/**
 * Phase 6I — Magnetic Effect coverage-readiness gate.
 *
 * Evaluates the reconstructed Magnetic Effect evidence pack and decides whether
 * Phase 6J (final lesson-seed authoring) can safely start. This gate NEVER sets
 * canTeach, never registers seeds, and never claims curated PYQ. It only reports
 * source-readiness.
 */

import {
  getMagneticEffectEvidencePack,
  type EvidenceConfidence,
  type MagneticChapterEvidencePack,
  type MagneticEvidenceRef,
} from "./source-overrides/magneticEffectEvidence";

export type MagneticCoverageGateResult = {
  chapterId: "phy-p1-c4";
  status: "blocked" | "draftable" | "curation_ready" | "needs_manual_source_review";
  score: number;
  requiredTopics: Array<{
    topicId: string;
    topicTitle: string;
    status: "covered" | "partial" | "missing";
    evidenceCount: number;
    warnings: string[];
  }>;
  missingCriticalTopics: string[];
  sourceQualityWarnings: string[];
  canStartPhase6J: boolean;
};

const FAKE_PREDICTION_PATTERNS = [
  /guaranteed question/i,
  /100\s*%\s*com(e|ing)/i,
  /sure question/i,
  /surely (will )?be asked/i,
  /definitely (will )?come/i,
  /confirm(ed)? question/i,
  /exact prediction/i,
];

// The topics a safe Phase 6J seed set must be able to teach from source.
const REQUIRED_TOPIC_IDS = [
  "magnetic-field-around-conductor",
  "direction-of-field-right-hand-rule",
  "solenoid",
  "electromagnet",
  "force-on-current-carrying-conductor",
  "electric-motor",
] as const;

function isSourceBacked(confidence: EvidenceConfidence): boolean {
  return confidence === "high" || confidence === "medium";
}

function allRefs(pack: MagneticChapterEvidencePack): MagneticEvidenceRef[] {
  return [
    ...pack.definitions.flatMap((d) => d.sourceRefs),
    ...pack.formulasAndRules.flatMap((f) => f.sourceRefs),
    ...pack.diagrams.flatMap((d) => d.sourceRefs),
    ...pack.questions.flatMap((q) => q.sourceRefs),
    ...pack.activities.flatMap((a) => a.sourceRefs),
  ];
}

export function evaluateMagneticEffectCoverageGate(
  pack: MagneticChapterEvidencePack = getMagneticEffectEvidencePack(),
): MagneticCoverageGateResult {
  const sourceQualityWarnings: string[] = [];

  const sourceBackedDefinitions = pack.definitions.filter((d) => isSourceBacked(d.confidence));
  const diagramAndActivityCount = pack.diagrams.length + pack.activities.length;
  const sourceBackedQuestions = pack.questions.filter((q) => isSourceBacked(q.confidence));

  // --- Hard requirement checks -------------------------------------------------
  const checks = {
    enoughDefinitions: sourceBackedDefinitions.length >= 5,
    enoughDiagrams: diagramAndActivityCount >= 3,
    enoughQuestions: sourceBackedQuestions.length >= 5,
    allSourceRefsPresent: allRefs(pack).length > 0 &&
      [...pack.definitions, ...pack.formulasAndRules, ...pack.diagrams, ...pack.questions, ...pack.activities].every(
        (item) => item.sourceRefs.length > 0,
      ),
    noEmptySourceMeta: allRefs(pack).every((r) => r.sourceBook.trim().length > 0 && r.chapterTitle.trim().length > 0),
    pageRangeKnown: Boolean(pack.pageRange && pack.pageRange.trim().length > 0),
  };

  if (!checks.enoughDefinitions) sourceQualityWarnings.push("Fewer than 5 source-backed definitions/key concepts.");
  if (!checks.enoughDiagrams) sourceQualityWarnings.push("Fewer than 3 diagram/activity evidence items.");
  if (!checks.enoughQuestions) sourceQualityWarnings.push("Fewer than 5 source-backed question evidence items.");
  if (!checks.allSourceRefsPresent) sourceQualityWarnings.push("Some evidence item is missing sourceRefs.");
  if (!checks.noEmptySourceMeta) sourceQualityWarnings.push("An evidence sourceRef has an empty sourceBook/chapterTitle.");
  if (!checks.pageRangeKnown) sourceQualityWarnings.push("Chapter page range is unknown.");

  // --- Honesty guards ----------------------------------------------------------
  const packText = JSON.stringify(pack);
  for (const pattern of FAKE_PREDICTION_PATTERNS) {
    if (pattern.test(packText)) {
      sourceQualityWarnings.push(`Evidence contains fake-prediction language (matched ${pattern}).`);
    }
  }

  // --- Required-topic coverage -------------------------------------------------
  const requiredTopics = REQUIRED_TOPIC_IDS.map((topicId) => {
    const topic = pack.coverageMap.find((t) => t.topicId === topicId);
    if (!topic) {
      return { topicId, topicTitle: topicId, status: "missing" as const, evidenceCount: 0, warnings: ["Topic not present in the coverage map."] };
    }
    const status: "covered" | "partial" | "missing" =
      topic.status === "source_backed" ? "covered" : topic.status === "not_found" ? "missing" : "partial";
    return {
      topicId: topic.topicId,
      topicTitle: topic.topicTitle,
      status,
      evidenceCount: topic.evidenceIds.length,
      warnings: topic.missingPieces,
    };
  });

  const missingCriticalTopics = requiredTopics.filter((t) => t.status === "missing").map((t) => t.topicId);
  const partialCriticalTopics = requiredTopics.filter((t) => t.status === "partial").map((t) => t.topicId);

  // --- Score -------------------------------------------------------------------
  const hardChecksPassed = Object.values(checks).filter(Boolean).length;
  const coveredCritical = requiredTopics.filter((t) => t.status === "covered").length;
  const score = Math.round(
    ((hardChecksPassed / Object.keys(checks).length) * 0.5 + (coveredCritical / REQUIRED_TOPIC_IDS.length) * 0.5) * 100,
  );

  // --- Status decision ---------------------------------------------------------
  const allHardChecksPass = hardChecksPassed === Object.keys(checks).length;
  const noFakeLanguage = !sourceQualityWarnings.some((w) => w.includes("fake-prediction"));
  const noMissingCritical = missingCriticalTopics.length === 0;

  let status: MagneticCoverageGateResult["status"];
  let canStartPhase6J: boolean;

  if (!noFakeLanguage || !checks.allSourceRefsPresent || !checks.noEmptySourceMeta) {
    status = "needs_manual_source_review";
    canStartPhase6J = false;
  } else if (allHardChecksPass && noMissingCritical) {
    status = "curation_ready";
    canStartPhase6J = true;
  } else if (checks.enoughDefinitions && checks.enoughQuestions && noMissingCritical) {
    // Enough core evidence to draft, even if some quality checks are soft.
    status = "draftable";
    canStartPhase6J = true;
  } else if (missingCriticalTopics.length > 0 || (!checks.enoughDefinitions && !checks.enoughQuestions)) {
    status = "blocked";
    canStartPhase6J = false;
  } else {
    status = "draftable";
    canStartPhase6J = false;
  }

  if (partialCriticalTopics.length > 0) {
    sourceQualityWarnings.push(`Partial source for: ${partialCriticalTopics.join(", ")}.`);
  }

  return {
    chapterId: "phy-p1-c4",
    status,
    score,
    requiredTopics,
    missingCriticalTopics,
    sourceQualityWarnings,
    canStartPhase6J,
  };
}