// export_format.js
"use strict";

const DIRS = {
	"1": [-1, 0], // up
	"2": [0, 1],  // right
	"3": [1, 0],  // down
	"4": [0, -1], // left
};

const isDigit = (ch) => ch >= "1" && ch <= "4";
const isLetter = (ch) => ch >= "A" && ch <= "Z";

function toGrid2D(grid) {
	if (Array.isArray(grid) && typeof grid[0] === "string") return grid.map(r => r.split(""));
	return grid; // assume 2D char array
}

function inBounds(H, W, r, c) {
	return r >= 0 && r < H && c >= 0 && c < W;
}

/**
 * Extract a word run for a clue cell at (r,c) with direction digit d.
 * Returns canonical representation where:
 *  - direction is only "horizontal"(right) or "vertical"(down)
 *  - startRow/startCol is the first letter cell in that canonical direction
 *  - arrowRow/arrowCol is immediately before the start (left or above)
 *  - word is read from grid in canonical order (start -> end)
 */
function extractPlacedFromClue(g, r, c, d, maxLen = 8, minLen = 2) {
	const H = g.length, W = g[0].length;
	const [dr, dc] = DIRS[d];

	// collect letter cells in the ORIGINAL direction away from the clue
	const cells = [];
	let rr = r + dr, cc = c + dc;
	while (inBounds(H, W, rr, cc) && isLetter(g[rr][cc]) && cells.length < maxLen) {
		cells.push([rr, cc]);
		rr += dr;
		cc += dc;
	}

	if (cells.length < minLen) return null;

	// Canonicalize so we always output right/down runs
	// If original was right (2) or down (3): start is first cell, arrow is clue cell
	// If original was left (4): start is the farthest-left cell, arrow is one cell left of start
	// If original was up (1): start is the topmost cell, arrow is one cell above start
	let startRow, startCol, arrowRow, arrowCol, direction;

	if (d === "2") { // right
		direction = "horizontal";
		[startRow, startCol] = cells[0];
		arrowRow = r;
		arrowCol = c; // clue cell is before start
	} else if (d === "3") { // down
		direction = "vertical";
		[startRow, startCol] = cells[0];
		arrowRow = r;
		arrowCol = c;
	} else if (d === "4") { // left => canonical right
		direction = "horizontal";
		// farthest left is last in cells list (because we walked left)
		[startRow, startCol] = cells[cells.length - 1];
		arrowRow = startRow;
		arrowCol = startCol - 1;
	} else if (d === "1") { // up => canonical down
		direction = "vertical";
		[startRow, startCol] = cells[cells.length - 1]; // topmost
		arrowRow = startRow - 1;
		arrowCol = startCol;
	} else {
		return null;
	}

	// Read the word from the grid in canonical order (right or down)
	const wordChars = [];
	if (direction === "horizontal") {
		for (let i = 0; i < cells.length; i++) {
			const ch = (inBounds(H, W, startRow, startCol + i) ? g[startRow][startCol + i] : "#");
			if (!isLetter(ch)) break;
			wordChars.push(ch);
		}
	} else {
		for (let i = 0; i < cells.length; i++) {
			const ch = (inBounds(H, W, startRow + i, startCol) ? g[startRow + i][startCol] : "#");
			if (!isLetter(ch)) break;
			wordChars.push(ch);
		}
	}

	const word = wordChars.join("");
	if (word.length < minLen || word.length > maxLen) return null;

	return {
		word,
		clue: word,          // placeholder; you’ll replace later
		startRow,
		startCol,
		direction,
		answer: word,
		arrowRow,
		arrowCol,
		// For cropping:
		_cells: direction === "horizontal"
			? Array.from({length: word.length}, (_, i) => [startRow, startCol + i])
			: Array.from({length: word.length}, (_, i) => [startRow + i, startCol]),
		_arrow: [arrowRow, arrowCol],
	};
}

/**
 * Transform your generator output into the JSON format you showed.
 * @param {Object} puz - { grid: string[]|char[][], clueMap?: object }
 */
function exportFormatFromFilled(puz, difficulty = 1, rewards = {coins: 50, stars: 2, hints: 1}) {
	const g = toGrid2D(puz.grid);
	const H = g.length, W = g[0].length;

	// 1) extract "placed" list from all clue digits in the filled grid
	const placed = [];
	const seen = new Set(); // avoid duplicates by start+dir
	for (let r = 0; r < H; r++) {
		for (let c = 0; c < W; c++) {
			const ch = g[r][c];
			if (!isDigit(ch)) continue;

			const p = extractPlacedFromClue(g, r, c, ch, 8, 2);
			if (!p) continue;

			const key = `${p.startRow},${p.startCol}:${p.direction}:${p.word}`;
			if (seen.has(key)) continue;
			seen.add(key);
			placed.push(p);
		}
	}

	if (placed.length === 0) {
		return {gridv2: g.map(row => row.map(ch => (isLetter(ch) ? ch : "#")).join("")), words: [], difficulty, rewards};
	}

	// 2) compute bounding box around all word cells + arrow cells, with 1-cell margin
	const allCells = [];
	for (const p of placed) {
		for (const [rr, cc] of p._cells) allCells.push([rr, cc]);
		allCells.push(p._arrow);
	}

	let minR = Math.min(...allCells.map(([r]) => r)) - 1;
	let minC = Math.min(...allCells.map(([, c]) => c)) - 1;
	let maxR = Math.max(...allCells.map(([r]) => r)) + 1;
	let maxC = Math.max(...allCells.map(([, c]) => c)) + 1;

	// 3) build a map of only the used letter cells (so everything else becomes '#')
	const letterAt = new Map();
	for (const p of placed) {
		for (const [rr, cc] of p._cells) {
			if (inBounds(H, W, rr, cc) && isLetter(g[rr][cc])) {
				letterAt.set(`${rr},${cc}`, g[rr][cc]);
			}
		}
	}

	// 4) render gridv2
	const gridv2 = [];
	for (let r = minR; r <= maxR; r++) {
		let row = "";
		for (let c = minC; c <= maxC; c++) {
			const ch = letterAt.get(`${r},${c}`);
			row += ch ? ch : "#";
		}
		gridv2.push(row);
	}

	// 5) words output with cropped coordinates
	const words_out = placed.map(p => ({
		word: p.word,
		clue: p.clue, // currently word itself
		startRow: p.startRow - minR,
		startCol: p.startCol - minC,
		direction: p.direction,
		answer: p.word,
		arrowRow: p.arrowRow - minR,
		arrowCol: p.arrowCol - minC,
	}));

	return {gridv2, words: words_out, difficulty, rewards};
}

module.exports = {exportFormatFromFilled};