package config

import (
	"net/url"
	"regexp"
	"strings"

	"github.com/pomerium/pomerium/internal/urlutil"
)

// FromURLMatchesRequestURL returns true if the from URL matches the request URL.
func FromURLMatchesRequestURL(fromURL, requestURL *url.URL) bool {
	for _, domain := range urlutil.GetDomainsForURL(fromURL) {
		if domain == requestURL.Host {
			return true
		}

		if !strings.Contains(domain, "*") {
			continue
		}

		reStr := WildcardToRegex(domain)
		re := regexp.MustCompile(reStr)
		if re.MatchString(requestURL.Host) {
			return true
		}
	}
	return false
}

// WildcardToRegex converts a wildcard string to a regular expression.
func WildcardToRegex(wildcard string) string {
	var b strings.Builder
	b.WriteByte('^')
	for {
		idx := strings.IndexByte(wildcard, '*')
		if idx < 0 {
			break
		}
		b.WriteString(regexp.QuoteMeta(wildcard[:idx]))
		b.WriteString("(.*)")
		wildcard = wildcard[idx+1:]
	}
	b.WriteString(regexp.QuoteMeta(wildcard))
	b.WriteByte('$')
	return b.String()
}