// The serverless backend for the contact form.
//
// A standalone `*.serverless.ts` — it is NOT part of a long-running api. The
// CLI bundles + ships it on its own:
//
//   voltro serverless dev    functions/sendMessage.serverless.ts   # run locally (:8910)
//   voltro serverless deploy --target node | cloudflare | scaleway # ship it
//
// It receives the form payload, validates it against `input`, and sends an
// email via Resend's HTTP API using the framework-provided `HttpClient`.
// Edge-safe: no `node:*`, so it also runs on a Cloudflare Worker.
//
// Secrets come from `ctx.env` (set at deploy time): RESEND_API_KEY is required;
// CONTACT_TO / CONTACT_FROM are optional overrides.

import { Effect, Schema } from 'effect'
import { HttpClient, HttpClientRequest } from '@effect/platform'
import { defineServerless, ServerlessHttpError } from '@voltro/serverless'

const EMAIL_RE = /^[^@\s]+@[^@\s]+\.[^@\s]+$/

export default defineServerless({
  name: 'send-message',
  method: 'POST',
  input: Schema.Struct({
    name: Schema.String.pipe(Schema.minLength(1), Schema.maxLength(120)),
    email: Schema.String.pipe(Schema.pattern(EMAIL_RE)),
    message: Schema.String.pipe(Schema.minLength(1), Schema.maxLength(5000)),
  }),
  output: Schema.Struct({ ok: Schema.Boolean }),
  runtime: { memoryMb: 128, timeoutSeconds: 10 },
  handler: ({ name, email, message }, ctx) =>
    Effect.gen(function* () {
      const apiKey = ctx.env.RESEND_API_KEY
      const to = ctx.env.CONTACT_TO ?? 'you@example.com'
      const from = ctx.env.CONTACT_FROM ?? 'Contact form <onboarding@resend.dev>'

      // No key wired yet → fail with a clear 503 the form can render. The
      // function never pretends to send: honest in dev, honest in prod.
      if (!apiKey) {
        return yield* Effect.fail(
          new ServerlessHttpError({
            status: 503,
            message: 'email-not-configured',
            detail: 'Set RESEND_API_KEY (+ optionally CONTACT_TO / CONTACT_FROM) in the function env.',
          }),
        )
      }

      const http = yield* HttpClient.HttpClient
      const request = HttpClientRequest.post('https://api.resend.com/emails').pipe(
        HttpClientRequest.setHeader('authorization', `Bearer ${apiKey}`),
        HttpClientRequest.bodyUnsafeJson({
          from,
          to: [to],
          reply_to: email,
          subject: `New message from ${name}`,
          text: `${message}\n\n— ${name} <${email}>`,
        }),
      )

      const response = yield* http.execute(request)
      if (response.status >= 400) {
        const detail = yield* response.text
        return yield* Effect.fail(new ServerlessHttpError({ status: 502, message: 'email-send-failed', detail }))
      }
      return { ok: true }
    }),
})