tetris/internal/game/game.go

package game

import (
	"fmt"
	"image/color"
	"math/rand"
	"time"

	"tetris/internal/tetromino"
	"tetris/internal/types"
	"tetris/pkg/config"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
)

// Game represents the main game state
type Game struct {
	board        [][]types.BlockType
	currentPiece *tetromino.Tetromino
	nextPiece    *tetromino.Tetromino
	dropCounter  int
	dropInterval int
	score        int
	level        int
	gameOver     bool
	lastMoveDown time.Time
	lastRotate   time.Time
}

// New creates a new game instance
func New() *Game {
	g := &Game{
		board:        make([][]types.BlockType, config.BoardHeight),
		dropInterval: config.InitialDropInterval,
		lastMoveDown: time.Now(),
		lastRotate:   time.Now(),
	}

	for i := range g.board {
		g.board[i] = make([]types.BlockType, config.BoardWidth)
	}

	g.spawnNewPiece()
	return g
}

// Update handles game logic updates
func (g *Game) Update() error {
	if g.gameOver {
		if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
			*g = *New()
			return nil
		}
		return nil
	}

	g.handleInput()
	g.updateDropCounter()
	return nil
}

// Draw renders the game state
func (g *Game) Draw(screen *ebiten.Image) {
	// Draw board background
	ebitenutil.DrawRect(screen, 0, 0, float64(config.BoardWidth*config.BlockSize), float64(config.BoardHeight*config.BlockSize), color.RGBA{40, 40, 40, 255})

	// Draw preview area background
	ebitenutil.DrawRect(screen, float64(config.PreviewX-config.BlockSize), 0, float64(6*config.BlockSize), float64(config.ScreenHeight), color.RGBA{30, 30, 30, 255})

	// Draw grid lines
	gridColor := color.RGBA{60, 60, 60, 255}
	for x := 0; x <= config.BoardWidth; x++ {
		ebitenutil.DrawLine(screen, float64(x*config.BlockSize), 0, float64(x*config.BlockSize), float64(config.BoardHeight*config.BlockSize), gridColor)
	}
	for y := 0; y <= config.BoardHeight; y++ {
		ebitenutil.DrawLine(screen, 0, float64(y*config.BlockSize), float64(config.BoardWidth*config.BlockSize), float64(y*config.BlockSize), gridColor)
	}

	// Draw placed blocks
	for y := range config.BoardHeight {
		for x := range config.BoardWidth {
			if g.board[y][x] != config.EmptyBlock {
				g.drawBlock(screen, x, y, g.board[y][x])
			}
		}
	}

	// Draw current piece and its ghost
	if g.currentPiece != nil {
		// Draw ghost piece
		ghostPiece := *g.currentPiece
		for {
			ghostPiece.Move(0, 1)
			if g.wouldCollide(&ghostPiece) {
				ghostPiece.Move(0, -1)
				break
			}
		}
		for _, pos := range ghostPiece.GetAbsolutePositions() {
			if pos[1] >= 0 {
				ghostColor := color.RGBA{128, 128, 128, 128}
				ebitenutil.DrawRect(screen,
					float64(pos[0]*config.BlockSize),
					float64(pos[1]*config.BlockSize),
					float64(config.BlockSize-1),
					float64(config.BlockSize-1),
					ghostColor)
			}
		}

		// Draw actual piece
		for _, pos := range g.currentPiece.GetAbsolutePositions() {
			if pos[1] >= 0 {
				g.drawBlock(screen, pos[0], pos[1], g.currentPiece.BlockType)
			}
		}
	}

	// Draw next piece preview
	if g.nextPiece != nil {
		previewLabel := "NEXT:"
		ebitenutil.DebugPrintAt(screen, previewLabel, config.PreviewX-config.BlockSize, config.BlockSize)

		for _, block := range g.nextPiece.Blocks {
			x := config.PreviewX + block.X*config.BlockSize
			y := config.PreviewY + block.Y*config.BlockSize
			ebitenutil.DrawRect(screen,
				float64(x),
				float64(y),
				float64(config.BlockSize-1),
				float64(config.BlockSize-1),
				types.BlockColors[g.nextPiece.BlockType])
		}
	}

	// Draw score and level with larger font
	scoreStr := fmt.Sprintf("Score: %d", g.score)
	levelStr := fmt.Sprintf("Level: %d", g.level)
	ebitenutil.DebugPrintAt(screen, scoreStr, config.PreviewX-config.BlockSize, config.ScreenHeight-4*config.BlockSize)
	ebitenutil.DebugPrintAt(screen, levelStr, config.PreviewX-config.BlockSize, config.ScreenHeight-3*config.BlockSize)

	if g.gameOver {
		gameOverStr := "Game Over!"
		restartStr := "Press SPACE to restart"
		ebitenutil.DebugPrintAt(screen, gameOverStr, config.PreviewX-config.BlockSize, config.ScreenHeight/2)
		ebitenutil.DebugPrintAt(screen, restartStr, config.PreviewX-config.BlockSize, config.ScreenHeight/2+20)
	}
}

// Layout implements ebiten.Game interface
func (g *Game) Layout(outsideWidth, outsideHeight int) (screenWidth, screenHeight int) {
	return config.ScreenWidth, config.ScreenHeight
}

// handleInput processes player input
func (g *Game) handleInput() {
	// Move left/right
	if inpututil.IsKeyJustPressed(ebiten.KeyLeft) {
		g.tryMove(-1, 0)
	}
	if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
		g.tryMove(1, 0)
	}

	// Rotate
	if inpututil.IsKeyJustPressed(ebiten.KeyUp) {
		if time.Since(g.lastRotate) > time.Millisecond*100 {
			g.tryRotate()
			g.lastRotate = time.Now()
		}
	}

	// Soft drop
	if ebiten.IsKeyPressed(ebiten.KeyDown) {
		if time.Since(g.lastMoveDown) > time.Millisecond*50 {
			g.tryMove(0, 1)
			g.lastMoveDown = time.Now()
		}
	}

	// Hard drop
	if inpututil.IsKeyJustPressed(ebiten.KeySpace) {
		g.hardDrop()
	}
}

// updateDropCounter handles automatic piece dropping
func (g *Game) updateDropCounter() {
	g.dropCounter++
	if g.dropCounter >= g.dropInterval {
		g.dropCounter = 0
		if !g.tryMove(0, 1) {
			g.lockPiece()
		}
	}
}

// tryMove attempts to move the current piece and returns success
func (g *Game) tryMove(dx, dy int) bool {
	if g.currentPiece == nil {
		return false
	}

	originalX, originalY := g.currentPiece.X, g.currentPiece.Y
	g.currentPiece.Move(dx, dy)

	if g.isColliding() {
		g.currentPiece.X, g.currentPiece.Y = originalX, originalY
		return false
	}

	return true
}

// tryRotate attempts to rotate the current piece with wall kicks
func (g *Game) tryRotate() bool {
	if g.currentPiece == nil {
		return false
	}

	// Store original state
	originalBlocks := make([]types.Block, len(g.currentPiece.Blocks))
	copy(originalBlocks, g.currentPiece.Blocks)

	// Try rotation
	g.currentPiece.Rotate()

	// Try wall kicks
	var kicks [][2]int
	if g.currentPiece.BlockType == types.IBlock {
		kicks = tetromino.IKicks
	} else {
		kicks = tetromino.NormalKicks
	}

	for _, kick := range kicks {
		originalX, originalY := g.currentPiece.X, g.currentPiece.Y
		g.currentPiece.Move(kick[0], kick[1])

		if !g.isColliding() {
			return true
		}

		// Reset position for next kick attempt
		g.currentPiece.X, g.currentPiece.Y = originalX, originalY
	}

	// All kicks failed, revert rotation
	g.currentPiece.Blocks = originalBlocks
	return false
}

// hardDrop drops the piece instantly to the bottom
func (g *Game) hardDrop() {
	if g.currentPiece == nil {
		return
	}

	dropDistance := 0
	for {
		if !g.tryMove(0, 1) {
			break
		}
		dropDistance++
	}

	// Award extra points for hard drop
	g.score += dropDistance * 2

	g.lockPiece()
}

// isColliding checks if the current piece is colliding with the board or boundaries
func (g *Game) isColliding() bool {
	if g.currentPiece == nil {
		return false
	}

	for _, pos := range g.currentPiece.GetAbsolutePositions() {
		x, y := pos[0], pos[1]

		// Check boundaries
		if x < 0 || x >= config.BoardWidth || y >= config.BoardHeight {
			return true
		}

		// Check collision with placed blocks (but allow pieces above the visible board)
		if y >= 0 && g.board[y][x] != config.EmptyBlock {
			return true
		}
	}

	return false
}

// lockPiece places the current piece on the board and spawns a new one
func (g *Game) lockPiece() {
	if g.currentPiece == nil {
		return
	}

	// Place the piece on the board
	for _, pos := range g.currentPiece.GetAbsolutePositions() {
		x, y := pos[0], pos[1]
		if y >= 0 && y < config.BoardHeight && x >= 0 && x < config.BoardWidth {
			g.board[y][x] = g.currentPiece.BlockType
		}
	}

	// Clear completed lines
	linesCleared := g.clearLines()

	// Update score and level
	g.updateScore(linesCleared)

	// Spawn new piece
	g.spawnNewPiece()

	// Check for game over
	if g.isColliding() {
		g.gameOver = true
	}
}

// clearLines removes completed lines and returns the number cleared
func (g *Game) clearLines() int {
	linesCleared := 0

	for y := config.BoardHeight - 1; y >= 0; y-- {
		if g.isLineFull(y) {
			g.removeLine(y)
			linesCleared++
			y++ // Check the same line again since everything moved down
		}
	}

	return linesCleared
}

// updateScore updates the score and level based on lines cleared
func (g *Game) updateScore(linesCleared int) {
	points := []int{0, 40, 100, 300, 1200} // Points for 0, 1, 2, 3, 4 lines
	if linesCleared <= 4 {
		g.score += points[linesCleared] * (g.level + 1)
	}

	// Increase level every 10 lines
	newLevel := g.score / 1000
	if newLevel > g.level {
		g.level = newLevel
		g.dropInterval = max(config.MinDropInterval, config.InitialDropInterval-g.level*3)
	}
}

// isLineFull checks if a line is completely filled
func (g *Game) isLineFull(y int) bool {
	for x := 0; x < config.BoardWidth; x++ {
		if g.board[y][x] == config.EmptyBlock {
			return false
		}
	}
	return true
}

// removeLine removes a line and shifts everything above down
func (g *Game) removeLine(lineY int) {
	for y := lineY; y > 0; y-- {
		copy(g.board[y], g.board[y-1])
	}
	// Clear the top line
	for x := 0; x < config.BoardWidth; x++ {
		g.board[0][x] = config.EmptyBlock
	}
}

// spawnNewPiece creates a new falling piece
func (g *Game) spawnNewPiece() {
	if g.nextPiece == nil {
		g.nextPiece = tetromino.New(types.BlockType(rand.Intn(7)+1), config.BoardWidth/2-1, 0)
	}

	g.currentPiece = g.nextPiece
	g.nextPiece = tetromino.New(types.BlockType(rand.Intn(7)+1), config.BoardWidth/2-1, 0)

	g.dropCounter = 0
}

// wouldCollide checks if a piece would collide at its current position
func (g *Game) wouldCollide(piece *tetromino.Tetromino) bool {
	for _, pos := range piece.GetAbsolutePositions() {
		x, y := pos[0], pos[1]

		// Check boundaries
		if x < 0 || x >= config.BoardWidth || y >= config.BoardHeight {
			return true
		}

		// Check collision with placed blocks
		if y >= 0 && g.board[y][x] != config.EmptyBlock {
			return true
		}
	}

	return false
}

// drawBlock draws a single block at the specified position
func (g *Game) drawBlock(screen *ebiten.Image, x, y int, blockType types.BlockType) {
	ebitenutil.DrawRect(screen,
		float64(x*config.BlockSize),
		float64(y*config.BlockSize),
		float64(config.BlockSize-1),
		float64(config.BlockSize-1),
		types.BlockColors[blockType])

	// Add a subtle border for 3D effect
	borderColor := color.RGBA{255, 255, 255, 50}
	ebitenutil.DrawRect(screen,
		float64(x*config.BlockSize),
		float64(y*config.BlockSize),
		float64(config.BlockSize-1),
		2,
		borderColor)
	ebitenutil.DrawRect(screen,
		float64(x*config.BlockSize),
		float64(y*config.BlockSize),
		2,
		float64(config.BlockSize-1),
		borderColor)
}

// max returns the maximum of two integers
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}