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from PIL import Image, ImageDraw, ImageFont, ImageChops
import numpy as np

def trim(im):
    i = np.array(im)
    i[i[:,:,3] == 0] = 0
    while True:
        if i[0].max() == 0: i = i[1:,:,:]
        else: break
    while True:
        if i[-1].max() == 0: i = i[:-1,:,:]
        else: break
    while True:
        if i[:,0].max() == 0: i = i[:,1:,:]
        else: break
    while True:
        if i[:,-1].max() == 0: i = i[:,:-1,:]
        else: break
    return Image.fromarray(i)

def str2img(s:str, fz:int):
    
    img = Image.new("RGBA", (300*len(s),300), (255,255,255,0))
    draw = ImageDraw.Draw(img)
    font = ImageFont.truetype(font_path, fz)

    draw.text((10, 0), s, (0,0,0), font=font)
    return trim(img)

def to_img(arr):
    return Image.fromarray((np.clip(arr, 0, 1).astype(np.float)*255).astype(np.uint8))

def to_arr(img):
    return np.array(img).astype(np.float) / 255

def place_text(canvas, s, fz, col):
    
    t = to_arr(str2img(s,fz))
    t[t[:,:,-1] > 0] = col
    x,y,_ = t.shape
    cx,cy,_ = canvas.shape
    assert cx >= x and cy >= y
    dx = int(.5*(cx-x)); dy = int(.5*(cy-y))
    canvas[dx:dx+x,dy:dy+y,:] += t
    return canvas

K = 2
def transform(canvas, c, _cache={}):
    _cache = {}
    cx,cy,_ = canvas.shape
    nc = np.zeros((cx,cy,4))

    def finv(x,y):
        x,y = x/cx * K - K/2, y/cy * K - K/2
        z = complex(x,y)
        
        r = abs(z)
        if r == 0: return True, 0,0
        r = (r+c)%1
        if r < 0: return False, 0,0
        z = z/abs(z) * r
        
        x,y = z.real, z.imag
        x,y = (x+K/2)/K * cx, (y+K/2)/K * cy
        return 0<=x<cx-1 and 0<=y<cy-1, x,y
    
    if (cx,cy,c) in _cache:
        finv_arr = _cache[(cx,cy,c)]
    else:
        finv_arr = [
            [finv(x,y) for x in range(cx)]
            for y in range(cy)
        ]
        _cache[(cx,cy,c)] = finv_arr
    
    for x in range(cx):
        for y in range(cy):
            
            if not (0<x<cx-1 and 0<y<cy-1): continue
            
            sxy = [finv_arr[y+j][x+k] for j in [0] for k in [0]]
            if sum(s for s,_,_ in sxy) != len(sxy): continue
            
            for _,nx,ny in sxy:
                iy,ix = int(ny), int(nx)
                fy,fx = ny%1, nx%1
                nc[x,y] += (
                    canvas[ix,iy] * fy * fx + 
                    canvas[ix+1,iy] * (1-fx) * fy +
                    canvas[ix,iy+1] * (1-fy) * fx +
                    canvas[ix+1,iy+1] * (1-fy) * (1-fx)
                )
            nc[x,y] /= len(sxy)
            
    return nc

J = 1
canvas = np.zeros((1800//J,1800//J,4))
canvas += np.array([7, 42, 95, 255], dtype=np.float)/255

canvas = place_text(canvas, "hello", 260//J, np.array([0, 1, 0.7, 1.]))
canvas = transform(canvas, 0.5)
canvas = place_text(canvas, "world", 260//J, np.array([1, 0.66, 0, 1.]))
canvas = transform(canvas, 0.5)

nc = to_img(canvas)
nc = to_arr(nc)

nframes = 80
cs = np.linspace(0,1,nframes)

for idx,c in list(enumerate(cs)):
    print(idx, end="\r")
    _nc = transform(nc, c)
    _nc = to_img(_nc)
    _nc.save(f"out/{idx}.png")

def gen_frame(path):
    im = Image.open(path)
    alpha = im.getchannel('A')
    im = im.convert('RGB').convert('P', palette=Image.ADAPTIVE, colors=255)
    mask = Image.eval(alpha, lambda a: 255 if a <=128 else 0)
    im.paste(255, mask)
    im.info['transparency'] = 255
    return im

imgs = [gen_frame(f"out/{idx}.png") for idx in range(nframes-1)][::-1]
imgs[0].save('dist/out.gif', save_all=True, append_images=imgs[1:])