"""Shared rendering for the demo: overlays and the looping sequence animation.

Used by app.py (live runs) and scripts/precompute.py (shipped payloads).
Color semantics everywhere: orange = the tube is judged smoke, gray = the
tube is rejected by the classifier.
"""

from pathlib import Path

from PIL import Image, ImageDraw, ImageFont

SMOKE = "#ea580c"
REJECTED = "#94a3b8"
INK = "#1e293b"

ANIM_WIDTH = 960
ANIM_FRAME_MS = 400


def font(size: int):
    try:
        return ImageFont.truetype("DejaVuSans-Bold.ttf", size)
    except OSError:
        return ImageFont.load_default()


def tube_is_smoke(tube: dict, threshold: float) -> bool:
    prob = tube["probability"]
    return prob is not None and prob >= threshold


def tube_color(tube: dict, threshold: float) -> str:
    return SMOKE if tube_is_smoke(tube, threshold) else REJECTED


def overlay_frame(payload: dict, paths: list[Path], idx: int, width: int | None = None) -> Image.Image:
    """Frame idx with each kept tube's fixed crop window, colored by verdict."""
    img = Image.open(paths[idx]).convert("RGB")
    if width and img.width > width:
        img = img.resize((width, round(img.height * width / img.width)), Image.LANCZOS)
    draw = ImageDraw.Draw(img)
    w, h = img.size
    fnt = font(16)
    threshold = payload["details"]["decision"]["threshold"]

    for tube in payload["details"]["tubes"]["kept"]:
        if not tube["stabilized_window"]:
            continue
        cx, cy, bw, bh = tube["stabilized_window"]
        x0, y0 = (cx - bw / 2) * w, (cy - bh / 2) * h
        x1, y1 = (cx + bw / 2) * w, (cy + bh / 2) * h
        color = tube_color(tube, threshold)
        draw.rectangle([x0, y0, x1, y1], outline=color, width=3)
        # tube_id is 0-based internally; display 1-based for readability
        draw.text((x0 + 3, max(0, y0 - 20)), f"tube {tube['tube_id'] + 1}", fill=color, font=fnt)

    draw.text((10, 8), f"frame {idx + 1}", fill="white", font=font(22))
    return img


def save_animation(payload: dict, paths: list[Path], out_path: Path) -> Path:
    """Looping animated WebP of the whole sequence with overlays burned in."""
    frames = [overlay_frame(payload, paths, i, width=ANIM_WIDTH) for i in range(len(paths))]
    frames[0].save(
        out_path,
        format="WEBP",
        save_all=True,
        append_images=frames[1:],
        duration=ANIM_FRAME_MS,
        loop=0,
        quality=78,
    )
    return out_path