import React, { useRef, useEffect, useState, useCallback } from 'react';
import type { AvailableMovesResponse, BoardState, Player } from '../types';

interface BoardCanvasProps {
  boardState: BoardState;
  selectedPlayer: Player | null;
  availableMoves?: AvailableMovesResponse | null;
  onSelectPlayer: (player: Player | null) => void;
  onHoverCoord?: (coord: { x: number; y: number } | null) => void;
}

export const BoardCanvas: React.FC<BoardCanvasProps> = ({
  boardState,
  selectedPlayer,
  availableMoves,
  onSelectPlayer,
  onHoverCoord,
}) => {
  const canvasRef = useRef<HTMLCanvasElement | null>(null);
  const containerRef = useRef<HTMLDivElement | null>(null);

  // Viewport transforms
  const [zoom, setZoom] = useState<number>(1);
  const [offset, setOffset] = useState<{ x: number; y: number }>({ x: 0, y: 0 });
  const [isDragging, setIsDragging] = useState<boolean>(false);
  const [dragStart, setDragStart] = useState<{ x: number; y: number }>({ x: 0, y: 0 });
  const [hoveredCoord, setHoveredCoord] = useState<{ x: number; y: number } | null>(null);
  const [hoveredPlayer, setHoveredPlayer] = useState<Player | null>(null);

  const { min_x, max_x, min_y, max_y } = boardState.config;
  const gridCellsX = max_x - min_x;
  const gridCellsY = max_y - min_y;
  const currentTurnId = boardState.turn.current_player_id;

  // Convert canvas pixel coordinates to grid coordinate (0..64)
  const pixelToGrid = useCallback(
    (px: number, py: number, width: number, height: number) => {
      const padding = 45;
      const arenaSize = Math.min(width - padding * 2, height - padding * 2);
      const startX = (width - arenaSize) / 2 + offset.x;
      const startY = (height - arenaSize) / 2 + offset.y;
      const cellSize = (arenaSize / gridCellsX) * zoom;

      const gx = Math.round((px - startX) / cellSize);
      const gy = Math.round((py - startY) / cellSize);

      if (gx >= min_x && gx <= max_x && gy >= min_y && gy <= max_y) {
        return { x: gx, y: gy };
      }
      return null;
    },
    [offset, zoom, gridCellsX, min_x, max_x, min_y, max_y]
  );

  const handleResetView = useCallback(() => {
    setZoom(1);
    setOffset({ x: 0, y: 0 });
  }, []);

  // Center camera on selected player
  useEffect(() => {
    if (selectedPlayer && containerRef.current) {
      const { width, height } = containerRef.current.getBoundingClientRect();
      const padding = 45;
      const arenaSize = Math.min(width - padding * 2, height - padding * 2);
      const cellSize = (arenaSize / gridCellsX) * zoom;

      const targetPx = (selectedPlayer.x - min_x) * cellSize;
      const targetPy = (selectedPlayer.y - min_y) * cellSize;

      setOffset({
        x: -(targetPx - arenaSize / 2),
        y: -(targetPy - arenaSize / 2),
      });
    }
  }, [selectedPlayer?.id, min_x, min_y, gridCellsX, zoom]);

  // Main render loop
  useEffect(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;
    const ctx = canvas.getContext('2d');
    if (!ctx) return;

    let animationFrameId: number;

    const render = () => {
      const dpr = window.devicePixelRatio || 1;
      const rect = canvas.getBoundingClientRect();
      const width = rect.width;
      const height = rect.height;

      if (canvas.width !== width * dpr || canvas.height !== height * dpr) {
        canvas.width = width * dpr;
        canvas.height = height * dpr;
      }

      ctx.save();
      ctx.scale(dpr, dpr);

      // Deep sci-fi cyberpunk background
      const bgGrad = ctx.createLinearGradient(0, 0, width, height);
      bgGrad.addColorStop(0, '#090d16');
      bgGrad.addColorStop(1, '#05070c');
      ctx.fillStyle = bgGrad;
      ctx.fillRect(0, 0, width, height);

      // Arena boundary calculation
      const padding = 45;
      const arenaSize = Math.min(width - padding * 2, height - padding * 2);
      const startX = (width - arenaSize) / 2 + offset.x;
      const startY = (height - arenaSize) / 2 + offset.y;
      const cellSize = (arenaSize / gridCellsX) * zoom;
      const totalWidth = cellSize * gridCellsX;
      const totalHeight = cellSize * gridCellsY;

      // Draw Arena Background
      ctx.fillStyle = '#0f172a';
      ctx.fillRect(startX, startY, totalWidth, totalHeight);

      // Clip grid area for internal drawing
      ctx.save();
      ctx.beginPath();
      ctx.rect(startX, startY, totalWidth, totalHeight);
      ctx.clip();

      // Minor grid lines
      ctx.lineWidth = 0.5;
      ctx.strokeStyle = '#1e293b';
      for (let i = 0; i <= gridCellsX; i++) {
        const x = startX + i * cellSize;
        ctx.beginPath();
        ctx.moveTo(x, startY);
        ctx.lineTo(x, startY + totalHeight);
        ctx.stroke();
      }
      for (let j = 0; j <= gridCellsY; j++) {
        const y = startY + j * cellSize;
        ctx.beginPath();
        ctx.moveTo(startX, y);
        ctx.lineTo(startX + totalWidth, y);
        ctx.stroke();
      }

      // Major grid lines every 8 cells
      ctx.lineWidth = 1.2;
      ctx.strokeStyle = '#334155';
      for (let i = 0; i <= gridCellsX; i += 8) {
        const x = startX + i * cellSize;
        ctx.beginPath();
        ctx.moveTo(x, startY);
        ctx.lineTo(x, startY + totalHeight);
        ctx.stroke();
      }
      for (let j = 0; j <= gridCellsY; j += 8) {
        const y = startY + j * cellSize;
        ctx.beginPath();
        ctx.moveTo(startX, y);
        ctx.lineTo(startX + totalWidth, y);
        ctx.stroke();
      }

      // Highlight hovered cell
      if (hoveredCoord) {
        const hx = startX + (hoveredCoord.x - min_x) * cellSize - cellSize / 2;
        const hy = startY + (hoveredCoord.y - min_y) * cellSize - cellSize / 2;
        ctx.fillStyle = 'rgba(56, 189, 248, 0.15)';
        ctx.fillRect(hx, hy, cellSize, cellSize);
        ctx.strokeStyle = 'rgba(56, 189, 248, 0.7)';
        ctx.lineWidth = 1;
        ctx.strokeRect(hx, hy, cellSize, cellSize);
      }

      // Highlight adjacent movement tiles for the active turn player
      const activePlayer = boardState.players.find((p) => p.id === currentTurnId);
      const highlightedBot = selectedPlayer || activePlayer;
      if (highlightedBot && availableMoves && availableMoves.player_id === highlightedBot.id) {
        Object.values(availableMoves.moves).forEach((move) => {
          const mx = startX + (move.target_x - min_x) * cellSize - cellSize / 2;
          const my = startY + (move.target_y - min_y) * cellSize - cellSize / 2;
          
          if (move.available) {
            ctx.fillStyle = 'rgba(16, 185, 129, 0.12)';
            ctx.strokeStyle = 'rgba(16, 185, 129, 0.5)';
            ctx.lineWidth = 1;
            ctx.fillRect(mx, my, cellSize, cellSize);
            ctx.strokeRect(mx, my, cellSize, cellSize);
          } else {
            ctx.fillStyle = 'rgba(239, 68, 68, 0.08)';
            ctx.strokeStyle = 'rgba(239, 68, 68, 0.3)';
            ctx.lineWidth = 0.8;
            ctx.fillRect(mx, my, cellSize, cellSize);
            ctx.strokeRect(mx, my, cellSize, cellSize);
          }
        });
      }

      // Draw active players
      const now = Date.now() / 400;
      const pulse = Math.sin(now) * 0.25 + 0.75;

      boardState.players.forEach((player) => {
        const px = startX + (player.x - min_x) * cellSize;
        const py = startY + (player.y - min_y) * cellSize;
        const isSelected = selectedPlayer?.id === player.id;
        const isCurrentTurn = currentTurnId === player.id;
        const isHovered = hoveredPlayer?.id === player.id;

        const baseRadius = Math.max(4, Math.min(cellSize * 0.45, 14));
        const radius = isSelected ? baseRadius * 1.35 : isHovered ? baseRadius * 1.2 : baseRadius;

        // Current turn beacon aura
        if (isCurrentTurn) {
          ctx.save();
          ctx.beginPath();
          ctx.arc(px, py, radius * (1.8 + pulse * 0.5), 0, Math.PI * 2);
          ctx.strokeStyle = '#fbbf24'; // Golden glow for active turn
          ctx.lineWidth = 2;
          ctx.setLineDash([4, 4]);
          ctx.stroke();
          ctx.restore();
        }

        // Glow effect
        ctx.save();
        ctx.shadowColor = player.color;
        ctx.shadowBlur = isCurrentTurn ? 24 : isSelected ? 18 : 8;

        // Outer beacon ring
        ctx.beginPath();
        ctx.arc(px, py, radius * (isSelected ? 1.5 * pulse : 1.25), 0, Math.PI * 2);
        ctx.strokeStyle = isCurrentTurn ? '#f59e0b' : player.color;
        ctx.globalAlpha = isSelected || isCurrentTurn ? 0.9 : 0.4;
        ctx.lineWidth = isCurrentTurn ? 2 : 1.5;
        ctx.stroke();

        // Main Player Token
        ctx.globalAlpha = 1.0;
        ctx.beginPath();
        ctx.arc(px, py, radius, 0, Math.PI * 2);
        ctx.fillStyle = player.color;
        ctx.fill();

        // Inner Core
        ctx.beginPath();
        ctx.arc(px, py, radius * 0.4, 0, Math.PI * 2);
        ctx.fillStyle = isCurrentTurn ? '#fef08a' : '#ffffff';
        ctx.fill();
        ctx.restore();

        // Label above player
        if (zoom > 1.8 || isSelected || isHovered || isCurrentTurn) {
          ctx.save();
          ctx.font = 'bold 11px monospace';
          ctx.textAlign = 'center';
          const text = isCurrentTurn ? `👑 ${player.name}` : player.name;
          const textMetrics = ctx.measureText(text);
          const bgWidth = textMetrics.width + 12;
          const bgHeight = 16;
          const labelY = py - radius - 8;

          ctx.fillStyle = 'rgba(15, 23, 42, 0.9)';
          ctx.strokeStyle = isCurrentTurn ? '#f59e0b' : player.color;
          ctx.lineWidth = 1;
          ctx.beginPath();
          ctx.roundRect(px - bgWidth / 2, labelY - 12, bgWidth, bgHeight, 4);
          ctx.fill();
          ctx.stroke();

          ctx.fillStyle = isCurrentTurn ? '#fbbf24' : '#f8fafc';
          ctx.fillText(text, px, labelY);
          ctx.restore();
        }
      });

      ctx.restore(); // end clip

      // Draw Board Border
      ctx.strokeStyle = '#38bdf8';
      ctx.lineWidth = 2;
      ctx.strokeRect(startX, startY, totalWidth, totalHeight);

      // Draw Coordinate Axis Rulers (0, 8, 16, 24, 32, 40, 48, 56, 64)
      ctx.font = '10px monospace';
      ctx.fillStyle = '#94a3b8';
      ctx.textAlign = 'center';

      for (let i = 0; i <= gridCellsX; i += 8) {
        const x = startX + i * cellSize;
        if (x >= startX - 5 && x <= startX + totalWidth + 5) {
          ctx.fillText(`${i}`, x, startY - 8);
          ctx.beginPath();
          ctx.moveTo(x, startY - 4);
          ctx.lineTo(x, startY);
          ctx.strokeStyle = '#475569';
          ctx.stroke();
        }
      }

      ctx.textAlign = 'right';
      for (let j = 0; j <= gridCellsY; j += 8) {
        const y = startY + j * cellSize;
        if (y >= startY - 5 && y <= startY + totalHeight + 5) {
          ctx.fillText(`${j}`, startX - 8, y + 3);
          ctx.beginPath();
          ctx.moveTo(startX - 4, y);
          ctx.lineTo(startX, y);
          ctx.strokeStyle = '#475569';
          ctx.stroke();
        }
      }

      ctx.restore();
      animationFrameId = requestAnimationFrame(render);
    };

    animationFrameId = requestAnimationFrame(render);
    return () => cancelAnimationFrame(animationFrameId);
  }, [
    boardState,
    selectedPlayer,
    hoveredPlayer,
    hoveredCoord,
    availableMoves,
    currentTurnId,
    offset,
    zoom,
    gridCellsX,
    gridCellsY,
    min_x,
    max_x,
    min_y,
    max_y,
  ]);

  // Mouse Drag to Pan
  const handleMouseDown = (e: React.MouseEvent) => {
    if (e.button === 0) {
      setIsDragging(true);
      setDragStart({ x: e.clientX - offset.x, y: e.clientY - offset.y });
    }
  };

  const handleMouseMove = (e: React.MouseEvent) => {
    if (!canvasRef.current) return;
    const rect = canvasRef.current.getBoundingClientRect();
    const mouseX = e.clientX - rect.left;
    const mouseY = e.clientY - rect.top;

    if (isDragging) {
      setOffset({
        x: e.clientX - dragStart.x,
        y: e.clientY - dragStart.y,
      });
    }

    const coord = pixelToGrid(mouseX, mouseY, rect.width, rect.height);
    setHoveredCoord(coord);
    onHoverCoord?.(coord);

    if (coord) {
      const match = boardState.players.find((p) => p.x === coord.x && p.y === coord.y);
      setHoveredPlayer(match || null);
    } else {
      setHoveredPlayer(null);
    }
  };

  const handleMouseUp = () => {
    setIsDragging(false);
  };

  // Wheel to Zoom
  const handleWheel = (e: React.WheelEvent) => {
    e.preventDefault();
    const zoomFactor = e.deltaY < 0 ? 1.15 : 0.88;
    setZoom((prev) => Math.min(Math.max(prev * zoomFactor, 0.5), 8.0));
  };

  // Click to Select Player or Coordinate
  const handleClick = () => {
    if (hoveredPlayer) {
      onSelectPlayer(hoveredPlayer);
    } else if (hoveredCoord) {
      const found = boardState.players.find((p) => p.x === hoveredCoord.x && p.y === hoveredCoord.y);
      onSelectPlayer(found || null);
    }
  };

  return (
    <div
      ref={containerRef}
      className="relative w-full h-full flex-1 overflow-hidden bg-slate-950 select-none cursor-crosshair"
      onMouseDown={handleMouseDown}
      onMouseMove={handleMouseMove}
      onMouseUp={handleMouseUp}
      onMouseLeave={() => {
        setIsDragging(false);
        setHoveredCoord(null);
        setHoveredPlayer(null);
      }}
      onWheel={handleWheel}
      onClick={handleClick}
    >
      <canvas ref={canvasRef} className="w-full h-full block" />

      {/* Floating Coordinate Display */}
      <div className="absolute top-4 left-4 bg-slate-900/85 backdrop-blur border border-slate-700/60 rounded-md px-3 py-1.5 text-xs font-mono text-slate-300 flex items-center gap-3 shadow-lg pointer-events-none">
        <span className="flex items-center gap-1.5 text-sky-400">
          <span className="w-2 h-2 rounded-full bg-sky-400 animate-pulse" />
          Grid: 64x64
        </span>
        <span className="text-slate-500">|</span>
        <span>
          Cursor:{' '}
          <strong className="text-emerald-400">
            {hoveredCoord ? `(${hoveredCoord.x}, ${hoveredCoord.y})` : '-- , --'}
          </strong>
        </span>
        <span className="text-slate-500">|</span>
        <span>
          Zoom: <strong className="text-amber-400">{(zoom * 100).toFixed(0)}%</strong>
        </span>
      </div>

      {/* Floating Reset View Button */}
      <div className="absolute top-4 right-4 flex gap-2">
        <button
          onClick={(e) => {
            e.stopPropagation();
            setZoom((z) => Math.min(z * 1.25, 8.0));
          }}
          className="bg-slate-900/80 hover:bg-slate-800 text-slate-200 border border-slate-700 p-2 rounded-lg text-xs font-mono backdrop-blur transition-all shadow"
          title="Zoom In"
        >
          +
        </button>
        <button
          onClick={(e) => {
            e.stopPropagation();
            setZoom((z) => Math.max(z * 0.8, 0.5));
          }}
          className="bg-slate-900/80 hover:bg-slate-800 text-slate-200 border border-slate-700 p-2 rounded-lg text-xs font-mono backdrop-blur transition-all shadow"
          title="Zoom Out"
        >
          -
        </button>
        <button
          onClick={(e) => {
            e.stopPropagation();
            handleResetView();
          }}
          className="bg-slate-900/80 hover:bg-slate-800 text-slate-200 border border-slate-700 px-3 py-2 rounded-lg text-xs font-mono backdrop-blur transition-all shadow"
          title="Reset View"
        >
          Reset View
        </button>
      </div>

      {/* Selected Player Overlay card */}
      {selectedPlayer && (
        <div className="absolute bottom-4 left-4 bg-slate-900/90 backdrop-blur-md border border-slate-700 p-3 rounded-xl shadow-xl flex items-center gap-3 text-xs max-w-sm">
          <div
            className="w-10 h-10 rounded-full flex items-center justify-center font-bold text-white shadow-md border-2 border-white/30"
            style={{ backgroundColor: selectedPlayer.color }}
          >
            {selectedPlayer.name.slice(0, 2).toUpperCase()}
          </div>
          <div className="flex-1 min-w-0">
            <div className="font-semibold text-slate-100 flex items-center gap-1.5 truncate">
              {selectedPlayer.name}
              {selectedPlayer.id === currentTurnId && (
                <span className="text-[10px] text-amber-400 font-mono">👑 Turn</span>
              )}
            </div>
            <div className="text-slate-400 font-mono text-[11px]">
              ID: {selectedPlayer.id} • Pos: ({selectedPlayer.x}, {selectedPlayer.y})
            </div>
          </div>
          <button
            onClick={(e) => {
              e.stopPropagation();
              onSelectPlayer(null);
            }}
            className="text-slate-400 hover:text-slate-200 p-1"
          >
            ✕
          </button>
        </div>
      )}
    </div>
  );
};