"""Offline conversion of generated guest art into the existing ANM1 format."""
from pathlib import Path
import struct
from PIL import Image

ROOT = Path(__file__).resolve().parents[2]
SOURCE = ROOT / "assets/sprites/hall/guest-cast-v1.png"
TARGET = ROOT / "assets/animations/hall/guest-cast-v1.bin"


def isolate(cell):
    alpha = cell.getchannel("A")
    pixels = alpha.load()
    remaining = {(x,y) for y in range(cell.height) for x in range(cell.width)
                 if pixels[x,y] >= 48}
    components = []
    while remaining:
        point = remaining.pop()
        component, pending = {point}, [point]
        while pending:
            x,y = pending.pop()
            for other in ((x-1,y),(x+1,y),(x,y-1),(x,y+1)):
                if other in remaining:
                    remaining.remove(other)
                    component.add(other)
                    pending.append(other)
        components.append(component)
    largest = max(components,key=len)
    mask = Image.new("L",cell.size)
    for x,y in largest:
        mask.putpixel((x,y),pixels[x,y])
    cell.putalpha(mask)
    return cell.crop(cell.getbbox())


def main():
    sheet = Image.open(SOURCE).convert("RGBA")
    frames = []
    # The approved sheet contains idle, three gait poses and a seated row.
    # Repeat the passing pose to close the four-phase walk without a jump.
    for column in range(6):
        boundaries = (0,277,535,795,1055,sheet.height)
        cells = [isolate(sheet.crop((column*sheet.width//6, boundaries[row],
                             (column+1)*sheet.width//6, boundaries[row+1])))
                 for row in range(5)]
        scale = min(120/max(cell.width for cell in cells[:4]),
                    204/max(cell.height for cell in cells[:4]))
        for row in (0, 1, 2, 3, 2, 4):
            cell = cells[row]
            pose_scale = min(scale,124/cell.width,160/cell.height) if row == 4 else scale
            size = (max(1, round(cell.width*pose_scale)), max(1, round(cell.height*pose_scale)))
            cell = cell.resize(size, Image.Resampling.LANCZOS)
            if column == 1 and row == 4:
                cell = cell.transpose(Image.Transpose.FLIP_LEFT_RIGHT)
            frame = Image.new("RGBA", (128, 224))
            frame.alpha_composite(cell, ((128-size[0])//2, 220-size[1]))
            frames.append(frame)
    payload = b"".join(frame.tobytes("raw", "BGRA") for frame in frames)
    TARGET.write_bytes(struct.pack("<4s4I", b"ANM1",128,224,len(frames),len(payload))+payload)
    contact = Image.new("RGBA", (6*128,6*224), (24,28,29,255))
    for index, frame in enumerate(frames):
        contact.alpha_composite(frame, ((index//6)*128,(index%6)*224))
    contact.save(ROOT / "build/guest-cast-preview.png")
    print("Packed six guests, six frames each:", TARGET)


if __name__ == "__main__":
    main()