"""Single-request bundle for the config-form widget scripts.

Every page used to carry one <script> tag per widget (34 of them, ~700 KB
uncompressed). On a Pi Zero 2 W serving a phone over WiFi, each tag is a
separate request the Python server has to answer. The files are plain scripts
that register themselves on window/LEDMatrixWidgets at load time, so
concatenating them in the same order is exactly equivalent to loading them
one by one — no module wrapper, no scope change.

The individual files stay on disk and keep working as direct URLs, which is
what plugin-loader.js and any third-party page expect.

BUNDLE_ORDER is the authority for which widgets ship; test_widget_scripts.py
checks it against the directory so a new widget can't be forgotten.
"""
import hashlib
from pathlib import Path
from threading import Lock

WIDGETS_DIR = Path(__file__).parent / "static" / "v3" / "js" / "widgets"

# Load order matters: the registry and base class must exist before the
# widgets that call them, and notification.js owns window.showNotification.
BUNDLE_ORDER = [
    "registry.js",
    "base-widget.js",
    "notification.js",
    "plugin-order-list.js",
    "file-upload.js",
    "checkbox-group.js",
    "custom-feeds.js",
    "array-table.js",
    "google-calendar-picker.js",
    "google-oauth.js",
    "day-selector.js",
    "time-range.js",
    "time-picker.js",
    "file-upload-single.js",
    "plugin-file-manager.js",
    "schedule-picker.js",
    # Basic input widgets
    "text-input.js",
    "number-input.js",
    "textarea.js",
    "select-dropdown.js",
    "font-selector.js",
    "style-editor.js",
    "toggle-switch.js",
    "radio-group.js",
    "date-picker.js",
    "slider.js",
    "color-picker.js",
    "email-input.js",
    "url-input.js",
    "password-input.js",
    "timezone-selector.js",
    "plugin-loader.js",
    # Reusable JSON file manager (used via x-widget: json-file-manager)
    "json-file-manager.js",
]

# Widget files that must NOT be bundled, with the reason.
EXCLUDED = {
    # Documentation example (docs/widget-guide.md); it registers the name
    # 'color-picker' and would shadow the real color-picker.js.
    "example-color-picker.js": "documentation example",
}

_lock = Lock()
_cache = {"version": None, "body": None}


def bundle_paths():
    """Widget files in load order (only those present on disk)."""
    return [WIDGETS_DIR / name for name in BUNDLE_ORDER if (WIDGETS_DIR / name).is_file()]


def bundle_version():
    """Cache-busting token: a fingerprint of every bundled file.

    Uses each file's name, nanosecond mtime and size, so an edit that lands
    in the same second as another file's, or leaves mtime behind the newest
    file, still changes the token (and the URL).
    """
    digest = hashlib.sha256()
    for path in bundle_paths():
        stat = path.stat()
        digest.update(f"{path.name}:{stat.st_mtime_ns}:{stat.st_size};".encode())
    return digest.hexdigest()[:12]


def build_bundle():
    """Concatenated widget sources, rebuilt only when a file changes."""
    version = bundle_version()
    with _lock:
        if _cache["version"] == version and _cache["body"] is not None:
            return _cache["body"], version
        parts = []
        for path in bundle_paths():
            source = path.read_text(encoding="utf-8")
            # A file ending in a line comment would swallow the next file's
            # first line, and a missing semicolon can join two statements.
            parts.append("/* %s */\n%s\n;\n" % (path.name, source))
        body = "".join(parts)
        _cache["version"] = version
        _cache["body"] = body
        return body, version