package gitsource

import (
	"fmt"
	"regexp"
	"strings"
)

var (
	githubTreeRe = regexp.MustCompile(`^https://([^/]*github[^/]*)/([^/]+)/([^/]+)/tree/([^/]+)(/.*)?$`)
	gitlabTreeRe = regexp.MustCompile(`^https://([^/]*gitlab[^/]*)/([^/]+)/([^/]+)/-/tree/([^/]+)(/.*)?$`)
)

// NormalizeURL converts pasted GitHub/GitLab web-tree URLs into plain git
// clone URLs and returns the implied discovery root ("" for the repo root).
// URLs that are already cloneable pass through unchanged.
func NormalizeURL(raw string) (url, root string, err error) {
	s := strings.TrimSpace(raw)
	if s == "" {
		return "", "", fmt.Errorf("empty source URL")
	}
	if m := githubTreeRe.FindStringSubmatch(s); m != nil {
		return fmt.Sprintf("https://%s/%s/%s.git", m[1], m[2], m[3]), strings.TrimPrefix(m[5], "/"), nil
	}
	if m := gitlabTreeRe.FindStringSubmatch(s); m != nil {
		return fmt.Sprintf("https://%s/%s/%s.git", m[1], m[2], m[3]), strings.TrimPrefix(m[5], "/"), nil
	}
	if strings.HasSuffix(s, ".git") {
		return s, "", nil
	}
	if m := regexp.MustCompile(`^https://([^/]*github[^/]*)/([^/]+)/([^/]+)$`).FindStringSubmatch(s); m != nil {
		return fmt.Sprintf("https://%s/%s/%s.git", m[1], m[2], m[3]), "", nil
	}
	if m := regexp.MustCompile(`^https://([^/]*gitlab[^/]*)/([^/]+)/([^/]+)$`).FindStringSubmatch(s); m != nil {
		return fmt.Sprintf("https://%s/%s/%s.git", m[1], m[2], m[3]), "", nil
	}
	if strings.HasPrefix(s, "file://") {
		return strings.TrimPrefix(s, "file://"), "", nil
	}
	return s, "", nil
}