import argparse
import base64
import os
import sys
import uuid
from typing import Optional

from dotenv import load_dotenv
from gigachat import GigaChat


DEFAULT_MODEL = "GigaChat"


def build_client(credentials: Optional[str], scope: Optional[str], model: Optional[str] = None) -> GigaChat:
    # verify_ssl_certs=False is sometimes needed depending on the environment,
    # but we will start with default.
    kwargs = {"verify_ssl_certs": False}
    if credentials:
        kwargs["credentials"] = credentials
    if scope:
        kwargs["scope"] = scope
    if model:
        kwargs["model"] = model
        
    return GigaChat(**kwargs)


def generate_text(client: GigaChat, model: str, prompt: str) -> str:
    # GigaChat client handles the model parameter in the constructor usually.
    # If we need to change model dynamically, we might need to rebuild client or check documentation
    # but for now, we rely on client being initialized with correct model or default.
    # The `chat` method only accepts string prompt in some versions.
    response = client.chat(prompt)
    return response.choices[0].message.content or ""


def cli() -> None:
    load_dotenv()
    
    parser = argparse.ArgumentParser(
        description="Send prompts to the GigaChat API and print the response."
    )
    parser.add_argument(
        "prompt",
        nargs="?",
        help="Optional prompt to send immediately. If omitted, the program enters interactive mode.",
    )
    parser.add_argument(
        "--model",
        default=DEFAULT_MODEL,
        help=f"GigaChat model to use (default: {DEFAULT_MODEL}).",
    )
    args = parser.parse_args()

    credentials = os.getenv("GIGACHAT_CREDENTIALS")
    scope = os.getenv("GIGACHAT_SCOPE")
    
    if not credentials:
        print(
            "Missing environment variable GIGACHAT_CREDENTIALS. "
            "Get your credentials from https://developers.sber.ru/studio and export them (or set in .env).",
            file=sys.stderr,
        )
        sys.exit(1)

    try:
        client = build_client(credentials, scope, args.model)
    except Exception as e:
        print(f"Failed to initialize GigaChat client: {e}", file=sys.stderr)
        sys.exit(1)

    if args.prompt:
        prompt = args.prompt.strip()
        if not prompt:
            print("Prompt is empty. Nothing to send.", file=sys.stderr)
            sys.exit(1)
        print_response(client, args.model, prompt)
        return

    print(
        f"GigaChat CLI (model: {args.model}). Enter an empty line to exit.",
        file=sys.stderr,
    )
    while True:
        try:
            prompt = input("> ").strip()
        except (EOFError, KeyboardInterrupt):
            print("\nExiting.", file=sys.stderr)
            break

        if not prompt:
            print("Goodbye!", file=sys.stderr)
            break

        print_response(client, args.model, prompt)


def print_response(client: GigaChat, model: str, prompt: str) -> None:
    try:
        text = generate_text(client, model, prompt)
    except Exception as exc:
        # It might be a specific GigaChat error related to auth
        print(f"Request failed: {exc}", file=sys.stderr)
        return

    if not text:
        print("(No text returned by the model.)", file=sys.stderr)
        return

    print(text)


if __name__ == "__main__":
    cli()