const FogOfWar = {
    // Set of revealed hex coordinates (as strings)
    revealed: new Set(),
    
    // Configuration
    VISION_RANGE: Config.player.VISION_RANGE,
    
    init() {
        this.revealed.clear();
        this.updateVisibility(player.position);
    },
    
    // Convert hex to string key for Set storage
    hexToKey(hex) {
        return `${hex.q},${hex.r}`;
    },
    
    // Check if a hex is currently visible
    isVisible(hex) {
        const playerPos = player.getCurrentPosition();
        const distance = this.getHexDistance(hex, playerPos);
        return distance <= this.VISION_RANGE;
    },
    
    // Check if a hex has been revealed
    isRevealed(hex) {
        return this.revealed.has(this.hexToKey(hex));
    },
    
    // Calculate distance between two hexes
    getHexDistance(a, b) {
        return Math.max(
            Math.abs(a.q - b.q),
            Math.abs(a.r - b.r),
            Math.abs((a.q + a.r) - (b.q + b.r))
        );
    },
    
    // Update visibility based on player position
    updateVisibility(center) {
        // Get all hexes within vision range
        for (let q = -this.VISION_RANGE; q <= this.VISION_RANGE; q++) {
            for (let r = -this.VISION_RANGE; r <= this.VISION_RANGE; r++) {
                const hex = {
                    q: center.q + q,
                    r: center.r + r
                };
                
                if (this.getHexDistance(center, hex) <= this.VISION_RANGE) {
                    this.revealed.add(this.hexToKey(hex));
                }
            }
        }
    },
    
    // Draw fog of war effect
    draw(ctx) {
        // Draw fog over unrevealed areas
        HexGrid.getViewportHexes().forEach(hex => {
            if (!this.isRevealed(hex) || !this.isVisible(hex)) {
                const pixel = HexGrid.toPixel(hex);
                const screenX = pixel.x - Camera.x;
                const screenY = pixel.y - Camera.y;
                
                ctx.fillStyle = this.isRevealed(hex) ? 
                    'rgba(0, 0, 0, 0.5)' :  // Darker fog for unexplored areas
                    'rgba(0, 0, 0, 0.8)';   // Lighter fog for explored but not visible
                
                // Draw fog hex
                ctx.beginPath();
                for (let i = 0; i < 6; i++) {
                    const angle = 2 * Math.PI / 6 * i;
                    const xPos = screenX + HexGrid.SIZE * Math.cos(angle);
                    const yPos = screenY + HexGrid.SIZE * Math.sin(angle);
                    if (i === 0) {
                        ctx.moveTo(xPos, yPos);
                    } else {
                        ctx.lineTo(xPos, yPos);
                    }
                }
                ctx.closePath();
                ctx.fill();
            }
        });
    }
};