/*
 * Copyright (C) 2025 Jakub Žitník
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

import { GoogleGenAI } from "@google/genai";
import fs from "fs/promises";

const TIMETABLE_PATH = "db/persistent/timetables.json";

export async function setup() {
  const timetable = JSON.parse(
    await fs.readFile(TIMETABLE_PATH, { encoding: "utf8" })
  );

  const ai = new GoogleGenAI({
    apiKey: process.env.GEMINI_API_KEY
  });

  const systemPrompt = await fs.readFile("./prompt.txt", "utf-8");

  /**
   * @param {Object} changesByClass
   *   {
   *     "1A": [ ...changes... ],
   *     "2B": [ ...changes... ]
   *   }
   * @param {number} dayIndex
   */
  return async (changesByClass, dayIndex) => {
    const input = {};

    for (const cls of Object.keys(changesByClass)) {
      input[cls] = {
        stableSchedule: timetable[cls][dayIndex],
        changes: changesByClass[cls]
      };
    }

    const response = await ai.models.generateContent({
      model: "gemini-3-flash-preview",
      config: {
        systemInstruction: {
          parts: [{ text: systemPrompt }]
        },
        temperature: 0
      },
      contents: [
        {
          role: "user",
          parts: [{ text: JSON.stringify(input) }]
        }
      ]
    });

    const aiOutput = response.text ?? "";

    try {
      return JSON.parse(aiOutput);
    } catch {
      return { invalid: true, reason: "AI output could not be parsed" };
    }
  };
}