/**
 * Lara Kiesewetter – Live Schachturnier
 * Stockfish evaluation
 */

/* global Chess */

function syncEvalBarHeight() {
    const boardEl = document.getElementById('board');
    const evalContainer = document.getElementById('eval-bar-container');
    if (boardEl && evalContainer) {
        const h = boardEl.offsetHeight;
        if (h > 100) evalContainer.style.minHeight = h + 'px';
    }
}

async function updateEvaluation() {
    if (!chess) return;
    const fen = chess.fen();

    if (lastEvalFen === fen && evalAbortController) return;
    lastEvalFen = fen;

    if (evalAbortController) {
        evalAbortController.abort();
    }
    evalAbortController = new AbortController();

    try {
        const res = await fetch('/evaluate', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ fen }),
            signal: evalAbortController.signal,
        });
        if (!res.ok) throw new Error('Eval fehlgeschlagen');

        const reader = res.body.getReader();
        const decoder = new TextDecoder();
        let buffer = '';

        while (true) {
            const { done, value } = await reader.read();
            if (done) break;

            buffer += decoder.decode(value, { stream: true });
            const lines = buffer.split('\n');
            buffer = lines.pop();

            for (const line of lines) {
                if (!line.trim()) continue;
                try {
                    displayEval(JSON.parse(line));
                } catch {}
            }
        }

        if (buffer.trim()) {
            try { displayEval(JSON.parse(buffer)); } catch {}
        }
    } catch (e) {
        if (e.name === 'AbortError') return;
        const el = document.getElementById('eval-score');
        if (el) el.textContent = '?';
    }
}

function displayEval(data) {
    const evalScore = document.getElementById('eval-score');
    const barFill = document.getElementById('eval-bar-fill');
    const barMarker = document.getElementById('eval-bar-marker');

    let scoreText = '0.00';
    let fillPercent = 50;

    if (data.scoreMate !== null && data.scoreMate !== undefined && data.scoreMate !== 0) {
        const mate = parseInt(data.scoreMate);
        const whiteMate = chess && chess.turn() === 'w' ? mate : -mate;
        if (whiteMate > 0) {
            scoreText = '#' + whiteMate;
            fillPercent = 100;
        } else {
            scoreText = '#' + Math.abs(whiteMate);
            fillPercent = 0;
        }
    } else if (data.scoreCp !== null && data.scoreCp !== undefined) {
        const cp = parseInt(data.scoreCp);
        const whiteCp = chess && chess.turn() === 'w' ? cp : -cp;
        const pawns = (whiteCp / 100).toFixed(2);
        scoreText = (whiteCp > 0 ? '+' : '') + pawns;
        fillPercent = 50 + whiteCp / 14;
        fillPercent = Math.max(0, Math.min(100, fillPercent));
    }

    evalScore.textContent = scoreText;

    if (barFill) barFill.style.height = fillPercent + '%';
    if (barMarker) barMarker.style.top = (100 - fillPercent) + '%';
}