package main

import (
	"net/http"
	"net/http/cgi"
	"os/exec"
	"strings"
)

// handleGitHTTP serves Git smart HTTP protocol requests by proxying to git-http-backend.
// This enables `git clone` over HTTPS.
func (s *server) handleGitHTTP(w http.ResponseWriter, r *http.Request, repo *RepoInfo) {
	gitHTTPBackend, err := exec.LookPath("git-http-backend")
	if err != nil {
		gitExecPath, err2 := exec.Command("git", "--exec-path").Output()
		if err2 != nil {
			http.Error(w, "git-http-backend not found", http.StatusInternalServerError)
			return
		}
		gitHTTPBackend = strings.TrimSpace(string(gitExecPath)) + "/git-http-backend"
	}

	// Strip the base URL prefix and repo name to get the path info that git-http-backend expects.
	// e.g. /baseurl/repo/info/refs -> /repo.git/info/refs
	pathInfo := r.URL.Path
	if s.baseURL != "" {
		pathInfo = strings.TrimPrefix(pathInfo, s.baseURL)
	}
	// Replace /<reponame>/ with /<reponame>.git/
	pathInfo = strings.Replace(pathInfo, "/"+repo.Name+"/", "/"+repo.Name+".git/", 1)

	handler := &cgi.Handler{
		Path: gitHTTPBackend,
		Env: []string{
			"GIT_PROJECT_ROOT=" + s.scanPath,
			"GIT_HTTP_EXPORT_ALL=1",
			"GIT_CONFIG_COUNT=1",
			"GIT_CONFIG_KEY_0=safe.directory",
			"GIT_CONFIG_VALUE_0=*",
		},
		InheritEnv: []string{"PATH"},
	}

	// Override PATH_INFO for the CGI handler.
	r2 := r.Clone(r.Context())
	r2.URL.Path = pathInfo

	handler.ServeHTTP(w, r2)
}

// isGitHTTPRequest returns true if the request is a Git smart HTTP protocol request.
func isGitHTTPRequest(r *http.Request) bool {
	query := r.URL.RawQuery

	if strings.HasSuffix(r.URL.Path, "/info/refs") &&
		(strings.Contains(query, "service=git-upload-pack") || strings.Contains(query, "service=git-receive-pack")) {
		return true
	}
	if strings.HasSuffix(r.URL.Path, "/git-upload-pack") || strings.HasSuffix(r.URL.Path, "/git-receive-pack") {
		return true
	}
	if strings.HasSuffix(r.URL.Path, "/HEAD") || strings.Contains(r.URL.Path, "/objects/") {
		return true
	}
	return false
}