#!/usr/bin/env python3
"""
Build a single self-contained HTML file from the source files.

Usage:
    python3 build.py [output.html]

If output is not given, defaults to 'background-final.html'.

This reads config.js to pick the active theme and inlines all CSS,
JS, and the noise.png texture into a single HTML document. After
building, the resulting standalone HTML can be opened directly in
a browser (file://) because all external resources are inlined.
"""

import base64
import os
import re
import sys

ROOT = os.path.dirname(os.path.abspath(__file__))


def read(path):
    with open(os.path.join(ROOT, path), 'r', encoding='utf-8') as f:
        return f.read()


def parse_config():
    """Extract window.CONFIG values from config.js."""
    src = read('config.js')
    out = {}
    for key in ['debug', 'theme', 'units', 'language', 'timeFormat']:
        m = re.search(r"\b%s\s*:\s*'([^']*)'" % key, src) or re.search(r'\b%s\s*:\s*(\d+)' % key, src)
        if m:
            out[key] = m.group(1)
    m = re.search(r'lat\s*:\s*([\d.]+)', src)
    if m:
        out['lat'] = m.group(1)
    m = re.search(r'lon\s*:\s*([-\d.]+)', src)
    if m:
        out['lon'] = m.group(1)
    return out


def main():
    out = sys.argv[1] if len(sys.argv) > 1 else 'background-final.html'

    cfg = parse_config()
    theme = cfg.get('theme', 'ash')

    html = read('background.html')

    # Read noise.png and inline as base64 data URI
    with open(os.path.join(ROOT, 'noise.png'), 'rb') as f:
        noise_b64 = base64.b64encode(f.read()).decode('ascii')

    # Replace noiseDataUri placeholder with the actual data URI
    html = html.replace(
        "'data:image/png;base64,PLACEHOLDER'",
        "'data:image/png;base64," + noise_b64 + "'"
    )

    # Resolve active theme css
    theme_css = read(theme + '.css')
    # Inline the active theme stylesheet at the end of <head>
    html = html.replace('</head>',
        '<style>\n' + theme_css + '\n</style>\n</head>',
        1)

    # Inline vendor scripts in the body, before the main script block
    for _, path in [
        ('three', 'vendor/three.min.js'),
        ('suncalc', 'vendor/suncalc.js'),
        ('vanta2', 'vendor/vanta.clouds2.min.js'),
        ('i18n',  'i18n.js'),
        ('config', 'config.js'),
    ]:
        body = read(path)
        html = html.replace('<script src="' + path + '"></script>',
            '<script>\n' + body + '\n</script>',
            1)

    with open(os.path.join(ROOT, out), 'w', encoding='utf-8') as f:
        f.write(html)

    print('Wrote ' + out + ' (' + str(len(html)) + ' bytes)')
    print('Config used:')
    for k in ('debug', 'theme', 'units', 'language', 'timeFormat', 'lat', 'lon'):
        if k in cfg:
            print('  ' + k + ' = ' + cfg[k])


if __name__ == '__main__':
    main()