"""Blueprint that surfaces upcoming CS events, optionally filtered."""

from __future__ import annotations

from datetime import datetime, timedelta
from typing import Any, Dict, List

from .base import AnalysisContext, Blueprint, BlueprintResult, Fact, normalize_datetime


class UpcomingEventsBlueprint(Blueprint):
    """Return upcoming department events."""

    name = "upcoming_events"

    def run(self, context: AnalysisContext, **kwargs: Any) -> BlueprintResult:
        keyword = (kwargs.get("keyword") or "").strip().lower()
        horizon_days = kwargs.get("horizon_days", 14)
        max_results = kwargs.get("max_results", 5)
        now = datetime.now()
        horizon = now + timedelta(days=horizon_days)

        filtered: List[Dict[str, Any]] = []
        for event in context.events:
            start = event.get("start")
            if start and isinstance(start, str):
                start = normalize_datetime(start)
            if start and isinstance(start, datetime):
                if start < now or (horizon_days is not None and start > horizon):
                    continue
            if keyword:
                haystack = " ".join(
                    str(bit or "").lower()
                    for bit in (event.get("title"), event.get("description"), event.get("tags"))
                )
                if keyword not in haystack:
                    continue
            filtered.append(event)

        filtered.sort(key=lambda evt: evt.get("start") or datetime.max)
        if max_results:
            filtered = filtered[:max_results]

        facts: List[Fact] = []
        for event in filtered:
            start_value = event.get("start")
            if isinstance(start_value, datetime):
                start_serialized = start_value.isoformat()
            else:
                start_serialized = start_value
            facts.append(
                Fact(
                    subject=event.get("title", "Untitled Event"),
                    predicate="upcoming_event",
                    value={
                        "title": event.get("title"),
                        "start": start_serialized,
                        "location": event.get("location"),
                        "description": event.get("description"),
                        "url": event.get("url"),
                    },
                    source=event.get("source"),
                    confidence=0.8,
                )
            )

        notes: List[str] = []
        if not facts:
            if keyword:
                notes.append(f"No upcoming events matched keyword '{keyword}'.")
            else:
                notes.append("No upcoming events found in cache.")

        return BlueprintResult(self.name, kwargs, facts=facts, notes=notes)