#!/usr/bin/env nix-shell
#!nix-shell -i python3 -p "python3.withPackages (pkgs: with pkgs; [ transformers pytorch keras ])"

import argparse
import sys
import transformers
import warnings


def trim_sentence(tokenizer: transformers.PreTrainedTokenizer, message: str) -> str:
    periodt = tokenizer.encode('.')[0]
    tokens = tokenizer.encode(message)
    for i in range(len(tokens) - 1, -1, -1):
        if tokens[i] == periodt:
            return tokenizer.decode(tokens[:i+1])
    return message


def generate(model: transformers.TextGenerationPipeline, prompt: str, **kwargs) -> str:
    out = model(
            prompt,
            do_sample=True,
            temperature=0.8,
            top_k=60,
            top_p=0.9,
            **kwargs)
    return trim_sentence(model.tokenizer, out[0]['generated_text'])


def load_model(model: str) -> transformers.TextGenerationPipeline:
    tokenizer = transformers.AutoTokenizer.from_pretrained(model)
    return transformers.pipeline(
            'text-generation',
            tokenizer=tokenizer,
            model=transformers.AutoModelForCausalLM.from_pretrained(model),
            pad_token_id=tokenizer.eos_token_id)


def pick_flavor() -> str:
    flavors = {
            'fantasy': "You are a wizard named Megumin from the kingdom\n"
                    "of Larion. You have in your inventory a wizard's staff\n"
                    "and a spellbook. You are arriving after a day's travel\n"
                    "at an enchanted tower where there's rumors of gold.\n"
                    "You walk up to the entrance of the tower.",
            'post apocalyptic': "You are a machinist named Azariel, living\n"
                    "in the city of New New York. It's been almost 10 years\n"
                    "since the bombs fell, but you still remember it as if\n"
                    "it were yesterday. You push these thoughts out of your\n"
                    "mind and focus on the task at hand: finding a water\n"
                    "purifier for your settlement. You arrive at an\n"
                    "abandoned settlement to the east of your home."
    }
    choices = []
    for i, (scenario, script) in enumerate(flavors.items()):
        print(f'{i}.\t{scenario}')
        choices.append(script)
    while True:
        choice = input('Choose a scenario: ')
        try:
            choice_int = int(choice)
        except ValueError:
            print('Input must be an integer.')
            continue
        try:
            return choices[choice_int]
        except IndexError:
            print('Index out of bounds.')
            continue


def wrap(message: str) -> str:
    res = list()
    for line in message.split('\n'):
        if len(line) < 72:
            res.append(line)
            continue
        split_line = list()
        for word in line.split(' '):
            if not split_line or len(' '.join(split_line)) + len(word) < 72:
                split_line.append(word)
                continue
            res.append(' '.join(split_line))
            split_line = [word]
        res.append(' '.join(split_line))
    return '\n'.join(res)


def main() -> None:
    parser = argparse.ArgumentParser('AI dungeon clone')
    parser.add_argument(
            '--model',
            default='EleutherAI/gpt-neo-125M',
            help='Model to use')
    args = parser.parse_args()
    model = load_model(args.model)
    script = pick_flavor()
    prologue = generate(model, script, max_new_tokens=20, forced_eos_token_id=model.tokenizer.eos_token_id)
    print(prologue)
    prompt = prologue
    prev_response_length = 0
    prev_response_lines = 0
    while True:
        try:
            msg = input('> You ')
        except EOFError:
            break
        if msg == '/retry':
            prompt = prompt[:-prev_response_length]
            print(f'\033[{prev_response_lines}A\033[J', end='')
        elif msg == '/edit':
            prompt = prompt[:-prev_response_length]
            print(f'\033[{prev_response_lines}A\033[J\r', end='')
            new_response = sys.stdin.read()
            prompt += new_response
            prev_response_length = len(new_response)
            prev_response_lines = len(new_response.split('\n'))
            continue
        else:
            if not msg.endswith('.'):
                msg += '.'
            prompt += f'You {msg}\n'
        prompt = prompt[-10000:]
        response = wrap(generate(
                model,
                prompt,
                return_full_text=False,
                max_new_tokens=50).strip())
        print(response)
        response += '\n'
        prompt += response
        prev_response_length = len(response)
        prev_response_lines = len(response.split('\n'))


if __name__ == '__main__':
    main()