"""Erzeugt Testfotos: mehrere Visitenkarten auf einem dunklen Untergrund."""
import io
import random

import numpy as np
from PIL import Image, ImageDraw


CARD_RATIO = 85.6 / 54.0


def _card(width: int = 420, seed: int = 0) -> Image.Image:
    """Eine weisse Karte mit ein paar dunklen Textzeilen."""
    height = round(width / CARD_RATIO)
    card = Image.new("RGB", (width, height), "white")
    draw = ImageDraw.Draw(card)
    rng = random.Random(seed)
    draw.line([(0.08 * width, 0.30 * height), (0.62 * width, 0.30 * height)], fill="black", width=6)
    draw.line([(0.08 * width, 0.44 * height), (0.48 * width, 0.44 * height)], fill=(70, 70, 70), width=3)
    for index in range(3):
        y = (0.62 + index * 0.10) * height
        draw.line(
            [(0.08 * width, y), ((0.30 + rng.random() * 0.35) * width, y)],
            fill=(90, 90, 90),
            width=2,
        )
    return card


def photo_with_cards(count: int = 6, size=(2400, 1800), angle_range: int = 8) -> np.ndarray:
    """Foto im BGR-Format mit `count` Karten in einem Raster."""
    background = Image.new("RGB", size, (38, 40, 44))
    rng = random.Random(count)
    columns = 2 if count <= 6 else 3
    rows = (count + columns - 1) // columns
    cell_width = size[0] // columns
    cell_height = size[1] // rows
    card_width = int(min(cell_width * 0.72, cell_height * 0.72 * CARD_RATIO))

    for index in range(count):
        column, row = index % columns, index // columns
        card = _card(card_width, seed=index)
        angle = rng.uniform(-angle_range, angle_range)
        rotated = card.rotate(angle, expand=True, resample=Image.BICUBIC)
        mask = Image.new("L", card.size, 255).rotate(
            angle, expand=True, resample=Image.BICUBIC
        )
        x = column * cell_width + (cell_width - rotated.width) // 2
        y = row * cell_height + (cell_height - rotated.height) // 2
        background.paste(rotated, (x, y), mask)

    return np.asarray(background)[:, :, ::-1].copy()


def photo_bytes(count: int = 6) -> bytes:
    array = photo_with_cards(count)
    buffer = io.BytesIO()
    Image.fromarray(array[:, :, ::-1]).save(buffer, format="JPEG", quality=92)
    return buffer.getvalue()