import { Message } from "discord.js";
import {
  ChatCompletionRequestMessage as OpenAIMessage,
  CreateChatCompletionRequest as ChatCompletionRequestData,
} from "openai";

import IQuota from "./IQuota";
import MessageCount from "./quota/messageCount";

export interface IConfigRequired {
  readonly calendarParams: Intl.DateTimeFormatOptions;
  /** Tokens to authentiate with */
  readonly tokens: {
    readonly Discord: string;
    readonly OpenAI: string;
  };
  /** Messages to append at the start of every chat history when sending to API */
  systemPrompt(context: Message): OpenAIMessage[];
  /** OpenAI model config */
  readonly chatCompletionParams: Omit<ChatCompletionRequestData, "messages" | "function_call" | "functions" | "n">;
  /** Limits for message selection */
  readonly readLimits: {
    /** Maximum message age to include (in miliseconds) */
    readonly time: number;
    /** Maximum number of messages to select (maximum 100) */
    readonly messages: number;
    /** Maximum total token usage for messages (counted locally) */
    readonly tokens: number;
  };
  /**
   * Quota parameters to use when checking limits
   * you can find some in `./quota`
   */
  readonly quota: IQuota;
}

export type IConfig = Partial<IConfigRequired>;

export default function newConfig(config?: IConfig): IConfigRequired {
  return { ...defaultConfig, ...config };
}

function envAsString(key: string): string | undefined {
  key = key.toLocaleUpperCase();
  return process.env[key];
}

function envAsNumber(key: string): number | undefined {
  key = key.toLocaleUpperCase();
  const value = Number(process.env[key]);
  return !Number.isNaN(value) ? value : undefined;
}

const defaultConfig: IConfigRequired = {
  calendarParams: {
    weekday: "short",
    year: "numeric",
    month: "short",
    day: "numeric",
    hour: "2-digit",
    minute: "2-digit",
    hour12: false,
  },
  tokens: {
    Discord: envAsString("TOKENS__DISCORD") ?? "",
    OpenAI: envAsString("TOKENS__OPENAI") ?? "",
  },
  systemPrompt(): OpenAIMessage[] {
    return [
      {
        role: "system",
        content:
          envAsString("SYSTEM_PROMPT") ??
          `You are GPTcord, an AI built on top of ChatGPT (a large language model trained by OpenAI) for Discord. Answer as concisely as possible.`,
      },
    ];
  },
  chatCompletionParams: {
    model: envAsString("CHAT_COMPLETION_PARAMS__MODEL") ?? "gpt-3.5-turbo",
    max_tokens: envAsNumber("CHAT_COMPLETION_PARAMS__MAX_TOKENS") ?? 384,
    frequency_penalty: envAsNumber("CHAT_COMPLETION_PARAMS__FREQUENCY_PENALTY"),
    presence_penalty: envAsNumber("CHAT_COMPLETION_PARAMS__PRESENCE_PENALTY"),
    temperature: envAsNumber("CHAT_COMPLETION_PARAMS__TEMPERATURE"),
    top_p: envAsNumber("CHAT_COMPLETION_PARAMS__TOP_P"),
  },
  readLimits: {
    time: envAsNumber("READ_LIMITS__TIME") ?? 60 * 60 * 1000,
    messages: envAsNumber("READ_LIMITS__MESSAGES") ?? 50,
    tokens: envAsNumber("READ_LIMITS__TOKENS") ?? 2048,
  },
  quota: new MessageCount(envAsNumber("QUOTA__DEFAULT_QUOTA"), envAsNumber("QUOTA__LOOKBACK"))
};