Import("env")

import gzip
import re
from pathlib import Path


ROOT = Path(env.subst("$PROJECT_DIR"))
DATA = ROOT / "data"
ASSETS = ("index.html", "styles.css", "app.js", "ship-sprite.svg")


def minify_html(source):
    return re.sub(r">\s+<", "><", source).strip()


def minify_css(source):
    source = re.sub(r"/\*.*?\*/", "", source, flags=re.S)
    return re.sub(r"\s*([{}:;,>])\s*", r"\1", source).strip()


def minify_js(source):
    output = []
    quote = ""
    escaped = False
    pending_space = False
    for character in source:
        if quote:
            output.append(character)
            if escaped:
                escaped = False
            elif character == "\\":
                escaped = True
            elif character == quote:
                quote = ""
            continue
        if character in ("'", '"', "`"):
            if pending_space and output and (output[-1].isalnum() or output[-1] in "_$"):
                output.append(" ")
            pending_space = False
            quote = character
            output.append(character)
        elif character.isspace():
            pending_space = True
        else:
            if pending_space and output and (output[-1].isalnum() or output[-1] in "_$") and (character.isalnum() or character in "_$"):
                output.append(" ")
            pending_space = False
            output.append(character)
    return "".join(output)


def compress_assets():
    for asset in ASSETS:
        path = DATA / asset
        text = path.read_text(encoding="utf-8")
        if asset.endswith(".html"):
            text = minify_html(text)
        elif asset.endswith(".css"):
            text = minify_css(text)
        elif asset.endswith(".js"):
            text = minify_js(text)
        (DATA / f"{asset}.gz").write_bytes(gzip.compress(text.encode("utf-8"), mtime=0))


compress_assets()