// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package util

import (
	"net/url"
	"path"
	"strings"

	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/setting"
)

// PathEscapeSegments escapes segments of a path while not escaping forward slash
func PathEscapeSegments(path string) string {
	slice := strings.Split(path, "/")
	for index := range slice {
		slice[index] = url.PathEscape(slice[index])
	}
	escapedPath := strings.Join(slice, "/")
	return escapedPath
}

// URLJoin joins url components, like path.Join, but preserving contents
func URLJoin(base string, elems ...string) string {
	// We do need to escape special chars here or else they can be silently discarded
	// in the ResolveReference call below
	base = PathEscapeSegments(base)
	if !strings.HasSuffix(base, "/") {
		base += "/"
	}
	baseURL, err := url.Parse(base)
	if err != nil {
		log.Error("URLJoin: Invalid base URL %s", base)
		return ""
	}
	joinedPath := path.Join(elems...)
	argURL, err := url.Parse(joinedPath)
	if err != nil {
		log.Error("URLJoin: Invalid arg %s", joinedPath)
		return ""
	}
	joinedURL := baseURL.ResolveReference(argURL).String()
	if !baseURL.IsAbs() && !strings.HasPrefix(base, "/") {
		return joinedURL[1:] // Removing leading '/' if needed
	}
	return joinedURL
}

// IsExternalURL checks if rawURL points to an external URL like http://example.com
func IsExternalURL(rawURL string) bool {
	parsed, err := url.Parse(rawURL)
	if err != nil {
		return true
	}
	appURL, _ := url.Parse(setting.AppURL)
	if len(parsed.Host) != 0 && strings.Replace(parsed.Host, "www.", "", 1) != strings.Replace(appURL.Host, "www.", "", 1) {
		return true
	}
	return false
}