import os
import secrets
from datetime import timedelta, timezone, datetime
from pathlib import Path
from typing import Optional

APP_ROOT = Path(__file__).resolve().parent

DB_PATH = os.environ.get("CHAT_DB_PATH", str(APP_ROOT / "chat.db"))
UPLOAD_DIR = Path(os.environ.get("CHAT_UPLOAD_DIR", str(APP_ROOT / "uploads")))

SECRET_KEY_PATH = os.environ.get(
    "CHAT_SECRET_KEY_PATH",
    str(Path(DB_PATH).resolve().parent / "flask_secret.key"),
)
CLIENT_HASH_KEY_PATH = os.environ.get(
    "CHAT_CLIENT_HASH_KEY_PATH",
    str(Path(DB_PATH).resolve().parent / "client_hash.key"),
)

MAX_ATTACHMENT_BYTES = 100 * 1024 * 1024
MAX_REQUEST_BYTES = max(110 * 1024 * 1024, MAX_ATTACHMENT_BYTES + 10 * 1024 * 1024)

MAX_MESSAGE_LENGTH = 1000
MAX_USERNAME_LENGTH = 30
MIN_USERNAME_LENGTH = 3
MIN_PASSWORD_LENGTH = 7
MAX_PASSWORD_LENGTH = 256
MAX_HISTORY_MESSAGES = 100
MAX_INCREMENTAL_MESSAGES = 100
MAX_FEED_MESSAGES = 50
MAX_THREAD_REPLIES = 100
MAX_ATTACHMENT_NAME_LENGTH = 150
ATTACHMENT_ORPHAN_TTL_HOURS = 24
ATTACHMENT_CLEANUP_INTERVAL_SECONDS = 60 * 60
INVITE_TTL_HOURS = 72
TEAM_INVITE_TTL_HOURS = 72
TYPING_TTL_SECONDS = 7
PRESENCE_TTL_SECONDS = 40
MAX_PROFILE_BIO_LENGTH = 5000
MAX_DISPLAY_NAME_LENGTH = 80
MAX_LOCATION_LENGTH = 120
MAX_WEBSITE_LENGTH = 300
MAX_CUSTOM_CSS_LENGTH = 20000
MAX_PROFILE_BADGE_LENGTH = 48
MAX_OWNED_TEAMS_PER_USER = 3
MAX_MESSAGE_EDIT_WINDOW_SECONDS = 15 * 60
MAX_SEARCH_QUERY_LENGTH = 120
MAX_SEARCH_RESULTS = 100
READ_RECEIPT_BATCH_LIMIT = 200
GROUP_CALL_PARTICIPANT_STALE_SECONDS = 45

PRIVATE_ACCESS_KEY = os.environ.get("PRIVATE_ACCESS_KEY", "").strip()

CALLS_BASE = os.environ.get("CALLS_BASE", "https://calls.example.com").rstrip("/")
CALL_HELPER_SHARED_SECRET = os.environ.get("CALL_HELPER_SHARED_SECRET", "").strip()
CALL_TOKEN_TTL_SECONDS = int(os.environ.get("CALL_TOKEN_TTL_SECONDS", "60"))

ALLOWED_ATTACHMENT_EXTENSIONS = {
    "txt",
    "pdf",
    "png",
    "jpg",
    "jpeg",
    "gif",
    "webp",
    "mp3",
    "wav",
    "ogg",
    "m4a",
    "aac",
    "flac",
    "mp4",
    "webm",
    "mov",
    "m4v",
    "ogv",
}

ALLOWED_ATTACHMENT_MIME_TYPES = {
    "text/plain",
    "application/pdf",
    "image/png",
    "image/jpeg",
    "image/gif",
    "image/webp",
    "audio/mpeg",
    "audio/mp3",
    "audio/wav",
    "audio/x-wav",
    "audio/ogg",
    "audio/mp4",
    "audio/aac",
    "audio/flac",
    "video/mp4",
    "video/webm",
    "video/quicktime",
    "video/ogg",
}

ROLES = {"user", "moderator", "admin"}
STATUSES = {"active", "disabled", "restricted", "blacklisted"}
ROOM_VISIBILITIES = {"public", "private"}

RATE_LIMITS = {
    "login": (8, 10 * 60),
    "register": (5, 60 * 60),
    "send": (30, 60),
    "admin": (60, 60),
    "attachment": (20, 60),
    "typing": (60, 60),
    "reaction": (120, 60),
    "profile": (30, 60),
    "settings": (30, 60),
}

PLACEHOLDER_SECRETS = {
    "",
    "change-this-secret-key",
    "replace-this-with-a-long-random-secret",
    "replace-me",
    "secret",
    "changeme",
}

RUNTIME_STATE = {
    "last_attachment_cleanup": 0.0,
}


def utc_now() -> datetime:
    return datetime.now(timezone.utc)


def now_iso() -> str:
    return utc_now().isoformat()


def parse_iso(value: Optional[str]) -> Optional[datetime]:
    if not value:
        return None
    try:
        parsed = datetime.fromisoformat(value)
    except ValueError:
        return None
    if not parsed.tzinfo:
        return parsed.replace(tzinfo=timezone.utc)
    return parsed


def load_or_create_key(path_value: str, env_value: str, min_length: int = 32) -> str:
    configured = os.environ.get(env_value, "").strip()
    if configured and configured.lower() not in PLACEHOLDER_SECRETS and len(configured) >= min_length:
        return configured

    path = Path(path_value)
    path.parent.mkdir(parents=True, exist_ok=True)

    if path.exists():
        existing = path.read_text(encoding="utf-8").strip()
        if len(existing) >= min_length:
            return existing

    generated = secrets.token_urlsafe(64)
    try:
        path.write_text(generated, encoding="utf-8")
        os.chmod(path, 0o600)
    except OSError:
        pass
    return generated


SECRET_KEY = load_or_create_key(SECRET_KEY_PATH, "FLASK_SECRET_KEY")
CLIENT_HASH_KEY = load_or_create_key(CLIENT_HASH_KEY_PATH, "CHAT_CLIENT_HASH_KEY")

TRUSTED_PROXY_HOPS = int(os.environ.get("TRUSTED_PROXY_HOPS", "0"))
SESSION_COOKIE_SECURE = (os.environ.get("SESSION_COOKIE_SECURE", "1") == "1")
PERMANENT_SESSION_LIFETIME = timedelta(days=14)


def get_asset_version() -> str:
    try:
        js_dir = APP_ROOT / "static" / "js"
        values = [int((APP_ROOT / "static" / "style.css").stat().st_mtime)]
        values.extend(int(path.stat().st_mtime) for path in js_dir.glob("*.js"))
        return str(max(values))
    except OSError:
        return "1"


def flask_config() -> dict:
    return {
        "MAX_CONTENT_LENGTH": MAX_REQUEST_BYTES,
        "SESSION_COOKIE_NAME": "chat_session",
        "SESSION_COOKIE_HTTPONLY": True,
        "SESSION_COOKIE_SAMESITE": "Lax",
        "SESSION_COOKIE_SECURE": SESSION_COOKIE_SECURE,
        "PERMANENT_SESSION_LIFETIME": PERMANENT_SESSION_LIFETIME,
    }


CONSTANTS = {
    "MAX_MESSAGE_LENGTH": MAX_MESSAGE_LENGTH,
    "MAX_HISTORY_MESSAGES": MAX_HISTORY_MESSAGES,
    "MAX_INCREMENTAL_MESSAGES": MAX_INCREMENTAL_MESSAGES,
    "MAX_FEED_MESSAGES": MAX_FEED_MESSAGES,
    "MAX_THREAD_REPLIES": MAX_THREAD_REPLIES,
    "MAX_ATTACHMENT_BYTES": MAX_ATTACHMENT_BYTES,
    "MAX_ATTACHMENT_NAME_LENGTH": MAX_ATTACHMENT_NAME_LENGTH,
    "ALLOWED_ATTACHMENT_EXTENSIONS": ALLOWED_ATTACHMENT_EXTENSIONS,
    "ALLOWED_ATTACHMENT_MIME_TYPES": ALLOWED_ATTACHMENT_MIME_TYPES,
    "INVITE_TTL_HOURS": INVITE_TTL_HOURS,
    "TEAM_INVITE_TTL_HOURS": TEAM_INVITE_TTL_HOURS,
    "TYPING_TTL_SECONDS": TYPING_TTL_SECONDS,
    "PRESENCE_TTL_SECONDS": PRESENCE_TTL_SECONDS,
    "MAX_SEARCH_QUERY_LENGTH": MAX_SEARCH_QUERY_LENGTH,
    "MAX_SEARCH_RESULTS": MAX_SEARCH_RESULTS,
    "READ_RECEIPT_BATCH_LIMIT": READ_RECEIPT_BATCH_LIMIT,
    "MAX_MESSAGE_EDIT_WINDOW_SECONDS": MAX_MESSAGE_EDIT_WINDOW_SECONDS,
    "MAX_DISPLAY_NAME_LENGTH": MAX_DISPLAY_NAME_LENGTH,
    "MAX_PROFILE_BIO_LENGTH": MAX_PROFILE_BIO_LENGTH,
    "MAX_LOCATION_LENGTH": MAX_LOCATION_LENGTH,
    "MAX_WEBSITE_LENGTH": MAX_WEBSITE_LENGTH,
    "MAX_CUSTOM_CSS_LENGTH": MAX_CUSTOM_CSS_LENGTH,
    "MAX_PROFILE_BADGE_LENGTH": MAX_PROFILE_BADGE_LENGTH,
    "MAX_OWNED_TEAMS_PER_USER": MAX_OWNED_TEAMS_PER_USER,
    "ROOM_VISIBILITIES": ROOM_VISIBILITIES,
    "ROLES": ROLES,
    "STATUSES": STATUSES,
    "GROUP_CALL_PARTICIPANT_STALE_SECONDS": GROUP_CALL_PARTICIPANT_STALE_SECONDS,
}