/**
 * PGN Parser - Parses PGN files and extracts game data
 */

function parsePGN(pgnText) {
    const games = [];
    // Split by game boundaries - each game starts with [Event
    const gameBlocks = pgnText.split(/\[\s*Event\s*"/);
    
    for (let i = 1; i < gameBlocks.length; i++) {
        const game = parseGameBlock(gameBlocks[i]);
        if (game) games.push(game);
    }
    
    return games;
}

function parseGameBlock(block) {
    try {
        const headers = {};

        // Der Event-Header fehlt, weil wir danach splitten – extrahiere ihn aus dem Blockanfang
        const eventEnd = block.indexOf('"]');
        if (eventEnd > 1) {
            headers.Event = block.substring(1, eventEnd);
        }

        const headerRegex = /^\s*\[(\w+)\s+"([^"]*)"\]/gm;
        let match;
        
        // Extract all headers
        let tempBlock = block;
        while ((match = headerRegex.exec(tempBlock)) !== null) {
            headers[match[1]] = match[2];
        }
        
        // Extract moves - everything after the last header
        const lastHeaderEnd = block.lastIndexOf('"]');
        let movesText = lastHeaderEnd > -1 ? block.substring(lastHeaderEnd + 2).trim() : '';
        
        // Remove comments from moves for cleaner parsing
        const moves = parseMoves(movesText);
        
        return {
            event: headers.Event || '',
            site: headers.Site || '',
            date: headers.Date || '',
            round: headers.Round || '',
            white: headers.White || '',
            black: headers.Black || '',
            result: headers.Result || '',
            termination: headers.Termination || '',
            whiteElo: headers.WhiteElo || '',
            blackElo: headers.BlackElo || '',
            whiteClock: headers.WhiteClock || '',
            blackClock: headers.BlackClock || '',
            moves: moves,
            isLive: headers.Termination === 'unterminated' || headers.Result === '*'
        };
    } catch (e) {
        console.error('Error parsing game:', e);
        return null;
    }
}

function parseMoves(movesText) {
    const moves = [];
    
    let clockWhite = null;
    let clockBlack = null;
    let color = 'w';
    
    const tokenRegex = /\d+\.\s*|\{[^}]*\}|\S+/g;
    const tokens = movesText.match(tokenRegex) || [];
    
    for (let i = 0; i < tokens.length; i++) {
        let token = tokens[i].trim();
        
        if (['1-0', '0-1', '1/2-1/2', '*'].includes(token)) {
            moves.push({ san: token, isResult: true, whiteClock: clockWhite, blackClock: clockBlack });
            continue;
        }
        
        if (/^\d+\.$/.test(token)) continue;
        
        if (token.startsWith('{')) {
            const clkMatch = token.match(/\[%clk\s+([\d:]+)\]/);
            if (clkMatch && moves.length > 0) {
                const lastMove = moves[moves.length - 1];
                if (!lastMove.isResult && lastMove.color) {
                    if (lastMove.color === 'w') {
                        clockWhite = clkMatch[1];
                    } else {
                        clockBlack = clkMatch[1];
                    }
                    lastMove.whiteClock = clockWhite;
                    lastMove.blackClock = clockBlack;
                }
            }
            continue;
        }
        
        const move = { san: token, isResult: false, whiteClock: clockWhite, blackClock: clockBlack, color };
        moves.push(move);
        color = color === 'w' ? 'b' : 'w';
    }
    
    return moves;
}

function filterLaraGames(games) {
    return games.filter(game => 
        game.white.toLowerCase().includes('kiesewetter') || 
        game.black.toLowerCase().includes('kiesewetter')
    );
}

function getLiveGame(laraGames) {
    // Return the game that is still in progress
    return laraGames.find(game => game.isLive) || null;
}

function getLatestGame(laraGames) {
    if (laraGames.length === 0) return null;
    // Sort by round number, return the highest round
    const sorted = [...laraGames].sort((a, b) => {
        const roundA = parseInt(a.round) || 0;
        const roundB = parseInt(b.round) || 0;
        return roundB - roundA;
    });
    return sorted[0];
}

window.parsePGN = parsePGN;
window.filterLaraGames = filterLaraGames;
window.getLiveGame = getLiveGame;
window.getLatestGame = getLatestGame;