import pygame

# Global constants

# Colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)
BLUE = (0, 0, 255)

# Screen dimensions
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600


class Player(pygame.sprite.Sprite):
    """
    This class represents the bar at the bottom that the player controls.
    """

    # -- Methods
    def __init__(self):
        """ Constructor function """

        # Call the parent's constructor
        super().__init__()

        # Create an image of the block, and fill it with a color.
        # This could also be an image loaded from the disk.
        width = 40
        height = 60
        self.image = pygame.Surface([width, height])
        self.image.fill(RED)

        # Set a reference to the image rect.
        self.rect = self.image.get_rect()

        # Set speed vector of player
        self.change_x = 0
        self.change_y = 0

        # List of sprites we can bump against
        self.level = None

    def update(self):
        """ Move the player. """

        # Move left/right
        self.rect.x += self.change_x

        # See if we hit anything
        block_hit_list = pygame.sprite.spritecollide(self, self.level.platform_list, False)
        for block in block_hit_list:
            # If we are moving right,
            # set our right side to the left side of the item we hit
            if self.change_x > 0:
                self.rect.right = block.rect.left
            elif self.change_x < 0:
                # Otherwise if we are moving left, do the opposite.
                self.rect.left = block.rect.right

        # Move up/down
        self.rect.y += self.change_y

        # Check and see if we hit anything
        block_hit_list = pygame.sprite.spritecollide(self, self.level.platform_list, False)
        for block in block_hit_list:

            # Reset our position based on the top/bottom of the object.
            if self.change_y > 0:
                self.rect.bottom = block.rect.top
            elif self.change_y < 0:
                self.rect.top = block.rect.bottom

            # Stop our vertical movement
            self.change_y = 0

            if isinstance(block, MovingPlatform):
                self.rect.x += block.change_x

    def go_up(self):
        """ Called when user hits the up arrow. """
        self.change_y = -6

    def go_down(self):
        """ Called when user hits the down arrow. """
        self.change_y = 6

    # Player-controlled movement:
    def go_left(self):
        """ Called when the user hits the left arrow. """
        self.change_x = -6

    def go_right(self):
        """ Called when the user hits the right arrow. """
        self.change_x = 6

    def stop_x(self):
        """ Called when the user lets off the keyboard. """
        self.change_x = 0

    def stop_y(self):
        """ Called when the user lets off the keyboard. """
        self.change_y = 0


class Platform(pygame.sprite.Sprite):
    """ Platform the user can jump on """

    def __init__(self, width, height):
        """ Platform constructor. Assumes constructed with user passing in
            an array of 5 numbers like what's defined at the top of this code.
            """
        super().__init__()

        self.image = pygame.Surface([width, height])
        self.image.fill(GREEN)

        self.rect = self.image.get_rect()


class MovingPlatform(Platform):
    """ This is a fancier platform that can actually move. """
    change_x = 0
    change_y = 0

    boundary_top = 0
    boundary_bottom = 0
    boundary_left = 0
    boundary_right = 0

    player = None

    level = None

    def update(self):
        """ Move the platform.
            If the player is in the way, it will shove the player
            out of the way. This does NOT handle what happens if a
            platform shoves a player into another object. Make sure
            moving platforms have clearance to push the player around
            or add code to handle what happens if they don't. """

        # Move left/right
        self.rect.x += self.change_x

        # See if we hit the player
        hit = pygame.sprite.collide_rect(self, self.player)
        if hit:
            # We did hit the player. Shove the player around and
            # assume he/she won't hit anything else.

            # If we are moving right, set our right side
            # to the left side of the item we hit
            if self.change_x < 0:
                self.player.rect.right = self.rect.left
            else:
                # Otherwise if we are moving left, do the opposite.
                self.player.rect.left = self.rect.right

        # Move up/down
        self.rect.y += self.change_y

        # Check and see if we the player
        hit = pygame.sprite.collide_rect(self, self.player)
        if hit:
            # We did hit the player. Shove the player around and
            # assume he/she won't hit anything else.

            # Reset our position based on the top/bottom of the object.
            if self.change_y < 0:
                self.player.rect.bottom = self.rect.top
            else:
                self.player.rect.top = self.rect.bottom

        # Check the boundaries and see if we need to reverse
        # direction.
        if self.rect.bottom > self.boundary_bottom or self.rect.top < self.boundary_top:
            self.change_y *= -1

        cur_pos = self.rect.x - self.level.world_shift
        if cur_pos < self.boundary_left or cur_pos > self.boundary_right:
            self.change_x *= -1


class Level(object):
    """ This is a generic super-class used to define a level.
        Create a child class for each level with level-specific
        info. """

    def __init__(self, player):
        """ Constructor. Pass in a handle to player. Needed for when moving
            platforms collide with the player. """
        self.platform_list = pygame.sprite.Group()
        self.enemy_list = pygame.sprite.Group()
        self.player = player

        # Background image
        self.background = None

        # How far this world has been scrolled left/right
        self.world_shift = 0
        self.level_limit = -1000

    # Update everything on this level
    def update(self):
        """ Update everything in this level."""
        self.platform_list.update()
        self.enemy_list.update()

    def draw(self, screen):
        """ Draw everything on this level. """

        # Draw the background
        screen.fill(BLUE)

        # Draw all the sprite lists that we have
        self.platform_list.draw(screen)
        self.enemy_list.draw(screen)

    def shift_world(self, shift_x):
        """ When the user moves left/right and we need to scroll everything:
        """

        # Keep track of the shift amount
        self.world_shift += shift_x

        # Go through all the sprite lists and shift
        for platform in self.platform_list:
            platform.rect.x += shift_x

        for enemy in self.enemy_list:
            enemy.rect.x += shift_x


# Create platforms for the level
class Level1(Level):
    """ Definition for level 1. """

    def __init__(self, player):
        """ Create level 1. """

        # Call the parent constructor
        Level.__init__(self, player)

        self.level_limit = -1500

        # Array with width, height, x, and y of platform
        level = [[210, 70, 500, 500],
                 [210, 70, 800, 400],
                 [210, 70, 1000, 500],
                 [210, 70, 1120, 280],
                 ]

        # Go through the array above and add platforms
        for platform in level:
            block = Platform(platform[0], platform[1])
            block.rect.x = platform[2]
            block.rect.y = platform[3]
            block.player = self.player
            self.platform_list.add(block)


def main():
    """ Main Program """
    pygame.init()

    # Set the height and width of the screen
    size = [SCREEN_WIDTH, SCREEN_HEIGHT]
    screen = pygame.display.set_mode(size)

    pygame.display.set_caption("Platformer with moving platforms")

    # Create the player
    player = Player()

    # Create all the levels
    level_list = [Level1(player)]

    # Set the current level
    current_level_no = 0
    current_level = level_list[current_level_no]

    active_sprite_list = pygame.sprite.Group()
    player.level = current_level

    player.rect.x = 340
    player.rect.y = SCREEN_HEIGHT - player.rect.height
    active_sprite_list.add(player)

    # Loop until the user clicks the close button.
    done = False

    # Used to manage how fast the screen updates
    clock = pygame.time.Clock()

    # -------- Main Program Loop -----------
    while not done:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                done = True

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_a:
                    player.go_left()
                if event.key == pygame.K_d:
                    player.go_right()
                if event.key == pygame.K_w:
                    player.go_up()
                if event.key == pygame.K_s:
                    player.go_down()

            if event.type == pygame.KEYUP:
                if event.key == pygame.K_a and player.change_x < 0:
                    player.stop_x()
                if event.key == pygame.K_d and player.change_x > 0:
                    player.stop_x()
                if event.key == pygame.K_w and player.change_y < 0:
                    player.stop_y()
                if event.key == pygame.K_s and player.change_y > 0:
                    player.stop_y()

        # Update the player.
        active_sprite_list.update()

        # Update items in the level
        current_level.update()

        # If the player gets near the right side, shift the world left (-x)
        if player.rect.right >= 500:
            diff = player.rect.right - 500
            player.rect.right = 500
            current_level.shift_world(-diff)

        # If the player gets near the left side, shift the world right (+x)
        if player.rect.left <= 120:
            diff = 120 - player.rect.left
            player.rect.left = 120
            current_level.shift_world(diff)

        # ALL CODE TO DRAW SHOULD GO BELOW THIS COMMENT
        current_level.draw(screen)
        active_sprite_list.draw(screen)

        # ALL CODE TO DRAW SHOULD GO ABOVE THIS COMMENT

        # Limit to 60 frames per second
        clock.tick(60)

        # Go ahead and update the screen with what we've drawn.
        pygame.display.flip()

    # Be IDLE friendly. If you forget this line, the program will 'hang'
    # on exit.
    pygame.quit()


if __name__ == "__main__":
    main()