import lettermint "github.com/lettermint/lettermint-go"

client, err := lettermint.New("your-api-token")
if err != nil {
    log.Fatal(err)
}

ctx := context.Background()
resp, err := client.Email(ctx).
    From("sender@example.com").
    To("recipient@example.com").
    Subject("Hello from Lettermint").
    Text("This is a test email sent using the Lettermint Go SDK.").
    Send()

if err != nil {
    log.Fatal(err)
}

fmt.Printf("Email sent with ID: %s\n", resp.MessageID)
fmt.Printf("Status: %s\n", resp.Status)

resp, err := client.Email(ctx).
    From("John Doe <sender@example.com>").
    To("recipient1@example.com", "recipient2@example.com").
    CC("cc@example.com").
    BCC("bcc@example.com").
    ReplyTo("reply@example.com").
    Subject("Hello from Lettermint").
    HTML("<h1>Hello</h1><p>This is an HTML email.</p>").
    Text("This is a plain text version of the email.").
    Headers(map[string]string{
        "X-Custom-Header": "Custom Value",
    }).
    Attach("attachment.txt", base64EncodedContent).
    AttachWithContentID("logo.png", base64EncodedLogo, "logo"). // Inline attachment
    IdempotencyKey("unique-id-123").
    Metadata(map[string]string{
        "user_id": "12345",
    }).
    Tag("campaign-123").
    Send()

resp, err := client.Email(ctx).
    From("sender@example.com").
    To("recipient@example.com").
    Subject("Email with inline image").
    HTML(`<p>Here is an image: <img src="cid:logo"></p>`).
    AttachWithContentID("logo.png", base64EncodedImage, "logo").
    Send()

resp, err := client.Email(ctx).
    From("sender@example.com").
    To("recipient@example.com").
    Subject("Hello from Lettermint").
    Text("Hello! This is a test email.").
    IdempotencyKey("unique-request-id-123").
    Send()

func webhookHandler(w http.ResponseWriter, r *http.Request) {
    event, err := lettermint.VerifyWebhookFromRequest(
        r,
        "your-webhook-secret",
        lettermint.DefaultWebhookTolerance,
    )
    if err != nil {
        http.Error(w, "Invalid signature", http.StatusUnauthorized)
        return
    }

    // Process the event
    switch event.Event {
    case "message.delivered":
        log.Printf("Email delivered to %s", event.Data.Recipient)
    case "message.hard_bounced":
        log.Printf("Hard bounce for %s", event.Data.Recipient)
    case "message.soft_bounced":
        log.Printf("Soft bounce for %s", event.Data.Recipient)
    }

    w.WriteHeader(http.StatusOK)
}

client, err := lettermint.New("your-api-token",
    lettermint.WithBaseURL("https://api.lettermint.co/v1"), // Optional
    lettermint.WithTimeout(30*time.Second),                  // Optional
    lettermint.WithHTTPClient(customHTTPClient),             // Optional
)

resp, err := client.Email(ctx).From("...").To("...").Subject("...").HTML("...").Send()
if err != nil {
    // Check for specific error types
    var apiErr *lettermint.APIError
    if errors.As(err, &apiErr) {
        fmt.Printf("API Error (%d): %s\n", apiErr.StatusCode, apiErr.Message)
        fmt.Printf("Validation errors: %v\n", apiErr.Errors)
    }

    // Check for error categories using errors.Is()
    if errors.Is(err, lettermint.ErrValidation) {
        // Handle validation errors (422)
    } else if errors.Is(err, lettermint.ErrUnauthorized) {
        // Handle authentication errors (401)
    } else if errors.Is(err, lettermint.ErrTimeout) {
        // Handle timeout errors
    } else if errors.Is(err, lettermint.ErrRateLimited) {
        // Handle rate limit errors (429)
    }
}