"""Resize the flicker frame PNGs to embeddable JPGs and inject into the HTML report.

Reads flicker_investigation_handover.html, replaces the static "ul.tight" frame
list in Section 1 with an inline gallery of base64-embedded JPGs, and writes
back the same file.
"""
import base64
import sys
from pathlib import Path

from PIL import Image

REPO   = Path(__file__).parent
PICS   = REPO / "data" / "pics"
HTML   = REPO / "flicker_investigation_continued.html"
TMP    = REPO / ".embed_tmp"

# (filename, caption)
FRAMES = [
    ("frame0362.png", "Frame 362 — baseline. Clean image."),
    ("frame0363.png", "Frame 363 — flicker. Vertical displacement; content recognisable but geometry wrong."),
    ("frame0370.png", "Frame 370 — flicker. Same vertical shift pattern."),
    ("frame0376.png", "Frame 376 — flicker. Lower-amplitude shift."),
    ("frame0381.png", "Frame 381 — flicker (most dramatic). Multi-band tearing; multiple partial frames stacked vertically."),
    ("frame0382.png", "Frame 382 — flicker. Frame after the dramatic shift; partial recovery still showing artifacts."),
]


def resize_to_jpg(src: Path, dst: Path, width: int = 800, quality: int = 75) -> None:
    """Resize src to width px and write as JPG at given quality, via Pillow."""
    img = Image.open(src)
    if img.mode != "RGB":
        img = img.convert("RGB")
    w, h = img.size
    if w > width:
        new_h = int(h * width / w)
        img = img.resize((width, new_h), Image.LANCZOS)
    img.save(dst, "JPEG", quality=quality, optimize=True)


def main() -> int:
    if not HTML.exists():
        print(f"missing {HTML}", file=sys.stderr); return 1

    TMP.mkdir(exist_ok=True)
    blocks = []
    for fname, caption in FRAMES:
        src = PICS / fname
        if not src.exists():
            print(f"skip (missing): {src}"); continue
        dst = TMP / (src.stem + ".jpg")
        resize_to_jpg(src, dst)
        b64 = base64.b64encode(dst.read_bytes()).decode("ascii")
        kb  = len(b64) * 3 // 4 // 1024
        blocks.append(
            f'<figure class="frame">\n'
            f'  <img src="data:image/jpeg;base64,{b64}" alt="{fname}">\n'
            f'  <figcaption>{caption}</figcaption>\n'
            f'</figure>'
        )
        print(f"embedded {fname} -> {kb} KB")

    if not blocks:
        print("no frames embedded; HTML unchanged"); return 1

    gallery = (
        '<div class="frame-gallery">\n'
        + "\n".join(blocks)
        + "\n</div>"
    )

    html = HTML.read_text(encoding="utf-8")

    placeholder = "<!-- FRAME_GALLERY_PLACEHOLDER -->"
    if placeholder not in html:
        print(f"WARNING: placeholder {placeholder!r} not found in HTML; "
              "no embedding done", file=sys.stderr)
        return 1
    new_html = html.replace(placeholder, gallery, 1)

    HTML.write_text(new_html, encoding="utf-8")
    print(f"wrote {HTML} ({len(new_html)//1024} KB)")
    return 0


if __name__ == "__main__":
    sys.exit(main())