"""Persistent configuration for PolterHID.

`settings.json` is deliberately kept outside the source tree and is created on
first boot. The web password is stored in clear text because TLS is explicitly
not used; use this only on a trusted training Wi-Fi network.
"""

try:
    import ujson as json
except ImportError:
    import json

DEFAULTS = {
    "wifi_ssid": "CHANGE_ME",
    "wifi_password": "CHANGE_ME",
    "web_password": "change-this-before-deploying",
    # Set false when validating on a board without the T-Dongle-S3 display.
    "display_enabled": False,
    "enabled": True,
    "return_enabled": True,
    "mouse_enabled": True,
    "mouse_distance": 1,
    "return_min_seconds": 45,
    "return_max_seconds": 120,
    "mouse_min_seconds": 20,
    "mouse_max_seconds": 60,
}

SETTINGS_FILE = "settings.json"


def load():
    """Return validated settings, creating the file on first boot."""
    values = DEFAULTS.copy()
    try:
        with open(SETTINGS_FILE, "r") as file:
            stored = json.load(file)
        if isinstance(stored, dict):
            for key in DEFAULTS:
                if key in stored:
                    values[key] = stored[key]
    except (OSError, ValueError):
        save(values)

    _validate(values)
    return values


def save(values):
    """Atomically replace the settings file where the port supports rename."""
    _validate(values)
    temporary = SETTINGS_FILE + ".tmp"
    with open(temporary, "w") as file:
        json.dump(values, file)
    try:
        import os
        os.remove(SETTINGS_FILE)
    except OSError:
        pass
    import os
    os.rename(temporary, SETTINGS_FILE)


def apply_form(values, form):
    """Update configurable runtime values from a decoded HTTP form."""
    for key in ("enabled", "return_enabled", "mouse_enabled"):
        values[key] = form.get(key) == "on"

    for key in (
        "return_min_seconds", "return_max_seconds",
        "mouse_min_seconds", "mouse_max_seconds", "mouse_distance",
    ):
        if key in form:
            try:
                values[key] = int(form[key])
            except (TypeError, ValueError):
                raise ValueError("%s must be a whole number" % key)

    _validate(values)


def _validate(values):
    for key in ("wifi_ssid", "wifi_password", "web_password"):
        if not isinstance(values.get(key), str) or not values[key]:
            raise ValueError("%s must be a non-empty string" % key)

    distance = values["mouse_distance"]
    if not isinstance(distance, int) or distance < 1 or distance > 127:
        raise ValueError("mouse distance must be between 1 and 127 pixels")

    for prefix in ("return", "mouse"):
        minimum = values[prefix + "_min_seconds"]
        maximum = values[prefix + "_max_seconds"]
        if not isinstance(minimum, int) or not isinstance(maximum, int):
            raise ValueError("%s intervals must be integers" % prefix)
        if minimum < 1 or maximum < minimum or maximum > 86400:
            raise ValueError("invalid %s interval" % prefix)