function normaliseText(value) {
  return String(value || "")
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, " ")
    .trim();
}

function sentenceCase(value) {
  const trimmed = String(value || "").trim();
  if (!trimmed) return "this uncertainty";
  return trimmed.charAt(0).toLowerCase() + trimmed.slice(1);
}

function buildNodeMap(graph) {
  return new Map((graph?.nodes || []).map((node) => [node.id, node]));
}

function collectRelatedNodes(node, graph) {
  if (!node || !graph) return [];

  const nodesById = buildNodeMap(graph);
  const relatedIds = new Set([
    ...(node.dependsOn || []),
    ...(node.affects || []),
    ...(node.childIds || []),
  ]);

  if (node.parentId) {
    relatedIds.add(node.parentId);
  }

  for (const edge of graph.edges || []) {
    if (edge.fromNodeId === node.id) {
      relatedIds.add(edge.toNodeId);
    }
    if (edge.toNodeId === node.id) {
      relatedIds.add(edge.fromNodeId);
    }
  }

  return [...relatedIds].map((nodeId) => nodesById.get(nodeId)).filter(Boolean);
}

function collectResolvedContextValues(graph) {
  const resolvedSet = new Set(graph?.resolvedNodeIds || []);

  return (graph?.nodes || [])
    .filter((node) => resolvedSet.has(node.id))
    .map((node) => node.value)
    .filter((value) => typeof value === "string" && value.trim().length > 0);
}

function extractMeaning(node) {
  const raw = `${node?.label || ""} ${node?.description || ""}`.trim();
  let meaning = String(
    node?.label || node?.description || "this uncertainty",
  ).trim();

  const lowered = normaliseText(raw);
  if (
    /\b(customer|user|buyer|stakeholder|recipient|audience)\b/.test(lowered)
  ) {
    return "the relevant customer, user, or value recipient";
  }

  meaning = meaning
    .replace(/^uncertainty regarding\s+/i, "")
    .replace(/^uncertainty about\s+/i, "")
    .replace(/^lack of\s+/i, "")
    .replace(/^unknown\s+/i, "")
    .replace(/^whether\s+/i, "")
    .replace(/^the\s+/, "")
    .trim();

  if (!meaning) {
    return "this uncertainty";
  }

  return sentenceCase(meaning);
}

function extractActionPhrase(texts) {
  for (const text of texts) {
    const value = String(text || "").trim();
    if (!value) continue;

    const matches = [
      value.match(/\b(?:whether|deciding|decision) to\s+([^.,;:]+)/i),
      value.match(/\b(?:justify|continuing|proceeding with)\s+([^.,;:]+)/i),
      value.match(
        /\b(build|launch|adopt|buy|continue|proceed|invest in|fund)\s+([^.,;:]+)/i,
      ),
    ].filter(Boolean);

    const match = matches[0];
    if (!match) continue;

    const phrase = (match[1] || `${match[1] || ""} ${match[2] || ""}`)
      .replace(/^to\s+/i, "")
      .trim();

    if (phrase) {
      return phrase;
    }
  }

  return null;
}

function toGerundPhrase(phrase) {
  const trimmed = String(phrase || "").trim();
  if (!trimmed) return "proceeding with this decision";

  const [firstWord, ...rest] = trimmed.split(/\s+/);
  const lower = firstWord.toLowerCase();
  const irregular = {
    be: "being",
    build: "building",
    continue: "continuing",
    decide: "deciding",
    proceed: "proceeding",
    launch: "launching",
    invest: "investing",
    fund: "funding",
    buy: "buying",
    pay: "paying",
    adopt: "adopting",
  };

  let gerund = irregular[lower];
  if (!gerund) {
    if (lower.endsWith("e") && !lower.endsWith("ee")) {
      gerund = `${lower.slice(0, -1)}ing`;
    } else {
      gerund = `${lower}ing`;
    }
  }

  return [gerund, ...rest].join(" ");
}

function detectStrategy({ node, graph, relatedNodes, combinedText, meaning }) {
  const text = normaliseText(combinedText);
  const relatedText = normaliseText(
    relatedNodes
      .map((relatedNode) => `${relatedNode.label} ${relatedNode.description}`)
      .join(" "),
  );
  const resolvedValues = collectResolvedContextValues(graph);
  const actionPhrase = extractActionPhrase([
    ...resolvedValues,
    ...relatedNodes.map((relatedNode) => relatedNode.value),
    ...relatedNodes.map((relatedNode) => relatedNode.label),
    ...relatedNodes.map((relatedNode) => relatedNode.description),
    graph?.centralStatement,
  ]);

  const decisionContext =
    /\b(decision|whether to|build|launch|continue|proceed|invest|allocate)\b/.test(
      `${text} ${relatedText} ${resolvedValues.join(" ")}`,
    ) || Boolean(actionPhrase);

  if (
    /\b(constraint|limit|budget|deadline|requirement|regulation|capacity)\b/.test(
      text,
    )
  ) {
    return { strategy: "constraint", meaning, actionPhrase };
  }

  if (/\b(customer|user|buyer|stakeholder|recipient|audience)\b/.test(text)) {
    return { strategy: "actor/customer", meaning, actionPhrase };
  }

  if (/\b(before|previous|baseline|prior|comparable state)\b/.test(text)) {
    return { strategy: "baseline", meaning, actionPhrase };
  }

  if (/\b(when|timing|timeline|duration|sequence|milestone)\b/.test(text)) {
    return { strategy: "transition/timing", meaning, actionPhrase };
  }

  const hasDefinitionLanguage =
    /\b(define|definition|meaning|term|terminology)\b/.test(text);
  const hasDecisionValueLanguage =
    decisionContext &&
    /\b(value|commercial value|commercial viability|viability|justify|sufficient|success|threshold|criterion)\b/.test(
      text,
    );
  const hasMeasurementLanguage =
    /\b(metric|measure|measurable|roi|revenue projection|benchmark)\b/.test(
      text,
    );

  if (hasDecisionValueLanguage && hasMeasurementLanguage) {
    return { strategy: "measurement", meaning, actionPhrase };
  }

  if (/\b(define|definition|meaning|term|terminology)\b/.test(text)) {
    return { strategy: "definition", meaning, actionPhrase };
  }

  if (hasDecisionValueLanguage) {
    return { strategy: "decision criterion", meaning, actionPhrase };
  }

  if (/\b(evidence|proof|validate|validation|signal|demand)\b/.test(text)) {
    return { strategy: "evidence", meaning, actionPhrase };
  }

  if (hasMeasurementLanguage) {
    return { strategy: "measurement", meaning, actionPhrase };
  }

  if (
    /\b(objective|goal|outcome|problem|job to be done|benefit)\b/.test(text)
  ) {
    return { strategy: "objective", meaning, actionPhrase };
  }

  if (
    node?.kind === "reported_claim" ||
    node?.kind === "conclusion" ||
    /\b(claim|assertion|true|false)\b/.test(text)
  ) {
    return { strategy: "evidence", meaning, actionPhrase };
  }

  return { strategy: "generic clarification", meaning, actionPhrase };
}

function buildQuestion({ strategy, meaning, actionPhrase }) {
  switch (strategy) {
    case "decision criterion":
      return actionPhrase
        ? `What outcome would demonstrate enough value to justify ${toGerundPhrase(actionPhrase)}?`
        : "What outcome would be sufficient to justify this decision?";
    case "definition":
      return `What does ${meaning} mean in this situation?`;
    case "evidence":
      return `What evidence would show whether ${meaning} is true?`;
    case "baseline":
      return `What was the comparable state before ${meaning}?`;
    case "actor/customer":
      return "Who experiences the problem or receives the value in this situation?";
    case "objective":
      return "What outcome is this decision or effort meant to achieve?";
    case "constraint":
      return "What constraint most limits the available options in this situation?";
    case "measurement":
      return `What measure would determine whether ${meaning} is sufficient?`;
    case "transition/timing":
      return `When does ${meaning} become relevant in the decision or change?`;
    default:
      return `What specific fact would resolve whether ${meaning} is true?`;
  }
}

function isCompoundQuestion(question) {
  const trimmed = String(question || "").trim();
  const questionMarks = (trimmed.match(/\?/g) || []).length;

  if (questionMarks !== 1) return true;
  if (/\?\s*(and|or)\b/i.test(trimmed)) return true;
  if (/\b(and|or)\b[^?]{0,80}\?/i.test(trimmed) && /,/.test(trimmed)) {
    return true;
  }

  return false;
}

function validateFormulatedQuestion(question, meaning) {
  const trimmed = String(question || "").trim();
  const lower = trimmed.toLowerCase();
  const meaningWords = normaliseText(meaning)
    .split(" ")
    .filter((word) => word.length > 3);
  const overlappingWord = meaningWords.find((word) => lower.includes(word));

  if (!trimmed) return false;
  if ((trimmed.match(/\?/g) || []).length !== 1) return false;
  if (isCompoundQuestion(trimmed)) return false;
  if (/^what is\s+/i.test(trimmed)) return false;
  if (/^how should uncertainty regarding\b/i.test(trimmed)) return false;
  if (/^what would resolve uncertainty regarding\b/i.test(trimmed))
    return false;
  if (
    /\bprice|pricing|price point\b/i.test(trimmed) &&
    !/\bprice\b/i.test(meaning)
  ) {
    return false;
  }
  if (
    !overlappingWord &&
    !/\b(decision|evidence|constraint|customer|value|outcome)\b/i.test(trimmed)
  ) {
    return false;
  }

  return true;
}

export function formulateQuestion({ node, graph, context = {} }) {
  const relatedNodes = collectRelatedNodes(node, graph);
  const meaning = extractMeaning(node);
  const combinedText = [
    node?.label,
    node?.description,
    ...relatedNodes.map((relatedNode) => relatedNode.label),
    ...relatedNodes.map((relatedNode) => relatedNode.description),
    graph?.centralStatement,
    ...(context.resolvedValues || []),
  ]
    .filter(Boolean)
    .join(" ");

  const detected = detectStrategy({
    node,
    graph,
    relatedNodes,
    combinedText,
    meaning,
  });

  let question = buildQuestion(detected);

  if (!validateFormulatedQuestion(question, meaning)) {
    question = `What evidence would resolve whether ${meaning} is true?`;
  }

  return {
    question,
    reason: `Formulated from graph context using the ${detected.strategy} strategy.`,
    strategy: detected.strategy,
  };
}