#!/usr/bin/env python3
"""Embeds the high-res HUD textures (port/assets/hud, made by
tools/hud_assets.py), the menus' titles (port/assets/titles, made by
tools/title_assets.py) and the fonts the text is drawn with
(port/assets/fonts) in the game as C data:

    python tools/embed_assets.py OUTPUT.c

writes OUTPUT.c with each PNG and the bitmap it stands for (its tag, index
and the checksum of its pixels, from port/assets/hud/layout.json and
port/assets/titles/titles.json), as
port/linux/src/hud_hires.h declares them. The builds generate it
(hud_assets_build, called by tools/linux_build.py, windows_build.py and
android_build.py), so the PNGs are the committed source and Android needs
no files beside its guest image.

The data are 32-bit words, not bytes: the Android build passes the guest's
assembly through tools/android_asm_convert.py, which rewrites identifiers in
operands and would garble a long .ascii string of binary data.
"""

import json
import struct
import sys
from pathlib import Path
from typing import Any, List

ROOT = Path(__file__).resolve().parent.parent
HUD_ASSETS = Path("port/assets/hud")
LAYOUT = HUD_ASSETS / "layout.json"
TITLE_ASSETS = Path("port/assets/titles")
TITLE_LIST = TITLE_ASSETS / "titles.json"
FONT_ASSETS = Path("port/assets/fonts")
FONT_LIST = FONT_ASSETS / "fonts.json"
PNG_SIGNATURE = b"\x89PNG\r\n\x1a\n"


def font_files() -> List[str]:
    """The font files fonts.json uses, each once."""
    if not (ROOT / FONT_LIST).is_file():
        return []
    fonts = json.loads((ROOT / FONT_LIST).read_text())["fonts"]
    return sorted({font["file"] for font in fonts})


def textures() -> List[tuple]:
    """The textures: each one's folder, its entry in its list, and whether
    it is a title."""
    result = []
    for folder, listing, title in ((HUD_ASSETS, LAYOUT, False), (TITLE_ASSETS, TITLE_LIST, True)):
        if (ROOT / listing).is_file():
            result += [(folder, asset, title) for asset in json.loads((ROOT / listing).read_text())["assets"]]
    return result


def hud_asset_inputs() -> List[Path]:
    """The files the generated source is made from."""
    inputs = [listing for listing in (LAYOUT, TITLE_LIST, FONT_LIST) if (ROOT / listing).is_file()]
    if not inputs:
        return []
    return [*inputs, *(folder / f"{asset['name']}.png" for folder, asset, _ in textures()),
            *(FONT_ASSETS / name for name in font_files())]


def hud_configure_inputs() -> List[Path]:
    """What configure.py is run again for: the lists of assets (and the
    folders, for files added or removed), not each file, which a change of a
    list may rename or remove."""
    inputs = []
    for folder, listing in ((HUD_ASSETS, LAYOUT), (TITLE_ASSETS, TITLE_LIST), (FONT_ASSETS, FONT_LIST)):
        if (ROOT / listing).is_file():
            inputs += [folder, listing]
    return inputs


def words(data: bytes) -> List[str]:
    """data as lines of 32-bit words (padded with zeros)."""
    padded = data + b"\0" * (-len(data) % 4)
    values = struct.unpack(f"<{len(padded) // 4}I", padded)
    return ["\t" + ", ".join(f"0x{word:08x}" for word in values[start:start + 8]) + ","
            for start in range(0, len(values), 8)]


def hud_assets_build(n: Any, prefix: str, output: Path) -> List[Path]:
    """Emits the rule that generates output; returns [output], or nothing
    when there are no assets."""
    inputs = hud_asset_inputs()
    if not inputs:
        return []
    n.rule(
        name=f"{prefix}_embed_assets",
        command="$python tools/embed_assets.py $out",
        description=f"{prefix.upper()} EMBED $out",
    )
    n.build(outputs=output, rule=f"{prefix}_embed_assets", implicit=[Path("tools/embed_assets.py"), *inputs])
    return [output]


def png_size(data: bytes, name: str) -> tuple:
    """The width and height of an 8-bit RGBA, non-interlaced PNG (the only
    kind port/linux/src/hud_hires.c reads)."""
    if data[:8] != PNG_SIGNATURE or data[12:16] != b"IHDR":
        sys.exit(f"{name}: not a PNG")
    width, height, depth, colour, _, _, interlace = struct.unpack(">IIBBBBB", data[16:29])
    if depth != 8 or colour != 6 or interlace != 0:
        sys.exit(f"{name}: must be 8-bit RGBA and not interlaced")
    return width, height


def main() -> None:
    if len(sys.argv) != 2:
        sys.exit("usage: embed_assets.py OUTPUT.c")
    lines = [
        "/* generated by tools/embed_assets.py from port/assets: do not edit */",
        "",
        '#include "hud_hires.h"',
        "",
    ]
    table = []
    for index, (folder, asset, title) in enumerate(textures()):
        name = f"{asset['name']}.png"
        data = (ROOT / folder / name).read_bytes()
        width, height = png_size(data, name)
        scale = asset["scale"]
        if (width, height) != (asset["width"] * scale, asset["height"] * scale):
            sys.exit(f"{name}: {width}x{height}, not {scale}x its bitmap's {asset['width']}x{asset['height']}")
        lines.append(f"static const unsigned int asset{index}[] = {{")
        lines.extend(words(data))
        lines.append("};")
        lines.append("")
        tag = asset["tag"].replace("\\", "\\\\")
        coverage = int(any(cell["kind"] == "meter" for cell in asset.get("cells", [])))
        table.append(f'\t{{ "{tag}", {asset["bitmap"]}, {width}, {height}, 0x{asset["crc"]:08x}u, {coverage}, '
                     f'{int(title)}, asset{index}, {len(data)} }},')
    lines.append("const struct hud_hires_embedded hud_hires_embedded[] =")
    lines.append("{")
    lines.extend(table)
    lines.append("};")
    lines.append(f"const unsigned int hud_hires_embedded_count = {len(table)};")
    lines.append("")
    # the fonts, and which draws each font tag (text_hires.h)
    lines.append('#include "text_hires.h"')
    lines.append("")
    files = font_files()
    for index, name in enumerate(files):
        lines.append(f"static const unsigned int font{index}[] = {{")
        lines.extend(words((ROOT / FONT_ASSETS / name).read_bytes()))
        lines.append("};")
        lines.append("")
    fonts = json.loads((ROOT / FONT_LIST).read_text())["fonts"] if files else []
    lines.append("const struct text_hires_embedded text_hires_embedded[] =")
    lines.append("{")
    for font in fonts:
        index = files.index(font["file"])
        tag = font["tag"].replace("\\", "\\\\")
        size = (ROOT / FONT_ASSETS / font["file"]).stat().st_size
        lines.append(f'\t{{ "{tag}", "{font["file"]}", font{index}, {size} }},')
    if not fonts:
        lines.append("\t{ 0 },")
    lines.append("};")
    lines.append(f"const unsigned int text_hires_embedded_count = {len(fonts)};")
    output = Path(sys.argv[1])
    output.parent.mkdir(parents=True, exist_ok=True)
    text = "\n".join(lines) + "\n"
    if not output.is_file() or output.read_text() != text:
        output.write_text(text)


if __name__ == "__main__":
    main()