snake_brython.py

from browser import document, html, window
from javascript import Math

score = 0
high_score = 0
px = py = 10
gs = tc = 20
ax = ay = 15
xv = yv = 0
trail = []
tail = 5
pre_pause = [0,0]
paused = False

def game():
    global px, py, tc, gs, ax, ay, trail, tail, score
    px += xv
    py += yv
    if px < 0:
        px = tc-1
    if px > tc-1:
        px = 0
    if py < 0:
        py = tc-1
    if py > tc-1:
        py = 0
    ctx.fillStyle = "black"
    ctx.fillRect(0, 0, canvas.width, canvas.height)
    ctx.fillStyle = "lime"
    for i in range(len(trail)):
        ctx.fillRect(trail[i][0]*gs, trail[i][1]*gs, gs-2, gs-2)
        if trail[i][0] == px and trail[i][1] == py:
            score = score if paused else 0 
            tail = 5
    trail.insert(0, [px, py])
    while len(trail) > tail:
        trail.pop()

    if ax == px and ay == py:
        tail += 1
        ax = Math.floor(Math.random()*tc)
        ay = Math.floor(Math.random()*tc)
        score += 1
    update_score(score)
    ctx.fillStyle = "red"
    ctx.fillRect(ax*gs, ay*gs, gs-2, gs-2)

def update_score(new_score):
    global high_score
    document["score"].innerHTML = "Score: " + str(new_score)
    if new_score > high_score:
        document["high-score"].innerHTML = "High Score: " + str(new_score)
        high_score = new_score
    
def key_push(evt):
    global xv, yv, pre_pause, paused
    key = evt.keyCode
    if key == 37 and not paused:
        xv = -1
        yv = 0
    elif key == 38 and not paused:
        xv = 0
        yv = -1
    elif key == 39 and not paused:
        xv = 1
        yv = 0
    elif key == 40 and not paused:
        xv = 0
        yv = 1
    elif key == 32:
        temp = [xv, yv]
        xv = pre_pause[0]
        yv = pre_pause[1]
        pre_pause = [*temp]
        paused = not paused
    
def show_instructions(evt):
    window.alert("Use the arrow keys to move and press spacebar to pause the game.")

canvas = document["game-board"]
ctx = canvas.getContext("2d")
document.addEventListener("keydown", key_push)
game_loop = window.setInterval(game, 1000/15)
instructions_btn = document["instructions-btn"]
instructions_btn.addEventListener("click", show_instructions)