const { runSelectQuery } = require('../utils/queries');

const generalSlots = [
    `10:00 - 10:30`, `10:45 - 11:15`, `11:30 - 12:00`, `12:15 - 12:45`, `13:00 - 13:30`,
    `13:45 - 14:15`, `14:30 - 15:00`, `15:15 - 15:45`, `16:00 - 16:30`, `16:45 - 17:15`, `17:30 - 18:00`
];

//async function to get list of booked slots for a given date
async function getBookedSlots(date) {
    if (!date) {
        throw new Error('Date is required');
    }

    // Ensure the date is in the correct format (YYYY-MM-DD)
    const isValidDate = /^\d{4}-\d{2}-\d{2}$/.test(date);
    if (!isValidDate) {
        throw new Error('Invalid date format. Expected YYYY-MM-DD');
    }

    try {
        const query = `
            SELECT slot FROM demo_requests WHERE demo_date = ?;
        `;
        const results = await runSelectQuery(query, date);

        console.log(`Fetched ${results.length} slots for date: ${date}`);

        // Check if results are empty
        if (!results || results.length === 0) {
            console.log(`No slots found for date: ${date}`);
            return [];  // Return an empty array if no slots are found
        }

        // Extract slots, with checks to ensure each result contains a 'slot' property
        const slots = results.map(result => {
            if (!result.slot) {
                console.warn(`No slot found for record: ${JSON.stringify(result)}`);
                return null;  // Handle cases where slot is undefined or null
            }
            return result.slot;
        }).filter(slot => slot !== null);  // Remove any null values (in case of missing slots)

        return slots;
    } catch (error) {
        console.error('Error fetching booked slots:', error.message);
        throw error;  // Re-throw the error after logging it
    }
}

//async function to get available slots for a given date
async function getAvailableSlots(date) {
    if (!date) {
        throw new Error('Date is required');
    }

    // Ensure the date is in the correct format (YYYY-MM-DD)
    const isValidDate = /^\d{4}-\d{2}-\d{2}$/.test(date);
    if (!isValidDate) {
        throw new Error('Invalid date format. Expected YYYY-MM-DD');
    }

    try {
        // Fetch the booked slots for the given date
        const bookedSlots = await getBookedSlots(date);
        console.log('Booked slots:', bookedSlots);

        // If no booked slots, all general slots are available
        if (bookedSlots.length === 0) {
            return generalSlots;
        }

        // Check if generalSlots exists and is an array
        if (!Array.isArray(generalSlots) || generalSlots.length === 0) {
            throw new Error('General slots are not properly defined');
        }

        // Filter the general slots to remove any booked slots
        const availableSlots = generalSlots.filter(slot => !bookedSlots.includes(slot));

        // Return the available slots
        return availableSlots;
    } catch (error) {
        console.error('Error fetching available slots:', error.message);
        throw error;  // Re-throw the error after logging it
    }
}

module.exports = { getAvailableSlots, getBookedSlots};