| 1 | // SPDX-License-Identifier: AGPL-3.0-or-later |
| 2 | |
| 3 | package email |
| 4 | |
| 5 | import ( |
| 6 | "bytes" |
| 7 | "context" |
| 8 | "encoding/json" |
| 9 | "fmt" |
| 10 | "io" |
| 11 | "net/http" |
| 12 | "time" |
| 13 | ) |
| 14 | |
| 15 | // ResendSender posts messages to the Resend transactional API |
| 16 | // (https://resend.com). Same shape as PostmarkSender — one HTTP POST per |
| 17 | // message, no templating, no batching. Resend's value vs. Postmark is |
| 18 | // near-instant onboarding (no human approval queue), which is why we |
| 19 | // keep both implementations selectable per-deploy. |
| 20 | type ResendSender struct { |
| 21 | APIKey string // Bearer token; ops creates this in the Resend dashboard |
| 22 | From string // verified sender address; domain must be verified in Resend |
| 23 | Endpoint string // optional override; defaults to resendAPI for tests |
| 24 | HTTP *http.Client |
| 25 | } |
| 26 | |
| 27 | // resendAPI is the canonical endpoint. Hard-coded — Resend is SaaS. |
| 28 | const resendAPI = "https://api.resend.com/emails" |
| 29 | |
| 30 | // resendPayload is the request body shape. The field names match |
| 31 | // Resend's documented JSON keys (lowercase singular). |
| 32 | type resendPayload struct { |
| 33 | From string `json:"from"` |
| 34 | To string `json:"to"` |
| 35 | Subject string `json:"subject"` |
| 36 | HTML string `json:"html"` |
| 37 | Text string `json:"text"` |
| 38 | } |
| 39 | |
| 40 | // Send implements Sender. |
| 41 | func (r *ResendSender) Send(ctx context.Context, m Message) error { |
| 42 | if m.From == "" { |
| 43 | m.From = r.From |
| 44 | } |
| 45 | body, err := json.Marshal(resendPayload(m)) |
| 46 | if err != nil { |
| 47 | return fmt.Errorf("resend: marshal: %w", err) |
| 48 | } |
| 49 | |
| 50 | endpoint := r.Endpoint |
| 51 | if endpoint == "" { |
| 52 | endpoint = resendAPI |
| 53 | } |
| 54 | req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewReader(body)) |
| 55 | if err != nil { |
| 56 | return fmt.Errorf("resend: request: %w", err) |
| 57 | } |
| 58 | req.Header.Set("Accept", "application/json") |
| 59 | req.Header.Set("Content-Type", "application/json") |
| 60 | req.Header.Set("Authorization", "Bearer "+r.APIKey) |
| 61 | |
| 62 | client := r.HTTP |
| 63 | if client == nil { |
| 64 | client = &http.Client{Timeout: 10 * time.Second} |
| 65 | } |
| 66 | resp, err := client.Do(req) |
| 67 | if err != nil { |
| 68 | return fmt.Errorf("resend: send: %w", err) |
| 69 | } |
| 70 | defer func() { _ = resp.Body.Close() }() |
| 71 | |
| 72 | if resp.StatusCode/100 != 2 { |
| 73 | // Resend returns a JSON error body like {"name":"...", "message":"..."}. |
| 74 | // Surface a snippet so operators can debug bad keys / unverified |
| 75 | // domains without re-running with curl. |
| 76 | snippet, _ := io.ReadAll(io.LimitReader(resp.Body, 512)) |
| 77 | return fmt.Errorf("resend: status %d: %s", resp.StatusCode, bytes.TrimSpace(snippet)) |
| 78 | } |
| 79 | return nil |
| 80 | } |
| 81 |