# Task 07: GHL API Client (Status Updates)

## Objective
Build `internal/ghl/api.go` — client for calling GHL APIs (update message status, post inbound messages).

## Reference
- Update Message Status: https://marketplace.gohighlevel.com/docs/ghl/conversations/update-message-status
- Add Inbound Message: https://marketplace.gohighlevel.com/docs/ghl/conversations/add-an-inbound-message

## Types (add to `internal/ghl/types.go`)

```go
type MessageStatusUpdate struct {
    Status       string `json:"status"`       // "delivered", "failed", "pending"
    ErrorCode    string `json:"error_code,omitempty"`
    ErrorMessage string `json:"error_message,omitempty"`
}

type InboundMessage struct {
    Type                   string `json:"type"`                              // "SMS"
    Message                string `json:"message"`
    Phone                  string `json:"phone"`                             // E.164
    ConversationProviderID string `json:"conversationProviderId,omitempty"`
}

type InboundMessageResponse struct {
    ConversationID string `json:"conversationId"`
    MessageID      string `json:"messageId"`
}
```

## APIClient struct

```go
type APIClient struct {
    baseURL    string
    httpClient *http.Client
}

func NewAPIClient() *APIClient {
    return &APIClient{
        baseURL:    "https://services.leadconnectorhq.com",
        httpClient: &http.Client{Timeout: 30 * time.Second},
    }
}
```

## Methods

### UpdateMessageStatus

```go
func (c *APIClient) UpdateMessageStatus(ctx context.Context, accessToken, messageID, status string) error
```

1. Build URL: `{baseURL}/conversations/messages/{messageID}/status`
2. Body: `{ "status": status }`
3. Headers:
   - `Authorization: Bearer {accessToken}`
   - `Content-Type: application/json`
   - `Version: 2021-04-15` (GHL API version header)
4. PUT request
5. On non-2xx: return error with status code + body
6. On success: return nil

### PostInboundMessage (Phase 2 — stub for now)

```go
func (c *APIClient) PostInboundMessage(ctx context.Context, accessToken string, msg *InboundMessage) (*InboundMessageResponse, error)
```

1. Build URL: `{baseURL}/conversations/messages/inbound`
2. Body: JSON of InboundMessage
3. Headers: same as above
4. POST request
5. Parse and return response

**Note:** Implement as a working stub — the full inbound flow is Phase 2, but the API client method should be ready.

## Key behaviors
- **GHL API version header:** `Version: 2021-04-15` — required on all GHL API calls
- **Bearer auth:** Use the OAuth access token for the specific locationId
- **Status values:** `"delivered"`, `"failed"`, `"pending"` — GHL expects these exact strings
- **Error on status update is non-fatal** — log it but don't cascade. The SMS was already sent (or failed to send). The status update is best-effort.
- **Retry on 401** — if status update returns 401, the token may have expired mid-request. The caller (webhook handler) should refresh and retry once.

## Acceptance Criteria
- [ ] `go build ./cmd/server/` succeeds
- [ ] `UpdateMessageStatus` sends PUT to correct URL
- [ ] `Authorization: Bearer` header set
- [ ] `Version: 2021-04-15` header set
- [ ] `Content-Type: application/json` header set
- [ ] Non-2xx returns descriptive error
- [ ] `PostInboundMessage` stub implemented with correct URL and method
- [ ] HTTP client has 30s timeout
- [ ] Context passed to all HTTP requests