#!/usr/bin/env node
"use strict";

/**
 * Swedish-style crossword generator (mask + fill)
 * Spec:
 *  - Grid 9x8
 *  - Letter cells: '#' (empty) or 'A'..'Z' (fixed)
 *  - Clue cells: '1'..'4' indicating direction:
 *      1=up, 2=right, 3=down, 4=left
 *  - Word length: 2..8
 *  - Words from word-list.txt (one per line, uppercase A-Z)
 *
 * Output:
 *  - GENERATED MASK (digits + #)
 *  - FILLED PUZZLE (digits + letters)
 *  - clue -> word mapping "r,c:d = WORD"
 */

const fs = require("fs");

const W = 9, H = 8;
const MIN_LEN = 2, MAX_LEN = 8;

const DIRS = {
	"1": [-1, 0],
	"2": [0, 1],
	"3": [1, 0],
	"4": [0, -1],
};
const IS_DIGIT = (ch) => ch >= "1" && ch <= "4";
const IS_LETTER = (ch) => ch >= "A" && ch <= "Z";
const IS_LETTER_CELL = (ch) => ch === "#" || IS_LETTER(ch);

function usage() {
	console.log(`Usage:
  node swedish_generator.js [--seed N] [--pop N] [--gens N] [--tries N] [--words word-list.txt]

Defaults:
  --seed 1
  --pop 18
  --gens 220
  --tries 25
  --words ./word-list.txt
`);
}

function parseArgs(argv) {
	const out = {seed: 1, pop: 18, gens: 220, tries: 25, wordsPath: "./word-list.txt"};
	for (let i = 2; i < argv.length; i++) {
		const a = argv[i];
		const v = argv[i + 1];
		if (a === "--help" || a === "-h") {
			usage();
			process.exit(0);
		}
		if (a === "--seed") out.seed = parseInt(v, 10), i++;
		else if (a === "--pop") out.pop = parseInt(v, 10), i++;
		else if (a === "--gens") out.gens = parseInt(v, 10), i++;
		else if (a === "--tries") out.tries = parseInt(v, 10), i++;
		else if (a === "--words") out.wordsPath = v, i++;
		else throw new Error(`Unknown arg: ${a}`);
	}
	return out;
}

/** seeded RNG (xorshift32) */
function makeRng(seed) {
	let x = (seed >>> 0) || 1;
	return {
		nextU32() {
			x ^= x << 13;
			x >>>= 0;
			x ^= x >>> 17;
			x >>>= 0;
			x ^= x << 5;
			x >>>= 0;
			return x >>> 0;
		},
		int(min, max) {
			const r = this.nextU32();
			return min + (r % (max - min + 1));
		},
		float() {
			return this.nextU32() / 0xFFFFFFFF;
		},
		pick(arr) {
			return arr[this.int(0, arr.length - 1)];
		}
	};
}

function deepCopyGrid(g) {
	return g.map(r => r.slice());
}

function gridToString(g) {
	return g.map(r => r.join("")).join("\n");
}

function makeEmptyGrid() {
	return Array.from({length: H}, () => Array.from({length: W}, () => "#"));
}

/** Load words and build fast length+pos index */
function loadWords(wordsPath) {
	let raw = "";
	try {
		raw = fs.readFileSync(wordsPath, "utf8");
	} catch {
		// fallback
		raw = "EU\nUUR\nAUTO\nBOOM\nHUIS\nKAT\nZEE\nRODE\nDRAAD\nKENNIS\nNETWERK\nPAKTE\n";
	}

	const words = raw
		.split(/\r?\n/g)
		.map(s => s.trim().toUpperCase())
		.filter(s => /^[A-Z]{2,8}$/.test(s));

	// index[len] = { words: string[], pos: Array(len) of [26 arrays of indices] }
	const index = new Map();
	for (const w of words) {
		const L = w.length;
		if (!index.has(L)) {
			const pos = Array.from({length: L}, () =>
				Array.from({length: 26}, () => [])
			);
			index.set(L, {words: [], pos});
		}
		const entry = index.get(L);
		const idx = entry.words.length;
		entry.words.push(w);
		for (let i = 0; i < L; i++) {
			entry.pos[i][w.charCodeAt(i) - 65].push(idx);
		}
	}
	return {words, index};
}

function intersectSorted(a, b) {
	const out = [];
	let i = 0, j = 0;
	while (i < a.length && j < b.length) {
		const x = a[i], y = b[j];
		if (x === y) {
			out.push(x);
			i++;
			j++;
		} else if (x < y) i++;
		else j++;
	}
	return out;
}

function candidateIndicesForPattern(indexEntry, pattern /* array char|null */) {
	const lists = [];
	for (let i = 0; i < pattern.length; i++) {
		const ch = pattern[i];
		if (ch && IS_LETTER(ch)) {
			lists.push(indexEntry.pos[i][ch.charCodeAt(0) - 65]);
		}
	}
	if (lists.length === 0) {
		// all candidates
		return Array.from({length: indexEntry.words.length}, (_, i) => i);
	}
	lists.sort((a, b) => a.length - b.length);
	let cur = lists[0];
	for (let k = 1; k < lists.length; k++) {
		cur = intersectSorted(cur, lists[k]);
		if (cur.length === 0) break;
	}
	return cur;
}

/** Slot extraction: from each clue cell (digit), read letters away while letter-cells (# or A-Z) */
function extractSlots(grid) {
	const slots = [];
	for (let r = 0; r < H; r++) {
		for (let c = 0; c < W; c++) {
			const d = grid[r][c];
			if (!IS_DIGIT(d)) continue;
			const [dr, dc] = DIRS[d];
			let rr = r + dr, cc = c + dc;
			if (rr < 0 || rr >= H || cc < 0 || cc >= W) continue;
			if (!IS_LETTER_CELL(grid[rr][cc])) continue;

			const cells = [];
			while (rr >= 0 && rr < H && cc >= 0 && cc < W) {
				const ch = grid[rr][cc];
				if (!IS_LETTER_CELL(ch)) break; // stops at clue digits (or other non-letter)
				cells.push([rr, cc]);
				rr += dr;
				cc += dc;
				if (cells.length > MAX_LEN) break;
			}
			slots.push({
				clue: [r, c, d],
				dir: d,
				cells,
				len: cells.length
			});
		}
	}
	return slots;
}

/** Fitness: penalty-based mask evaluation + dictionary-based feasibility hints */
function fitness(grid, dictIndex) {
	let penalty = 0;

	// 1) clue density (avoid "all digits")
	let clueCount = 0, letterCount = 0;
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		const ch = grid[r][c];
		if (IS_DIGIT(ch)) clueCount++;
		else if (IS_LETTER_CELL(ch)) letterCount++;
	}
	const targetClues = Math.round(W * H * 0.25);  // ~18
	penalty += 8 * Math.abs(clueCount - targetClues);

	// 2) slots + length + candidate viability
	const slots = extractSlots(grid);

	if (slots.length === 0) return 1e9;

	// coverage counts per letter cell: horizontal vs vertical
	const covH = Array.from({length: H}, () => Array(W).fill(0));
	const covV = Array.from({length: H}, () => Array(W).fill(0));

	for (const s of slots) {
		const horizontal = (s.dir === "2" || s.dir === "4");
		if (s.len < MIN_LEN) penalty += 8000;
		else if (s.len > MAX_LEN) penalty += 8000 + (s.len - MAX_LEN) * 500;

		// candidate count hint (not full fill, but strong signal)
		if (s.len >= MIN_LEN && s.len <= MAX_LEN && dictIndex && dictIndex.has(s.len)) {
			const entry = dictIndex.get(s.len);
			const pattern = s.cells.map(([r, c]) => {
				const ch = grid[r][c];
				return IS_LETTER(ch) ? ch : null;
			});
			const candIdx = candidateIndicesForPattern(entry, pattern);
			const n = candIdx.length;
			if (n === 0) penalty += 12000;         // impossible slot
			else penalty += Math.floor(400 / Math.log2(n + 2)); // prefer higher branching
		} else {
			// no words of that length available
			if (s.len >= MIN_LEN && s.len <= MAX_LEN) penalty += 12000;
		}

		// mark coverage
		for (const [r, c] of s.cells) {
			if (horizontal) covH[r][c] += 1;
			else covV[r][c] += 1;
		}
	}

	// 3) coverage penalties per letter cell
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		const ch = grid[r][c];
		if (!IS_LETTER_CELL(ch)) continue;
		const h = covH[r][c], v = covV[r][c];
		if (h === 0 && v === 0) penalty += 1500;
		else if (h > 0 && v > 0) penalty += 0;
		else if (h + v === 1) penalty += 200;
		else penalty += 600; // multiple same-direction passes
	}

	// 4) clue clustering penalty (8-connected components)
	const seen = Array.from({length: H}, () => Array(W).fill(false));
	const nbrs8 = [
		[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]
	];
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		if (!IS_DIGIT(grid[r][c]) || seen[r][c]) continue;
		const q = [[r, c]];
		seen[r][c] = true;
		let size = 0;
		while (q.length) {
			const [x, y] = q.pop();
			size++;
			for (const [dr, dc] of nbrs8) {
				const nx = x + dr, ny = y + dc;
				if (nx < 0 || nx >= H || ny < 0 || ny >= W) continue;
				if (seen[nx][ny]) continue;
				if (!IS_DIGIT(grid[nx][ny])) continue;
				seen[nx][ny] = true;
				q.push([nx, ny]);
			}
		}
		if (size >= 2) penalty += (size - 1) * 120;
	}

	// 5) dead-end-ish penalty: letter cell surrounded by non-letters on 3+ sides
	const nbrs4 = [[-1, 0], [1, 0], [0, -1], [0, 1]];
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		if (!IS_LETTER_CELL(grid[r][c])) continue;
		let walls = 0;
		for (const [dr, dc] of nbrs4) {
			const rr = r + dr, cc = c + dc;
			if (rr < 0 || rr >= H || cc < 0 || cc >= W) {
				walls++;
				continue;
			}
			const ch = grid[rr][cc];
			if (!IS_LETTER_CELL(ch)) walls++;
		}
		if (walls >= 3) penalty += 400;
	}

	return penalty;
}

/** Helpers to ensure a clue has room for at least MIN_LEN */
function hasRoomForClue(grid, r, c, d) {
	const [dr, dc] = DIRS[d];
	let rr = r + dr, cc = c + dc;
	let run = 0;
	while (rr >= 0 && rr < H && cc >= 0 && cc < W && IS_LETTER_CELL(grid[rr][cc]) && run < MAX_LEN) {
		run++;
		rr += dr;
		cc += dc;
	}
	return run >= MIN_LEN;
}

/** Random initialization: mostly letters, some clues with room */
function randomMask(rng) {
	const g = makeEmptyGrid();
	const targetClues = Math.round(W * H * 0.25); // ~18
	let placed = 0;
	let guard = 0;
	while (placed < targetClues && guard++ < 2000) {
		const r = rng.int(0, H - 1);
		const c = rng.int(0, W - 1);
		if (IS_DIGIT(g[r][c])) continue;
		const d = String(rng.int(1, 4));
		g[r][c] = d;
		if (!hasRoomForClue(g, r, c, d)) {
			g[r][c] = "#";
			continue;
		}
		placed++;
	}
	return g;
}

/** Mutation: toggle a few cells with a "centralized" bias */
function mutate(rng, grid) {
	const g = deepCopyGrid(grid);

	// pick a center point to bias mutations (paper-style "centralized")
	const cx = rng.int(0, H - 1);
	const cy = rng.int(0, W - 1);

	const steps = 4;
	for (let k = 0; k < steps; k++) {
		// gaussian-ish around (cx,cy) using sum of uniforms trick
		const rr = clamp(cx + (rng.int(-2, 2) + rng.int(-2, 2)), 0, H - 1);
		const cc = clamp(cy + (rng.int(-2, 2) + rng.int(-2, 2)), 0, W - 1);

		const cur = g[rr][cc];
		if (IS_DIGIT(cur)) {
			// remove clue
			g[rr][cc] = "#";
		} else {
			// add clue with room
			const d = String(rng.int(1, 4));
			g[rr][cc] = d;
			if (!hasRoomForClue(g, rr, cc, d)) g[rr][cc] = "#";
		}
	}

	return g;
}

function clamp(x, a, b) { return Math.max(a, Math.min(b, x)); }

/** Angled crossover through center (closer to the paper than row-split) */
function crossover(rng, a, b) {
	const out = makeEmptyGrid();
	const cx = (H - 1) / 2;
	const cy = (W - 1) / 2;
	const theta = rng.float() * Math.PI; // 0..pi

	// line normal
	const nx = Math.cos(theta);
	const ny = Math.sin(theta);

	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		const x = r - cx, y = c - cy;
		const side = x * nx + y * ny;
		out[r][c] = (side >= 0) ? a[r][c] : b[r][c];
	}

	// cleanup: if a clue has no room, turn it back into '#'
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		const ch = out[r][c];
		if (IS_DIGIT(ch) && !hasRoomForClue(out, r, c, ch)) out[r][c] = "#";
	}

	return out;
}

/** Hillclimber (accept improving mutations) */
function hillclimb(rng, start, dictIndex, limit) {
	let best = deepCopyGrid(start);
	let bestF = fitness(best, dictIndex);
	let fails = 0;

	while (fails < limit) {
		const cand = mutate(rng, best);
		const f = fitness(cand, dictIndex);
		if (f < bestF) {
			best = cand;
			bestF = f;
			fails = 0;
		} else {
			fails++;
		}
	}
	return best;
}

/** Similarity filter to avoid duplicates */
function similarity(a, b) {
	let same = 0;
	for (let r = 0; r < H; r++) for (let c = 0; c < W; c++) {
		if (a[r][c] === b[r][c]) same++;
	}
	return same / (W * H);
}

/** Memetic mask generator */
function generateMask(rng, dictIndex, popSize, gens) {
	// init + strong hillclimb
	let pop = [];
	for (let i = 0; i < popSize; i++) {
		const g = randomMask(rng);
		pop.push(hillclimb(rng, g, dictIndex, 400)); // strong-ish
	}

	for (let gen = 0; gen < gens; gen++) {
		const children = [];
		// create children from random pairs
		const pairs = Math.max(popSize, Math.floor(popSize * 1.5));
		for (let k = 0; k < pairs; k++) {
			const p1 = pop[rng.int(0, pop.length - 1)];
			const p2 = pop[rng.int(0, pop.length - 1)];
			const child = crossover(rng, p1, p2);
			children.push(hillclimb(rng, child, dictIndex, 120)); // weak repair
		}

		// merge + sort by fitness
		pop = pop.concat(children);
		pop.sort((x, y) => fitness(x, dictIndex) - fitness(y, dictIndex));

		// similarity cull
		const next = [];
		for (const cand of pop) {
			if (next.length >= popSize) break;
			let ok = true;
			for (const kept of next) {
				if (similarity(cand, kept) > 0.92) {
					ok = false;
					break;
				}
			}
			if (ok) next.push(cand);
		}
		pop = next;
	}

	pop.sort((x, y) => fitness(x, dictIndex) - fitness(y, dictIndex));
	return pop[0];
}

/** CSP fill: MRV + backtracking, using dictionary index */
function fillMask(mask, dictIndex) {
	const grid = deepCopyGrid(mask);
	const slots = extractSlots(grid)
		.filter(s => s.len >= MIN_LEN && s.len <= MAX_LEN);

	// precompute slot directions for coverage sanity
	for (const s of slots) {
		const entry = dictIndex.get(s.len);
		if (!entry) return {ok: false, grid, clueMap: {}};
	}

	const used = new Set();
	const assigned = new Map(); // slotKey -> word

	function slotKey(s) {
		const [r, c, d] = s.clue;
		return `${r},${c}:${d}`;
	}

	function patternForSlot(s) {
		return s.cells.map(([r, c]) => {
			const ch = grid[r][c];
			return IS_LETTER(ch) ? ch : null;
		});
	}

	function candidatesForSlot(s) {
		const entry = dictIndex.get(s.len);
		const pat = patternForSlot(s);
		const idxs = candidateIndicesForPattern(entry, pat);
		// map to words; filter repeats
		const out = [];
		for (const idx of idxs) {
			const w = entry.words[idx];
			if (!used.has(w)) out.push(w);
		}
		return out;
	}

	function placeWord(s, w) {
		const undo = [];
		for (let i = 0; i < s.cells.length; i++) {
			const [r, c] = s.cells[i];
			const prev = grid[r][c];
			const ch = w[i];
			if (prev === "#") {
				undo.push([r, c, prev]);
				grid[r][c] = ch;
			} else if (prev !== ch) {
				return null; // conflict
			}
		}
		return undo;
	}

	function undoPlace(undo) {
		for (const [r, c, prev] of undo) grid[r][c] = prev;
	}

	function chooseMRV() {
		let best = null;
		let bestCands = null;

		for (const s of slots) {
			const k = slotKey(s);
			if (assigned.has(k)) continue;
			const cands = candidatesForSlot(s);
			if (cands.length === 0) return {slot: null, cands: null}; // dead end
			if (!best || cands.length < bestCands.length) {
				best = s;
				bestCands = cands;
				if (cands.length === 1) break;
			}
		}
		return {slot: best, cands: bestCands};
	}

	function backtrack() {
		const {slot, cands} = chooseMRV();
		if (slot === null && cands === null) return false;
		if (!slot) return true; // all assigned

		const k = slotKey(slot);

		// simple LCV-ish: prefer words that introduce more crosses (more fixed letters)
		cands.sort((a, b) => scoreWord(slot, b) - scoreWord(slot, a));

		for (const w of cands) {
			const undo = placeWord(slot, w);
			if (!undo) continue;

			used.add(w);
			assigned.set(k, w);

			if (backtrack()) return true;

			assigned.delete(k);
			used.delete(w);
			undoPlace(undo);
		}
		return false;
	}

	function scoreWord(slot, word) {
		// higher score: matches more already-fixed letters (less disruptive) and creates constraints
		let score = 0;
		for (let i = 0; i < slot.cells.length; i++) {
			const [r, c] = slot.cells[i];
			const prev = grid[r][c];
			if (prev !== "#" && prev === word[i]) score += 2;
			// prefer setting letters in cells that are crossed by another slot:
			// approximate by counting adjacent clue cells? keep cheap:
			score += 0.1;
		}
		return score;
	}

	const ok = backtrack();

	const clueMap = {};
	for (const [k, v] of assigned.entries()) clueMap[k] = v;

	return {ok, grid, clueMap};
}

/** Top-level: try generating mask + fill until success */
function generatePuzzle(opts) {
	const rng = makeRng(opts.seed);
	const dict = loadWords(opts.wordsPath);

	let best = null;
	for (let attempt = 1; attempt <= opts.tries; attempt++) {
		const mask = generateMask(rng, dict.index, opts.pop, opts.gens);
		const filled = fillMask(mask, dict.index);
		if (filled.ok) {
			best = {mask, filled};
			break;
		}
	}
	return best;
}

// ---- main ----
(function main() {
	const opts = parseArgs(process.argv);
	const res = generatePuzzle(opts);

	if (!res) {
		console.error("Failed to generate a fillable puzzle. Try increasing --tries/--gens, or provide a richer word-list.txt.");
		process.exit(1);
	}

	const maskStr = gridToString(res.mask);
	const filledStr = gridToString(res.filled.grid);

	console.log("=== GENERATED MASK ===");
	console.log(maskStr);

	console.log("\n=== FILLED PUZZLE ===");
	console.log(filledStr);

	console.log("\n=== CLUE -> WORD ===");
	// stable-ish ordering
	Object.keys(res.filled.clueMap)
		.sort((a, b) => a.localeCompare(b))
		.forEach(k => console.log(`${k} = ${res.filled.clueMap[k]}`));
})();