from __future__ import annotations

from collections import Counter
from typing import Any


def build_reaction(emoji: str, target_event_id: str) -> dict[str, Any]:
    return {
        "m.relates_to": {
            "rel_type": "m.annotation",
            "event_id": target_event_id,
            "key": emoji,
        },
    }


def extract_reaction(event: Any) -> dict[str, str] | None:
    content = event.source.get("content", {}) if hasattr(event, "source") else {}
    relates_to = content.get("m.relates_to", {})
    if relates_to.get("rel_type") != "m.annotation":
        return None
    return {
        "target_event_id": relates_to.get("event_id", ""),
        "key": relates_to.get("key", ""),
    }


def summarize_reactions(events: list[dict[str, Any]]) -> dict[str, dict]:
    key_counter: Counter[str] = Counter()
    user_keys: dict[str, set[str]] = {}
    last_sender: dict[str, str] = {}

    for evt in events:
        sender = evt.get("sender", "")
        key = evt.get("key", "")
        target = evt.get("target_event_id", "")

        if not key or not target:
            continue

        key_counter[key] += 1

        if target not in user_keys:
            user_keys[target] = set()
        user_keys[target].add(sender)

        last_sender[key] = sender

    result: dict[str, dict] = {}
    for target, users in user_keys.items():
        result[target] = {
            "total_reactions": sum(
                count
                for k, count in key_counter.items()
                if any(e.get("target_event_id") == target and e.get("key") == k for e in events)
            ),
            "unique_reactors": len(users),
            "keys": [
                {"key": k, "count": count}
                for k, count in key_counter.items()
                if any(e.get("target_event_id") == target and e.get("key") == k for e in events)
            ],
        }
    return result


_COMMON_EMOJI_MAP = {
    "👍": "+1",
    "👎": "-1",
    "❤️": "heart",
    "😄": "smile",
    "🎉": "party",
    "🚀": "rocket",
    "👀": "eyes",
    "✅": "check",
}


def select_reaction(available: list[dict[str, Any]], query: str) -> dict[str, Any] | None:
    normalized = _COMMON_EMOJI_MAP.get(query, query).lower()

    for entry in available:
        key = entry.get("key", "")
        if key == query or key.lower() == normalized:
            return entry

    return available[0] if available else None


def build_batch_remove(
    client_reactions: list[dict[str, Any]],
    target_event_id: str,
) -> list[dict[str, Any]]:
    return [
        build_reaction(r.get("key", ""), target_event_id)
        for r in client_reactions
        if r.get("target_event_id") == target_event_id
    ]