import { err, ok, type CommandContext } from "@tailor-platform/erp-kit/core";
import { Decimal } from "decimal.js";
import type { BankStatementLineFlowDirection } from "../generated/enums";
import type { Transaction } from "../generated/kysely-tailordb";
import {
  BankAccountInactiveError,
  BankAccountNotFoundError,
  BankStatementInvalidError,
} from "../lib/errors.generated";

export interface CreateBankStatementLineInput {
  lineNumber: number;
  bookingDate: Date;
  valueDate?: Date;
  flowDirection: BankStatementLineFlowDirection;
  amount: string;
  bankReference?: string;
  endToEndId?: string;
  counterpartyName?: string;
  counterpartyAccount?: string;
  description?: string;
}

export interface CreateBankStatementInput {
  bankAccountId: string;
  statementNumber: string;
  statementDate: Date;
  openingBalance: string;
  closingBalance: string;
  importedAt?: Date;
  lines: CreateBankStatementLineInput[];
}

export async function run<
  HF extends Record<string, unknown> = Record<string, never>,
  LF extends Record<string, unknown> = Record<string, never>,
>(
  db: Transaction,
  input: Omit<CreateBankStatementInput, "lines"> &
    HF & {
      lines: (CreateBankStatementLineInput & LF)[];
    },
  _ctx: CommandContext,
) {
  const {
    bankAccountId,
    statementNumber,
    statementDate,
    openingBalance,
    closingBalance,
    importedAt,
    lines,
    ...headerCustomFields
  } = input;
  const bankAccount = await db
    .selectFrom("BankAccount")
    .selectAll()
    .where("id", "=", bankAccountId)
    .executeTakeFirst();
  if (!bankAccount) return err(new BankAccountNotFoundError(bankAccountId));
  if (bankAccount.status !== "ACTIVE") return err(new BankAccountInactiveError(bankAccountId));
  if (statementNumber.trim() === "" || lines.length === 0) {
    return err(new BankStatementInvalidError(statementNumber));
  }

  const seenLineNumbers = new Set<number>();
  let movement = new Decimal(0);
  for (const line of lines) {
    if (
      !Number.isInteger(line.lineNumber) ||
      line.lineNumber < 1 ||
      seenLineNumbers.has(line.lineNumber)
    ) {
      return err(new BankStatementInvalidError(`${statementNumber}:${line.lineNumber}`));
    }
    seenLineNumbers.add(line.lineNumber);
    const amount = new Decimal(line.amount);
    if (amount.lte(0))
      return err(new BankStatementInvalidError(`${statementNumber}:${line.lineNumber}`));
    movement = line.flowDirection === "CREDIT" ? movement.plus(amount) : movement.minus(amount);
  }
  if (!new Decimal(openingBalance).plus(movement).eq(closingBalance)) {
    return err(new BankStatementInvalidError(statementNumber));
  }

  const bankStatement = await db
    .insertInto("BankStatement")
    .values({
      ...(headerCustomFields as Record<string, unknown>),
      bankAccountId,
      statementNumber,
      statementDate,
      openingBalance,
      closingBalance,
      importedAt: importedAt ?? new Date(),
    })
    .returningAll()
    .executeTakeFirstOrThrow();

  const bankStatementLines = await db
    .insertInto("BankStatementLine")
    .values(
      lines.map((line) => {
        const {
          lineNumber,
          bookingDate,
          valueDate,
          flowDirection,
          amount,
          bankReference,
          endToEndId,
          counterpartyName,
          counterpartyAccount,
          description,
          ...lineCustomFields
        } = line;
        return {
          ...(lineCustomFields as Record<string, unknown>),
          bankStatementId: bankStatement.id,
          lineNumber,
          bookingDate,
          valueDate: valueDate ?? null,
          flowDirection,
          amount,
          reconciliationStatus: "UNRECONCILED",
          currentBankReconciliationId: null,
          bankReference: bankReference ?? null,
          endToEndId: endToEndId ?? null,
          counterpartyName: counterpartyName ?? null,
          counterpartyAccount: counterpartyAccount ?? null,
          description: description ?? null,
        };
      }),
    )
    .returningAll()
    .execute();

  return ok({ bankStatement, bankStatementLines });
}