import {
  getChapters,
  getDefinitions,
  getFormulas,
  getNumericalPatterns,
  getQuestions,
  getVisualLessonFrames,
  type ChapterSummary,
} from "@/lib/knowledge-base/sslc-physics";
import type { LessonSeedSourceRef } from "./physicsLessonSeeds";
import { getMagneticEffectEvidencePack } from "./source-overrides/magneticEffectEvidence";

export type PhysicsChapterSourcePack = {
  subject: "Physics";
  chapterId: string;
  chapterTitle: string;
  sourceBook: string;
  pageRange?: string;
  sourceRefs: LessonSeedSourceRef[];
  extractedSignals: {
    formulas: string[];
    definitions: string[];
    possibleQuestions: string[];
    keyTerms: string[];
    diagrams: string[];
    numericalPatterns: string[];
  };
  coverageConfidence: "high" | "medium" | "low";
  warnings: string[];
  /** True when the extracted signals were repaired from a manual source-evidence override (Phase 6I). */
  sourceRepaired?: boolean;
};

/**
 * Manual source-evidence overrides (Phase 6I). These do NOT create lesson seeds
 * and do NOT make a chapter teachable — they only repair thin auto-extraction so
 * the source pack reflects the real (source-referenced) chapter scope.
 */
type SourceEvidenceOverride = {
  definitions: string[];
  keyTerms: string[];
  diagrams: string[];
  possibleQuestions: string[];
};

function magneticEffectOverride(): SourceEvidenceOverride {
  const pack = getMagneticEffectEvidencePack();
  return {
    definitions: pack.definitions.map((d) => `${d.term}: ${d.definition}`),
    keyTerms: pack.keyTerms,
    diagrams: pack.diagrams.map((d) => `${d.title}: ${d.visualDescription}`),
    possibleQuestions: pack.questions.map((q) => q.question),
  };
}

function evidenceOverrideFor(chapterId: string): SourceEvidenceOverride | null {
  if (chapterId === "phy-p1-c4") return magneticEffectOverride();
  return null;
}

const SOURCE_BOOK = "Kerala SCERT Physics, Standard X (2025)";
const MAX_SIGNAL_LENGTH = 180;
const MAX_SIGNALS_PER_KIND = 20;

function asRecord(value: unknown): Record<string, unknown> {
  return value && typeof value === "object" ? (value as Record<string, unknown>) : {};
}

function readString(value: unknown): string {
  return typeof value === "string" ? value.trim() : "";
}

function getChapterTitle(chapter: ChapterSummary): string {
  const maybeTitle = chapter as ChapterSummary & { title?: string };
  return chapter.chapter_title?.trim() || maybeTitle.title?.trim() || chapter.chapter_id;
}

function compactText(value: string): string {
  return value.replace(/\s+/g, " ").trim().slice(0, MAX_SIGNAL_LENGTH);
}

function unique(values: string[]): string[] {
  return Array.from(new Set(values.map(compactText).filter(Boolean))).slice(0, MAX_SIGNALS_PER_KIND);
}

function firstText(record: Record<string, unknown>, keys: string[]): string {
  for (const key of keys) {
    const value = readString(record[key]);
    if (value) return value;
  }
  return "";
}

function sourcePageRange(chapter: ChapterSummary): string | undefined {
  const printedStart = Number(chapter.printed_start_page);
  const printedEnd = Number(chapter.printed_end_page);
  if (Number.isFinite(printedStart) && printedStart > 0) {
    return Number.isFinite(printedEnd) && printedEnd >= printedStart
      ? `${printedStart}-${printedEnd}`
      : String(printedStart);
  }

  const pdfStart = Number(chapter.pdf_start_page);
  const pdfEnd = Number(chapter.pdf_end_page);
  if (Number.isFinite(pdfStart) && pdfStart > 0) {
    return Number.isFinite(pdfEnd) && pdfEnd >= pdfStart ? `${pdfStart}-${pdfEnd}` : String(pdfStart);
  }

  return undefined;
}

function buildSourceRef(chapter: ChapterSummary): LessonSeedSourceRef {
  const pageRange = sourcePageRange(chapter);
  const chapterTitle = getChapterTitle(chapter);
  return {
    label: pageRange
      ? `Kerala SSLC Physics - ${chapterTitle} (pp. ${pageRange})`
      : `Kerala SSLC Physics - ${chapterTitle}`,
    sourceBook: SOURCE_BOOK,
    chapterTitle,
    pageRange,
    url: null,
    confidence: chapter.needs_review ? "needs_review" : "source_backed",
  };
}

function formulaSignals(chapterId: string): string[] {
  return unique(
    (getFormulas(chapterId) ?? []).map((item) => {
      const record = asRecord(item);
      const formula = firstText(record, ["formula", "formula_used", "equation", "expression"]);
      const name = firstText(record, ["name", "title", "formula_name", "pattern_name"]);
      return formula && name ? `${name}: ${formula}` : formula || name;
    }),
  );
}

function definitionSignals(chapterId: string): string[] {
  return unique(
    getDefinitions(chapterId).map((item) => {
      const term = item.term?.trim() ?? "";
      const definition = item.definition?.trim() ?? "";
      return definition ? `${term}: ${definition}` : term;
    }),
  );
}

function questionSignals(chapterId: string): string[] {
  return unique(getQuestions(chapterId).map((item) => item.question));
}

function termSignals(chapterId: string): string[] {
  const fromDefinitions = getDefinitions(chapterId).map((item) => item.term);
  const fromQuestions = getQuestions(chapterId).flatMap((item) => item.keywords ?? []);
  const fromFormulas = (getFormulas(chapterId) ?? []).map((item) => firstText(asRecord(item), ["name", "title"]));
  return unique([...fromDefinitions, ...fromQuestions, ...fromFormulas]);
}

function numericalSignals(chapterId: string): string[] {
  return unique(
    (getNumericalPatterns(chapterId) ?? []).map((item) => {
      const record = asRecord(item);
      const pattern = firstText(record, ["pattern_name", "title", "name"]);
      const formula = firstText(record, ["formula_used", "formula", "equation"]);
      return pattern && formula ? `${pattern}: ${formula}` : pattern || formula;
    }),
  );
}

function diagramSignals(chapterId: string): string[] {
  return unique(
    (getVisualLessonFrames(chapterId) ?? []).flatMap((item) => {
      const record = asRecord(item);
      const title = firstText(record, ["title", "frame_title", "name"]);
      const idea = firstText(record, ["diagramDescription", "description", "teacherAction", "visual_idea"]);
      return [title, idea];
    }),
  );
}

function buildWarnings(signals: PhysicsChapterSourcePack["extractedSignals"], sourceRefs: LessonSeedSourceRef[]): string[] {
  const warnings: string[] = [];
  if (sourceRefs.length === 0) warnings.push("Missing chapter source reference.");
  if (signals.definitions.length === 0) warnings.push("No extracted definitions; concept missions need human curation.");
  if (signals.formulas.length === 0) warnings.push("No extracted formulas; formula/numerical missions need review.");
  if (signals.possibleQuestions.length < 10) warnings.push("Thin possible-question coverage.");
  if (signals.diagrams.length === 0) warnings.push("No extracted visual-board/diagram signal.");
  if (signals.numericalPatterns.length === 0) warnings.push("No extracted numerical pattern.");
  return warnings;
}

function confidenceFor(signals: PhysicsChapterSourcePack["extractedSignals"], sourceRefs: LessonSeedSourceRef[]): "high" | "medium" | "low" {
  if (sourceRefs.length === 0) return "low";
  if (signals.definitions.length === 0 && signals.formulas.length === 0) return "low";

  const signalScore = [
    signals.definitions.length > 0,
    signals.formulas.length > 0,
    signals.possibleQuestions.length >= 10,
    signals.diagrams.length > 0,
    signals.numericalPatterns.length > 0,
  ].filter(Boolean).length;

  if (signalScore >= 4) return "high";
  if (signalScore >= 2) return "medium";
  return "low";
}

function buildPack(chapter: ChapterSummary): PhysicsChapterSourcePack {
  const sourceRefs = [buildSourceRef(chapter)];
  const extractedSignals: PhysicsChapterSourcePack["extractedSignals"] = {
    formulas: formulaSignals(chapter.chapter_id),
    definitions: definitionSignals(chapter.chapter_id),
    possibleQuestions: questionSignals(chapter.chapter_id),
    keyTerms: termSignals(chapter.chapter_id),
    diagrams: diagramSignals(chapter.chapter_id),
    numericalPatterns: numericalSignals(chapter.chapter_id),
  };

  const override = evidenceOverrideFor(chapter.chapter_id);
  if (override) {
    extractedSignals.definitions = unique([...extractedSignals.definitions, ...override.definitions]);
    extractedSignals.keyTerms = unique([...extractedSignals.keyTerms, ...override.keyTerms]);
    extractedSignals.diagrams = unique([...extractedSignals.diagrams, ...override.diagrams]);
    extractedSignals.possibleQuestions = unique([...extractedSignals.possibleQuestions, ...override.possibleQuestions]);
  }

  const warnings = buildWarnings(extractedSignals, sourceRefs);
  if (override) {
    warnings.push(
      "Source manually repaired from the extracted textbook question bank and figure references (Phase 6I evidence override).",
    );
  }

  return {
    subject: "Physics",
    chapterId: chapter.chapter_id,
    chapterTitle: getChapterTitle(chapter),
    sourceBook: SOURCE_BOOK,
    pageRange: sourceRefs[0]?.pageRange,
    sourceRefs,
    extractedSignals,
    coverageConfidence: confidenceFor(extractedSignals, sourceRefs),
    warnings,
    sourceRepaired: Boolean(override),
  };
}

export function getPhysicsSourcePacks(): PhysicsChapterSourcePack[] {
  return getChapters().map(buildPack);
}

export function getPhysicsSourcePack(chapterId: string): PhysicsChapterSourcePack | null {
  return getPhysicsSourcePacks().find((pack) => pack.chapterId === chapterId) ?? null;
}