/**
 * Copyright since 2025 Mifos Initiative
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

import { Observable } from 'rxjs';

import { ProductsService } from 'app/products/products.service';
import { ClientsService } from 'app/clients/clients.service';
import { SavingsService } from 'app/savings/savings.service';
import { FixedDepositsService } from 'app/deposits/fixed-deposits/fixed-deposits.service';
import { RecurringDepositsService } from 'app/deposits/recurring-deposits/recurring-deposits.service';
import { SystemService } from 'app/system/system.service';
import { AccountingService } from 'app/accounting/accounting.service';
import { UsersService } from 'app/users/users.service';
import { OrganizationService } from 'app/organization/organization.service';

/**
 * The services a maker-checker review screen needs in order to read an entity's current state.
 * Passed in rather than injected here so this stays a plain lookup table with no Angular wiring.
 */
export interface EntityFetchServices {
  products: ProductsService;
  clients: ClientsService;
  savings: SavingsService;
  fixedDeposits: FixedDepositsService;
  recurringDeposits: RecurringDepositsService;
  system: SystemService;
  accounting: AccountingService;
  users: UsersService;
  organization: OrganizationService;
}

/**
 * Entities with exactly one row in the whole tenant (a global settings screen, not a record with an
 * id) - Working Days being the first. These commands carry no resourceId at all, so the normal
 * "no id, no lookup" guard below is relaxed for exactly this set; every other entity's behavior is
 * unchanged.
 */
const SINGLETON_ENTITIES: ReadonlySet<string> = new Set(['WORKINGDAYS']);

/**
 * Maps a maker-checker `entityName` to the existing API that returns that entity as it stands today,
 * so an UPDATE can be shown as OLD -> NEW and a DELETE can show what is about to be removed.
 *
 * Every entry reuses an API the application already calls elsewhere - nothing new was added on the
 * backend. Products are fetched with `template=true` because that response also carries the option
 * lists (`accountingRuleOptions`, `interestCompoundingPeriodTypeOptions`, ...) the payload's bare ids
 * refer to.
 *
 * An entity absent from this table simply has no current-state lookup; callers fall back to rendering
 * the submitted payload, which is what every entity did before this table existed.
 */
const ENTITY_FETCHERS: Record<string, (id: string, s: EntityFetchServices) => Observable<any>> = {
  // ---- Products ----------------------------------------------------------------
  SAVINGSPRODUCT: (id, s) => s.products.getSavingProduct(id, true),
  CURRENTPRODUCT: (id, s) => s.products.getCurrentProduct(id, true),
  SHAREPRODUCT: (id, s) => s.products.getShareProduct(id, true),
  LOANPRODUCT: (id, s) => s.products.getLoanProduct(id, true),
  FIXEDDEPOSITPRODUCT: (id, s) => s.products.getFixedDepositProductAndTemplate(id),
  RECURRINGDEPOSITPRODUCT: (id, s) => s.products.getRecurringDepositProduct(id, true),
  CHARGE: (id, s) => s.products.getCharge(id, true),

  // ---- Accounts ----------------------------------------------------------------
  SAVINGSACCOUNT: (id, s) => s.savings.getSavingsAccountData(id),
  // Deposit accounts must be read through their own endpoints: /savingsaccounts omits the deposit
  // terms (depositAmount, depositPeriod, charts, ...), so comparing against it reports every one of
  // those as newly added.
  FIXEDDEPOSITACCOUNT: (id, s) => s.fixedDeposits.getFixedDepositsAccountData(id),
  RECURRINGDEPOSITACCOUNT: (id, s) => s.recurringDeposits.getRecurringDepositsAccountAndTemplate(id),

  // ---- People and administration ----------------------------------------------
  CLIENT: (id, s) => s.clients.getClientData(id, true),
  ROLE: (id, s) => s.system.getRole(id),
  USER: (id, s) => s.users.getUser(id),
  GLACCOUNT: (id, s) => s.accounting.getGlAccount(id, true),

  // ---- Singleton settings screens ----------------------------------------------
  // No resourceId - the command applies to the one Working Days row the tenant has.
  WORKINGDAYS: (id, s) => s.organization.getWorkingDays()
};

/** Whether this screen can read the entity's current state, and therefore produce a real diff. */
export function canFetchEntity(entityName: string | undefined | null): boolean {
  return !!ENTITY_FETCHERS[(entityName ?? '').toUpperCase()];
}

/**
 * Returns the entity as it stands today, or null when there is no mapping for it or no resource to
 * read - in which case the caller keeps showing the submitted payload rather than failing.
 */
export function fetchCurrentEntity(
  entityName: string | undefined | null,
  resourceId: string | number | undefined | null,
  services: EntityFetchServices
): Observable<any> | null {
  const key = (entityName ?? '').toUpperCase();
  const fetcher = ENTITY_FETCHERS[key];
  if (!fetcher) {
    return null;
  }
  const hasResourceId = resourceId !== null && resourceId !== undefined && resourceId !== '';
  if (!hasResourceId && !SINGLETON_ENTITIES.has(key)) {
    return null;
  }
  return fetcher(String(resourceId ?? ''), services);
}

/**
 * The handful of fields worth showing for a DELETE, whose payload is empty - the checker needs to
 * recognise *which* record is about to go, not read its full configuration. Keys are tried in order
 * and the first present one wins; anything not listed falls back to a generic set.
 */
const DELETE_SUMMARY_KEYS: Record<string, string[]> = {
  SAVINGSPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  CURRENTPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  SHAREPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  LOANPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  FIXEDDEPOSITPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  RECURRINGDEPOSITPRODUCT: [
    'name',
    'shortName',
    'description',
    'currency'
  ],
  CHARGE: [
    'name',
    'currency',
    'amount',
    'chargeAppliesTo',
    'chargeTimeType'
  ],
  CLIENT: [
    'displayName',
    'accountNo',
    'officeName',
    'status',
    'mobileNo',
    'emailAddress'
  ],
  SAVINGSACCOUNT: [
    'accountNo',
    'clientName',
    'savingsProductName',
    'status',
    'currency'
  ],
  FIXEDDEPOSITACCOUNT: [
    'accountNo',
    'clientName',
    'savingsProductName',
    'status',
    'currency'
  ],
  RECURRINGDEPOSITACCOUNT: [
    'accountNo',
    'clientName',
    'savingsProductName',
    'status',
    'currency'
  ],
  ROLE: [
    'name',
    'description',
    'disabled'
  ],
  USER: [
    'username',
    'firstname',
    'lastname',
    'email',
    'officeName'
  ],
  GLACCOUNT: [
    'name',
    'glCode',
    'type',
    'usage',
    'description'
  ]
};

const GENERIC_SUMMARY_KEYS = [
  'name',
  'displayName',
  'accountNo',
  'shortName',
  'username',
  'description',
  'status'
];

/** Field names worth surfacing for the entity about to be deleted. */
export function deleteSummaryKeys(entityName: string | undefined | null): string[] {
  return DELETE_SUMMARY_KEYS[(entityName ?? '').toUpperCase()] ?? GENERIC_SUMMARY_KEYS;
}