// TODO move types
import {
  BANK_INITIAL_REFRESH_TOKEN,
  BANK_OAUTH_CLIENT_ID,
  BANK_OAUTH_CLIENT_SECRET,
} from "@/../config.ts"
import logger from "@/logger.ts"
import dayjs from "dayjs"

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
}

interface AccessToken {
  access_token: string
  expires_in: number
}

interface RefreshToken {
  refresh_token: string
  expires_in: number
}

export interface Transaction {
  id: string
  date: string
  amount: number
  description: string
  cleanedDescription: string
  remoteAccountName: string

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

export type Bank = Sparebank1

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

export class Sparebank1Impl implements Sparebank1 {
  private static baseUrl = "https://api.sparebank1.no"
  private _accessToken: AccessToken | undefined
  private _refreshToken: RefreshToken | undefined

  private set accessToken(accessToken: AccessToken) {
    this._accessToken = accessToken
  }

  private set refreshToken(refreshToken: RefreshToken) {
    this._refreshToken = refreshToken
  }

  private async getAccessToken(): Promise<string> {
    const accessToken = this._accessToken
    if (!accessToken) {
      const response = await this.fetchNewRefreshToken()
      return response.access_token
    }
    return accessToken.access_token
  }

  private async getRefreshToken(): Promise<string> {
    const refreshToken = this._refreshToken
    // TODO check if valid, use jsonwebtoken npm library?
    const isValid = true
    if (!refreshToken) {
      return BANK_INITIAL_REFRESH_TOKEN
    } else if (isValid) {
      return refreshToken.refresh_token
    } else {
      const response = await this.fetchNewRefreshToken()
      return response.refresh_token
    }
  }

  async fetchNewRefreshToken(): Promise<OAuthTokenResponse> {
    const refreshToken: string = await this.getRefreshToken()
    const queries = new URLSearchParams({
      client_id: BANK_OAUTH_CLIENT_ID,
      client_secret: BANK_OAUTH_CLIENT_SECRET,
      refresh_token: refreshToken,
      grant_type: "refresh_token",
    })
    const response = await fetch(`${Sparebank1Impl.baseUrl}/token?${queries}`)

    if (!response.ok) {
      throw new Error("Failed to fetch refresh token")
    }

    const oAuthToken: OAuthTokenResponse = await response.json()
    this.accessToken = {
      access_token: oAuthToken.access_token,
      expires_in: oAuthToken.expires_in,
    }
    this.refreshToken = {
      refresh_token: oAuthToken.refresh_token,
      expires_in: oAuthToken.refresh_token_expires_in,
    }
    return oAuthToken
  }

  async transactionsPastDay(
    accountKeys: ReadonlyArray<string> | string,
  ): Promise<ReadonlyArray<Transaction>> {
    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: lastDay.toString(),
      toDate: today.toString(),
    })

    const accessToken = await this.getAccessToken()
    const response = await fetch(
      `${Sparebank1Impl.baseUrl}/transactions?${queries}`,
      {
        headers: {
          Authorization: `Bearer ${accessToken}`,
        },
      },
    )
    if (response.ok) {
      return response.json()
    } else {
      logger.warn(
        `transactionsPastDay returned a ${response.status} with the text ${response.statusText}`,
      )
      return []
    }
  }
}