"""Signal messenger platform adapter.

Connects to a signal-cli daemon running in HTTP mode.
Inbound messages arrive via SSE (Server-Sent Events) streaming.
Outbound messages and actions use JSON-RPC 2.0 over HTTP.

Based on PR #268 by ibhagwan, rebuilt with bug fixes.

Requires:
  - signal-cli installed and running: signal-cli daemon --http 127.0.0.1:8080
  - SIGNAL_HTTP_URL and SIGNAL_ACCOUNT environment variables set
"""

import asyncio
import base64
import json
import logging
import os
import random
import re
import time
from datetime import datetime, timezone
from pathlib import Path
from typing import Dict, List, Optional, Any
from urllib.parse import unquote

import httpx

from gateway.config import Platform, PlatformConfig
from gateway.platforms.base import (
    BasePlatformAdapter,
    MessageEvent,
    MessageType,
    SendResult,
    cache_image_from_bytes,
    cache_audio_from_bytes,
    cache_document_from_bytes,
    cache_image_from_url,
)

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------
SIGNAL_MAX_ATTACHMENT_SIZE = 100 * 1024 * 1024  # 100 MB
MAX_MESSAGE_LENGTH = 8000  # Signal message size limit
TYPING_INTERVAL = 8.0  # seconds between typing indicator refreshes
SSE_RETRY_DELAY_INITIAL = 2.0
SSE_RETRY_DELAY_MAX = 60.0
HEALTH_CHECK_INTERVAL = 30.0  # seconds between health checks
HEALTH_CHECK_STALE_THRESHOLD = 120.0  # seconds without SSE activity before concern

# E.164 phone number pattern for redaction
_PHONE_RE = re.compile(r"\+[1-9]\d{6,14}")


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def _redact_phone(phone: str) -> str:
    """Redact a phone number for logging: +15551234567 -> +155****4567."""
    if not phone:
        return "<none>"
    if len(phone) <= 8:
        return phone[:2] + "****" + phone[-2:] if len(phone) > 4 else "****"
    return phone[:4] + "****" + phone[-4:]


def _parse_comma_list(value: str) -> List[str]:
    """Split a comma-separated string into a list, stripping whitespace."""
    return [v.strip() for v in value.split(",") if v.strip()]


def _guess_extension(data: bytes) -> str:
    """Guess file extension from magic bytes."""
    if data[:4] == b"\x89PNG":
        return ".png"
    if data[:2] == b"\xff\xd8":
        return ".jpg"
    if data[:4] == b"GIF8":
        return ".gif"
    if len(data) >= 12 and data[:4] == b"RIFF" and data[8:12] == b"WEBP":
        return ".webp"
    if data[:4] == b"%PDF":
        return ".pdf"
    if len(data) >= 8 and data[4:8] == b"ftyp":
        return ".mp4"
    if data[:4] == b"OggS":
        return ".ogg"
    if len(data) >= 2 and data[0] == 0xFF and (data[1] & 0xE0) == 0xE0:
        return ".mp3"
    if data[:2] == b"PK":
        return ".zip"
    return ".bin"


def _is_image_ext(ext: str) -> bool:
    return ext.lower() in (".jpg", ".jpeg", ".png", ".gif", ".webp")


def _is_audio_ext(ext: str) -> bool:
    return ext.lower() in (".mp3", ".wav", ".ogg", ".m4a", ".aac")


_EXT_TO_MIME = {
    ".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".png": "image/png",
    ".gif": "image/gif", ".webp": "image/webp",
    ".ogg": "audio/ogg", ".mp3": "audio/mpeg", ".wav": "audio/wav",
    ".m4a": "audio/mp4", ".aac": "audio/aac",
    ".mp4": "video/mp4", ".pdf": "application/pdf", ".zip": "application/zip",
}


def _ext_to_mime(ext: str) -> str:
    """Map file extension to MIME type."""
    return _EXT_TO_MIME.get(ext.lower(), "application/octet-stream")


def _render_mentions(text: str, mentions: list) -> str:
    """Replace Signal mention placeholders (\\uFFFC) with readable @identifiers.

    Signal encodes @mentions as the Unicode object replacement character
    with out-of-band metadata containing the mentioned user's UUID/number.
    """
    if not mentions or "\uFFFC" not in text:
        return text
    # Sort mentions by start position (reverse) to replace from end to start
    # so indices don't shift as we replace
    sorted_mentions = sorted(mentions, key=lambda m: m.get("start", 0), reverse=True)
    for mention in sorted_mentions:
        start = mention.get("start", 0)
        length = mention.get("length", 1)
        # Use the mention's number or UUID as the replacement
        identifier = mention.get("number") or mention.get("uuid") or "user"
        replacement = f"@{identifier}"
        text = text[:start] + replacement + text[start + length:]
    return text


def check_signal_requirements() -> bool:
    """Check if Signal is configured (has URL and account)."""
    return bool(os.getenv("SIGNAL_HTTP_URL") and os.getenv("SIGNAL_ACCOUNT"))


# ---------------------------------------------------------------------------
# Signal Adapter
# ---------------------------------------------------------------------------

class SignalAdapter(BasePlatformAdapter):
    """Signal messenger adapter using signal-cli HTTP daemon."""

    platform = Platform.SIGNAL

    def __init__(self, config: PlatformConfig):
        super().__init__(config, Platform.SIGNAL)

        extra = config.extra or {}
        self.http_url = extra.get("http_url", "http://127.0.0.1:8080").rstrip("/")
        self.account = extra.get("account", "")
        self.ignore_stories = extra.get("ignore_stories", True)

        # Parse allowlists — group policy is derived from presence of group allowlist
        group_allowed_str = os.getenv("SIGNAL_GROUP_ALLOWED_USERS", "")
        self.group_allow_from = set(_parse_comma_list(group_allowed_str))

        # HTTP client
        self.client: Optional[httpx.AsyncClient] = None

        # Background tasks
        self._sse_task: Optional[asyncio.Task] = None
        self._health_monitor_task: Optional[asyncio.Task] = None
        self._typing_tasks: Dict[str, asyncio.Task] = {}
        self._running = False
        self._last_sse_activity = 0.0
        self._sse_response: Optional[httpx.Response] = None

        # Normalize account for self-message filtering
        self._account_normalized = self.account.strip()

        logger.info("Signal adapter initialized: url=%s account=%s groups=%s",
                     self.http_url, _redact_phone(self.account),
                     "enabled" if self.group_allow_from else "disabled")

    # ------------------------------------------------------------------
    # Lifecycle
    # ------------------------------------------------------------------

    async def connect(self) -> bool:
        """Connect to signal-cli daemon and start SSE listener."""
        if not self.http_url or not self.account:
            logger.error("Signal: SIGNAL_HTTP_URL and SIGNAL_ACCOUNT are required")
            return False

        self.client = httpx.AsyncClient(timeout=30.0)

        # Health check — verify signal-cli daemon is reachable
        try:
            resp = await self.client.get(f"{self.http_url}/api/v1/check", timeout=10.0)
            if resp.status_code != 200:
                logger.error("Signal: health check failed (status %d)", resp.status_code)
                return False
        except Exception as e:
            logger.error("Signal: cannot reach signal-cli at %s: %s", self.http_url, e)
            return False

        self._running = True
        self._last_sse_activity = time.time()
        self._sse_task = asyncio.create_task(self._sse_listener())
        self._health_monitor_task = asyncio.create_task(self._health_monitor())

        logger.info("Signal: connected to %s", self.http_url)
        return True

    async def disconnect(self) -> None:
        """Stop SSE listener and clean up."""
        self._running = False

        if self._sse_task:
            self._sse_task.cancel()
            try:
                await self._sse_task
            except asyncio.CancelledError:
                pass

        if self._health_monitor_task:
            self._health_monitor_task.cancel()
            try:
                await self._health_monitor_task
            except asyncio.CancelledError:
                pass

        # Cancel all typing tasks
        for task in self._typing_tasks.values():
            task.cancel()
        self._typing_tasks.clear()

        if self.client:
            await self.client.aclose()
            self.client = None

        logger.info("Signal: disconnected")

    # ------------------------------------------------------------------
    # SSE Streaming (inbound messages)
    # ------------------------------------------------------------------

    async def _sse_listener(self) -> None:
        """Listen for SSE events from signal-cli daemon."""
        url = f"{self.http_url}/api/v1/events?account={self.account}"
        backoff = SSE_RETRY_DELAY_INITIAL

        while self._running:
            try:
                logger.debug("Signal SSE: connecting to %s", url)
                async with self.client.stream(
                    "GET", url,
                    headers={"Accept": "text/event-stream"},
                    timeout=None,
                ) as response:
                    self._sse_response = response
                    backoff = SSE_RETRY_DELAY_INITIAL  # Reset on successful connection
                    self._last_sse_activity = time.time()
                    logger.info("Signal SSE: connected")

                    buffer = ""
                    async for chunk in response.aiter_text():
                        if not self._running:
                            break
                        buffer += chunk
                        while "\n" in buffer:
                            line, buffer = buffer.split("\n", 1)
                            line = line.strip()
                            if not line:
                                continue
                            # Parse SSE data lines
                            if line.startswith("data:"):
                                data_str = line[5:].strip()
                                if not data_str:
                                    continue
                                self._last_sse_activity = time.time()
                                try:
                                    data = json.loads(data_str)
                                    await self._handle_envelope(data)
                                except json.JSONDecodeError:
                                    logger.debug("Signal SSE: invalid JSON: %s", data_str[:100])
                                except Exception:
                                    logger.exception("Signal SSE: error handling event")

            except asyncio.CancelledError:
                break
            except httpx.HTTPError as e:
                if self._running:
                    logger.warning("Signal SSE: HTTP error: %s (reconnecting in %.0fs)", e, backoff)
            except Exception as e:
                if self._running:
                    logger.warning("Signal SSE: error: %s (reconnecting in %.0fs)", e, backoff)

            if self._running:
                # Add 20% jitter to prevent thundering herd on reconnection
                jitter = backoff * 0.2 * random.random()
                await asyncio.sleep(backoff + jitter)
                backoff = min(backoff * 2, SSE_RETRY_DELAY_MAX)

        self._sse_response = None

    # ------------------------------------------------------------------
    # Health Monitor
    # ------------------------------------------------------------------

    async def _health_monitor(self) -> None:
        """Monitor SSE connection health and force reconnect if stale."""
        while self._running:
            await asyncio.sleep(HEALTH_CHECK_INTERVAL)
            if not self._running:
                break

            elapsed = time.time() - self._last_sse_activity
            if elapsed > HEALTH_CHECK_STALE_THRESHOLD:
                logger.warning("Signal: SSE idle for %.0fs, checking daemon health", elapsed)
                try:
                    resp = await self.client.get(
                        f"{self.http_url}/api/v1/check", timeout=10.0
                    )
                    if resp.status_code == 200:
                        # Daemon is alive but SSE is idle — update activity to
                        # avoid repeated warnings (connection may just be quiet)
                        self._last_sse_activity = time.time()
                        logger.debug("Signal: daemon healthy, SSE idle")
                    else:
                        logger.warning("Signal: health check failed (%d), forcing reconnect", resp.status_code)
                        self._force_reconnect()
                except Exception as e:
                    logger.warning("Signal: health check error: %s, forcing reconnect", e)
                    self._force_reconnect()

    def _force_reconnect(self) -> None:
        """Force SSE reconnection by closing the current response."""
        if self._sse_response and not self._sse_response.is_stream_consumed:
            try:
                asyncio.create_task(self._sse_response.aclose())
            except Exception:
                pass
            self._sse_response = None

    # ------------------------------------------------------------------
    # Message Handling
    # ------------------------------------------------------------------

    async def _handle_envelope(self, envelope: dict) -> None:
        """Process an incoming signal-cli envelope."""
        # Unwrap nested envelope if present
        envelope_data = envelope.get("envelope", envelope)

        # Filter syncMessage envelopes (sent transcripts, read receipts, etc.)
        # signal-cli may set syncMessage to null vs omitting it, so check key existence
        if "syncMessage" in envelope_data:
            return

        # Extract sender info
        sender = (
            envelope_data.get("sourceNumber")
            or envelope_data.get("sourceUuid")
            or envelope_data.get("source")
        )
        sender_name = envelope_data.get("sourceName", "")
        sender_uuid = envelope_data.get("sourceUuid", "")

        if not sender:
            logger.debug("Signal: ignoring envelope with no sender")
            return

        # Self-message filtering — prevent reply loops
        if self._account_normalized and sender == self._account_normalized:
            return

        # Filter stories
        if self.ignore_stories and envelope_data.get("storyMessage"):
            return

        # Get data message — also check editMessage (edited messages contain
        # their updated dataMessage inside editMessage.dataMessage)
        data_message = (
            envelope_data.get("dataMessage")
            or (envelope_data.get("editMessage") or {}).get("dataMessage")
        )
        if not data_message:
            return

        # Check for group message
        group_info = data_message.get("groupInfo")
        group_id = group_info.get("groupId") if group_info else None
        is_group = bool(group_id)

        # Group message filtering — derived from SIGNAL_GROUP_ALLOWED_USERS:
        # - No env var set → groups disabled (default safe behavior)
        # - Env var set with group IDs → only those groups allowed
        # - Env var set with "*" → all groups allowed
        # DM auth is fully handled by run.py (_is_user_authorized)
        if is_group:
            if not self.group_allow_from:
                logger.debug("Signal: ignoring group message (no SIGNAL_GROUP_ALLOWED_USERS)")
                return
            if "*" not in self.group_allow_from and group_id not in self.group_allow_from:
                logger.debug("Signal: group %s not in allowlist", group_id[:8] if group_id else "?")
                return

        # Build chat info
        chat_id = sender if not is_group else f"group:{group_id}"
        chat_type = "group" if is_group else "dm"

        # Extract text and render mentions
        text = data_message.get("message", "")
        mentions = data_message.get("mentions", [])
        if text and mentions:
            text = _render_mentions(text, mentions)

        # Process attachments
        attachments_data = data_message.get("attachments", [])
        media_urls = []
        media_types = []

        if attachments_data and not getattr(self, "ignore_attachments", False):
            for att in attachments_data:
                att_id = att.get("id")
                att_size = att.get("size", 0)
                if not att_id:
                    continue
                if att_size > SIGNAL_MAX_ATTACHMENT_SIZE:
                    logger.warning("Signal: attachment too large (%d bytes), skipping", att_size)
                    continue
                try:
                    cached_path, ext = await self._fetch_attachment(att_id)
                    if cached_path:
                        # Use contentType from Signal if available, else map from extension
                        content_type = att.get("contentType") or _ext_to_mime(ext)
                        media_urls.append(cached_path)
                        media_types.append(content_type)
                except Exception:
                    logger.exception("Signal: failed to fetch attachment %s", att_id)

        # Build session source
        source = self.build_source(
            chat_id=chat_id,
            chat_name=group_info.get("groupName") if group_info else sender_name,
            chat_type=chat_type,
            user_id=sender,
            user_name=sender_name or sender,
            user_id_alt=sender_uuid if sender_uuid else None,
            chat_id_alt=group_id if is_group else None,
        )

        # Determine message type from media
        msg_type = MessageType.TEXT
        if media_types:
            if any(mt.startswith("audio/") for mt in media_types):
                msg_type = MessageType.VOICE
            elif any(mt.startswith("image/") for mt in media_types):
                msg_type = MessageType.IMAGE

        # Parse timestamp from envelope data (milliseconds since epoch)
        ts_ms = envelope_data.get("timestamp", 0)
        if ts_ms:
            try:
                timestamp = datetime.fromtimestamp(ts_ms / 1000, tz=timezone.utc)
            except (ValueError, OSError):
                timestamp = datetime.now(tz=timezone.utc)
        else:
            timestamp = datetime.now(tz=timezone.utc)

        # Build and dispatch event
        event = MessageEvent(
            source=source,
            text=text or "",
            message_type=msg_type,
            media_urls=media_urls,
            media_types=media_types,
            timestamp=timestamp,
        )

        logger.debug("Signal: message from %s in %s: %s",
                      _redact_phone(sender), chat_id[:20], (text or "")[:50])

        await self.handle_message(event)

    # ------------------------------------------------------------------
    # Attachment Handling
    # ------------------------------------------------------------------

    async def _fetch_attachment(self, attachment_id: str) -> tuple:
        """Fetch an attachment via JSON-RPC and cache it. Returns (path, ext)."""
        result = await self._rpc("getAttachment", {
            "account": self.account,
            "attachmentId": attachment_id,
        })

        if not result:
            return None, ""

        # Result is base64-encoded file content
        raw_data = base64.b64decode(result)
        ext = _guess_extension(raw_data)

        if _is_image_ext(ext):
            path = cache_image_from_bytes(raw_data, ext)
        elif _is_audio_ext(ext):
            path = cache_audio_from_bytes(raw_data, ext)
        else:
            path = cache_document_from_bytes(raw_data, ext)

        return path, ext

    # ------------------------------------------------------------------
    # JSON-RPC Communication
    # ------------------------------------------------------------------

    async def _rpc(self, method: str, params: dict, rpc_id: str = None) -> Any:
        """Send a JSON-RPC 2.0 request to signal-cli daemon."""
        if not self.client:
            logger.warning("Signal: RPC called but client not connected")
            return None

        if rpc_id is None:
            rpc_id = f"{method}_{int(time.time() * 1000)}"

        payload = {
            "jsonrpc": "2.0",
            "method": method,
            "params": params,
            "id": rpc_id,
        }

        try:
            resp = await self.client.post(
                f"{self.http_url}/api/v1/rpc",
                json=payload,
                timeout=30.0,
            )
            resp.raise_for_status()
            data = resp.json()

            if "error" in data:
                logger.warning("Signal RPC error (%s): %s", method, data["error"])
                return None

            return data.get("result")

        except Exception as e:
            logger.warning("Signal RPC %s failed: %s", method, e)
            return None

    # ------------------------------------------------------------------
    # Sending
    # ------------------------------------------------------------------

    async def send(
        self,
        chat_id: str,
        content: str,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Send a text message."""
        await self._stop_typing_indicator(chat_id)

        params: Dict[str, Any] = {
            "account": self.account,
            "message": content,
        }

        if chat_id.startswith("group:"):
            params["groupId"] = chat_id[6:]
        else:
            params["recipient"] = [chat_id]

        result = await self._rpc("send", params)

        if result is not None:
            return SendResult(success=True)
        return SendResult(success=False, error="RPC send failed")

    async def send_typing(self, chat_id: str, metadata=None) -> None:
        """Send a typing indicator."""
        params: Dict[str, Any] = {
            "account": self.account,
        }

        if chat_id.startswith("group:"):
            params["groupId"] = chat_id[6:]
        else:
            params["recipient"] = [chat_id]

        await self._rpc("sendTyping", params, rpc_id="typing")

    async def send_image(
        self,
        chat_id: str,
        image_url: str,
        caption: Optional[str] = None,
        **kwargs,
    ) -> SendResult:
        """Send an image. Supports http(s):// and file:// URLs."""
        await self._stop_typing_indicator(chat_id)

        # Resolve image to local path
        if image_url.startswith("file://"):
            file_path = unquote(image_url[7:])
        else:
            # Download remote image to cache
            try:
                file_path = await cache_image_from_url(image_url)
            except Exception as e:
                logger.warning("Signal: failed to download image: %s", e)
                return SendResult(success=False, error=str(e))

        if not file_path or not Path(file_path).exists():
            return SendResult(success=False, error="Image file not found")

        # Validate size
        file_size = Path(file_path).stat().st_size
        if file_size > SIGNAL_MAX_ATTACHMENT_SIZE:
            return SendResult(success=False, error=f"Image too large ({file_size} bytes)")

        params: Dict[str, Any] = {
            "account": self.account,
            "message": caption or "",
            "attachments": [file_path],
        }

        if chat_id.startswith("group:"):
            params["groupId"] = chat_id[6:]
        else:
            params["recipient"] = [chat_id]

        result = await self._rpc("send", params)
        if result is not None:
            return SendResult(success=True)
        return SendResult(success=False, error="RPC send with attachment failed")

    async def send_document(
        self,
        chat_id: str,
        file_path: str,
        caption: Optional[str] = None,
        filename: Optional[str] = None,
        **kwargs,
    ) -> SendResult:
        """Send a document/file attachment."""
        await self._stop_typing_indicator(chat_id)

        if not Path(file_path).exists():
            return SendResult(success=False, error="File not found")

        params: Dict[str, Any] = {
            "account": self.account,
            "message": caption or "",
            "attachments": [file_path],
        }

        if chat_id.startswith("group:"):
            params["groupId"] = chat_id[6:]
        else:
            params["recipient"] = [chat_id]

        result = await self._rpc("send", params)
        if result is not None:
            return SendResult(success=True)
        return SendResult(success=False, error="RPC send document failed")

    # ------------------------------------------------------------------
    # Typing Indicators
    # ------------------------------------------------------------------

    async def _start_typing_indicator(self, chat_id: str) -> None:
        """Start a typing indicator loop for a chat."""
        if chat_id in self._typing_tasks:
            return  # Already running

        async def _typing_loop():
            try:
                while True:
                    await self.send_typing(chat_id)
                    await asyncio.sleep(TYPING_INTERVAL)
            except asyncio.CancelledError:
                pass

        self._typing_tasks[chat_id] = asyncio.create_task(_typing_loop())

    async def _stop_typing_indicator(self, chat_id: str) -> None:
        """Stop a typing indicator loop for a chat."""
        task = self._typing_tasks.pop(chat_id, None)
        if task:
            task.cancel()
            try:
                await task
            except asyncio.CancelledError:
                pass

    # ------------------------------------------------------------------
    # Chat Info
    # ------------------------------------------------------------------

    async def get_chat_info(self, chat_id: str) -> Dict[str, Any]:
        """Get information about a chat/contact."""
        if chat_id.startswith("group:"):
            return {
                "name": chat_id,
                "type": "group",
                "chat_id": chat_id,
            }

        # Try to resolve contact name
        result = await self._rpc("getContact", {
            "account": self.account,
            "contactAddress": chat_id,
        })

        name = chat_id
        if result and isinstance(result, dict):
            name = result.get("name") or result.get("profileName") or chat_id

        return {
            "name": name,
            "type": "dm",
            "chat_id": chat_id,
        }