"""
用 PIL 渲染 ASCII 像素风位图字体图集。

用法:
    python tools/gen_font_atlas.py [output_dir]

默认输出目录: assets/font/
生成: font_atlas.png, font_atlas.h

字符范围: ASCII 32~126
字体: 优先使用 assets/font/ndrtyyl-prqyys-undertale-hebrew-uppercase.ttf，
      不存在时回退到系统等宽字体（Courier New / Consolas / monospace）

像素格式: (R << 24) | (G << 16) | (B << 8) | A
生成端会把 alpha 阈值化为 0/255，匹配当前 DrawContext::draw_text 的像素风绘制路径。
"""

import os
import sys

from PIL import Image, ImageDraw, ImageFont


FIRST_CHAR = 32
LAST_CHAR = 126
NUM_CHARS = LAST_CHAR - FIRST_CHAR + 1  # 95
COLUMNS = 16
ROWS = (NUM_CHARS + COLUMNS - 1) // COLUMNS  # 6


def find_mono_font(size: int) -> ImageFont.FreeTypeFont:
    repo_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    candidates = [
        os.path.join(repo_root, "assets/font", "ndrtyyl-prqyys-undertale-hebrew-uppercase.ttf"),
        "C:/Windows/Fonts/consola.ttf",   # Consolas (Windows)
        "C:/Windows/Fonts/cour.ttf",      # Courier New (Windows)
        "/usr/share/fonts/truetype/dejavu/DejaVuSansMono.ttf",  # Linux
        "/usr/share/fonts/truetype/liberation/LiberationMono-Regular.ttf",
    ]
    for path in candidates:
        if os.path.exists(path):
            return ImageFont.truetype(path, size)

    return ImageFont.load_default()


def generate(output_dir: str):
    font = find_mono_font(14)

    # 测量完整 ASCII 字符集的尺寸。
    # 不能只用 "M"：它没有下伸部，按它算高度会裁掉 g/j/p/q/y/_ 等字符。
    tmp_img = Image.new("RGBA", (1, 1))
    tmp_draw = ImageDraw.Draw(tmp_img)
    chars = [chr(FIRST_CHAR + i) for i in range(NUM_CHARS)]
    bboxes = [tmp_draw.textbbox((0, 0), ch, font=font) for ch in chars]

    pad = 1
    min_left = min(b[0] for b in bboxes)
    min_top = min(b[1] for b in bboxes)
    max_right = max(b[2] for b in bboxes)
    max_bottom = max(b[3] for b in bboxes)

    # 等宽字体仍使用统一 cell。宽度用字体 advance，避免窄字符影响字距；
    # 高度用全字符 bbox，保证下伸字符不被裁切。
    max_advance = max(tmp_draw.textlength(ch, font=font) for ch in chars)
    char_w = int(max_advance + 0.9999) + pad * 2
    char_h = (max_bottom - min_top) + pad * 2

    atlas_w = COLUMNS * char_w
    atlas_h = ROWS * char_h

    img = Image.new("RGBA", (atlas_w, atlas_h), (0, 0, 0, 0))
    draw = ImageDraw.Draw(img)

    for i in range(NUM_CHARS):
        ch = chr(FIRST_CHAR + i)
        col = i % COLUMNS
        row = i // COLUMNS
        x = col * char_w + pad - min_left
        y = row * char_h + pad - min_top
        draw.text((x, y), ch, fill=(255, 255, 255, 255), font=font)

    # 像素风：把 TrueType 抗锯齿 alpha 二值化。
    # 渲染端目前只判断 alpha 是否非 0；如果保留半透明边缘，会被画成实心像素导致发胖/毛边。
    threshold = 128
    for py in range(atlas_h):
        for px in range(atlas_w):
            _, _, _, a = img.getpixel((px, py))
            img.putpixel((px, py), (255, 255, 255, 255) if a >= threshold else (0, 0, 0, 0))

    png_path = os.path.join(output_dir, "font_atlas.png")
    img.save(png_path)

    # 生成 C 头文件：将每行像素打包成 bit 行（每像素 1 bit，白色=1，透明=0）
    # 这样每个 glyph 的一行只需要 char_w/8 个字节
    # 但为了简单，这里直接存储为 uint32_t RGBA 像素数组
    # 使用时白色像素用指定颜色替换，透明像素跳过

    pixels = []
    for y in range(atlas_h):
        for x in range(atlas_w):
            r, g, b, a = img.getpixel((x, y))
            pixels.append((r << 24) | (g << 16) | (b << 8) | a)

    h_path = os.path.join(output_dir, "font_atlas.h")
    with open(h_path, "w", encoding="utf-8") as f:
        f.write("// Auto-generated by tools/gen_font_atlas.py\n")
        f.write("#pragma once\n#include <cstdint>\n\n")
        f.write(f"static const int32_t font_atlas_width = {atlas_w};\n")
        f.write(f"static const int32_t font_atlas_height = {atlas_h};\n")
        f.write(f"static const int32_t font_char_w = {char_w};\n")
        f.write(f"static const int32_t font_char_h = {char_h};\n")
        f.write(f"static const int32_t font_first_char = {FIRST_CHAR};\n")
        f.write(f"static const int32_t font_columns = {COLUMNS};\n\n")
        f.write(f"static const uint32_t font_atlas_pixels[] = {{\n")

        for i in range(0, len(pixels), 16):
            chunk = pixels[i:i + 16]
            line = ", ".join(f"0x{p:08X}" for p in chunk)
            f.write(f"    {line},\n")

        f.write("};\n")

    print(f"Atlas: {atlas_w}x{atlas_h}, char: {char_w}x{char_h}")
    print(f"Generated: {png_path}, {h_path}")


def main():
    if len(sys.argv) >= 2:
        out_dir = sys.argv[1]
    else:
        out_dir = os.path.join(
            os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
            "assets", "font"
        )

    os.makedirs(out_dir, exist_ok=True)
    generate(out_dir)


if __name__ == "__main__":
    main()