"""节拍行者封面生成：1080x1920 深色底 + 游戏名 + 玩法提示。"""
import math
import os

from PIL import Image, ImageDraw, ImageFont

W, H = 1080, 1920
ROOT = "/home/ubuntu/SoundGame/web/rhythm"
FONT = os.path.join(ROOT, "gen", "NotoSansSC-Bold.ttf")

img = Image.new("RGB", (W, H), (10, 12, 24))
d = ImageDraw.Draw(img)

# 底部到中部渐亮
for y in range(H):
    t = y / H
    r = int(10 + 20 * t)
    g = int(12 + 14 * t)
    b = int(24 + 46 * t)
    d.line([(0, y), (W, y)], fill=(r, g, b))

# 律动音柱装饰（模拟频谱柱，青/品红双色）
bars = 24
bw = W // bars
for i in range(bars):
    h = int(120 + 260 * abs(math.sin(i * 1.7) * 0.6 + math.sin(i * 0.9) * 0.4))
    color = (0, 229, 255) if i % 2 == 0 else (255, 64, 129)
    x0 = i * bw + 8
    d.rounded_rectangle([x0, H - 320 - h, x0 + bw - 16, H - 320], 10, fill=color)
    # 顶部镜像倒影（暗一些）
    dim = tuple(c // 3 for c in color)
    d.rounded_rectangle([x0, 260, x0 + bw - 16, 260 + h // 2], 10, fill=dim)

# 节拍圆点（四四拍）
for i in range(4):
    cx = W // 2 - 180 + i * 120
    cy = H - 180
    fill = (255, 215, 64) if i == 0 else (60, 66, 90)
    d.ellipse([cx - 28, cy - 28, cx + 28, cy + 28], fill=fill)

f_title = ImageFont.truetype(FONT, 220)
f_sub = ImageFont.truetype(FONT, 56)
f_small = ImageFont.truetype(FONT, 40)

title = "节拍行者"
bbox = d.textbbox((0, 0), title, font=f_title)
tw = bbox[2] - bbox[0]
ty = H // 2 - 260
# 描边阴影 + 主字
d.text((W // 2 - tw // 2 + 6, ty + 8), title, font=f_title, fill=(0, 0, 0))
d.text((W // 2 - tw // 2, ty), title, font=f_title, fill=(240, 245, 255))

sub = "听音踩点 · 跟上节拍"
bbox = d.textbbox((0, 0), sub, font=f_sub)
d.text((W // 2 - (bbox[2] - bbox[0]) // 2, ty + 300), sub, font=f_sub, fill=(0, 229, 255))

hint = "滑上下左右 · 单击 · 双击"
bbox = d.textbbox((0, 0), hint, font=f_small)
d.text((W // 2 - (bbox[2] - bbox[0]) // 2, ty + 410), hint, font=f_small, fill=(150, 160, 190))

out = os.path.join(ROOT, "cover.png")
img.save(out)
print("saved", out, img.size)