import type { AccountingProvider, OAuthTokens, IncomeEntry, ExpenseEntry } from "./types"
import { redirectUri } from "./types"

// QuickBooks Online. Docs: https://developer.intuit.com/app/developer/qbo/docs/develop
const CLIENT_ID = process.env.QBO_CLIENT_ID ?? ""
const CLIENT_SECRET = process.env.QBO_CLIENT_SECRET ?? ""
const ENV = (process.env.QBO_ENVIRONMENT ?? "sandbox").toLowerCase()
const API_BASE = ENV === "production" ? "https://quickbooks.api.intuit.com" : "https://sandbox-quickbooks.api.intuit.com"
const TOKEN_URL = "https://oauth.platform.intuit.com/oauth2/v1/tokens/bearer"
const MINOR = "73"

function basicAuth() {
  return "Basic " + Buffer.from(`${CLIENT_ID}:${CLIENT_SECRET}`).toString("base64")
}

async function tokenRequest(form: Record<string, string>): Promise<OAuthTokens> {
  const res = await fetch(TOKEN_URL, {
    method: "POST",
    headers: { Authorization: basicAuth(), "Content-Type": "application/x-www-form-urlencoded", Accept: "application/json" },
    body: new URLSearchParams(form),
  })
  if (!res.ok) throw new Error(`QuickBooks token error ${res.status}: ${await res.text()}`)
  const j = (await res.json()) as { access_token: string; refresh_token: string; expires_in: number }
  return {
    accessToken: j.access_token,
    refreshToken: j.refresh_token,
    expiresAt: new Date(Date.now() + j.expires_in * 1000).toISOString(),
    realmId: null,
    orgName: null,
  }
}

async function api(tokens: OAuthTokens, path: string, init?: RequestInit) {
  const res = await fetch(`${API_BASE}/v3/company/${tokens.realmId}/${path}${path.includes("?") ? "&" : "?"}minorversion=${MINOR}`, {
    ...init,
    headers: { Authorization: `Bearer ${tokens.accessToken}`, Accept: "application/json", "Content-Type": "application/json", ...(init?.headers ?? {}) },
  })
  if (!res.ok) throw new Error(`QuickBooks API ${res.status}: ${(await res.text()).slice(0, 300)}`)
  return res.json()
}

async function query<T = Record<string, unknown>>(tokens: OAuthTokens, q: string): Promise<T[]> {
  const j = await api(tokens, `query?query=${encodeURIComponent(q)}`)
  const key = Object.keys(j.QueryResponse ?? {}).find((k) => Array.isArray(j.QueryResponse[k]))
  return key ? j.QueryResponse[key] : []
}

export const quickbooks: AccountingProvider = {
  id: "quickbooks",
  label: "QuickBooks Online",
  configured: () => Boolean(CLIENT_ID && CLIENT_SECRET),

  getAuthUrl(state) {
    const p = new URLSearchParams({
      client_id: CLIENT_ID,
      response_type: "code",
      scope: "com.intuit.quickbooks.accounting",
      redirect_uri: redirectUri("quickbooks"),
      state,
    })
    return `https://appcenter.intuit.com/connect/oauth2?${p.toString()}`
  },

  async exchangeCode(code, realmId) {
    const tokens = await tokenRequest({ grant_type: "authorization_code", code, redirect_uri: redirectUri("quickbooks") })
    tokens.realmId = realmId ?? null
    try {
      const info = await api(tokens, "companyinfo/" + tokens.realmId)
      tokens.orgName = info?.CompanyInfo?.CompanyName ?? null
    } catch {
      /* name is best-effort */
    }
    return tokens
  },

  async refresh(tokens) {
    const next = await tokenRequest({ grant_type: "refresh_token", refresh_token: tokens.refreshToken })
    next.realmId = tokens.realmId
    next.orgName = tokens.orgName
    return next
  },

  async pushIncome(tokens, entries) {
    if (!entries.length) return { synced: 0 }
    // Post each rent payment as a SalesReceipt against the first Service item.
    const items = await query<{ Id: string }>(tokens, "SELECT Id FROM Item WHERE Type='Service' MAXRESULTS 1")
    const itemRef = items[0]?.Id
    if (!itemRef) throw new Error("No QuickBooks Service item found to record income against")
    let synced = 0
    for (const e of entries) {
      await api(tokens, "salesreceipt", {
        method: "POST",
        body: JSON.stringify({
          TxnDate: e.date,
          PrivateNote: `${e.description} [pmn:${e.externalId}]`,
          Line: [{ Amount: e.amount, DetailType: "SalesItemLineDetail", Description: e.description, SalesItemLineDetail: { ItemRef: { value: itemRef }, Qty: 1, UnitPrice: e.amount } }],
        }),
      })
      synced++
    }
    return { synced }
  },

  async pushExpense(tokens, entries) {
    if (!entries.length) return { synced: 0 }
    const banks = await query<{ Id: string }>(tokens, "SELECT Id FROM Account WHERE AccountType='Bank' MAXRESULTS 1")
    const expenses = await query<{ Id: string }>(tokens, "SELECT Id FROM Account WHERE AccountType='Expense' MAXRESULTS 1")
    const bankRef = banks[0]?.Id
    const expRef = expenses[0]?.Id
    if (!bankRef || !expRef) throw new Error("No QuickBooks Bank/Expense account found to record expenses against")
    let synced = 0
    for (const e of entries) {
      await api(tokens, "purchase", {
        method: "POST",
        body: JSON.stringify({
          PaymentType: "Cash",
          AccountRef: { value: bankRef },
          TxnDate: e.date,
          PrivateNote: `${e.description} [pmn:${e.externalId}]`,
          Line: [{ Amount: e.amount, DetailType: "AccountBasedExpenseLineDetail", Description: e.description, AccountBasedExpenseLineDetail: { AccountRef: { value: expRef } } }],
        }),
      })
      synced++
    }
    return { synced }
  },
}