'use server';

import { z } from 'zod';
import { revalidatePath } from 'next/cache';
import { redirect } from 'next/navigation';
import clientPromise from './mongodb';
import { ObjectId } from 'mongodb';
import { BillAttachment } from './db-types';

export type State = {
    errors?: {
        billName?: string[];
        billAttachment?: string[],
        billNotes?: string[],
    };
    message?:string | null;
}

const FormSchema = z.object({
    _id: z.string(),
    billName: z.coerce.string().min(1, "Bill Name is required."),
    billNotes: z.string(),
  });

const UpdateBill = FormSchema.omit({ _id: true });

/**
 * converts the file to a format stored in the database
 * @param billAttachment 
 * @returns 
 */
const serializeAttachment = async (billAttachment: File | null) => {

    if (!billAttachment) {
        return null;
    }

    const {
        name: fileName,
        size: fileSize,
        type: fileType,
        lastModified: fileLastModified,
    } = billAttachment;

    if(!fileName || fileName === 'undefined') {
        return null;
    }

    // convert the file contents to a base64 string
    const fileContents = await billAttachment.arrayBuffer();
    const fileContentsBase64 = Buffer.from(fileContents).toString('base64');

    // create an object to store the file in the database
    return({
        fileName: decodeURIComponent(fileName),
        fileSize,
        fileType,
        fileLastModified,
        fileContentsBase64,
    } as BillAttachment);
}

/**
 * Server-side action which creates a new bill
 * @param locationId location of the bill
 * @param billId ID of the bill
 * @param prevState previous state of the form
 * @param formData form data
 * @returns 
 */
export async function updateBill(locationId: string, billId:string, prevState:State, formData: FormData) {

    const validatedFields = UpdateBill.safeParse({
        billName: formData.get('billName'),
        billNotes: formData.get('billNotes'),
    });

    // If form validation fails, return errors early. Otherwise, continue...
    if(!validatedFields.success) {
        console.log("updateBill.validation-error");
        return({
            errors: validatedFields.error.flatten().fieldErrors,
            message: "Missing Fields. Field to Update Bill.",
        });
    }

    const {
        billName,
        billNotes,
    } = validatedFields.data;

    const billPaid = formData.get('billPaid') === 'on';

    // update the bill in the mongodb
    const client = await clientPromise;
    const db = client.db("rezije");
    
    const billAttachment = await serializeAttachment(formData.get('billAttachment') as File);

    // if there is an attachment, update the attachment field
    // otherwise, do not update the attachment field
    const mongoDbSet = billAttachment ? {
        "bills.$[elem].name": billName,
        "bills.$[elem].paid": billPaid,
        "bills.$[elem].attachment": billAttachment,
        "bills.$[elem].notes": billNotes,
    }: {
        "bills.$[elem].name": billName,
        "bills.$[elem].paid": billPaid,
        "bills.$[elem].notes": billNotes,
    };


    // find a location with the given locationID
    const post = await db.collection<Location>("lokacije").updateOne(
        {
            _id: locationId // find a location with the given locationID
        },
        {
            $set: mongoDbSet
        }, {
            arrayFilters: [
                { "elem._id": { $eq: new ObjectId(billId) } } // find a bill with the given billID
            ]
        });

    // clear the cache for the path
    revalidatePath('/');
    // go to the bill list
    redirect('/');
}

export async function gotoHome() {
    redirect('/');   
}