/**
 * SMS sending — per-org, bring your own key.
 *
 * Supported providers:
 * - Twilio
 *
 * Each charity pastes their Twilio credentials in Settings.
 * SMS comes from THEIR number.
 */

interface SmsConfig {
  provider: string
  accountSid: string
  authToken: string
  fromNumber: string
}

interface SendResult {
  success: boolean
  messageId?: string
  error?: string
}

/**
 * Send an SMS using the org's configured provider.
 */
export async function sendSms(
  config: SmsConfig,
  to: string,
  body: string
): Promise<SendResult> {
  if (!config.accountSid || !config.authToken || !config.fromNumber) {
    return { success: false, error: "SMS not configured" }
  }

  try {
    if (config.provider === "twilio") {
      return await sendViaTwilio(config, to, body)
    }
    return { success: false, error: `Unknown provider: ${config.provider}` }
  } catch (err) {
    console.error("[SMS]", err)
    return { success: false, error: String(err) }
  }
}

async function sendViaTwilio(
  config: SmsConfig, to: string, body: string
): Promise<SendResult> {
  // Normalize UK number
  let phone = to.replace(/[\s\-\(\)]/g, "")
  if (phone.startsWith("0")) phone = "+44" + phone.slice(1)
  if (!phone.startsWith("+")) phone = "+" + phone

  const url = `https://api.twilio.com/2010-04-01/Accounts/${config.accountSid}/Messages.json`
  const auth = Buffer.from(`${config.accountSid}:${config.authToken}`).toString("base64")

  const res = await fetch(url, {
    method: "POST",
    headers: {
      "Authorization": `Basic ${auth}`,
      "Content-Type": "application/x-www-form-urlencoded",
    },
    body: new URLSearchParams({
      To: phone,
      From: config.fromNumber,
      Body: body,
    }),
  })

  const data = await res.json()

  if (data.sid) {
    return { success: true, messageId: data.sid }
  }
  return { success: false, error: data.message || "Twilio error" }
}