"""BAN YARO — Direktnachrichten"""
import logging
from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel
from database import db
from auth import get_current_user

router = APIRouter()
logger = logging.getLogger(__name__)


def _conv_key(a: int, b: int):
    """Normalisiert Konversations-User-IDs: user_a < user_b."""
    return (min(a, b), max(a, b))


@router.get("/conversations")
async def list_conversations(user=Depends(get_current_user)):
    uid = user["id"]
    with db() as conn:
        rows = conn.execute("""
            SELECT c.id, c.last_msg_at,
                   CASE WHEN c.user_a_id=? THEN c.user_b_id ELSE c.user_a_id END AS partner_id,
                   CASE WHEN c.user_a_id=? THEN ub.name    ELSE ua.name    END AS partner_name,
                   (SELECT text FROM direct_messages
                    WHERE conversation_id=c.id AND is_deleted=0
                    ORDER BY created_at DESC LIMIT 1) AS last_text,
                   (SELECT COUNT(*) FROM direct_messages
                    WHERE conversation_id=c.id
                      AND sender_id != ?
                      AND is_deleted=0
                      AND created_at > COALESCE(
                            CASE WHEN c.user_a_id=? THEN c.a_read_at ELSE c.b_read_at END,
                            '1970-01-01'
                          )
                   ) AS unread_count
            FROM conversations c
            JOIN users ua ON ua.id=c.user_a_id
            JOIN users ub ON ub.id=c.user_b_id
            WHERE c.user_a_id=? OR c.user_b_id=?
            ORDER BY COALESCE(c.last_msg_at, c.created_at) DESC
        """, (uid, uid, uid, uid, uid, uid)).fetchall()
    return [dict(r) for r in rows]


class StartConvModel(BaseModel):
    partner_id: int


@router.post("/conversations", status_code=201)
async def start_conversation(data: StartConvModel, user=Depends(get_current_user)):
    uid = user["id"]
    if uid == data.partner_id:
        raise HTTPException(400, "Du kannst dir selbst keine Nachrichten schicken.")

    a, b = _conv_key(uid, data.partner_id)
    with db() as conn:
        f = conn.execute("""
            SELECT 1 FROM friendships
            WHERE ((requester_id=? AND addressee_id=?) OR (requester_id=? AND addressee_id=?))
              AND status='accepted'
        """, (uid, data.partner_id, data.partner_id, uid)).fetchone()
        if not f:
            raise HTTPException(403, "Ihr seid noch keine Freunde.")

        existing = conn.execute(
            "SELECT id FROM conversations WHERE user_a_id=? AND user_b_id=?", (a, b)
        ).fetchone()
        if existing:
            return {"conversation_id": existing["id"]}

        cur = conn.execute(
            "INSERT INTO conversations (user_a_id, user_b_id) VALUES (?,?)", (a, b)
        )
        return {"conversation_id": cur.lastrowid}


@router.get("/conversations/{conv_id}")
async def get_messages(conv_id: int, offset: int = 0, limit: int = 50,
                       user=Depends(get_current_user)):
    uid = user["id"]
    with db() as conn:
        conv = conn.execute(
            "SELECT * FROM conversations WHERE id=? AND (user_a_id=? OR user_b_id=?)",
            (conv_id, uid, uid)
        ).fetchone()
        if not conv:
            raise HTTPException(404, "Konversation nicht gefunden.")

        partner_id = conv["user_b_id"] if conv["user_a_id"] == uid else conv["user_a_id"]
        partner = conn.execute("SELECT name FROM users WHERE id=?", (partner_id,)).fetchone()

        msgs = conn.execute("""
            SELECT m.id, m.sender_id, m.text, m.is_deleted, m.created_at,
                   u.name AS sender_name
            FROM direct_messages m
            JOIN users u ON u.id=m.sender_id
            WHERE m.conversation_id=?
            ORDER BY m.created_at ASC
            LIMIT ? OFFSET ?
        """, (conv_id, limit, offset)).fetchall()

    return {
        "conversation_id": conv_id,
        "partner_id":      partner_id,
        "partner_name":    partner["name"] if partner else "Unbekannt",
        "messages":        [dict(m) for m in msgs],
    }


class SendMsgModel(BaseModel):
    text: str


@router.post("/conversations/{conv_id}/messages", status_code=201)
async def send_message(conv_id: int, data: SendMsgModel, user=Depends(get_current_user)):
    uid = user["id"]
    text = data.text.strip()
    if not text:
        raise HTTPException(400, "Nachricht darf nicht leer sein.")
    if len(text) > 2000:
        raise HTTPException(400, "Nachricht zu lang (max. 2000 Zeichen).")

    with db() as conn:
        conv = conn.execute(
            "SELECT * FROM conversations WHERE id=? AND (user_a_id=? OR user_b_id=?)",
            (conv_id, uid, uid)
        ).fetchone()
        if not conv:
            raise HTTPException(404, "Konversation nicht gefunden.")

        partner_id = conv["user_b_id"] if conv["user_a_id"] == uid else conv["user_a_id"]

        cur = conn.execute("""
            INSERT INTO direct_messages (conversation_id, sender_id, text) VALUES (?,?,?)
        """, (conv_id, uid, text))
        msg_id = cur.lastrowid

        conn.execute(
            "UPDATE conversations SET last_msg_at=datetime('now') WHERE id=?",
            (conv_id,)
        )

    try:
        from routes.push import send_push_to_user
        preview = text[:100] + ("…" if len(text) > 100 else "")
        send_push_to_user(partner_id, {
            "title": f"Nachricht von {user['name']}",
            "body":  preview,
            "type":  "chat_message",
            "tag":   f"chat-{conv_id}",
            "data":  {"page": "chat", "conversation_id": conv_id},
        })
    except Exception:
        pass

    return {"id": msg_id, "ok": True}


@router.post("/conversations/{conv_id}/read")
async def mark_read(conv_id: int, user=Depends(get_current_user)):
    uid = user["id"]
    with db() as conn:
        conv = conn.execute(
            "SELECT * FROM conversations WHERE id=? AND (user_a_id=? OR user_b_id=?)",
            (conv_id, uid, uid)
        ).fetchone()
        if not conv:
            raise HTTPException(404)
        field = "a_read_at" if conv["user_a_id"] == uid else "b_read_at"
        conn.execute(
            f"UPDATE conversations SET {field}=datetime('now') WHERE id=?",
            (conv_id,)
        )
    return {"ok": True}


@router.delete("/messages/{msg_id}")
async def delete_message(msg_id: int, user=Depends(get_current_user)):
    uid = user["id"]
    with db() as conn:
        msg = conn.execute(
            "SELECT id FROM direct_messages WHERE id=? AND sender_id=?", (msg_id, uid)
        ).fetchone()
        if not msg:
            raise HTTPException(404, "Nachricht nicht gefunden.")
        conn.execute(
            "UPDATE direct_messages SET is_deleted=1, text='[gelöscht]' WHERE id=?",
            (msg_id,)
        )
    return {"ok": True}