package client

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
)

// APIError is returned for every non-2xx API response. Validation contains
// field-specific messages for 422 responses; Message contains ordinary API
// error strings.
type APIError struct {
	StatusCode int
	Message    string
	Validation map[string]string
	Body       string
}

// Error implements error using the API message or HTTP status.
func (e *APIError) Error() string {
	switch {
	case e.Message != "":
		return fmt.Sprintf("gardomatic API: %s (%d)", e.Message, e.StatusCode)
	case len(e.Validation) != 0:
		return fmt.Sprintf("gardomatic API: validation failed (%d)", e.StatusCode)
	default:
		return fmt.Sprintf("gardomatic API: request failed (%d)", e.StatusCode)
	}
}

func newAPIError(response *http.Response, body []byte) *APIError {
	apiError := &APIError{
		StatusCode: response.StatusCode,
		Body:       strings.TrimSpace(string(body)),
	}

	var envelope struct {
		Error json.RawMessage `json:"error"`
	}
	if err := json.Unmarshal(body, &envelope); err != nil || len(envelope.Error) == 0 {
		return apiError
	}
	if err := json.Unmarshal(envelope.Error, &apiError.Message); err == nil {
		return apiError
	}
	_ = json.Unmarshal(envelope.Error, &apiError.Validation)
	return apiError
}