"""Draw what the ball will trace, as a PNG (top view, looking down through the glass)."""
import math

from PIL import Image, ImageDraw

COLORS = {'pattern': (60, 45, 30), 'erase': (205, 190, 165), 'travel': (200, 60, 60)}
SAND = (236, 222, 196)


def render(segments, rho_max_mm, path, size=900, invert_theta=False, transparent=False):
    """segments: [(kind, [(theta_deg, rho_mm), ...])] in machine units. transparent: no square
    background behind the sand disc (for the web page)."""
    im = Image.new('RGBA', (size, size), (0, 0, 0, 0)) if transparent else Image.new('RGB', (size, size), (250, 250, 248))
    d = ImageDraw.Draw(im)
    c = size / 2
    s = (size / 2 - 12) / rho_max_mm
    d.ellipse([c - rho_max_mm * s - 6, c - rho_max_mm * s - 6, c + rho_max_mm * s + 6, c + rho_max_mm * s + 6],
              fill=SAND, outline=(150, 135, 110), width=3)
    sign = -1 if invert_theta else 1     # show the pattern as it should look, not as the motor turns
    for kind, pts in segments:
        xy = [(c + r * s * math.cos(math.radians(sign * t)), c - r * s * math.sin(math.radians(sign * t)))
              for t, r in pts]
        if len(xy) > 1:
            d.line(xy, fill=COLORS.get(kind, (0, 0, 0)), width=max(1, size // 400) if kind == 'pattern' else 1)
    im.save(path)
    return path


def sheet(jobs, rho_max_mm, path, tile=420, invert_theta=False, cols=3):
    """One tile per pattern (each drawn after its erase), with the name under it."""
    import os
    import tempfile
    n = len(jobs)
    cols = min(cols, n)
    rows = (n + cols - 1) // cols
    out = Image.new('RGB', (cols * tile, rows * (tile + 28)), (250, 250, 248))
    d = ImageDraw.Draw(out)
    with tempfile.TemporaryDirectory() as tmp:
        for i, (name, segs) in enumerate(jobs):
            f = os.path.join(tmp, f'{i}.png')
            render([s for s in segs if s[0] != 'erase'], rho_max_mm, f, size=tile, invert_theta=invert_theta)
            x, y = (i % cols) * tile, (i // cols) * (tile + 28)
            out.paste(Image.open(f), (x, y))
            d.text((x + 12, y + tile + 6), name, fill=(40, 40, 40))
    out.save(path)
    return path