/**
 * Behaviour Selection — Experiment 19 (Passive)
 *
 * A small deterministic selector that maps Investigation State Assessment
 * output to one of five behaviours: Acknowledge, Clarify, Summarise, Continue,
 * Pause.
 *
 * This experiment tests whether behaviour selection is useful. It does not
 * change engine behaviour — it only observes and reports through Developer
 * Details.
 *
 * Design reference: docs/behaviour-selection.md (v0.1 Implementation Brief)
 */

/* ── Behaviour constants ──────────────────────────────────── */

const BEHAVIOURS = [
  "acknowledge",
  "clarify",
  "summarise",
  "continue",
  "pause",
];

const PRIORITIES = {
  acknowledge: 1,
  clarify: 2,
  summarise: 3,
  pause: 4,
  continue: 5, // default
};

/* ── Selection rules (one rule per behaviour) ─────────────── */

function selectAcknowledge(assessment) {
  if (assessment.conversationHealth.value === "healthy" && assessment.phase.confidence !== "low") {
    return {
      behaviour: "acknowledge",
      confidence: "medium",
      reason: "Healthy conversation with established context — user provided useful information that warrants acknowledgment before introducing new uncertainty."
    };
  }
  return null;
}

function selectClarify(assessment) {
  if (assessment.conversationHealth.value === "too_broad") {
    return {
      behaviour: "clarify",
      confidence: "high",
      reason: "Conversation health is too broad — investigation may be spreading too thin. Narrow focus through a specific clarification question."
    };
  }

  if (assessment.phase.value === "orienting" && assessment.phase.evidence?.observationDensity < 3) {
    return {
      behaviour: "clarify",
      confidence: "medium",
      reason: "Investigation is in orienting phase with insufficient observations (< 3). A targeted clarification question will anchor the starting point."
    };
  }

  return null;
}

function selectSummarise(assessment) {
  if (assessment.phase.value === "synthesising") {
    return {
      behaviour: "summarise",
      confidence: "high",
      reason: "Investigation is in synthesising phase — connected observations have accumulated and a restatement of current understanding will compress without losing detail."
    };
  }

  if (assessment.phase.value === "concluding") {
    return {
      behaviour: "summarise",
      confidence: "high",
      reason: "Investigation is concluding — a summary of resolved understanding provides closure anchor before the user decides next steps."
    };
  }

  // Turn-count based summarisation (conservative threshold)
  if (assessment.phase.evidence?.resolvedNodeCount >= 3 && assessment.progress.value === "steady") {
    return {
      behaviour: "summarise",
      confidence: "medium",
      reason: "Three or more items resolved with steady progress — enough accumulated understanding warrants a compression pass."
    };
  }

  return null;
}

function selectPause(assessment) {
  if (assessment.phase.value === "focusing" && assessment.progress.value === "stalled") {
    return {
      behaviour: "pause",
      confidence: "high",
      reason: "Focusing phase with stalled progress — the investigation has reached a single active unknown but momentum has stopped. Hold space rather than pushing for more."
    };
  }

  if (assessment.conversationHealth.value === "user_overloaded") {
    return {
      behaviour: "pause",
      confidence: "medium",
      reason: "User appears overloaded — reduce pressure by acknowledging progress before inviting further contribution."
    };
  }

  return null;
}

/* ── Main selector ─────────────────────────────────────────── */

/**
 * Select a behaviour based on investigation state assessment.
 *
 * Applies five deterministic rules in priority order. If no rule fires,
 * returns continue (the default).
 *
 * @param {Object} assessment — Investigation State Assessment from Exp 18
 * @param {string} assessment.version   — Assessment version
 * @param {string} assessment.confidence — Overall confidence (high/medium/low)
 * @param {Object} assessment.phase     — Phase assessment { value, confidence, signals, evidence }
 * @param {Object} assessment.progress  — Progress assessment { value, confidence, signals, evidence }
 * @param {Object} assessment.conversationHealth — Health assessment { value, confidence, signals, evidence }
 * @returns {{ behaviour: string, confidence: string, reason: string }}
 */
export function selectBehaviour(assessment) {
  if (!assessment) {
    return {
      behaviour: "continue",
      confidence: "low",
      reason: "No assessment available — defaulting to continue (ask next question).",
      priority: PRIORITIES.continue
    };
  }

  // Guard against partial assessment objects with missing sub-structures
  if (!assessment.conversationHealth || !assessment.phase) {
    return {
      behaviour: "continue",
      confidence: "low",
      reason: "Assessment incomplete — missing required dimensions, defaulting to continue (ask next question).",
      priority: PRIORITIES.continue
    };
  }

  // Apply rules in priority order
  let result = selectAcknowledge(assessment);
  if (result) return { ...result, priority: PRIORITIES.acknowledge };

  result = selectClarify(assessment);
  if (result) return { ...result, priority: PRIORITIES.clarify };

  result = selectSummarise(assessment);
  if (result) return { ...result, priority: PRIORITIES.summarise };

  result = selectPause(assessment);
  if (result) return { ...result, priority: PRIORITIES.pause };

  // Default — Continue
  return {
    behaviour: "continue",
    confidence: "low",
    reason: "No explicit rule matched — defaulting to continue (ask the next question).",
    priority: PRIORITIES.continue
  };
}

export const BEHAVIOUR_OPTIONS = BEHAVIOURS;
export default selectBehaviour;