/**
 * 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/.
 */

/**
 * Where an active Fixed Deposit sits relative to its own maturity date.
 *
 * MATURED accounts are the ones staff actually need to act on -- the FD has run its course but is
 * still ACTIVE in the core, meaning nobody has applied the maturity instruction yet (or the
 * scheduled job hasn't reached it). DUE_SOON and UPCOMING exist so a branch can see what's coming
 * before it lands, not just after.
 */
export type FdMaturityStage = 'MATURED' | 'DUE_SOON' | 'UPCOMING' | 'ON_TRACK';

/** Day-count thresholds, measured forward from today toward the maturity date. */
export const FD_MATURITY_POLICY = {
  /** Maturing within this many days counts as DUE_SOON. */
  dueSoonDays: 7,
  /** Maturing within this many days (and not already DUE_SOON) counts as UPCOMING. */
  upcomingDays: 30
};

export interface FdMaturityStageMeta {
  stage: FdMaturityStage;
  label: string;
  /** Colour key the template maps to a badge/tile class. */
  tone: 'info' | 'warn' | 'danger' | 'neutral';
  summary: string;
}

export const FD_MATURITY_STAGES: Record<FdMaturityStage, FdMaturityStageMeta> = {
  MATURED: {
    stage: 'MATURED',
    label: 'Matured',
    tone: 'danger',
    summary: 'Past maturity date and still active -- the maturity instruction has not been applied yet.'
  },
  DUE_SOON: {
    stage: 'DUE_SOON',
    label: `Maturing ≤ ${FD_MATURITY_POLICY.dueSoonDays} Days`,
    tone: 'warn',
    summary: 'Matures within the week.'
  },
  UPCOMING: {
    stage: 'UPCOMING',
    label: `Maturing ≤ ${FD_MATURITY_POLICY.upcomingDays} Days`,
    tone: 'info',
    summary: 'Matures within the month.'
  },
  ON_TRACK: {
    stage: 'ON_TRACK',
    label: 'On Track',
    tone: 'neutral',
    summary: 'Maturity date is further out.'
  }
};

/** FD types the manual-renewal action applies to. SPECIAL is architecturally forced to Transfer to
 *  Savings server-side and can never be Reinvest-configured, so it's never renewable here. */
const RENEWABLE_FD_TYPES = [
  'SINGLE',
  'DOUBLE'
];

/** DepositAccountOnClosureType labels, for the "what will happen automatically" sub-label shown on a
 *  matured row that already carries an explicit instruction from account-opening. */
const ON_CLOSURE_TYPE_LABELS: Record<number, string> = {
  200: 'Transfer to Savings',
  300: 'Reinvest Principal + Interest',
  400: 'Reinvest Principal Only'
};

/** One active Fixed Deposit account, positioned on the maturity ladder. */
export interface FdMaturityRow {
  id: number;
  accountNo: string;
  clientId: number | null;
  clientName: string;
  productName: string;
  maturityDate: string;
  depositAmount: number | null;
  maturityAmount: number | null;
  /** Negative once the maturity date has passed. */
  daysRemaining: number;
  /** 0 while not yet matured; how many days past maturity otherwise. */
  daysOverdue: number;
  stage: FdMaturityStage;
  meta: FdMaturityStageMeta;
  /** Null/0 -- no buffer configured; renewing after the maturity date itself pays gap interest. */
  renewalGracePeriodDays: number | null;
  linkedAccountId: number | null;
  /** The account's own stored DepositAccountOnClosureType, raw -- null when none was chosen at
   *  account-opening. On a renewable row that DOES carry one (grace-period case: the account picked
   *  Reinvest, and is only waiting because the product also has a grace window), the Renew dialog
   *  pre-selects this rather than presenting a neutral, undecided choice -- the maker already decided
   *  what this FD should do, grace only changed when that gets carried out. */
  onClosureType: number | null;
  /** True only when the account was opened with NO maturity instruction at all (the officer left
   *  Maturity Instructions blank at account-opening) -- that's the one case nothing else will ever
   *  act on this FD, so the Dashboard's manual Renew action is meaningful. An account that WAS given
   *  an explicit instruction (Transfer to Savings or either Reinvest option) auto-processes on its
   *  own via the nightly job, exactly as it always has -- the Dashboard only reports on those, it
   *  doesn't also offer to renew them. */
  isReinvestEligible: boolean;
  /** True once matured AND eligible -- the only case where nothing has auto-processed it, so a
   *  manual action from the Dashboard is meaningful. */
  renewable: boolean;
  /** Only meaningful when renewable -- true if still inside the grace window (backdated renewal,
   *  no gap interest), false if the window has passed (renews from today, gap interest applies). */
  withinGraceWindow: boolean;
  /** Set on a matured row that is NOT renewable because it already carries an explicit instruction --
   *  what it was configured to do at account-opening, shown so staff can see at a glance what tonight's
   *  job will do without opening the account. Null for a renewable row (nothing decided yet) or a row
   *  that isn't matured. */
  configuredInstructionLabel: string | null;
}

/** Days between two ISO dates, positive when `later` is after `earlier`. */
function daysBetween(earlier: string, later: string): number {
  const a = new Date(`${earlier}T00:00:00Z`).getTime();
  const b = new Date(`${later}T00:00:00Z`).getTime();
  return Math.round((b - a) / 86400000);
}

/** Which rung of the ladder an account is on, from how many days remain until maturity. */
export function maturityStage(daysRemaining: number): FdMaturityStage {
  if (daysRemaining <= 0) {
    return 'MATURED';
  }
  if (daysRemaining <= FD_MATURITY_POLICY.dueSoonDays) {
    return 'DUE_SOON';
  }
  if (daysRemaining <= FD_MATURITY_POLICY.upcomingDays) {
    return 'UPCOMING';
  }
  return 'ON_TRACK';
}

/** Builds one dashboard row from a raw `/fixeddepositaccounts` list item and today's ISO date. */
export function buildMaturityRow(
  fd: {
    id: number;
    accountNo: string;
    clientId?: number;
    clientName?: string;
    savingsProductName?: string;
    productName?: string;
    fdType?: string;
    maturityDate: string;
    depositAmount?: number;
    maturityAmount?: number;
    onClosureType?: number;
    linkedAccountId?: number;
    renewalGracePeriodDays?: number;
  },
  today: string
): FdMaturityRow | null {
  if (!fd.maturityDate) {
    // No maturity date means the account isn't fully assembled yet (e.g. a chart not applied) --
    // nothing sound to bucket it by, so it's left off the worklist rather than shown wrong.
    return null;
  }
  const daysRemaining = daysBetween(today, fd.maturityDate);
  const stage = maturityStage(daysRemaining);
  // No grace configured reads as a 0-day buffer, not "not renewable" -- it only shrinks the backdate
  // window, matching the backend's default (renewMaturedFixedDeposit treats a missing value as 0).
  const gracePeriodDays = fd.renewalGracePeriodDays ?? 0;
  // Mirrors updateMaturityDetails()'s own "will I auto-process this?" check exactly, inverted: the
  // nightly job leaves an account alone (never touches it) only when it was opened with NO maturity
  // instruction at all -- that's the one case the Dashboard's Renew action exists for. An account
  // opened WITH an explicit instruction auto-processes tonight regardless of the product's renewal
  // grace period (the grace window never delays it), so it's never renewable here either way.
  const isReinvestEligible =
    !!fd.fdType && RENEWABLE_FD_TYPES.includes(fd.fdType as string) && fd.onClosureType == null;
  const renewable = stage === 'MATURED' && isReinvestEligible;
  const withinGraceWindow = renewable && daysOverdueFor(daysRemaining) <= gracePeriodDays;
  const configuredInstructionLabel =
    stage === 'MATURED' && !renewable && fd.onClosureType != null
      ? (ON_CLOSURE_TYPE_LABELS[fd.onClosureType] ?? null)
      : null;

  return {
    id: fd.id,
    accountNo: fd.accountNo || '',
    clientId: fd.clientId ?? null,
    clientName: fd.clientName || '—',
    productName: fd.productName || fd.savingsProductName || '—',
    maturityDate: fd.maturityDate,
    depositAmount: fd.depositAmount ?? null,
    maturityAmount: fd.maturityAmount ?? null,
    daysRemaining,
    daysOverdue: daysOverdueFor(daysRemaining),
    stage,
    meta: FD_MATURITY_STAGES[stage],
    renewalGracePeriodDays: gracePeriodDays,
    linkedAccountId: fd.linkedAccountId ?? null,
    onClosureType: fd.onClosureType ?? null,
    isReinvestEligible,
    renewable,
    withinGraceWindow,
    configuredInstructionLabel
  };
}

function daysOverdueFor(daysRemaining: number): number {
  return daysRemaining < 0 ? -daysRemaining : 0;
}

export interface FdMaturitySummary {
  total: number;
  matured: number;
  dueSoon: number;
  upcoming: number;
  onTrack: number;
}

export function maturitySummary(rows: FdMaturityRow[]): FdMaturitySummary {
  return {
    total: rows.length,
    matured: rows.filter((r) => r.stage === 'MATURED').length,
    dueSoon: rows.filter((r) => r.stage === 'DUE_SOON').length,
    upcoming: rows.filter((r) => r.stage === 'UPCOMING').length,
    onTrack: rows.filter((r) => r.stage === 'ON_TRACK').length
  };
}

/** Sorts the worklist so the most overdue, then the soonest-to-mature, rows come first. */
export function sortMaturityRows(rows: FdMaturityRow[]): FdMaturityRow[] {
  const rank: Record<FdMaturityStage, number> = {
    MATURED: 0,
    DUE_SOON: 1,
    UPCOMING: 2,
    ON_TRACK: 3
  };
  return [...rows].sort((a, b) => rank[a.stage] - rank[b.stage] || a.daysRemaining - b.daysRemaining);
}