#!/usr/bin/env python3
"""Generate GiteaHubSync app icons (pure stdlib, no PIL).
Design: rounded gradient tile (blue -> teal) + white double sync arrows."""
import os
import struct
import zlib

BASE = os.path.join(os.path.dirname(os.path.abspath(__file__)), "GiteaHubSync")


class Canvas:
    def __init__(self, w, h, scale=4):
        self.w, self.h, self.s = w, h, scale
        self.W, self.H = w * scale, h * scale
        self.px = [(0, 0, 0, 0)] * (self.W * self.H)

    def _set(self, x, y, rgba):
        if 0 <= x < self.W and 0 <= y < self.H:
            i = y * self.W + x
            r, g, b, a = rgba
            orr, og, ob, oa = self.px[i]
            na = a / 255.0 + oa / 255.0 * (1 - a / 255.0)
            if na == 0:
                self.px[i] = (0, 0, 0, 0)
            else:
                nr = (r * a / 255.0 + orr * oa / 255.0 * (1 - a / 255.0)) / na
                ng = (g * a / 255.0 + og * ob / 255.0 * (1 - a / 255.0)) / na
                nb = (b * a / 255.0 + ob * oa / 255.0 * (1 - a / 255.0)) / na
                self.px[i] = (int(nr), int(ng), int(nb), int(na * 255))

    def line(self, x1, y1, x2, y2, thick, rgba):
        steps = int(max(abs(x2 - x1), abs(y2 - y1)) * 2) + 1
        for i in range(steps + 1):
            t = i / steps
            cx, cy = x1 + (x2 - x1) * t, y1 + (y2 - y1) * t
            r = thick / 2.0
            for yy in range(int(cy - r) - 1, int(cy + r) + 2):
                for xx in range(int(cx - r) - 1, int(cx + r) + 2):
                    if (xx - cx) ** 2 + (yy - cy) ** 2 <= r * r:
                        self._set(xx, yy, rgba)

    def triangle(self, pts, rgba):
        ys = [p[1] for p in pts]
        for y in range(int(min(ys)), int(max(ys)) + 1):
            xints = []
            for i in range(3):
                x1, y1 = pts[i]
                x2, y2 = pts[(i + 1) % 3]
                if y1 == y2:
                    continue
                if min(y1, y2) <= y < max(y1, y2):
                    t = (y - y1) / (y2 - y1)
                    xints.append(x1 + t * (x2 - x1))
            if len(xints) >= 2:
                xints.sort()
                for x in range(int(xints[0]), int(xints[-1]) + 1):
                    self._set(x, y, rgba)

    def gradient_fill(self, x, y, w, h, rad, c1, c2):
        for yy in range(y, y + h):
            t = (yy - y) / max(h - 1, 1)
            r = int(c1[0] + (c2[0] - c1[0]) * t)
            g = int(c1[1] + (c2[1] - c1[1]) * t)
            b = int(c1[2] + (c2[2] - c1[2]) * t)
            for xx in range(x, x + w):
                dx = max(x + rad - xx, xx - (x + w - 1 - rad), 0)
                dy = max(y + rad - yy, yy - (y + h - 1 - rad), 0)
                if dx * dx + dy * dy <= rad * rad:
                    self._set(xx, yy, (r, g, b, 255))

    def save(self, path):
        s = self.s
        rows = []
        for y in range(self.h):
            row = bytearray([0])
            for x in range(self.w):
                rs = gs = bs = as_ = 0
                cnt = 0
                for dy in range(s):
                    for dx in range(s):
                        p = self.px[(y * s + dy) * self.W + (x * s + dx)]
                        rs += p[0]; gs += p[1]; bs += p[2]; as_ += p[3]
                        cnt += 1
                row += bytes((rs // cnt, gs // cnt, bs // cnt, as_ // cnt))
            rows.append(bytes(row))
        raw = b"".join(rows)

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

        png = b"\x89PNG\r\n\x1a\n"
        png += chunk(b"IHDR", struct.pack(">IIBBBBB", self.w, self.h, 8, 6, 0, 0, 0))
        png += chunk(b"IDAT", zlib.compress(raw, 9))
        png += chunk(b"IEND", b"")
        with open(path, "wb") as f:
            f.write(png)


def draw_icon(size):
    c = Canvas(size, size)
    S = c.s
    W = c.W
    m = int(size * 0.05) * S
    # 渐变圆角瓷砖：蓝 -> 青
    c.gradient_fill(m, m, W - 2 * m, c.H - 2 * m, int(size * 0.22) * S,
                    (37, 99, 235), (13, 148, 136))
    white = (255, 255, 255, 255)
    t = int(size * 0.055) * S          # 箭杆粗细
    ah = int(size * 0.11) * S          # 箭头大小
    y1 = int(size * 0.42) * S          # 上箭头中心线
    y2 = int(size * 0.58) * S          # 下箭头中心线
    # 上箭头：向左的杆 + 左箭头
    c.line(W * 0.40, y1, W * 0.68, y1, t, white)
    c.triangle([(W * 0.70, y1), (W * 0.70 - ah, y1 - ah * 0.62), (W * 0.70 - ah, y1 + ah * 0.62)], white)
    # 下箭头：向右的杆 + 右箭头
    c.line(W * 0.32, y2, W * 0.60, y2, t, white)
    c.triangle([(W * 0.30, y2), (W * 0.30 + ah, y2 - ah * 0.62), (W * 0.30 + ah, y2 + ah * 0.62)], white)
    return c


def main():
    for size, rel in [(256, "ICON_256.PNG"), (64, "ICON.PNG")]:
        draw_icon(size).save(os.path.join(BASE, rel))
        print("built", rel)
    img = os.path.join(BASE, "app", "ui", "images")
    os.makedirs(img, exist_ok=True)
    for size, name in [(256, "icon_256.png"), (64, "icon_64.png")]:
        draw_icon(size).save(os.path.join(img, name))
        print("built", name)


if __name__ == "__main__":
    main()