"""
CameraService — HTTP client for Hikvision ISAPI.

All endpoints use HTTP Basic auth with the camera's web credentials.
Credentials are resolved from device SSH overrides (reusing the same
username/password fields) — camera HTTP auth often matches SSH.

ISAPI base: http://<ip>/ISAPI/
"""

import logging
import xml.etree.ElementTree as ET
from dataclasses import dataclass
from typing import AsyncIterator, Optional

import httpx

from app.models.device import Device
from app.models.object import Object
from app.services.crypto import decrypt

log = logging.getLogger(__name__)


@dataclass
class CameraResult:
    success: bool
    status_code: int = 0
    body: str = ""
    data: dict = None
    error: str = ""

    def __post_init__(self):
        if self.data is None:
            self.data = {}


def _resolve_camera_credentials(device: Device, obj: Object) -> tuple[str, str, int]:
    """
    Returns (username, password, http_port).

    Priority:
      1. connection_params.username / connection_params.password (plaintext, set via DeviceEditModal)
      2. ssh_user_override / ssh_pass_override_enc (legacy)
      3. object ssh_user / ssh_pass_enc
    """
    cp = device.connection_params or {}
    meta = device.device_meta or {}

    port = int(meta.get("http_port", 80))

    user = (cp.get("username") or device.ssh_user_override or obj.ssh_user or "admin")

    if cp.get("password"):
        password = str(cp["password"])  # plaintext from connection_params (DeviceEditModal)
        pwd_source = "connection_params.password"
    elif device.ssh_pass_override_enc:
        password = decrypt(device.ssh_pass_override_enc)
        pwd_source = "ssh_pass_override_enc"
    else:
        # Do NOT fall back to obj.ssh_pass_enc — object SSH password is for servers, not cameras
        password = ""
        pwd_source = "empty"

    log.info(
        "[camera] %s | user=%r port=%d pwd_source=%s pwd_len=%d cp_keys=%s",
        device.ip, user, port, pwd_source, len(password), list(cp.keys()),
    )
    return user, password, port


def _xml_to_dict(element: ET.Element) -> dict:
    """Recursively convert an XML element to a dict (simple, no attributes)."""
    result = {}
    for child in element:
        # Strip namespace if present: {ns}tag → tag
        tag = child.tag.split("}")[-1] if "}" in child.tag else child.tag
        if len(child):
            result[tag] = _xml_to_dict(child)
        else:
            result[tag] = child.text
    return result


async def isapi_get(
    device: Device,
    obj: Object,
    path: str,
    timeout: int = 10,
) -> CameraResult:
    """Send GET to ISAPI endpoint, return parsed XML body."""
    user, password, port = _resolve_camera_credentials(device, obj)
    url = f"http://{device.ip}:{port}/ISAPI/{path.lstrip('/')}"

    try:
        async with httpx.AsyncClient(auth=(user, password), timeout=timeout) as client:
            resp = await client.get(url)
    except httpx.TimeoutException:
        return CameraResult(success=False, error="Connection timed out")
    except Exception as exc:
        return CameraResult(success=False, error=str(exc))

    body = resp.text
    data: dict = {}
    if body.strip().startswith("<"):
        try:
            root = ET.fromstring(body)
            data = _xml_to_dict(root)
        except ET.ParseError:
            pass

    return CameraResult(
        success=resp.status_code < 400,
        status_code=resp.status_code,
        body=body,
        data=data,
    )


async def isapi_snapshot(
    device: Device,
    obj: Object,
    channel: int = 1,
    timeout: int = 10,
) -> tuple[bytes, str]:
    """
    Fetch a JPEG snapshot from the camera via ISAPI.
    Returns (image_bytes, content_type). Raises RuntimeError on failure.
    """
    user, password, port = _resolve_camera_credentials(device, obj)

    # Try connection_params.frame_url first (custom snapshot URL)
    frame_url: Optional[str] = (device.connection_params or {}).get("frame_url")
    if frame_url:
        url = frame_url
    else:
        # Hikvision: channel 1 main stream = 101, channel 2 = 201, etc.
        url = f"http://{device.ip}:{port}/ISAPI/Streaming/channels/{channel}01/picture?snapShotImageType=JPEG"

    log.info("[camera] snapshot GET %s (user=%r)", url, user)
    try:
        async with httpx.AsyncClient(auth=(user, password), timeout=timeout) as client:
            resp = await client.get(url)
    except httpx.TimeoutException:
        raise RuntimeError("Камера не отвечает (timeout)")
    except Exception as exc:
        raise RuntimeError(str(exc))

    log.info("[camera] snapshot response HTTP %d, content-type=%s, len=%d",
             resp.status_code, resp.headers.get("content-type"), len(resp.content))

    if resp.status_code == 401:
        raise RuntimeError(
            f"401 — user={user!r} password={password!r} url={url}"
        )
    if resp.status_code >= 400:
        raise RuntimeError(f"Камера вернула HTTP {resp.status_code}, url={url}")

    content_type = resp.headers.get("content-type", "image/jpeg")
    return resp.content, content_type


async def mjpeg_stream(
    device: Device,
    obj: Object,
    channel: int = 1,
    timeout: int = 30,
) -> AsyncIterator[bytes]:
    """
    Proxy MJPEG stream from camera. Yields raw bytes chunks.
    Tries connection_params.stream_url (if it looks like http/mjpeg),
    then falls back to Hikvision ISAPI MJPEG endpoint.
    """
    user, password, port = _resolve_camera_credentials(device, obj)
    cp = device.connection_params or {}

    stream_url = str(cp.get("stream_url", "")) if cp.get("stream_url") else ""
    if stream_url.startswith("http"):
        url = stream_url
    else:
        url = f"http://{device.ip}:{port}/ISAPI/Streaming/channels/{channel}01/httppreview"

    async with httpx.AsyncClient(auth=(user, password), timeout=httpx.Timeout(timeout)) as client:
        async with client.stream("GET", url) as resp:
            if resp.status_code == 401:
                raise RuntimeError("Ошибка авторизации (401)")
            if resp.status_code >= 400:
                raise RuntimeError(f"Камера вернула HTTP {resp.status_code}")
            async for chunk in resp.aiter_bytes(chunk_size=4096):
                yield chunk


async def isapi_put(
    device: Device,
    obj: Object,
    path: str,
    xml_body: str,
    timeout: int = 10,
) -> CameraResult:
    """Send PUT with XML body to ISAPI endpoint."""
    user, password, port = _resolve_camera_credentials(device, obj)
    url = f"http://{device.ip}:{port}/ISAPI/{path.lstrip('/')}"

    try:
        async with httpx.AsyncClient(auth=(user, password), timeout=timeout) as client:
            resp = await client.put(
                url,
                content=xml_body.encode(),
                headers={"Content-Type": "application/xml"},
            )
    except httpx.TimeoutException:
        return CameraResult(success=False, error="Connection timed out")
    except Exception as exc:
        return CameraResult(success=False, error=str(exc))

    return CameraResult(
        success=resp.status_code < 400,
        status_code=resp.status_code,
        body=resp.text,
    )