx
 * logic exactly):
 *   A. Fresh thread  → startFocused resets + formulates (unchanged)
 *   B. Reopened+has  → startFocused preserves accumulated state, no formulate
 *   C. Prior contrib preserved and visible
 *   D. No follow-up auto-selected
 *   E. User selects follow-up B -> B becomes active, same original targetNodeId
 *   F. Submit answer to B -> new contribution appended, previous still present
 */

import { describe, expect, it } from "vitest";

// --- helpers that mirror production code exactly ---

function simulateAppendContribution(contributions, contribution) {
  return [
    ...contributions,
    {
      ...contribution,
      id: `contrib-${String(contributions.length + 1).padStart(4, "0")}`,
      sequence: contributions.length + 1,
    },
  ];
}

/**
 * Simulates startFocused(nodeId) with priorContribs check.
 * Mirrors reasoning-workspace.jsx:1118-1158 exactly.
 * Returns {investigations, formulationCalled}.
 */
function simulateStartFocused(nodeId, focusedInvestigations, focusedContributions) {
  const target = nodeId;
  let updatedInvestigations = { ...focusedInvestigations };
  let formulationCalled = false;

  const priorContribs = (focusedContributions || []).filter(
    (c) => c.targetNodeId === target,
  );

  if (priorContribs.length > 0) {
    // Reopen path - resumes from accumulated contribution history.
    const latest = priorContribs[priorContribs.length - 1];

    updatedInvestigations = {
      ...updatedInvestigations,
      [target]: {
        status: "formulated",
        question: latest.question || "",
        answer: latest.answer ?? null,
        result: latest.possibleFollowUpQuestions
          ? {
              observations: latest.observations || [],
              uncertainties: latest.uncertainties || [],
              assumptions: latest.assumptions || [],
              relationships: latest.relationships || [],
              possibleFollowUpQuestions: latest.possibleFollowUpQuestions,
            }
          : null,
        error: null,
      },
    };

    // doFormulate is NOT called
    formulationCalled = false;
  } else {
    // Fresh thread path - unchanged original behaviour.
    updatedInvestigations = {
      ...updatedInvestigations,
      [target]: {
        status: "formulating",
        question: "",
        answer: null,
        result: null,
        error: null,
      },
    };
    formulationCalled = true;
  }

  return { investigations: updatedInvestigations, formulationCalled };
}

/** Simulates setFollowUpQuestion(followUpText). */
function simulateSetFollowUpQuestion(investigations, targetNodeId, followUpText) {
  const updated = { ...investigations };
  if (!updated[targetNodeId]) return updated;
  updated[targetNodeId] = {
    ...updated[targetNodeId],
    question: followUpText.trim(),
    answer: null,
  };
  return updated;
}

/** Simulates handleDeconstructSubmit -> appends contribution + updates investigations. */
function simulateDeconstructSubmit(investigations, focusedContributions, targetNodeId, answerText, deconstructResult) {
  // Append contribution
  const newContrib = simulateAppendContribution(focusedContributions, {
    targetNodeId,
    question: investigations[targetNodeId]?.question || "",
    answer: answerText,
    observations: deconstructResult.observations || [],
    uncertainties: deconstructResult.uncertainties || [],
    assumptions: deconstructResult.assumptions || [],
    relationships: deconstructResult.relationships || [],
    possibleFollowUpQuestions: deconstructResult.possibleFollowUpQuestions || [],
  });

  // Update investigations entry
  const updatedInvestigations = {
    ...investigations,
    [targetNodeId]: {
      ...investigations[targetNodeId],
      result: deconstructResult,
      answer: answerText,
    },
  };

  return { investigations: updatedInvestigations, contributions: newContrib };
}

// --- A. Fresh thread reopen retains existing fresh-thread behaviour ---

describe("reopen - fresh thread (no prior contributions)", () => {
  it("A: startFocused resets state and calls doFormulate when no contributions exist", () => {
    const nodeId = "nk-fresh";
    const initialInvestigations = {};
    const contributions = []; // empty - this is a fresh thread

    const result = simulateStartFocused(nodeId, initialInvestigations, contributions);

    expect(result.formulationCalled).toBe(true);
    expect(result.investigations[nodeId].status).toBe("formulating");
    expect(result.investigations[nodeId].question).toBe("");
    expect(result.investigations[nodeId].result).toBeNull();
  });

  it("A2: existing investigation state for a different node is preserved", () => {
    const freshId = "nk-fresh-2";
    const otherId = "nk-other";

    const priorState = {
      [otherId]: {
        status: "formulated",
        question: "Some other question?",
        answer: "Answer to other",
        result: null,
        error: null,
      },
    };

    const result = simulateStartFocused(freshId, priorState, []);

    expect(result.investigations[otherId].question).toBe("Some other question?");
    expect(result.investigations[freshId].status).toBe("formulating");
  });
});

// --- B. Reopened thread with contributions does NOT restart from original question ---

describe("reopen - thread with prior contributions", () => {
  it("B: startFocused does NOT call doFormulate when prior contributions exist", () => {
    const nodeId = "nk-thread";
    const contribution = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "What is the founder's tacit knowledge?",
      answer: "Most processes are undocumented.",
      observations: ["documentation is minimal"],
      uncertainties: ["formal docs can't capture tacit knowledge"],
      assumptions: ["documentation is primary mechanism"],
      relationships: [{ from: "founder", to: "processes", type: "holds" }],
      possibleFollowUpQuestions: [
        "What specific processes does the founder hold?",
        "How does knowledge transfer work in practice?",
      ],
    });

    const result = simulateStartFocused(nodeId, {}, contribution);

    expect(result.formulationCalled).toBe(false);
    expect(result.investigations[nodeId].status).toBe("formulated");
    expect(result.investigations[nodeId].question).toBe("What is the founder's tacit knowledge?");
    expect(result.investigations[nodeId].result.possibleFollowUpQuestions).toEqual([
      "What specific processes does the founder hold?",
      "How does knowledge transfer work in practice?",
    ]);
  });

  it("B2: question from original (not new formulation) is preserved", () => {
    const nodeId = "nk-thread-orig";
    const origQuestion = "Can the founder's processes be captured in documentation?";
    const contribution = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: origQuestion,
      answer: "Partially - but critical knowledge remains tacit.",
      observations: [],
      uncertainties: [],
      assumptions: [],
      relationships: [],
      possibleFollowUpQuestions: ["What specific processes are lost?"],
    });

    const result = simulateStartFocused(nodeId, {}, contribution);

    expect(result.investigations[nodeId].question).toBe(origQuestion);
  });
});

// --- C. Prior contribution remains visible/preserved ---

describe("prior contribution preservation", () => {
  it("C: prior contribution fields survive reopen", () => {
    const nodeId = "nk-preserve";
    const contrib = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "What are the core assumptions?",
      answer: "That the board has full information.",
      observations: ["board receives monthly reports"],
      uncertainties: ["whether reports contain sufficient detail"],
      assumptions: ["monthly cadence is adequate"],
      relationships: [{ from: "reports", to: "decisions", type: "informs" }],
      possibleFollowUpQuestions: ["What if reports are incomplete?"],
    });

    const result = simulateStartFocused(nodeId, {}, contrib);

    expect(result.investigations[nodeId].answer).toBe("That the board has full information.");
    expect(result.investigations[nodeId].result.observations).toEqual(["board receives monthly reports"]);
    expect(result.investigations[nodeId].result.uncertainties).toEqual(["whether reports contain sufficient detail"]);
    expect(result.investigations[nodeId].result.assumptions).toEqual(["monthly cadence is adequate"]);
    expect(result.investigations[nodeId].result.relationships).toEqual([
      { from: "reports", to: "decisions", type: "informs" },
    ]);
  });

  it("C2: multiple prior contributions - latest is restored", () => {
    const nodeId = "nk-multi";
    let contributions = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "Q1?",
      answer: "A1",
      observations: ["o1"],
      uncertainties: ["u1"],
      assumptions: ["a1"],
      relationships: [],
      possibleFollowUpQuestions: ["fuq-from-Q1"],
    });

    contributions = simulateAppendContribution(contributions, {
      targetNodeId: nodeId,
      question: "Q2?",
      answer: "A2",
      observations: ["o2"],
      uncertainties: ["u2"],
      assumptions: ["a2"],
      relationships: [],
      possibleFollowUpQuestions: ["fuq-from-Q2"],
    });

    const result = simulateStartFocused(nodeId, {}, contributions);

    expect(result.investigations[nodeId].question).toBe("Q2?");
    expect(result.investigations[nodeId].answer).toBe("A2");
    expect(result.investigations[nodeId].result.observations).toEqual(["o2"]);
  });
});

// --- D. No follow-up auto-selected after reopen ---

describe("no automatic follow-up selection on reopen", () => {
  it("D: reopened thread shows follow-ups but does not set any as active", () => {
    const nodeId = "nk-no-auto";
    const contributions = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "What remains unclear?",
      answer: "The transition timeline.",
      observations: [],
      uncertainties: ["timing is uncertain"],
      assumptions: [],
      relationships: [],
      possibleFollowUpQuestions: ["What triggers Phase 2?", "Who owns Phase 3?"],
    });

    const result = simulateStartFocused(nodeId, {}, contributions);

    // Follow-ups are visible in result but not auto-selected as the active question.
    expect(result.investigations[nodeId].result.possibleFollowUpQuestions).toHaveLength(2);
    // The active question remains what it was from prior work (not a follow-up).
    expect(result.investigations[nodeId].question).toBe("What remains unclear?");
  });
});

// --- E. User selects follow-up B -> B becomes active ---

describe("follow-up selection after reopen", () => {
  it("E: selecting a follow-up question updates the focused question, retains targetNodeId", () => {
    const nodeId = "nk-followup-e";
    let contributions = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "What are the key risks?",
      answer: "Regulatory and market risks.",
      observations: [],
      uncertainties: [],
      assumptions: [],
      relationships: [],
      possibleFollowUpQuestions: ["Follow-up A", "Follow-up B"],
    });

    let { investigations } = simulateStartFocused(nodeId, {}, contributions);

    // Verify the question from the contribution is active (not a follow-up)
    expect(investigations[nodeId].question).toBe("What are the key risks?");

    // User clicks on "Follow-up B"
    investigations = simulateSetFollowUpQuestion(investigations, nodeId, "Follow-up B");

    expect(investigations[nodeId].question).toBe("Follow-up B");
    // targetNodeId is unchanged (the original graph node ID is retained)
    expect(contributions[0].targetNodeId).toBe(nodeId);
  });
});

// --- F. Submit answer to follow-up -> appends contribution ---

describe("submitting follow-up answer appends new contribution", () => {
  it("F: deconstruct on follow-up B appends new contribution, preserves prior", () => {
    const nodeId = "nk-append-f";

    // Step 1: initial contribution (from prior session)
    let contributions = simulateAppendContribution([], {
      targetNodeId: nodeId,
      question: "Initial investigation question?",
      answer: "Initial answer.",
      observations: ["o1"],
      uncertainties: ["u1"],
      assumptions: [],
      relationships: [],
      possibleFollowUpQuestions: ["Follow-up A", "Follow-up B"],
    });

    // Step 2: reopen (simulated by startFocused restoring)
    let result = simulateStartFocused(nodeId, {}, contributions);
    let investigations = result.investigations;

    expect(investigations[nodeId].question).toBe("Initial investigation question?");

    // Step 3: user selects follow-up B
    investigations = simulateSetFollowUpQuestion(investigations, nodeId, "Follow-up B");
    expect(investigations[nodeId].question).toBe("Follow-up B");

    // Step 4: submit answer to follow-up B (re-enters existing deconstruct path)
    const deconstructResult = {
      observations: ["o2", "o3"],
      uncertainties: ["u2"],
      assumptions: ["a1"],
      relationships: [{ from: "x", to: "y", type: "depends_on" }],
      possibleFollowUpQuestions: ["Next-level question?"],
    };

    const submitResult = simulateDeconstructSubmit(
      investigations,
      contributions,
      nodeId,
      "Answer to follow-up B.",
      deconstructResult,
    );

    // New contribution appended
    expect(submitResult.contributions).toHaveLength(2);
    expect(submitResult.contributions[1].question).toBe("Follow-up B");
    expect(submitResult.contributions[1].answer).toBe("Answer to follow-up B.");

    // Previous contribution still present and unchanged
    expect(submitResult.contributions[0].question).toBe("Initial investigation question?");
    expect(submitResult.contributions[0].targetNodeId).toBe(nodeId);

    // Same original targetNodeId retained
    expect(submitResult.contributions[0].targetNodeId).toBe(submitResult.contributions[1].targetNodeId);
  });
});