import { Router } from 'express';
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { initScrabbleDictionary, isValidWord, chooseMove } from './scrabbleEngine.js';
import { initGhostDictionary, judge as ghostJudge, chooseLetter as ghostChooseLetter, suggestWords as ghostSuggestWords } from './ghostEngine.js';
import {
  initWordLadderDictionary,
  generatePuzzle as ladderGeneratePuzzle,
  generateVersusPuzzles as ladderGenerateVersus,
  chooseAIMove as ladderChooseAIMove,
  hintMove as ladderHintMove,
  validWordsOfLength as ladderValidWords,
} from './wordLadderEngine.js';
import {
  generatePuzzle as wordSearchGenerate,
  listThemes as wordSearchThemes,
} from './wordSearchEngine.js';
import { generatePuzzle as sudokuGenerate } from './sudokuEngine.js';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const WORDLIST_PATH = path.join(__dirname, '../data/wordlists/enable1.txt');

// Common words used to build a player-friendly Wordle answer pool.
// These are well-known 5-letter English words that make fair Wordle puzzles.
const COMMON_WORDS = new Set([
  'ABOUT','ABOVE','ABUSE','ACTOR','ACUTE','ADMIT','ADOPT','ADULT','AFTER',
  'AGAIN','AGENT','AGREE','AHEAD','ALARM','ALBUM','ALERT','ALIGN','ALIVE',
  'ALLEY','ALLOW','ALONE','ALONG','ALTER','ANGEL','ANGLE','ANGRY','ANKLE',
  'ANNEX','ANNOY','APART','APPLE','APPLY','APRIL','ARENA','ARGUE','ARISE',
  'ARMOR','ARRAY','ARROW','ASIDE','ASKED','ASSET','AVOID','AWARD','AWARE',
  'AWFUL','BADLY','BAKER','BASIC','BASIS','BATCH','BEACH','BEGAN','BEGIN',
  'BEING','BELOW','BENCH','BIBLE','BIRTH','BLACK','BLADE','BLAME','BLAND',
  'BLANK','BLAST','BLAZE','BLEED','BLEND','BLESS','BLIND','BLOCK','BLOOD',
  'BLOWN','BOARD','BONUS','BOOST','BOUND','BRAIN','BRAND','BRAVE','BREAD',
  'BREAK','BREED','BRICK','BRIDE','BRIEF','BRING','BROAD','BROKE','BROOK',
  'BROWN','BRUSH','BUILD','BUILT','BUNCH','BURNT','BUYER','CACHE','CANDY',
  'CARGO','CARRY','CATCH','CAUSE','CHAIN','CHAIR','CHAOS','CHARM','CHASE',
  'CHEAP','CHECK','CHEEK','CHEER','CHESS','CHEST','CHIEF','CHILD','CHINA',
  'CIVIC','CIVIL','CLAIM','CLASS','CLEAN','CLEAR','CLERK','CLICK','CLIFF',
  'CLIMB','CLING','CLOCK','CLOSE','CLOUD','COACH','COAST','COULD','COUNT',
  'COURT','COVER','CRACK','CRAFT','CRASH','CRAZY','CREAM','CREEK','CRIME',
  'CRISP','CROSS','CROWD','CROWN','CRUEL','CRUSH','CURVE','CYCLE','DAILY',
  'DANCE','DEATH','DEBUT','DELAY','DENSE','DEPOT','DEPTH','DERBY','DEVIL',
  'DIGIT','DIRTY','DOING','DOUBT','DOUGH','DRAFT','DRAIN','DRAMA','DRANK',
  'DRAWN','DREAM','DRESS','DRIED','DRIFT','DRILL','DRINK','DRIVE','DROVE',
  'DRUGS','DRUMS','DRUNK','DWELL','DYING','EAGER','EARLY','EARTH','EIGHT',
  'ELECT','EMAIL','EMPTY','ENEMY','ENJOY','ENTER','ENTRY','EQUAL','ERROR',
  'ESSAY','EVERY','EVENT','EXACT','EXIST','EXTRA','FAINT','FAIRY','FAITH',
  'FALSE','FANCY','FAULT','FEAST','FENCE','FETCH','FEVER','FEWER','FIELD',
  'FIFTH','FIFTY','FIGHT','FINAL','FLAIR','FLAME','FLASH','FLEET','FLESH',
  'FLOAT','FLOOD','FLOOR','FLOUR','FLUID','FOCUS','FORCE','FORGE','FORUM',
  'FOUND','FRANK','FRAUD','FRESH','FRONT','FROST','FROZE','FRUIT','FULLY',
  'FUNDS','FUNNY','GHOST','GIANT','GIVEN','GLASS','GLOBE','GLOOM','GLOSS',
  'GLOVE','GOING','GRACE','GRADE','GRAIN','GRAND','GRANT','GRASP','GRASS',
  'GRAVE','GREAT','GREEN','GREET','GRIEF','GRIND','GROAN','GROSS','GROUP',
  'GROVE','GROWN','GUARD','GUESS','GUEST','GUIDE','GUILT','GUISE','GUSTO',
  'HABIT','HAPPY','HARSH','HEART','HEAVY','HENCE','HINGE','HONEY','HONOR',
  'HORSE','HOTEL','HOUSE','HUMAN','HUMOR','HURRY','IDEAL','IMAGE','IMPLY',
  'INBOX','INDEX','INNER','INPUT','INTER','INTRO','ISSUE','JAPAN','JOINT',
  'JOUST','JUDGE','JUICE','JUICY','JUMBO','KARMA','KNIFE','KNOCK','KNOWN',
  'LABEL','LARGE','LASER','LATER','LAUGH','LAYER','LEARN','LEASE','LEAVE',
  'LEGAL','LEVEL','LIGHT','LIMIT','LINEN','LIVER','LOCAL','LODGE','LOGIC',
  'LOOSE','LOVER','LOWER','LUCKY','LUNAR','LYING','MAGIC','MAJOR','MAKER',
  'MARCH','MATCH','MAYOR','MEDIA','MERIT','METAL','MIGHT','MINOR','MINUS',
  'MIXED','MODEL','MONEY','MONTH','MORAL','MOTOR','MOUNT','MOUSE','MOUTH',
  'MOVED','MOVIE','MUSIC','NAIVE','NEVER','NIGHT','NOISE','NORTH','NOTED',
  'NOVEL','NURSE','OCCUR','OFFER','OFTEN','ONSET','OPERA','ORBIT','ORDER',
  'OTHER','OUTER','OUNCE','OWNER','PAINT','PANEL','PAPER','PARTY','PASTA',
  'PATCH','PAUSE','PEACE','PEARL','PEDAL','PENNY','PERCH','PHASE','PHONE',
  'PHOTO','PIANO','PIECE','PILOT','PITCH','PIXEL','PIZZA','PLACE','PLAIN',
  'PLANE','PLANT','PLATE','PLAZA','PLEAD','PLUCK','PLUMB','PLUME','PLUMP',
  'PLUNGE','POINT','POKER','POLAR','POUND','POWER','PRESS','PRICE','PRIDE',
  'PRIME','PRINT','PRIOR','PRIZE','PROBE','PROOF','PROSE','PROUD','PROVE',
  'PROXY','PULSE','PUPIL','QUEEN','QUERY','QUEST','QUEUE','QUICK','QUIET',
  'QUITE','QUOTA','QUOTE','RADAR','RADIO','RAISE','RALLY','RANCH','RANGE',
  'RAPID','RATIO','REACH','READY','REALM','REBEL','REFER','REIGN','RELAX',
  'REPLY','RIGHT','RIGID','RISKY','RIVAL','RIVER','ROBOT','ROCKY','ROMAN',
  'ROUGH','ROUND','ROUTE','ROYAL','RULER','RUMOR','RURAL','SAINT','SALAD',
  'SAUCE','SCALE','SCALD','SCENE','SCOUT','SCREW','SEIZE','SENSE','SERVE',
  'SEVEN','SHADE','SHAKE','SHALL','SHAME','SHAPE','SHARE','SHARP','SHELF',
  'SHIFT','SHIRT','SHOCK','SHOOT','SHORT','SHOUT','SIGHT','SINCE','SIXTH',
  'SIXTY','SIZED','SKILL','SLEEP','SLICE','SLIDE','SLOPE','SLUMP','SMALL',
  'SMART','SMELL','SMILE','SMOKE','SOLAR','SOLID','SOLVE','SORRY','SOUND',
  'SOUTH','SPACE','SPARK','SPEAK','SPELL','SPEND','SPICE','SPILL','SPINE',
  'SPLIT','SPOKE','SPORT','SPRAY','SQUAD','STACK','STAFF','STAGE','STAIN',
  'STAKE','STALE','STALL','STAND','START','STATE','STEAL','STEEL','STEEP',
  'STICK','STILL','STOCK','STOOD','STORE','STORM','STORY','STRAP','STRAW',
  'STRIP','STUDY','STUFF','STYLE','SUGAR','SUITE','SUPER','SURGE','SWAMP',
  'SWEAR','SWEAT','SWEEP','SWEET','SWEPT','SWIFT','SWING','SWORE','SWORN',
  'TABLE','TAKEN','TASTE','TEACH','TEETH','TENSE','TERMS','THANK','THEIR',
  'THEME','THERE','THESE','THICK','THING','THINK','THIRD','THOSE','THREE',
  'THREW','THROW','TIGHT','TIMER','TIRED','TITLE','TODAY','TOKEN','TONAL',
  'TOPIC','TOTAL','TOUCH','TOUGH','TRACE','TRACK','TRADE','TRAIL','TRAIN',
  'TRAIT','TRASH','TREAT','TREND','TRIAL','TRIBE','TRICK','TRIED','TROOP',
  'TRUCK','TRULY','TRUMP','TRUNK','TRUTH','TUMOR','TWICE','TWIST','TYPICAL',
  'ULTRA','UNDER','UNION','UNITE','UNITY','UNTIL','UPPER','UPSET','URBAN',
  'USAGE','UTTER','VALID','VALUE','VALVE','VERSE','VIDEO','VIGOR','VIRAL',
  'VIRUS','VISIT','VITAL','VIVID','VOICE','VOTER','WAIST','WASTE','WATCH',
  'WATER','WEARY','WEIGH','WEIRD','WHILE','WHITE','WHOLE','WHOSE','WIDER',
  'WITCH','WOMAN','WOMEN','WORLD','WORRY','WORSE','WORST','WORTH','WOULD',
  'WOUND','WRIST','WRITE','WROTE','YOUNG','YOURS','YOUTH','ZONAL',
]);

// ── Load word sets at startup ─────────────────────────────────────────────────

let allFiveLetterWords = null; // Set<string> — all valid 5-letter ENABLE words
let answerPool = null;         // string[] — shuffleable answer list

function loadWordLists() {
  if (allFiveLetterWords) return;

  let raw = '';
  try {
    raw = fs.readFileSync(WORDLIST_PATH, 'utf8');
  } catch (err) {
    console.warn('[words] ENABLE word list not found, using fallback.');
    raw = [...COMMON_WORDS].join('\n');
  }

  const allWords = raw.split('\n').map(w => w.trim().toUpperCase());

  const enableFive = new Set(
    allWords.filter(w => w.length === 5 && /^[A-Z]{5}$/.test(w)),
  );

  allFiveLetterWords = enableFive;

  // Scrabble dictionary: every ENABLE word of legal play length (2–15 letters).
  const scrabbleWords = new Set(
    allWords.filter(w => w.length >= 2 && w.length <= 15 && /^[A-Z]+$/.test(w)),
  );
  initScrabbleDictionary(scrabbleWords);
  console.log(`[words] loaded ${scrabbleWords.size} Scrabble words (2–15 letters)`);

  // Ghost dictionary: every ENABLE word of length >= 4 (shorter words don't count).
  const ghostWords = allWords.filter(w => w.length >= 4 && /^[A-Z]+$/.test(w));
  initGhostDictionary(ghostWords);
  console.log(`[words] loaded ${ghostWords.length} Ghost words (4+ letters)`);

  // Word Ladder dictionaries: 3- and 4-letter words for the two game variants.
  const ladderThree = allWords.filter(w => /^[A-Z]{3}$/.test(w));
  const ladderFour = allWords.filter(w => /^[A-Z]{4}$/.test(w));
  initWordLadderDictionary(ladderThree, ladderFour);
  console.log(`[words] loaded Word Ladder dictionaries (${ladderThree.length} 3-letter, ${ladderFour.length} 4-letter)`);

  // Answer pool: prefer curated common words that are also in ENABLE;
  // supplement with additional ENABLE words up to a healthy pool size.
  const curated = [...COMMON_WORDS].filter(w => enableFive.has(w));
  answerPool = curated.length >= 200 ? curated : [...enableFive];

  console.log(`[words] loaded ${enableFive.size} valid 5-letter words, ${answerPool.length} answer candidates`);
}

loadWordLists();

// ── Router ────────────────────────────────────────────────────────────────────

const router = Router();

// GET /api/words/wordle/start
// Returns a random answer word plus the full valid-word pool for the client.
router.get('/wordle/start', (_req, res) => {
  const answer = answerPool[Math.floor(Math.random() * answerPool.length)];
  res.json({ answer, validWords: [...allFiveLetterWords] });
});

// POST /api/words/wordle/validate  { word: string }
// Quick single-word validation (used as a lightweight alternative to the full pool).
router.post('/wordle/validate', (req, res) => {
  const word = (req.body?.word ?? '').trim().toUpperCase();
  if (!/^[A-Z]{5}$/.test(word)) {
    return res.json({ valid: false });
  }
  res.json({ valid: allFiveLetterWords.has(word) });
});

// ── Scrabble ──────────────────────────────────────────────────────────────────

// POST /api/words/scrabble/validate  { words: string[] }
// Validates every word a human move forms. Returns the list of invalid ones.
router.post('/scrabble/validate', (req, res) => {
  const words = Array.isArray(req.body?.words) ? req.body.words : [];
  const invalid = words
    .map(w => String(w).trim().toUpperCase())
    .filter(w => !isValidWord(w));
  res.json({ valid: invalid.length === 0, invalid });
});

// POST /api/words/scrabble/ai-move  { board, rack, skill, firstMove, bagCount }
// Returns the AI's chosen move: a play, an exchange, or a pass.
router.post('/scrabble/ai-move', (req, res) => {
  const { board, rack, skill, firstMove, bagCount } = req.body ?? {};
  if (!Array.isArray(board) || !Array.isArray(rack)) {
    return res.status(400).json({ error: 'board and rack are required' });
  }
  const move = chooseMove({
    board,
    rack,
    skill: Number(skill) || 3,
    firstMove: !!firstMove,
    bagCount: Number(bagCount) || 0,
  });
  res.json(move);
});

// ── Ghost ───────────────────────────────────────────────────────────────────

// POST /api/words/ghost/judge  { fragment: string }
// Grades the fragment a player just formed: a completed word, or off-dictionary,
// both lose the round for whoever made the move.
router.post('/ghost/judge', (req, res) => {
  const fragment = String(req.body?.fragment ?? '');
  res.json(ghostJudge(fragment));
});

// POST /api/words/ghost/ai-move  { fragment: string, skill: number }
// Returns the AI's letter and how the resulting fragment grades.
router.post('/ghost/ai-move', (req, res) => {
  const fragment = String(req.body?.fragment ?? '');
  const skill = Number(req.body?.skill) || 3;
  res.json(ghostChooseLetter(fragment, skill));
});

// POST /api/words/ghost/suggest  { prefix: string, max?: number }
// Example safe words the loser could have headed toward from the faced prefix.
router.post('/ghost/suggest', (req, res) => {
  const prefix = String(req.body?.prefix ?? '');
  const max = Number(req.body?.max) || 3;
  res.json({ words: ghostSuggestWords(prefix, max) });
});

// ── Word Ladder ────────────────────────────────────────────────────────────────

// GET /api/words/wordladder/start?length=3|4&versus=true|false
// Solo: { player, opponent: null, validWords }.
// Versus: { player, opponent, validWords } — two puzzles of equal par.
router.get('/wordladder/start', (req, res) => {
  const length = Number(req.query.length) === 3 ? 3 : 4;
  const versus = String(req.query.versus) === 'true';
  const validWords = ladderValidWords(length);
  if (versus) {
    const { player, opponent } = ladderGenerateVersus(length);
    return res.json({ player, opponent, validWords });
  }
  res.json({ player: ladderGeneratePuzzle(length), opponent: null, validWords });
});

// POST /api/words/wordladder/ai-move  { current, target, skill }
// Advances the AI opponent one rung toward its target.
router.post('/wordladder/ai-move', (req, res) => {
  const current = String(req.body?.current ?? '');
  const target = String(req.body?.target ?? '');
  const skill = Number(req.body?.skill) || 3;
  res.json(ladderChooseAIMove(current, target, skill));
});

// POST /api/words/wordladder/hint  { current, target }
// One valid next step on a shortest path toward the target.
router.post('/wordladder/hint', (req, res) => {
  const current = String(req.body?.current ?? '');
  const target = String(req.body?.target ?? '');
  res.json({ word: ladderHintMove(current, target) });
});

// ── Word Search ──────────────────────────────────────────────────────────────

// ── Hangman ──────────────────────────────────────────────────────────────────

const HANGMAN_WORDS = {
  easy: [
    { word: 'CAT',    hint: 'A common household pet',          category: 'Animals' },
    { word: 'DOG',    hint: 'Man\'s best friend',              category: 'Animals' },
    { word: 'SUN',    hint: 'It lights up the day',            category: 'Nature'  },
    { word: 'FISH',   hint: 'Lives in water',                  category: 'Animals' },
    { word: 'BIRD',   hint: 'Has wings and feathers',          category: 'Animals' },
    { word: 'TREE',   hint: 'Tall plant with a trunk',         category: 'Nature'  },
    { word: 'CAKE',   hint: 'Sweet birthday treat',            category: 'Food'    },
    { word: 'STAR',   hint: 'Twinkles in the night sky',       category: 'Nature'  },
    { word: 'FROG',   hint: 'Hops and croaks',                 category: 'Animals' },
    { word: 'RAIN',   hint: 'Falls from clouds',               category: 'Nature'  },
    { word: 'DUCK',   hint: 'Says quack',                      category: 'Animals' },
    { word: 'SNOW',   hint: 'White and cold',                  category: 'Nature'  },
    { word: 'BEAR',   hint: 'Loves honey',                     category: 'Animals' },
    { word: 'MILK',   hint: 'Comes from a cow',                category: 'Food'    },
    { word: 'MOON',   hint: 'Orbits the Earth',                category: 'Nature'  },
    { word: 'WOLF',   hint: 'Howls at the moon',               category: 'Animals' },
    { word: 'CORN',   hint: 'Yellow vegetable on a cob',       category: 'Food'    },
    { word: 'ROSE',   hint: 'A thorny flower',                 category: 'Nature'  },
    { word: 'LION',   hint: 'King of the jungle',              category: 'Animals' },
    { word: 'LEAF',   hint: 'Falls from trees in autumn',      category: 'Nature'  },
  ],
  medium: [
    { word: 'CASTLE',   hint: 'A medieval fortress',              category: 'Places'    },
    { word: 'JUNGLE',   hint: 'Dense tropical forest',            category: 'Nature'    },
    { word: 'PLANET',   hint: 'Orbits a star',                    category: 'Space'     },
    { word: 'BRIDGE',   hint: 'Spans a river or gap',             category: 'Structures'},
    { word: 'CAMERA',   hint: 'Used to take photos',              category: 'Objects'   },
    { word: 'DRAGON',   hint: 'Mythical fire-breathing creature', category: 'Fantasy'   },
    { word: 'FOREST',   hint: 'Dense woodland',                   category: 'Nature'    },
    { word: 'GUITAR',   hint: 'Six-stringed instrument',          category: 'Music'     },
    { word: 'ISLAND',   hint: 'Land surrounded by water',         category: 'Places'    },
    { word: 'KNIGHT',   hint: 'Armored medieval warrior',         category: 'History'   },
    { word: 'LEMON',    hint: 'Sour yellow citrus fruit',         category: 'Food'      },
    { word: 'MARBLE',   hint: 'Smooth polished stone',            category: 'Objects'   },
    { word: 'ORANGE',   hint: 'A citrus fruit or color',          category: 'Food'      },
    { word: 'PENCIL',   hint: 'Used for writing and drawing',     category: 'Objects'   },
    { word: 'PUZZLE',   hint: 'A brain-teasing challenge',        category: 'Games'     },
    { word: 'RABBIT',   hint: 'Hops and has long ears',           category: 'Animals'   },
    { word: 'ROCKET',   hint: 'Launches into space',              category: 'Space'     },
    { word: 'SCHOOL',   hint: 'Where students learn',             category: 'Places'    },
    { word: 'SPIDER',   hint: 'Eight-legged arachnid',            category: 'Animals'   },
    { word: 'TURTLE',   hint: 'Has a shell on its back',          category: 'Animals'   },
    { word: 'VIOLIN',   hint: 'Bowed string instrument',          category: 'Music'     },
    { word: 'WINDOW',   hint: 'Lets in light and air',            category: 'Structures'},
    { word: 'WINTER',   hint: 'The coldest season',               category: 'Nature'    },
    { word: 'WIZARD',   hint: 'Casts magical spells',             category: 'Fantasy'   },
  ],
  hard: [
    { word: 'ARCHITECT',   hint: 'Designs buildings',                  category: 'Professions' },
    { word: 'BACKPACK',    hint: 'Worn on your back for carrying',      category: 'Objects'     },
    { word: 'BREAKFAST',   hint: 'The first meal of the day',           category: 'Food'        },
    { word: 'BUTTERFLY',   hint: 'Colorful winged insect',              category: 'Animals'     },
    { word: 'CALENDAR',    hint: 'Tracks days and months',              category: 'Objects'     },
    { word: 'CHOCOLATE',   hint: 'Sweet treat from cacao beans',        category: 'Food'        },
    { word: 'CLOCKWORK',   hint: 'Gears and springs mechanism',         category: 'Objects'     },
    { word: 'CROCODILE',   hint: 'Large reptile in rivers',             category: 'Animals'     },
    { word: 'DAUGHTER',    hint: 'Female offspring',                    category: 'People'      },
    { word: 'DISCOVERY',   hint: 'Finding something new',               category: 'Concepts'    },
    { word: 'EARTHQUAKE',  hint: 'Shaking of the ground',               category: 'Nature'      },
    { word: 'FINGERTIP',   hint: 'End of a finger',                     category: 'Body'        },
    { word: 'FIREWORKS',   hint: 'Colorful sky explosions',             category: 'Events'      },
    { word: 'FLAMINGO',    hint: 'Pink bird that stands on one leg',    category: 'Animals'     },
    { word: 'GEOGRAPHY',   hint: 'Study of Earth and its features',     category: 'Science'     },
    { word: 'HURRICANE',   hint: 'Powerful tropical storm',             category: 'Nature'      },
    { word: 'JELLYFISH',   hint: 'Translucent ocean creature',          category: 'Animals'     },
    { word: 'KANGAROO',    hint: 'Marsupial that hops',                 category: 'Animals'     },
    { word: 'LIGHTHOUSE',  hint: 'Tower with a guiding beacon',         category: 'Structures'  },
    { word: 'MUSHROOM',    hint: 'A fungus with a cap',                 category: 'Nature'      },
    { word: 'PORCUPINE',   hint: 'Covered in sharp quills',             category: 'Animals'     },
    { word: 'QUICKSAND',   hint: 'Wet sand that sucks you in',          category: 'Nature'      },
    { word: 'SUBMARINE',   hint: 'Vessel that travels underwater',      category: 'Vehicles'    },
    { word: 'TELESCOPE',   hint: 'Used to observe distant objects',     category: 'Science'     },
    { word: 'THUNDERSTORM',hint: 'Rain with lightning and thunder',     category: 'Nature'      },
    { word: 'WATERFALL',   hint: 'Water cascading over a cliff',        category: 'Nature'      },
  ],
};

// GET /api/words/hangman/start?difficulty=easy|medium|hard
router.get('/hangman/start', (req, res) => {
  const difficulty = ['easy', 'medium', 'hard'].includes(req.query.difficulty)
    ? req.query.difficulty : 'medium';
  const pool = HANGMAN_WORDS[difficulty];
  const entry = pool[Math.floor(Math.random() * pool.length)];
  res.json({ word: entry.word, hint: entry.hint, category: entry.category, maxWrong: 7 });
});

// ── Word Search ──────────────────────────────────────────────────────────────

// GET /api/words/wordsearch/start?difficulty=easy|medium|hard&theme=random|space|...
// Returns a generated puzzle: { difficulty, theme, themeLabel, size, words, placements, grid }.
router.get('/wordsearch/start', (req, res) => {
  const difficulty = String(req.query.difficulty ?? 'medium').toLowerCase();
  const theme = req.query.theme ? String(req.query.theme).toLowerCase() : 'random';
  res.json(wordSearchGenerate({ difficulty, theme }));
});

// GET /api/words/wordsearch/themes — list of { id, label } for the start panel.
router.get('/wordsearch/themes', (_req, res) => {
  res.json({ themes: wordSearchThemes() });
});

// GET /api/words/sudoku/start?difficulty=very-easy|easy|regular|hard|brutal
router.get('/sudoku/start', (req, res) => {
  const VALID = ['very-easy', 'easy', 'regular', 'hard', 'brutal'];
  const difficulty = VALID.includes(req.query.difficulty) ? req.query.difficulty : 'regular';
  res.json(sudokuGenerate(difficulty));
});

export default router;