import os
import re
from typing import Dict, List, Any
from jinja2 import Environment, FileSystemLoader
from lib.types import PagesDict

DEFAULT_TEMPLATE_DIR = 'templates'
DEFAULT_OUTPUT_DIR = 'html'


def get_template_files(template_dir: str = DEFAULT_TEMPLATE_DIR) -> List[str]:
    """Return template filenames from the provided template directory."""
    if not os.path.exists(template_dir):
        return []
    return [
        name
        for name in os.listdir(template_dir)
        if name.endswith('.html') and not name.startswith('_')
    ]


def get_css_files(output_dir: str = DEFAULT_OUTPUT_DIR) -> List[str]:
    """Return CSS file paths contained in the output directory's css folder."""
    css_dir = os.path.join(output_dir, 'css')
    if not os.path.exists(css_dir):
        return []
    return [
        os.path.join(css_dir, name)
        for name in os.listdir(css_dir)
        if name.endswith('.css')
    ]


def get_js_files(output_dir: str = DEFAULT_OUTPUT_DIR) -> List[str]:
    """Return JavaScript file paths contained in the output directory's js folder."""
    js_dir = os.path.join(output_dir, 'js')
    if not os.path.exists(js_dir):
        return []
    return [
        os.path.join(js_dir, name)
        for name in os.listdir(js_dir)
        if name.endswith('.js')
    ]


def render_template(
    template_name: str,
    context: Dict[str, Any],
    template_dir: str = DEFAULT_TEMPLATE_DIR) -> str:
    """Render a Jinja2 template with the provided context."""
    env = Environment(loader=FileSystemLoader(template_dir))
    template = env.get_template(template_name)
    return template.render(context)


def set_active_page_by_url(pages: PagesDict, page_url: str) -> None:
    """Mutate navigation dictionary to mark the active page."""
    for key, value in pages.items():
        # value is a PageEntry TypedDict
        value['active'] = key == page_url


def minify_js(js: str) -> str:
    """Minify JavaScript by removing comments and redundant whitespace."""
    js = re.sub(r'//.*?\n|/\*.*?\*/', '', js, flags=re.DOTALL)
    js = re.sub(r'\s+', ' ', js)
    js = re.sub(r';\s+', ';\n', js)
    js = re.sub(r'\n+', ' ', js)
    return js.strip()


def minify_css(css: str) -> str:
    """Minify CSS by removing comments and redundant whitespace."""
    css = re.sub(r'/\*.*?\*/', '', css, flags=re.DOTALL)
    css = re.sub(r'\s+', ' ', css)
    css = re.sub(r';\s+', ';\n', css)
    css = re.sub(r'\s+([\{\s])', r'\1', css)
    css = re.sub(r'\s+}', '}', css)
    css = re.sub(r'\n+', ' ', css)
    return css.strip()


def minify_html(html: str) -> str:
    """Minify HTML by removing comments and redundant whitespace."""
    html = re.sub(r'<!--.*?-->', '', html, flags=re.DOTALL)
    html = re.sub(r'\s+', ' ', html)
    html = re.sub(r'>\s+<', '><', html)
    html = re.sub(r'<\s+', '<', html)
    html = re.sub(r'\s+</', '</', html)
    return html.strip()


def css_minifier(output_dir: str = DEFAULT_OUTPUT_DIR) -> None:
    """Minify all CSS files within the output directory."""
    for css_path in get_css_files(output_dir):
        with open(css_path, 'r', encoding='utf-8') as handle:
            content = handle.read()
        minified = minify_css(content)
        with open(css_path, 'w', encoding='utf-8') as handle:
            handle.write(minified)


def js_minifier(output_dir: str = DEFAULT_OUTPUT_DIR) -> None:
    """Minify all JavaScript files within the output directory."""
    for js_path in get_js_files(output_dir):
        with open(js_path, 'r', encoding='utf-8') as handle:
            content = handle.read()
        minified = minify_js(content)
        with open(js_path, 'w', encoding='utf-8') as handle:
            handle.write(minified)


__all__ = [
    'DEFAULT_OUTPUT_DIR',
    'DEFAULT_TEMPLATE_DIR',
    'get_template_files',
    'get_css_files',
    'get_js_files',
    'render_template',
    'set_active_page_by_url',
    'minify_js',
    'minify_css',
    'minify_html',
    'css_minifier',
    'js_minifier',
]