import os
from pathlib import Path

import aiosqlite
import gradio as gr
import tiktoken
from openai import AsyncOpenAI

# =========================
# Конфигурация
# =========================

DB_DIR = Path("./data")
DB_PATH = DB_DIR / "chats.db"

CHAT_IDS = ["chat1", "chat2", "chat3", "chat4", "chat5"]

# Ограничение входного контекста
INPUT_TOKEN_LIMIT = 4096

# Ограничение ответа модели
OUTPUT_TOKEN_LIMIT = 1024

MODEL_NAME = "gpt-4o-mini"


def ensure_db_dir():
    DB_DIR.mkdir(parents=True, exist_ok=True)


# =========================
# Переменные окружения
# =========================

authorized_users_str = os.getenv("AUTHORIZED_USERS")
if not authorized_users_str:
    raise ValueError("Переменная окружения AUTHORIZED_USERS не установлена")
AUTHORIZED_USERS = dict(user.split(":") for user in authorized_users_str.split(","))

proctor_links = os.getenv("PROCTOR_LINKS")
if not proctor_links:
    raise ValueError("Переменная окружения PROCTOR_LINKS не установлена")
PROCTOR_LINKS = dict(user.split(":", 1) for user in proctor_links.split(","))

SYSTEM_PROMPT = os.getenv("SYSTEM_PROMPT", "Ты полезный ассистент.")

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
if not OPENAI_API_KEY:
    raise ValueError("Переменная окружения OPENAI_API_KEY не установлена")


# =========================
# OpenAI client
# =========================

client = AsyncOpenAI(api_key=OPENAI_API_KEY)


# =========================
# Подсчет токенов и обрезка истории
# =========================

def get_encoder(model_name: str = MODEL_NAME):
    try:
        return tiktoken.encoding_for_model(model_name)
    except Exception:
        return tiktoken.get_encoding("cl100k_base")


def count_message_tokens(messages, model_name: str = MODEL_NAME) -> int:
    enc = get_encoder(model_name)
    total = 0

    # Приблизительный расчет для chat messages
    for msg in messages:
        total += 4
        total += len(enc.encode(msg.get("role", "")))
        total += len(enc.encode(msg.get("content", "")))
    total += 2

    return total


def trim_messages_to_limit(
    system_prompt: str,
    history: list,
    new_user_message: str,
    model_name: str = MODEL_NAME,
    input_limit: int = INPUT_TOKEN_LIMIT,
):
    base_messages = [{"role": "system", "content": system_prompt}]
    candidate_history = history[:] if history else []

    final_messages = base_messages + candidate_history + [
        {"role": "user", "content": new_user_message}
    ]

    while len(final_messages) > 2 and count_message_tokens(final_messages, model_name) > input_limit:
        if candidate_history:
            candidate_history.pop(0)
        else:
            break

        final_messages = base_messages + candidate_history + [
            {"role": "user", "content": new_user_message}
        ]

    # Если даже без истории сообщение слишком длинное — режем само сообщение
    if count_message_tokens(final_messages, model_name) > input_limit:
        enc = get_encoder(model_name)

        system_only_tokens = count_message_tokens(base_messages, model_name)
        allowed_for_user = max(1, input_limit - system_only_tokens - 20)

        trimmed_user_message = enc.decode(enc.encode(new_user_message)[:allowed_for_user])

        final_messages = base_messages + [
            {"role": "user", "content": trimmed_user_message}
        ]

    return final_messages


# =========================
# Работа с БД
# =========================

async def init_db():
    ensure_db_dir()
    async with aiosqlite.connect(DB_PATH) as db:
        for chat_id in CHAT_IDS:
            await db.execute(f"""
                CREATE TABLE IF NOT EXISTS {chat_id} (
                    id INTEGER PRIMARY KEY AUTOINCREMENT,
                    username TEXT NOT NULL,
                    role TEXT NOT NULL,
                    content TEXT NOT NULL,
                    timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
                )
            """)
        await db.commit()


async def save_message(chat_id, username, role, content):
    ensure_db_dir()
    async with aiosqlite.connect(DB_PATH) as db:
        await db.execute(
            f"INSERT INTO {chat_id} (username, role, content) VALUES (?, ?, ?)",
            (username, role, content),
        )
        await db.commit()


async def load_history(chat_id, username):
    ensure_db_dir()
    async with aiosqlite.connect(DB_PATH) as db:
        async with db.execute(
            f"""
            SELECT role, content
            FROM {chat_id}
            WHERE username = ?
            ORDER BY timestamp ASC, id ASC
            """,
            (username,),
        ) as cursor:
            history = []
            async for row in cursor:
                history.append({"role": row[0], "content": row[1]})
            return history


async def clear_history(chat_id, username):
    ensure_db_dir()
    async with aiosqlite.connect(DB_PATH) as db:
        await db.execute(
            f"DELETE FROM {chat_id} WHERE username = ?",
            (username,),
        )
        await db.commit()
    return []


# =========================
# Основная логика
# =========================

async def send_message(message, history, username, chat_id):
    if not username:
        error_msg = "Ошибка: пользователь не авторизован."
        return "", (history or []) + [{"role": "assistant", "content": error_msg}]

    if not chat_id or chat_id not in CHAT_IDS:
        error_msg = "Ошибка: выбран некорректный чат."
        return "", (history or []) + [{"role": "assistant", "content": error_msg}]

    if not message or not message.strip():
        return "", history

    history = history or []
    clean_message = message.strip()

    await save_message(chat_id, username, "user", clean_message)

    if clean_message.lower() == "proctorlink":
        if username in PROCTOR_LINKS:
            assistant_response = PROCTOR_LINKS[username]
        else:
            assistant_response = "Вас нет в списке пользователей с доступом к прокторингу."

        await save_message(chat_id, username, "assistant", assistant_response)

        new_history = history + [
            {"role": "user", "content": clean_message},
            {"role": "assistant", "content": assistant_response},
        ]
        return "", new_history

    messages = trim_messages_to_limit(
        system_prompt=SYSTEM_PROMPT,
        history=history,
        new_user_message=clean_message,
        model_name=MODEL_NAME,
        input_limit=INPUT_TOKEN_LIMIT,
    )

    try:
        response = await client.chat.completions.create(
            model=MODEL_NAME,
            messages=messages,
            temperature=0.7,
            max_tokens=OUTPUT_TOKEN_LIMIT,
            timeout=120,
        )
        assistant_response = response.choices[0].message.content or ""
    except Exception as e:
        print(f"OpenAI API error: {e}")
        assistant_response = "Error: Could not connect to the AI service."

    await save_message(chat_id, username, "assistant", assistant_response)

    new_history = history + [
        {"role": "user", "content": clean_message},
        {"role": "assistant", "content": assistant_response},
    ]
    return "", new_history


# =========================
# UI helpers
# =========================

def set_username(request: gr.Request):
    return request.username if request else None


def update_chat_id(selected_chat):
    return selected_chat


async def load_chat_history(username, chat_id):
    if username and chat_id:
        try:
            return await load_history(chat_id, username)
        except Exception as e:
            print(f"Load history error: {e}")
            return [{"role": "assistant", "content": "Не удалось загрузить историю чата."}]
    return []


async def handle_clear_history(username, chat_id):
    if username and chat_id:
        try:
            await clear_history(chat_id, username)
        except Exception as e:
            print(f"Clear history error: {e}")
            return [{"role": "assistant", "content": "Не удалось очистить историю чата."}]
    return []


# =========================
# CSS
# =========================

custom_css = """
#chatbot {
    width: 100% !important;
    max-width: 1200px !important;
    margin: 0 auto !important;
    height: 65vh !important;
    overflow-y: auto;
    border: 1px solid #ccc;
    border-radius: 8px;
}
#chatbot .message {
    font-size: 16px !important;
    padding: 10px;
}
#submit_btn, #load_history_btn, #clear_history_btn {
    background-color: #4CAF50 !important;
    color: white !important;
    margin: 5px !important;
    border-radius: 5px;
}
#clear_history_btn {
    background-color: #ff4444 !important;
}
#msg {
    width: 100% !important;
    max-width: 1200px !important;
    margin: 10px auto !important;
    border-radius: 5px;
}
#chat_selector {
    margin-bottom: 20px !important;
}
"""


# =========================
# Интерфейс
# =========================

with gr.Blocks(css=custom_css, theme=gr.themes.Soft()) as demo:
    username_state = gr.State()
    chat_id_state = gr.State(value="chat1")

    chat_selector = gr.Dropdown(
        choices=CHAT_IDS,
        label="Выберите чат",
        value="chat1",
        elem_id="chat_selector",
    )

    with gr.Column(elem_id="chatbot_container"):
        chatbot = gr.Chatbot(type="messages", elem_id="chatbot")

    msg = gr.Textbox(
        label="Ваше сообщение",
        placeholder="Введите ваше сообщение...",
        elem_id="msg",
    )

    with gr.Row():
        submit_btn = gr.Button("Отправить", elem_id="submit_btn")
        load_history_btn = gr.Button("Загрузить историю", elem_id="load_history_btn")
        clear_history_btn = gr.Button("Очистить историю", elem_id="clear_history_btn")

    demo.load(init_db, inputs=None, outputs=None)
    demo.load(set_username, inputs=None, outputs=username_state)

    chat_selector.change(update_chat_id, inputs=chat_selector, outputs=chat_id_state)

    chat_id_state.change(
        load_chat_history,
        inputs=[username_state, chat_id_state],
        outputs=chatbot,
    )
    username_state.change(
        load_chat_history,
        inputs=[username_state, chat_id_state],
        outputs=chatbot,
    )

    load_history_btn.click(
        load_chat_history,
        inputs=[username_state, chat_id_state],
        outputs=chatbot,
    )

    clear_history_btn.click(
        handle_clear_history,
        inputs=[username_state, chat_id_state],
        outputs=chatbot,
    )

    submit_btn.click(
        send_message,
        inputs=[msg, chatbot, username_state, chat_id_state],
        outputs=[msg, chatbot],
    )

    msg.submit(
        send_message,
        inputs=[msg, chatbot, username_state, chat_id_state],
        outputs=[msg, chatbot],
    )


# =========================
# Запуск
# =========================

if __name__ == "__main__":
    ensure_db_dir()
    demo.queue(default_concurrency_limit=40, max_size=50).launch(
        auth=[(u, p) for u, p in AUTHORIZED_USERS.items()],
        share=True,
        ssr_mode=False,
    )