package api

import (
	"fmt"
	"strings"
)

// APIError is a task the gateway refused or could not complete.
//
// It carries the gateway's own code so the caller can react to a specific
// failure (bad credentials, unknown zone, name server mismatch) without
// matching on message text.
type APIError struct {
	Code   string
	Text   string
	Object string
	Stid   string
}

func (e *APIError) Error() string {
	var b strings.Builder
	if e.Code != "" {
		fmt.Fprintf(&b, "%s: %s", e.Code, e.Text)
	} else {
		b.WriteString(e.Text)
	}
	if e.Object != "" {
		fmt.Fprintf(&b, " (object: %s)", e.Object)
	}
	return b.String()
}

// fromResult builds an error from a failed result block. The actionable code
// and text live in msg, not in status, so msg is preferred.
func fromResult(r Result, stid string) *APIError {
	e := &APIError{Stid: stid}

	var pick *Msg
	for i := range r.Msg {
		m := &r.Msg[i]
		// A notification ("N") alongside an error ("E") is not the failure.
		if strings.EqualFold(m.Type, "error") || strings.HasPrefix(m.Code, "E") {
			pick = m
			break
		}
		if pick == nil {
			pick = m
		}
	}
	switch {
	case pick != nil && pick.Text != "":
		e.Code, e.Text = pick.Code, pick.Text
	case r.Status.Text != "":
		e.Code, e.Text = r.Status.Code, r.Status.Text
	default:
		e.Text = "the gateway reported a failure without a message"
	}
	if pick != nil && pick.Object != nil {
		e.Object = pick.Object.Type + " " + pick.Object.Value
	}
	return e
}