import copy
from typing import Any, Dict, List


class ChatApp:
    def __init__(self, channels: List[str], noise_channels: List[str]):
        all_channels = list(dict.fromkeys(channels + noise_channels))
        self.channels = all_channels
        self.messages: Dict[str, List[Dict]] = {ch: [] for ch in all_channels}
        self._episode_messages: List[Dict] = []

    def snapshot(self) -> Dict[str, Any]:
        return {
            "channels": self.channels,
            "messages_posted_this_episode": copy.deepcopy(self._episode_messages),
        }

    def post_message(self, args: Dict[str, Any]) -> Dict[str, Any]:
        channel = args.get("channel", "")
        text = args.get("text", "")
        if not channel or not text:
            return {"ok": False, "error": "Both 'channel' and 'text' are required"}
        if channel not in self.channels:
            return {"ok": False, "error": f"Channel '{channel}' not found. Use chat.list_channels to see available channels."}
        msg = {"channel": channel, "text": text}
        self.messages[channel].append(msg)
        self._episode_messages.append(msg)
        return {"ok": True, "data": {"channel": channel, "delivered": True}, "side_effects": [f"message posted to {channel}"]}

    def read_channel(self, args: Dict[str, Any]) -> Dict[str, Any]:
        channel = args.get("channel", "")
        limit = min(args.get("limit", 20), 50)
        if channel not in self.channels:
            return {"ok": False, "error": f"Channel '{channel}' not found"}
        msgs = self.messages[channel][-limit:]
        return {"ok": True, "data": {"channel": channel, "messages": copy.deepcopy(msgs)}}

    def list_channels(self, args: Dict[str, Any]) -> Dict[str, Any]:
        return {"ok": True, "data": self.channels}

    def search(self, args: Dict[str, Any]) -> Dict[str, Any]:
        query = args.get("query", "").lower()
        results = []
        for ch, msgs in self.messages.items():
            for m in msgs:
                if query in m["text"].lower():
                    results.append({"channel": ch, "text": m["text"]})
        return {"ok": True, "data": results[:20]}