"""Genere les icones PNG de la PWA sans dependance externe.

Usage : python scripts/generate_icons.py
Les fichiers sont ecrits dans frontend/public/icons/.
"""

from __future__ import annotations

import struct
import zlib
from pathlib import Path

OUTPUT_DIR = Path(__file__).resolve().parent.parent / "frontend" / "public" / "icons"

INDIGO = (79, 70, 229, 255)
WHITE = (255, 255, 255, 255)
LIGHT = (199, 210, 254, 255)
MID = (165, 180, 252, 255)
SUPERSAMPLE = 3


class Canvas:
    def __init__(self, size: int) -> None:
        self.size = size
        self.buffer = bytearray(size * size * 4)

    def set_pixel(self, x: int, y: int, color: tuple[int, int, int, int]) -> None:
        if 0 <= x < self.size and 0 <= y < self.size:
            offset = (y * self.size + x) * 4
            self.buffer[offset : offset + 4] = bytes(color)

    def fill_rounded_rect(
        self, x0: float, y0: float, x1: float, y1: float, radius: float, color
    ) -> None:
        for y in range(int(y0), int(y1)):
            for x in range(int(x0), int(x1)):
                cx = min(max(x, x0 + radius), x1 - radius)
                cy = min(max(y, y0 + radius), y1 - radius)
                if (x - cx) ** 2 + (y - cy) ** 2 <= radius * radius:
                    self.set_pixel(x, y, color)

    def fill_circle(self, cx: float, cy: float, radius: float, color) -> None:
        for y in range(int(cy - radius), int(cy + radius) + 1):
            for x in range(int(cx - radius), int(cx + radius) + 1):
                if (x - cx) ** 2 + (y - cy) ** 2 <= radius * radius:
                    self.set_pixel(x, y, color)

    def draw_segment(self, x0, y0, x1, y1, width, color) -> None:
        half = width / 2
        dx, dy = x1 - x0, y1 - y0
        length_sq = dx * dx + dy * dy or 1
        min_x, max_x = int(min(x0, x1) - half - 1), int(max(x0, x1) + half + 1)
        min_y, max_y = int(min(y0, y1) - half - 1), int(max(y0, y1) + half + 1)

        for y in range(min_y, max_y + 1):
            for x in range(min_x, max_x + 1):
                t = max(0.0, min(1.0, ((x - x0) * dx + (y - y0) * dy) / length_sq))
                px, py = x0 + t * dx, y0 + t * dy
                if (x - px) ** 2 + (y - py) ** 2 <= half * half:
                    self.set_pixel(x, y, color)

    def downsample(self, factor: int) -> "Canvas":
        target = Canvas(self.size // factor)
        area = factor * factor
        for y in range(target.size):
            for x in range(target.size):
                totals = [0, 0, 0, 0]
                for sy in range(factor):
                    row = (y * factor + sy) * self.size
                    for sx in range(factor):
                        offset = (row + x * factor + sx) * 4
                        for channel in range(4):
                            totals[channel] += self.buffer[offset + channel]
                target.set_pixel(x, y, tuple(value // area for value in totals))
        return target

    def to_png(self, path: Path) -> None:
        rows = bytearray()
        stride = self.size * 4
        for y in range(self.size):
            rows.append(0)  # filtre "None"
            rows.extend(self.buffer[y * stride : (y + 1) * stride])

        def chunk(tag: bytes, data: bytes) -> bytes:
            return (
                struct.pack(">I", len(data))
                + tag
                + data
                + struct.pack(">I", zlib.crc32(tag + data) & 0xFFFFFFFF)
            )

        header = struct.pack(">IIBBBBB", self.size, self.size, 8, 6, 0, 0, 0)
        png = (
            b"\x89PNG\r\n\x1a\n"
            + chunk(b"IHDR", header)
            + chunk(b"IDAT", zlib.compress(bytes(rows), 9))
            + chunk(b"IEND", b"")
        )
        path.write_bytes(png)


def render(size: int, content_scale: float, corner_ratio: float) -> Canvas:
    """Dessine l'icone : un noeud racine relie a trois branches."""
    canvas = Canvas(size)
    canvas.fill_rounded_rect(0, 0, size, size, size * corner_ratio, INDIGO)

    unit = size / 512 * content_scale
    center = size / 2
    offset = center - 256 * unit

    def point(x: float, y: float) -> tuple[float, float]:
        return (offset + x * unit, offset + y * unit)

    root = point(168, 256)
    targets = [point(336, 160), point(336, 256), point(336, 352)]
    for target in targets:
        canvas.draw_segment(root[0], root[1], target[0], target[1], 18 * unit, WHITE)

    canvas.fill_circle(root[0], root[1], 46 * unit, WHITE)
    for index, target in enumerate(targets):
        canvas.fill_circle(target[0], target[1], 30 * unit, MID if index == 1 else LIGHT)
    return canvas


def build(size: int, filename: str, content_scale: float, corner_ratio: float) -> None:
    large = render(size * SUPERSAMPLE, content_scale, corner_ratio)
    large.downsample(SUPERSAMPLE).to_png(OUTPUT_DIR / filename)
    print(f"ecrit {filename} ({size}x{size})")


def main() -> None:
    OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
    build(192, "icon-192.png", 1.0, 0.22)
    build(512, "icon-512.png", 1.0, 0.22)
    # Icone maskable : contenu reduit pour rester dans la zone sure.
    build(512, "icon-maskable-512.png", 0.62, 0.5)


if __name__ == "__main__":
    main()