e-commerce/web_backend/src/main/java/org/hso/ecommerce/controller/intern/accounting/AccountingController.java

package org.hso.ecommerce.controller.intern.accounting;

import org.hso.ecommerce.entities.booking.Booking;
import org.hso.ecommerce.entities.booking.BookingAccountEntry;
import org.hso.ecommerce.entities.booking.BookingReason;
import org.hso.ecommerce.repos.booking.BookingRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

@Controller
public class AccountingController {

    @Autowired
    private BookingRepository bookingRepository = null;

    /**
     * A description used to render the html template for the overview of all bookings
     */
    static class TemplateBooking {
        public String datetime;
        public String amount;
        public String source;
        public String sourceAddr;
        public String sourceBalance;
        public String destination;
        public String destinationAddr;
        public String destinationBalance;
        public String reason;
        public String reference;
        public String referenceAddr;
    }

    /**
     * A description used to render the html template for bookings on a specific account
     */
    public static class ShortTemplateBooking {
        public String datetime;
        public String amount;
        public String source;
        public String sourceAddr;
        public String balance;
        public String reason;
        public String reference;
        public String referenceAddr;
    }

    public static class ShortTemplateBookingResult {
        public final String balance;
        public final List<ShortTemplateBooking> bookings;

        public ShortTemplateBookingResult(String balance, List<ShortTemplateBooking> bookings) {
            this.balance = balance;
            this.bookings = bookings;
        }
    }

    /**
     * Used to check which side of the booking (source or destination) is the account we are currently looking at.
     */
    public interface AccountFilter {
        boolean matches(BookingAccountEntry account);
    }

    /**
     * Renders template information for the bookings of one specific account.
     *
     * @param bookings       The (already fetched) booking entities to display
     * @param currentAccount A filter matching the account that is to be displayed
     * @return A collection result containing the final balance and all booking entries.
     */
    public ShortTemplateBookingResult buildShortTemplate(List<Booking> bookings, AccountFilter currentAccount) {
        List<ShortTemplateBooking> templateBookings = new ArrayList<>();
        for (Booking booking : bookings) {
            ShortTemplateBooking tb = new ShortTemplateBooking();
            tb.datetime = new SimpleDateFormat("dd.MM.yyyy HH:mm").format(booking.created);
            tb.reason = booking.reason.comment;
            tb.reference = describeReference(booking.reason);
            tb.referenceAddr = linkToReference(booking.reason);
            if (booking.destination != null && currentAccount.matches(booking.destination)) {
                // Money was transferred onto the account we are looking at.
                tb.amount = fmtEuro(booking.amountCent);
                if (booking.source != null) {
                    tb.source = describeAccount(booking.source);
                    tb.sourceAddr = linkAddrOfAccount(booking.source);
                } else {
                    tb.source = "-";
                    tb.sourceAddr = null;
                }
                tb.balance = fmtEuro(booking.destination.newSumCent);
            } else if (booking.source != null && currentAccount.matches(booking.source)) {
                // Money was transferred away from the account we are looking at.
                tb.amount = fmtEuro(-booking.amountCent); // Negative because of the transfer away
                if (booking.destination != null) {
                    tb.source = describeAccount(booking.destination); // 'source' means 'the other account' in this case
                    tb.sourceAddr = linkAddrOfAccount(booking.destination);
                } else {
                    tb.source = "-";
                    tb.sourceAddr = null;
                }
                tb.balance = fmtEuro(booking.source.newSumCent);
            } else {
                throw new RuntimeException(
                        "This booking should not appear in this list, because neither source nor destination is the account we are looking at.");
            }
            templateBookings.add(tb);
        }

        String balance = templateBookings.isEmpty() ? fmtEuro(0) : templateBookings.get(0).balance;
        return new ShortTemplateBookingResult(balance, templateBookings);
    }

    public static String fmtEuro(long amountCent) {
        return String.format("%.2f EUR", amountCent / 100.0);
    }

    private String describeAccount(BookingAccountEntry account) {
        if (account.isMainAccount) {
            return "Hauptkonto";
        } else if (account.isVATAccount) {
            return "Mehrwertsteuer";
        } else if (account.supplierAccount != null) {
            return "Lieferant " + account.supplierAccount.id;
        } else if (account.userAccount != null) {
            return "Kunde " + account.userAccount.id;
        } else {
            return "- unbekannt -";
        }
    }

    private String linkAddrOfAccount(BookingAccountEntry account) {
        if (account.isMainAccount) {
            return "/intern/accounting/main";
        } else if (account.isVATAccount) {
            return "/intern/accounting/vat";
        } else if (account.supplierAccount != null) {
            return "/intern/suppliers/" + account.supplierAccount.id;
        } else if (account.userAccount != null) {
            return "/intern/customers/" + account.userAccount.id;
        } else {
            return null;
        }
    }

    private String describeReference(BookingReason reason) {
        if (reason.customerOrder != null) {
            return reason.customerOrder.id + "";
        } else if (reason.customerPayment != null) {
            return "Bezahlung mit Kreditkarte " + reason.customerPayment.payment.creditCardNumber;
        } else if (reason.supplierOrder != null) {
            return "Lieferanten-Bestellung " + reason.supplierOrder.supplier.name;
        } else if (reason.supplierPayment != null) {
            return "Lieferanten-Zahlung " + reason.supplierPayment.name;
        } else {
            return "-";
        }
    }

    private String linkToReference(BookingReason reason) {
        if (reason.customerOrder != null) {
            return "/intern/customerOrders/" + reason.customerOrder.id;
        } else if (reason.supplierPayment != null) {
            return "/intern/suppliers/#q=" + reason.supplierPayment.id;
        } else if (reason.supplierOrder != null) {
            return "/intern/supplierOrders/#q=" + reason.supplierOrder.id;
        } else {
            return null;
        }
    }

    @GetMapping("/intern/accounting/")
    public String accounting(Model model) {
        List<Booking> bookings = bookingRepository.allBookingsReverseChronologically();
        List<TemplateBooking> templateBookings = new ArrayList<>();
        for (Booking booking : bookings) {
            TemplateBooking tb = new TemplateBooking();
            tb.datetime = new SimpleDateFormat("dd.MM.yyyy HH:mm").format(booking.created);
            tb.amount = fmtEuro(booking.amountCent);
            if (booking.source != null) {
                tb.source = describeAccount(booking.source);
                tb.sourceAddr = linkAddrOfAccount(booking.source);
                tb.sourceBalance = fmtEuro(booking.source.newSumCent);
            } else {
                tb.source = "-";
                tb.sourceAddr = null;
                tb.sourceBalance = "-";
            }
            if (booking.destination != null) {
                tb.destination = describeAccount(booking.destination);
                tb.destinationAddr = linkAddrOfAccount(booking.destination);
                tb.destinationBalance = fmtEuro(booking.destination.newSumCent);
            } else {
                tb.destination = "-";
                tb.destinationAddr = null;
                tb.destinationBalance = "-";
            }
            tb.reason = booking.reason.comment;
            tb.reference = describeReference(booking.reason);
            tb.referenceAddr = linkToReference(booking.reason);
            templateBookings.add(tb);
        }

        model.addAttribute("bookings", templateBookings);
        return "intern/accounting/index";
    }

    @GetMapping("/intern/accounting/vat")
    public String accountingVat(Model model) {
        List<Booking> bookings = bookingRepository.vatBookingsReverseChronologically();
        ShortTemplateBookingResult result = buildShortTemplate(bookings, account -> account.isVATAccount);
        model.addAttribute("balance", result.balance);
        model.addAttribute("bookings", result.bookings);
        return "intern/accounting/vat";
    }

    @GetMapping("/intern/accounting/main")
    public String accountingIntern(Model model) {
        List<Booking> bookings = bookingRepository.mainBookingsReverseChronologically();
        ShortTemplateBookingResult result = buildShortTemplate(bookings, account -> account.isMainAccount);
        model.addAttribute("balance", result.balance);
        model.addAttribute("bookings", result.bookings);
        return "intern/accounting/main";
    }
}