import json
import logging
import uuid
from collections.abc import Awaitable, Callable

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings
from app.llm.client import get_dm_system_prompt, get_llm_client
from app.llm.context import build_context
from app.llm.json_utils import fix_double_escaped_unicode
from app.llm.tools import character_sheet, dice, end_game, link_existing_character, monster, world_state
from app.models.character import Character
from app.models.game import Game, GameParticipant
from app.models.message import Message
from app.models.user import User
from app.rag.adventure_retrieval import build_adventure_rag_block
from app.rag.retrieval import build_rag_block

logger = logging.getLogger("app.llm.orchestrator")

MAX_TOOL_ROUNDS = 5
MAX_TOKENS = 4096

TOOLS = [
    {"type": "function", "function": dice.TOOL_SCHEMA},
    {"type": "function", "function": character_sheet.TOOL_SCHEMA},
    {"type": "function", "function": end_game.TOOL_SCHEMA},
    {"type": "function", "function": monster.TOOL_SCHEMA},
    {"type": "function", "function": world_state.TOOL_SCHEMA},
    {"type": "function", "function": link_existing_character.TOOL_SCHEMA},
]


async def _execute_tool_call(
    session: AsyncSession, game_id: uuid.UUID, tool_name: str, tool_input: dict
) -> dict:
    """Runs one tool call. Errors are returned as a payload (not raised), so the DM sees them
    as a tool result and can recover instead of the whole turn crashing."""
    try:
        if tool_name == "roll_dice":
            return dice.roll(tool_input["notation"])
        if tool_name == "upsert_character_sheet":
            return await character_sheet.upsert(session, game_id, tool_input)
        if tool_name == "end_game":
            return await end_game.end(session, game_id, tool_input)
        if tool_name == "update_monster_hp":
            return await monster.update(session, game_id, tool_input)
        if tool_name == "update_world_state":
            return await world_state.update(session, game_id, tool_input)
        if tool_name == "link_existing_character":
            return await link_existing_character.link(session, game_id, tool_input)
        return {"error": f"Unknown tool {tool_name!r}"}
    except Exception as exc:  # noqa: BLE001
        logger.warning("Tool call %s failed: %s", tool_name, exc)
        await session.rollback()
        return {"error": str(exc)}


async def _request_player_roll(
    session: AsyncSession, participant: GameParticipant, notation: str, reason: str
) -> dict:
    """Handles a roll_dice call for a player who rolls their own physical dice: validates the
    notation without touching the RNG, records it as the participant's pending roll (picked up
    and cleared at the top of their next turn), and returns a tool result that tells the DM to
    ask for it and wait instead of rolling itself."""
    try:
        dice.parse_notation(notation)
    except ValueError as exc:
        return {"error": str(exc)}

    participant.pending_roll = {"notation": notation, "reason": reason}
    await session.commit()

    return {
        "awaiting_player_roll": True,
        "notation": notation,
        "reason": reason,
        "note": (
            f"Der Spieler würfelt selbst mit physischen Würfeln. Nenne ihm klar und knapp, was er "
            f"würfeln soll ({notation}" + (f", {reason}" if reason else "") + "), und warte auf "
            "seine Antwort mit dem Ergebnis in einer künftigen Nachricht — würfle nicht selbst und "
            "erfinde kein Ergebnis."
        ),
    }


def _format_character_sheet(character: Character) -> str:
    parts = [
        f"- {character.name} ({character.race or '?'} {character.char_class or '?'}, Stufe {character.level})"
    ]
    if character.stats:
        parts.append(f"  Werte: {character.stats}")
    hp = None
    if character.current_hp is not None or character.max_hp is not None:
        hp = f"{character.current_hp if character.current_hp is not None else '?'}/{character.max_hp if character.max_hp is not None else '?'}"
    if hp:
        parts.append(f"  TP: {hp}")
    if character.combat_stats:
        parts.append(f"  Kampfwerte: {character.combat_stats}")
    if character.abilities:
        ability_names = ", ".join(a.get("name", "") for a in character.abilities if isinstance(a, dict))
        parts.append(f"  Fähigkeiten: {ability_names}")
    if character.equipment:
        parts.append(f"  Ausrüstung: {', '.join(character.equipment)}")
    if character.description:
        parts.append(f"  Hintergrund: {character.description}")
    return "\n".join(parts)


async def _check_hp_game_over(session: AsyncSession, game_id: uuid.UUID, result: dict) -> str | None:
    """After an upsert_character_sheet call, auto-ends the game if the character it touched
    dropped to 0 HP or below. Returns the end reason if the game was just ended, else None."""
    current_hp = result.get("current_hp")
    if current_hp is None or current_hp > 0:
        return None

    game = await session.get(Game, game_id)
    if game is None or game.status == "ended":
        return None

    reason = f"{result.get('name', 'Ein Charakter')} ist bei {current_hp} Trefferpunkten zusammengebrochen."
    game.status = "ended"
    game.ended_reason = reason
    await session.commit()
    return reason


async def run_dm_turn(
    session: AsyncSession,
    game_id: uuid.UUID,
    latest_player_message: str | None = None,
    user_id: uuid.UUID | None = None,
    on_roll: Callable[[str], Awaitable[None]] | None = None,
    on_awaiting_roll: Callable[[str, str], Awaitable[None]] | None = None,
    on_game_ended: Callable[[str], Awaitable[None]] | None = None,
) -> Message:
    client = get_llm_client()
    system_prompt = get_dm_system_prompt()

    participant: GameParticipant | None = None
    if user_id is not None:
        participant = (
            await session.execute(
                select(GameParticipant).where(
                    GameParticipant.game_id == game_id, GameParticipant.user_id == user_id
                )
            )
        ).scalar_one_or_none()

    if participant is not None and participant.pending_roll:
        pending = participant.pending_roll
        system_prompt += (
            f"\n\nOffene Würfelanfrage: Du hast {pending.get('notation')} "
            f"({pending.get('reason') or 'ohne Angabe'}) angefragt, der Spieler würfelt selbst. "
            "Seine gerade eingegangene Nachricht enthält vermutlich das Ergebnis dieses Wurfs — "
            "nimm die genannte Zahl direkt als Wurfergebnis, würfle NICHT selbst und frag nicht "
            "erneut danach, außer die Nachricht beantwortet die Anfrage erkennbar nicht."
        )
        # Consumed either way — if the message didn't actually answer it, the DM asking again
        # via roll_dice creates a fresh pending_roll for next time.
        participant.pending_roll = None
        await session.commit()

    game = await session.get(Game, game_id)
    if game is not None:
        system_prompt = (
            f"{system_prompt}\n\n"
            "Spiel-Rahmendaten (vom Ersteller beim Anlegen bereits festgelegt — NICHT erneut "
            "abfragen, in Session 0 höchstens knapp bestätigen):\n"
            f"Name: {game.name}\nBeschreibung: {game.description}"
        )

        participant_names = (
            await session.execute(
                select(User.name)
                .join(GameParticipant, GameParticipant.user_id == User.id)
                .where(GameParticipant.game_id == game_id)
            )
        ).scalars().all()
        if participant_names:
            system_prompt += (
                "\n\nBereits beigetretene Spieler (über Login/Einladungslink — NICHT nach Anzahl "
                "oder Namen fragen): " + ", ".join(participant_names) + ". Weitere können jederzeit "
                "über den Einladungslink dazukommen; du erkennst sie automatisch am Namen, sobald sie schreiben."
            )

        linked_characters = (
            await session.execute(
                select(Character)
                .join(GameParticipant, GameParticipant.character_id == Character.id)
                .where(GameParticipant.game_id == game_id)
            )
        ).scalars().all()
        if linked_characters:
            sheets = "\n".join(_format_character_sheet(c) for c in linked_characters)
            system_prompt += (
                "\n\nBekannte Charakterblätter (bereits vollständig vorhanden — NICHT erneut nach "
                "Werten/Ausrüstung/Hintergrund fragen, nur bei tatsächlichen Änderungen über "
                f"upsert_character_sheet aktualisieren):\n{sheets}"
            )

    await world_state.refresh_if_due(session, game_id, client, settings.dm_model)
    world_summary = await world_state.get_summary(session, game_id)
    if world_summary:
        system_prompt = (
            f"{system_prompt}\n\nBisheriger Weltzustand (automatisch/von dir über update_world_state "
            f"aktuell gehalten — der Chatverlauf unten zeigt nur ein aktuelles Fenster, das hier "
            f"trägt alles Ältere):\n{world_summary}"
        )

    if latest_player_message:
        rag_block = await build_rag_block(session, latest_player_message)
        if rag_block:
            system_prompt = f"{system_prompt}\n\n{rag_block}"

        adventure_block = await build_adventure_rag_block(session, game_id, latest_player_message)
        if adventure_block:
            system_prompt = f"{system_prompt}\n\n{adventure_block}"

    messages = [{"role": "system", "content": system_prompt}]
    messages.extend(await build_context(session, game_id))

    final_text = ""
    for _ in range(MAX_TOOL_ROUNDS):
        response = await client.chat.completions.create(
            model=settings.dm_model,
            max_tokens=MAX_TOKENS,
            messages=messages,
            tools=TOOLS,
        )
        choice = response.choices[0]
        message = choice.message
        final_text = message.content or ""

        if not message.tool_calls:
            break

        messages.append(message.model_dump(exclude_unset=True))

        for tool_call in message.tool_calls:
            tool_input = fix_double_escaped_unicode(json.loads(tool_call.function.arguments))

            if tool_call.function.name == "roll_dice" and participant is not None and participant.self_rolls:
                notation = tool_input.get("notation", "")
                reason = tool_input.get("reason", "")
                result = await _request_player_roll(session, participant, notation, reason)
                if "error" not in result and on_awaiting_roll is not None:
                    await on_awaiting_roll(notation, reason)
            else:
                if tool_call.function.name == "roll_dice" and on_roll is not None:
                    await on_roll(tool_input.get("notation", ""))
                result = await _execute_tool_call(session, game_id, tool_call.function.name, tool_input)

            end_reason = None
            if tool_call.function.name == "end_game" and "reason" in result:
                end_reason = result["reason"]
            elif tool_call.function.name == "upsert_character_sheet":
                end_reason = await _check_hp_game_over(session, game_id, result)
                if end_reason:
                    result = {**result, "game_ended": True, "end_reason": end_reason}
            if end_reason and on_game_ended is not None:
                await on_game_ended(end_reason)

            messages.append(
                {
                    "role": "tool",
                    "tool_call_id": tool_call.id,
                    "content": json.dumps(result, ensure_ascii=False),
                }
            )
    else:
        if not final_text:
            final_text = "(Der Dungeon Master braucht einen Moment länger als erwartet — bitte versuche es erneut.)"

    dm_message = Message(game_id=game_id, sender_type="dm", content=final_text)
    session.add(dm_message)
    await session.commit()
    await session.refresh(dm_message)
    return dm_message