package fa

import (
	"errors"
	"fmt"
)

// Sentinel errors. Callers should use errors.Is to test for these.
var (
	// ErrNotFound is returned when FA renders a "not found" system message
	// or an HTTP 404. Covers deleted submissions, unknown users, etc.
	ErrNotFound = errors.New("fa: not found")

	// ErrUnauthorized is returned when an endpoint requires authentication
	// (the SDK was called without cookies, or the cookies were rejected by FA).
	ErrUnauthorized = errors.New("fa: unauthorized cookies missing or invalid")

	// ErrCloudflareChallenge is returned when Cloudflare interposes a JS
	// challenge or managed challenge. Callers must refresh their cf_clearance
	// cookie and User-Agent in a real browser, then retry.
	ErrCloudflareChallenge = errors.New("fa: cloudflare challenge refresh cf_clearance")

	// ErrRateLimited is returned when FA or Cloudflare responds with HTTP 429
	// and the transport's retry budget has been exhausted.
	ErrRateLimited = errors.New("fa: rate limited by server")

	// ErrSystemMessage is the umbrella error for any FA "system-message" page
	// that doesn't match a more specific sentinel. Wrap in a *SystemMessageError
	// for the title/body.
	ErrSystemMessage = errors.New("fa: system message")

	// ErrParse is returned when the HTML parser cannot extract a required field.
	// Often indicates FA changed its markup.
	ErrParse = errors.New("fa: parse error")
)

// SystemMessageError carries the title and body of a FA system-message page
// that doesn't classify into one of the more specific sentinels.
type SystemMessageError struct {
	Title string
	Body  string
}

func (e *SystemMessageError) Error() string {
	if e.Title == "" {
		return "fa: system message: " + e.Body
	}
	return fmt.Sprintf("fa: system message: %s: %s", e.Title, e.Body)
}

// Is allows errors.Is(err, ErrSystemMessage) to match.
func (e *SystemMessageError) Is(target error) bool {
	return target == ErrSystemMessage
}

// HTTPError wraps a non-success HTTP response that the transport surfaces
// to the caller after exhausting retries.
type HTTPError struct {
	StatusCode int
	URL        string
}

func (e *HTTPError) Error() string {
	return fmt.Sprintf("fa: http %d for %s", e.StatusCode, e.URL)
}