"""
tools/caldav_tool.py — CalDAV calendar access (Mailcow / SOGo).

Credential keys (set via /settings):
  mailcow_host          — e.g. mail.yourdomain.com
  mailcow_username      — e.g. you@yourdomain.com
  mailcow_password      — account or app password
  caldav_calendar_name  — optional display-name filter; if omitted uses first calendar found

Uses principal discovery (/SOGo/dav/<username>/) to find calendars automatically.
No hardcoded URL path — works regardless of internal calendar slug.

All datetimes are stored as UTC internally. Display times are converted
to the configured timezone (Europe/Oslo by default).

create/update/delete require user confirmation.
Max events returned: 100.
"""
from __future__ import annotations

import logging
import traceback
from datetime import datetime, timedelta, timezone
from typing import Any

import caldav
import vobject
from dateutil import parser as dateutil_parser

from ..config import settings
from ..context_vars import current_user
from ..database import credential_store
from .base import BaseTool, ToolResult

logger = logging.getLogger(__name__)


async def _get_caldav_config(user_id: str | None = None) -> dict:
    """
    Per-user CalDAV config lookup — no system-wide fallback.

    Each user (including admin) configures their own CalDAV credentials in Settings → CalDAV.
    Returns a dict with url, username, password, calendar_name (any may be None/empty).
    """
    if user_id:
        from ..database import user_settings_store
        return {
            "url":           await user_settings_store.get(user_id, "caldav_url"),
            "username":      await user_settings_store.get(user_id, "caldav_username"),
            "password":      await user_settings_store.get(user_id, "caldav_password"),
            "calendar_name": await user_settings_store.get(user_id, "caldav_calendar_name"),
        }

    return {"url": None, "username": None, "password": None, "calendar_name": None}

MAX_EVENTS = 100


class CalDAVTool(BaseTool):
    name = "caldav"
    description = (
        "Manage calendar events via CalDAV (Mailcow/SOGo). "
        "Operations: list_events, get_event, create_event, update_event, delete_event. "
        "create_event, update_event, and delete_event require user confirmation. "
        "All dates should be in ISO8601 format (e.g. '2026-02-17T14:00:00+01:00')."
    )
    input_schema = {
        "type": "object",
        "properties": {
            "operation": {
                "type": "string",
                "enum": ["list_events", "get_event", "create_event", "update_event", "delete_event"],
            },
            "start_date": {
                "type": "string",
                "description": "Start of date range for list_events (ISO8601)",
            },
            "end_date": {
                "type": "string",
                "description": "End of date range for list_events (ISO8601). Default: 30 days after start",
            },
            "event_id": {
                "type": "string",
                "description": "Event UID for get/update/delete operations",
            },
            "summary": {
                "type": "string",
                "description": "Event title for create/update",
            },
            "start": {
                "type": "string",
                "description": "Event start datetime (ISO8601) for create/update",
            },
            "end": {
                "type": "string",
                "description": "Event end datetime (ISO8601) for create/update",
            },
            "description": {
                "type": "string",
                "description": "Event description/notes for create/update",
            },
            "location": {
                "type": "string",
                "description": "Event location for create/update",
            },
        },
        "required": ["operation"],
    }
    requires_confirmation = False  # checked per-operation in execute()
    allowed_in_scheduled_tasks = True

    async def _get_client(self) -> tuple[caldav.DAVClient, caldav.Calendar]:
        """Return (client, calendar). Raises RuntimeError if credentials missing."""
        # Resolve current user from context (may be None for scheduled/agent runs)
        user = current_user.get()
        user_id = user.id if user else None

        cfg = await _get_caldav_config(user_id=user_id)
        url = cfg.get("url")
        username = cfg.get("username")
        password = cfg.get("password")
        calendar_name = cfg.get("calendar_name") or ""

        if not url or not username or not password:
            raise RuntimeError(
                "CalDAV credentials not configured. "
                "Set them in Settings → CalDAV / CardDAV."
            )

        # Normalise scheme — users often enter just the hostname
        if not url.startswith(("http://", "https://")):
            url = "https://" + url

        # Build principal URL: if the stored URL is already the full principal URL use it directly;
        # otherwise append the SOGo-style path.
        if "/SOGo/dav/" in url or url.rstrip("/").endswith(username):
            principal_url = url.rstrip("/") + "/"
        else:
            principal_url = f"{url.rstrip('/')}/SOGo/dav/{username}/"
        if calendar_name:
            logger.info("[caldav] Connecting — principal_url=%s  username=%s  calendar_filter=%r",
                        principal_url, username, calendar_name)
        else:
            logger.info("[caldav] Connecting — principal_url=%s  username=%s  "
                        "calendar_filter=(none set — will use first found; "
                        "set 'caldav_calendar_name' credential to pick a specific one)",
                        principal_url, username)

        client = caldav.DAVClient(url=principal_url, username=username, password=password)

        logger.debug("[caldav] Fetching principal…")
        principal = client.principal()
        logger.debug("[caldav] Principal URL: %s", principal.url)

        logger.debug("[caldav] Discovering calendars…")
        calendars = principal.calendars()
        if not calendars:
            logger.error("[caldav] No calendars found for %s", username)
            raise RuntimeError("No calendars found for this account")

        logger.info("[caldav] Found %d calendar(s): %s",
                    len(calendars),
                    ", ".join(f"{c.name!r} ({c.url})" for c in calendars))

        if calendar_name:
            needle = calendar_name.lower()
            # Exact match first, then substring fallback
            match = next((c for c in calendars if (c.name or "").lower() == needle), None)
            if match is None:
                match = next((c for c in calendars if needle in (c.name or "").lower()), None)
            if match is None:
                names = ", ".join(c.name or "?" for c in calendars)
                logger.error("[caldav] Calendar %r not found. Available: %s", calendar_name, names)
                raise RuntimeError(
                    f"Calendar '{calendar_name}' not found. Available: {names}"
                )
            logger.info("[caldav] Using calendar %r  url=%s", match.name, match.url)
            return client, match

        chosen = calendars[0]
        logger.info("[caldav] Using first calendar: %r  url=%s", chosen.name, chosen.url)
        return client, chosen

    async def execute(
        self,
        operation: str,
        start_date: str = "",
        end_date: str = "",
        event_id: str = "",
        summary: str = "",
        start: str = "",
        end: str = "",
        description: str = "",
        location: str = "",
        **kwargs,
    ) -> ToolResult:
        logger.info("[caldav] execute  operation=%s  summary=%r  start=%r  end=%r  event_id=%r",
                    operation, summary, start, end, event_id)

        try:
            _, calendar = await self._get_client()
        except RuntimeError as e:
            logger.error("[caldav] Connection/credential error: %s", e)
            return ToolResult(success=False, error=str(e))
        except Exception as e:
            logger.error("[caldav] Unexpected connection error: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV connection error: {e}")

        if operation == "list_events":
            return self._list_events(calendar, start_date, end_date)
        if operation == "get_event":
            if not event_id:
                return ToolResult(success=False, error="event_id is required for get_event")
            return self._get_event(calendar, event_id)
        if operation == "create_event":
            if not (summary and start and end):
                return ToolResult(success=False, error="summary, start, and end are required for create_event")
            return self._create_event(calendar, summary, start, end, description, location)
        if operation == "update_event":
            if not event_id:
                return ToolResult(success=False, error="event_id is required for update_event")
            return self._update_event(calendar, event_id, summary, start, end, description, location)
        if operation == "delete_event":
            if not event_id:
                return ToolResult(success=False, error="event_id is required for delete_event")
            return self._delete_event(calendar, event_id)

        logger.warning("[caldav] Unknown operation: %r", operation)
        return ToolResult(success=False, error=f"Unknown operation: {operation!r}")

    # ── Read operations ───────────────────────────────────────────────────────

    def _list_events(self, calendar: caldav.Calendar, start_date: str, end_date: str) -> ToolResult:
        try:
            if start_date:
                start_dt = dateutil_parser.parse(start_date).replace(tzinfo=timezone.utc)
            else:
                start_dt = datetime.now(timezone.utc)

            if end_date:
                end_dt = dateutil_parser.parse(end_date).replace(tzinfo=timezone.utc)
            else:
                end_dt = start_dt + timedelta(days=30)

            logger.info("[caldav] list_events  range=%s → %s  calendar_url=%s",
                        start_dt.isoformat(), end_dt.isoformat(), calendar.url)

            events = calendar.date_search(start=start_dt, end=end_dt, expand=True)
            events = events[:MAX_EVENTS]

            logger.info("[caldav] list_events  returned %d event(s)", len(events))

            result = []
            for event in events:
                summary = _get_property(event, "summary", "No title")
                ev_start = _get_dt_str(event, "dtstart")
                ev_end   = _get_dt_str(event, "dtend")
                logger.debug("[caldav]   event: %r  start=%s  end=%s", summary, ev_start, ev_end)
                result.append({
                    "id": _get_uid(event),
                    "summary": summary,
                    "start": ev_start,
                    "end": ev_end,
                    "location": _get_property(event, "location", ""),
                    "description_preview": _get_property(event, "description", "")[:100],
                })

            return ToolResult(
                success=True,
                data={"events": result, "count": len(result)},
            )

        except Exception as e:
            logger.error("[caldav] list_events failed: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV list error: {e}")

    def _get_event(self, calendar: caldav.Calendar, event_id: str) -> ToolResult:
        logger.info("[caldav] get_event  event_id=%s", event_id)
        try:
            event = _find_event(calendar, event_id)
            if event is None:
                logger.warning("[caldav] get_event: event not found: %s", event_id)
                return ToolResult(success=False, error=f"Event not found: {event_id}")

            data = {
                "id": _get_uid(event),
                "summary": _get_property(event, "summary", ""),
                "start": _get_dt_str(event, "dtstart"),
                "end": _get_dt_str(event, "dtend"),
                "location": _get_property(event, "location", ""),
                "description": _get_property(event, "description", ""),
            }
            logger.info("[caldav] get_event found: %r  start=%s", data["summary"], data["start"])
            return ToolResult(success=True, data=data)
        except Exception as e:
            logger.error("[caldav] get_event failed: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV get error: {e}")

    # ── Write operations ──────────────────────────────────────────────────────

    def _create_event(
        self,
        calendar: caldav.Calendar,
        summary: str,
        start: str,
        end: str,
        description: str,
        location: str,
    ) -> ToolResult:
        import uuid
        logger.info("[caldav] create_event  summary=%r  start=%s  end=%s  location=%r  calendar_url=%s",
                    summary, start, end, location, calendar.url)
        try:
            start_dt = dateutil_parser.parse(start)
            end_dt = dateutil_parser.parse(end)
            logger.debug("[caldav] create_event  parsed  start_dt=%s  end_dt=%s", start_dt, end_dt)

            uid = str(uuid.uuid4())
            ical = _build_ical(uid, summary, start_dt, end_dt, description, location)
            logger.debug("[caldav] create_event  ical payload:\n%s", ical)

            calendar.add_event(ical)
            logger.info("[caldav] create_event  success  uid=%s", uid)

            return ToolResult(
                success=True,
                data={"created": True, "uid": uid, "summary": summary},
            )
        except Exception as e:
            logger.error("[caldav] create_event failed: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV create error: {e}")

    def _update_event(
        self,
        calendar: caldav.Calendar,
        event_id: str,
        summary: str,
        start: str,
        end: str,
        description: str,
        location: str,
    ) -> ToolResult:
        logger.info("[caldav] update_event  event_id=%s  summary=%r  start=%s  end=%s",
                    event_id, summary, start, end)
        try:
            event = _find_event(calendar, event_id)
            if event is None:
                logger.warning("[caldav] update_event: event not found: %s", event_id)
                return ToolResult(success=False, error=f"Event not found: {event_id}")

            vevent = event.vobject_instance.vevent

            if summary:
                vevent.summary.value = summary
            if start:
                vevent.dtstart.value = dateutil_parser.parse(start)
            if end:
                vevent.dtend.value = dateutil_parser.parse(end)
            if description:
                if hasattr(vevent, "description"):
                    vevent.description.value = description
                else:
                    vevent.add("description").value = description
            if location:
                if hasattr(vevent, "location"):
                    vevent.location.value = location
                else:
                    vevent.add("location").value = location

            event.save()
            logger.info("[caldav] update_event  success  uid=%s", event_id)
            return ToolResult(success=True, data={"updated": True, "uid": event_id})

        except Exception as e:
            logger.error("[caldav] update_event failed: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV update error: {e}")

    def _delete_event(self, calendar: caldav.Calendar, event_id: str) -> ToolResult:
        logger.info("[caldav] delete_event  event_id=%s", event_id)
        try:
            event = _find_event(calendar, event_id)
            if event is None:
                logger.warning("[caldav] delete_event: event not found: %s", event_id)
                return ToolResult(success=False, error=f"Event not found: {event_id}")
            event.delete()
            logger.info("[caldav] delete_event  success  uid=%s", event_id)
            return ToolResult(success=True, data={"deleted": True, "uid": event_id})
        except Exception as e:
            logger.error("[caldav] delete_event failed: %s\n%s", e, traceback.format_exc())
            return ToolResult(success=False, error=f"CalDAV delete error: {e}")

    def confirmation_description(self, operation: str = "", summary: str = "", event_id: str = "", **kwargs) -> str:
        if operation == "create_event":
            start = kwargs.get("start", "")
            return f"Create calendar event: '{summary}' at {start}"
        if operation == "update_event":
            return f"Update calendar event: {event_id}" + (f" → '{summary}'" if summary else "")
        if operation == "delete_event":
            return f"Permanently delete calendar event: {event_id}"
        return f"{operation}: {event_id or summary}"


# ── Helpers ───────────────────────────────────────────────────────────────────

def _get_uid(event: caldav.Event) -> str:
    try:
        return str(event.vobject_instance.vevent.uid.value)
    except Exception:
        return ""


def _get_property(event: caldav.Event, prop: str, default: str = "") -> str:
    try:
        return str(getattr(event.vobject_instance.vevent, prop).value)
    except Exception:
        return default


def _get_dt_str(event: caldav.Event, prop: str) -> str:
    try:
        val = getattr(event.vobject_instance.vevent, prop).value
        if isinstance(val, datetime):
            return val.isoformat()
        return str(val)
    except Exception:
        return ""


def _find_event(calendar: caldav.Calendar, uid: str) -> caldav.Event | None:
    """Find an event by UID. Returns None if not found."""
    try:
        # Try direct URL lookup first
        for event in calendar.events():
            if _get_uid(event) == uid:
                return event
    except Exception:
        pass
    return None


def _build_ical(
    uid: str,
    summary: str,
    start: datetime,
    end: datetime,
    description: str,
    location: str,
) -> str:
    now = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
    start_str = start.strftime("%Y%m%dT%H%M%S")
    end_str = end.strftime("%Y%m%dT%H%M%S")
    tz = "Europe/Oslo"

    lines = [
        "BEGIN:VCALENDAR",
        "VERSION:2.0",
        "PRODID:-//aide//aide//EN",
        "BEGIN:VEVENT",
        f"UID:{uid}",
        f"DTSTAMP:{now}",
        f"DTSTART;TZID={tz}:{start_str}",
        f"DTEND;TZID={tz}:{end_str}",
        f"SUMMARY:{summary}",
    ]
    if description:
        lines.append(f"DESCRIPTION:{description.replace(chr(10), '\\n')}")
    if location:
        lines.append(f"LOCATION:{location}")
    lines += ["END:VEVENT", "END:VCALENDAR"]
    return "\r\n".join(lines)