sparebank1_actual_budget_integration/src/bank/sparebank1.ts

// TODO move types
import { BANK_INITIAL_REFRESH_TOKEN } from "@/../config.ts"
import logger from "@/logger.ts"
import dayjs from "dayjs"
import { Database } from "better-sqlite3"
import {
  fetchToken,
  insertTokens,
  type TokenResponse,
} from "@/bank/db/queries.ts"
import * as Api from "./sparebank1Api.ts"
import { toISODateString } from "@/date.ts"

export interface OAuthTokenResponse {
  access_token: string
  expires_in: number
  refresh_token_expires_in: number
  refresh_token_absolute_expires_in: number
  token_type: "Bearer"
  refresh_token: string
}

export interface Transaction {
  id: string
  nonUniqueId: string
  date: number // Unix time
  amount: number // Amount in NOK
  cleanedDescription: string
  remoteAccountName: string

  [key: string]: string | number | boolean | unknown
}

export interface TransactionResponse {
  transactions: ReadonlyArray<Transaction>
}

export type Bank = Sparebank1

export interface Sparebank1 {
  transactionsPastDay: (
    accountKeys: ReadonlyArray<string> | string,
  ) => Promise<TransactionResponse>
}

export class Sparebank1Impl implements Sparebank1 {
  private static baseUrl = "https://api.sparebank1.no"
  private readonly db: Database

  constructor(db: Database) {
    this.db = db
  }

  private async getAccessToken(): Promise<string> {
    const accessToken = fetchToken(this.db, "access-token")

    if (accessToken && this.isValidToken(accessToken)) {
      return accessToken.token
    }
    const response = await this.fetchNewTokens()
    return response.access_token
  }

  private isValidToken(tokenResponse: TokenResponse): boolean {
    // TODO make sure the same timezone is used. Db uses UTC
    return dayjs().isBefore(tokenResponse.expires_at)
  }

  private async getRefreshToken(): Promise<string> {
    const tokenResponse = fetchToken(this.db, "refresh-token")
    logger.debug(`Database returned refresh token: '%o'`, tokenResponse)
    if (!tokenResponse) {
      return BANK_INITIAL_REFRESH_TOKEN
    } else if (this.isValidToken(tokenResponse)) {
      return tokenResponse.token
    }
    // TODO clear database, if refresh token is invalid, will cause Exceptions on each call
    throw new Error("Refresh token is expired. Create a new one")
  }

  async fetchNewTokens(): Promise<OAuthTokenResponse> {
    const refreshToken = await this.getRefreshToken()
    logger.debug(`Found refresh token '${refreshToken}'`)
    const result = await Api.refreshToken(refreshToken)

    if (result.status === "failure") {
      throw logger.error({
        err: new Error(`Failed to fetch refresh token: '${result.data}'`),
      })
    }
    const oAuthToken = result.data

    insertTokens(this.db, oAuthToken)
    return oAuthToken
  }

  async transactionsPastDay(
    accountKeys: ReadonlyArray<string> | string,
  ): Promise<TransactionResponse> {
    const today = dayjs()
    const lastDay = today.subtract(1, "day")

    const queries = new URLSearchParams({
      // TODO allow multiple accountKeys
      accountKey:
        typeof accountKeys === "string" ? accountKeys : accountKeys[0],
      fromDate: toISODateString(lastDay),
      toDate: toISODateString(today),
    })

    const accessToken = await this.getAccessToken()
    logger.debug(`Found access token '${accessToken}'`)
    const url = `${Sparebank1Impl.baseUrl}/personal/banking/transactions?${queries}`
    logger.debug(`Sending GET request to '${url}'`)
    const response = await fetch(url, {
      headers: {
        Authorization: `Bearer ${accessToken}`,
        Accept: "application/vnd.sparebank1.v1+json;charset=utf-8",
      },
    })
    logger.debug(`Received response with status '${response.status}'`)
    if (response.ok) {
      return response.json()
    } else {
      logger.warn(await response.json())
      return { transactions: [] }
    }
  }
}