from __future__ import annotations

import ipaddress
import logging
import os
import re
from pathlib import Path
from urllib.parse import urlparse

logger = logging.getLogger(__name__)

ALLOWED_IMAGE_EXTENSIONS = {".png", ".jpg", ".jpeg", ".gif", ".webp", ".bmp", ".heic", ".heif", ".avif"}
ALLOWED_VIDEO_EXTENSIONS = {".mp4", ".mov", ".m4v", ".webm"}
ALLOWED_AUDIO_EXTENSIONS = {".mp3", ".m4a", ".aac", ".wav", ".ogg", ".oga"}

MAX_URL_LENGTH = 2000
DEFAULT_MEDIA_MAX_MB = 10

_SSRF_BLOCKED_NETWORKS = [
    ipaddress.IPv4Network("127.0.0.0/8"),
    ipaddress.IPv4Network("10.0.0.0/8"),
    ipaddress.IPv4Network("172.16.0.0/12"),
    ipaddress.IPv4Network("192.168.0.0/16"),
    ipaddress.IPv4Network("169.254.0.0/16"),
    ipaddress.IPv6Network("::1/128"),
    ipaddress.IPv6Network("fc00::/7"),
    ipaddress.IPv6Network("fe80::/10"),
]


def validate_media_url(url: str) -> bool:
    if not url:
        return False

    if len(url) > MAX_URL_LENGTH:
        logger.warning("LINE media URL too long: %d characters", len(url))
        return False

    parsed = urlparse(url)
    if parsed.scheme != "https":
        logger.warning("LINE media URL must use HTTPS: %s", parsed.scheme)
        return False

    if not parsed.hostname:
        return False

    return _check_ssrf(parsed.hostname)


def _check_ssrf(hostname: str) -> bool:
    try:
        addr = ipaddress.ip_address(hostname)
    except ValueError:
        return True

    for network in _SSRF_BLOCKED_NETWORKS:
        if addr in network:
            logger.warning("LINE SSRF blocked: hostname=%s network=%s", hostname, network)
            return False

    return True


def detect_media_type(filename: str) -> str:
    ext = Path(filename).suffix.lower()

    if ext in ALLOWED_IMAGE_EXTENSIONS:
        return "image"
    if ext in ALLOWED_VIDEO_EXTENSIONS:
        return "video"
    if ext in ALLOWED_AUDIO_EXTENSIONS:
        return "audio"

    return "file"


def validate_media_size(data: bytes, max_mb: int = DEFAULT_MEDIA_MAX_MB) -> bool:
    max_bytes = max_mb * 1024 * 1024
    return len(data) <= max_bytes


def sanitize_filename(filename: str) -> str:
    name = Path(filename).name
    name = re.sub(r'[<>:"/\\|?*]', "_", name)
    return name or "file"