/**
 * Simple SGF parser for extracting moves from SGF files
 */

export interface SgfMove {
  color: 'black' | 'white';
  x: number;
  y: number;
}

export interface SgfData {
  boardSize: number;
  moves: SgfMove[];
}

/**
 * Parse SGF content and extract board size and moves
 */
export function parseSgf(sgfContent: string): SgfData {
  const moves: SgfMove[] = [];
  let boardSize = 19; // default

  // Extract board size
  const sizeMatch = sgfContent.match(/SZ\[(\d+)\]/);
  if (sizeMatch) {
    boardSize = parseInt(sizeMatch[1], 10);
  }

  // Extract moves - pattern like ;B[dd] or ;W[ed]
  const movePattern = /;([BW])\[([a-z]{0,2})\]/g;
  let match;

  while ((match = movePattern.exec(sgfContent)) !== null) {
    const color = match[1] === 'B' ? 'black' : 'white';
    const coords = match[2];

    // Empty brackets mean pass
    if (!coords) {
      continue;
    }

    // Convert SGF coordinates (aa = top-left) to 0-based x,y
    const x = coords.charCodeAt(0) - 97; // 'a' = 0
    const y = coords.charCodeAt(1) - 97;

    moves.push({ color, x, y });
  }

  return { boardSize, moves };
}

/**
 * Load and parse an SGF file from a URL
 */
export async function loadSgf(url: string): Promise<SgfData> {
  const response = await fetch(url);
  const content = await response.text();
  return parseSgf(content);
}