"""Placeholder PNG generator — рендерит per-cell offline placeholder
("CAMERA LABEL — НЕТ СИГНАЛА") при controller startup.

Filter cuda_grid looks up "<placeholder_icon>_<pad>.png" first (per-cell),
fallback к "<placeholder_icon>.png" generic. Этот module генерирует
per-cell PNG с camera label из FrigateBridge config — user меняет label
в yaml, controller restarts, PNGs регенерируются.

Поддерживает UTF-8 (Russian text) через PIL freetype — недоступно в filter's
basic FT_Get_Char_Index path (single-byte only).
"""

from __future__ import annotations

from pathlib import Path

import structlog
from PIL import Image, ImageDraw, ImageFont

log = structlog.get_logger()

_FONT_PATH = "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf"


def _font(size: int) -> ImageFont.FreeTypeFont | ImageFont.ImageFont:
    try:
        return ImageFont.truetype(_FONT_PATH, size=size)
    except OSError:
        return ImageFont.load_default()


def render_placeholder(
    label: str,
    width: int = 480,
    height: int = 120,
) -> Image.Image:
    """2-line transparent PNG: camera label (top, yellow) + 'НЕТ СИГНАЛА' (bottom, gray).
    Transparent bg — filter заполняет cell black, потом blit'ит этот PNG поверх."""
    img = Image.new("RGBA", (width, height), (0, 0, 0, 0))
    draw = ImageDraw.Draw(img)

    label_font = _font(36)
    sub_font = _font(28)

    bbox_l = draw.textbbox((0, 0), label, font=label_font)
    lw, lh = bbox_l[2] - bbox_l[0], bbox_l[3] - bbox_l[1]
    label_y = height // 2 - lh - 4
    draw.text(((width - lw) // 2, label_y),
              label, fill=(255, 230, 100, 255), font=label_font)

    sub_text = "НЕТ СИГНАЛА"
    bbox_s = draw.textbbox((0, 0), sub_text, font=sub_font)
    sw, sh = bbox_s[2] - bbox_s[0], bbox_s[3] - bbox_s[1]
    sub_y = height // 2 + 4
    draw.text(((width - sw) // 2, sub_y),
              sub_text, fill=(220, 220, 220, 230), font=sub_font)

    return img


def generate_placeholders(icon_dir: Path, labels: dict[int, str],
                          base_name: str = "offline") -> None:
    """Generates <base>_<pad>.png для each (pad → label) entry.
    Also generic <base>.png (fallback когда pad index без custom label)."""
    icon_dir.mkdir(parents=True, exist_ok=True)
    for pad, label in labels.items():
        img = render_placeholder(label)
        path = icon_dir / f"{base_name}_{pad}.png"
        tmp = path.with_suffix(".png.tmp")
        img.save(tmp, "PNG")
        tmp.replace(path)
        log.info("placeholder.rendered", pad=pad, label=label, path=str(path))

    img = render_placeholder("СИГНАЛ ПОТЕРЯН")
    path = icon_dir / f"{base_name}.png"
    tmp = path.with_suffix(".png.tmp")
    img.save(tmp, "PNG")
    tmp.replace(path)
    log.info("placeholder.rendered_generic", path=str(path))