using System;
using System.Threading;

namespace FlappyBird {
    class Program {
        // Constants
        static string scoreText = "Your score is: ";
        static float factor = 32/1.4f;
        static int pipeInterval = 60;
        static int height = 15;
        static int width = 30;
        static int FPS = 60;

        // Game variables
        static char[,] board;
        static int spaceHeight = height/5;
        static float jumpVel = height/factor;
        static bool gameOver, startOver = true;
        static int birdX = width/16+1, score = 0;
        static float birdY = height/2f, velY = 0f;
        static float gravity = height/(factor*10);

        static void Main() {
            while (startOver) {
                gameOver = false;
                board = new char[width + 2, height + 2];

                // Fill the 'board' Array with blank spaces
                for (int i = 0; i < board.GetLength(0); i++)
                    for (int j = 0; j < board.GetLength(1); j++) {
                        bool xC = i%(board.GetLength(0)-1)==0;
                        bool yC = j%(board.GetLength(1)-1)==0;
                        board[i, j] = (xC||yC)?'#':' ';
                    }
                
                // Place the bird on the board
                int rBY = board.GetLength(1)-1-(int)Math.Round(birdY);
                board[birdX, rBY] = 'O';
                
                // Draw the board
                Console.Clear();
                Console.WriteLine($"{scoreText}{score}");
                for (int j = 0; j < board.GetLength(1); j++) {
                    for (int i = 0; i < board.GetLength(0); i++) {
                        string pipeCon = (i < board.GetLength(0)-1) ? "|" : "";
                        bool yC = j%(board.GetLength(1)-1)==0;
                        pipeCon = (yC && pipeCon != "") ? "#" : pipeCon;
                        Console.Write($"{board[i, j]}{pipeCon}");
                    }
                    Console.WriteLine();
                }
                

                // Start the game loop
                Console.ReadKey(true);
                int frameCount = 0;
                while (!gameOver) {
                    char[,] copy = board.Clone() as char[,];

                    // Move all pipes to the left every other frame
                    if (frameCount % 2 == 0) {
                        bool hasInvremented = false;
                        for (int i = 1; i < board.GetLength(0)-1; i++)
                            for (int j = 1; j < board.GetLength(1)-1; j++)
                                if (board[i, j] == '$') {
                                    board[i, j] = ' ';
                                    if (i-1 > 0) {
                                        if (board[i-1, j] == 'O')
                                            gameEnd();
                                        board[i-1, j] = '$';
                                        if (i-1 == birdX && !hasInvremented) {
                                            score++;
                                            hasInvremented = true;
                                        }
                                    }
                                }
                    }

                    // Generate pipe after 'pipeInterval' amount of frames
                    if (frameCount % pipeInterval == 0) {
                        Random rng = new Random();
                        int pipeX = board.GetLength(0)-2;
                        int spaceY = rng.Next(2,board.GetLength(1)-6-spaceHeight);
                        for (int j = 1; j < board.GetLength(1)-1; j++)
                            if (j < spaceY || j > spaceY+spaceHeight)
                                board[pipeX, j] = '$';
                    }

                    // Handle key presses for jumping and exiting
                    if (Console.KeyAvailable)
                        switch (Console.ReadKey(true).Key) {
                            case ConsoleKey.Escape:
                                Environment.Exit(0);
                                break;
                            case ConsoleKey.Spacebar:
                                velY = jumpVel;
                                break;
                        }
                    // Handle velocity
                    velY -= gravity;
                    float avy = Math.Abs(velY);
                    velY = (avy > jumpVel) ? ((avy/velY)*jumpVel) : velY;
                    // Handle position
                    birdY += velY;
                    if (birdY < 1)
                        gameEnd();
                    if (birdY > board.GetLength(1)-2)
                        velY = 0;
                    birdY = Math.Max(birdY, 1);
                    birdY = Math.Min(birdY, board.GetLength(1)-2);
                    // Update bird position on board
                    int tempY = board.GetLength(1)-1-(int)Math.Round(birdY);
                    if (tempY != rBY) {
                        board[birdX, rBY] = ' ';
                        if (board[birdX, tempY] == '$')
                            gameEnd();
                        board[birdX, tempY] = 'O';
                        rBY = tempY;
                    }

                    // Update the display based on changes between the 'board' and 'copy'
                    Console.SetCursorPosition(scoreText.Length, 0);
                    Console.Write(score);
                    for (int j = 1; j < board.GetLength(1)-1; j++)
                        for (int i = 1; i < board.GetLength(0)-1; i++) {
                            char bC = board[i, j];
                            if (bC != copy[i, j]) {
                                Console.SetCursorPosition(i*2, j+1);
                                ConsoleColor col = (bC=='O')?ConsoleColor.Yellow:((bC=='$')?ConsoleColor.Green:ConsoleColor.White);
                                Console.ForegroundColor = col;
                                Console.Write(bC);
                            }
                        }

                    // End of game loop
                    frameCount = (frameCount+1)%(FPS*4);
                    Console.SetCursorPosition(board.GetLength(0)*2-1, board.GetLength(1));
                    Thread.Sleep(1000/FPS);
                }
            }
        }

        static void gameEnd() {
            Console.Clear();
            Console.ForegroundColor = ConsoleColor.Red;
            Console.Write("You lost! ");
            Console.ForegroundColor = ConsoleColor.White;
            Console.WriteLine("Start over? (Y/n)");
            string uin = Console.ReadLine();
            if (uin.ToLower() == "n")
                startOver = false;
            else {
                birdY = height/2f;
                velY = 0f;
                score = 0;
            }
            gameOver = true;
            // Environment.Exit(0);
        }
    }
}