// Copyright 2014 The Gogs Authors. All rights reserved.
// Copyright 2016 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 cmd

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"regexp"
	"strconv"
	"strings"
	"time"

	"code.gitea.io/gitea/models"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/pprof"
	"code.gitea.io/gitea/modules/private"
	"code.gitea.io/gitea/modules/setting"

	"github.com/dgrijalva/jwt-go"
	"github.com/unknwon/com"
	"github.com/urfave/cli"
)

const (
	lfsAuthenticateVerb = "git-lfs-authenticate"
)

// CmdServ represents the available serv sub-command.
var CmdServ = cli.Command{
	Name:        "serv",
	Usage:       "This command should only be called by SSH shell",
	Description: `Serv provide access auth for repositories`,
	Action:      runServ,
	Flags: []cli.Flag{
		cli.BoolFlag{
			Name: "enable-pprof",
		},
		cli.BoolFlag{
			Name: "debug",
		},
	},
}

func setup(logPath string, debug bool) {
	if !debug {
		_ = log.DelLogger("console")
	}
	setting.NewContext()
	if debug {
		setting.ProdMode = false
	}
}

func parseCmd(cmd string) (string, string) {
	ss := strings.SplitN(cmd, " ", 2)
	if len(ss) != 2 {
		return "", ""
	}
	return ss[0], strings.Replace(ss[1], "'/", "'", 1)
}

var (
	allowedCommands = map[string]models.AccessMode{
		"git-upload-pack":    models.AccessModeRead,
		"git-upload-archive": models.AccessModeRead,
		"git-receive-pack":   models.AccessModeWrite,
		lfsAuthenticateVerb:  models.AccessModeNone,
	}
	alphaDashDotPattern = regexp.MustCompile(`[^\w-\.]`)
)

func fail(userMessage, logMessage string, args ...interface{}) {
	fmt.Fprintln(os.Stderr, "Gitea:", userMessage)

	if len(logMessage) > 0 {
		if !setting.ProdMode {
			fmt.Fprintf(os.Stderr, logMessage+"\n", args...)
		}
	}

	os.Exit(1)
}

func runServ(c *cli.Context) error {
	// FIXME: This needs to internationalised
	setup("serv.log", c.Bool("debug"))

	if setting.SSH.Disabled {
		println("Gitea: SSH has been disabled")
		return nil
	}

	if len(c.Args()) < 1 {
		if err := cli.ShowSubcommandHelp(c); err != nil {
			fmt.Printf("error showing subcommand help: %v\n", err)
		}
		return nil
	}

	keys := strings.Split(c.Args()[0], "-")
	if len(keys) != 2 || keys[0] != "key" {
		fail("Key ID format error", "Invalid key argument: %s", c.Args()[0])
	}
	keyID := com.StrTo(keys[1]).MustInt64()

	cmd := os.Getenv("SSH_ORIGINAL_COMMAND")
	if len(cmd) == 0 {
		key, user, err := private.ServNoCommand(keyID)
		if err != nil {
			fail("Internal error", "Failed to check provided key: %v", err)
		}
		if key.Type == models.KeyTypeDeploy {
			println("Hi there! You've successfully authenticated with the deploy key named " + key.Name + ", but Gitea does not provide shell access.")
		} else {
			println("Hi there, " + user.Name + "! You've successfully authenticated with the key named " + key.Name + ", but Gitea does not provide shell access.")
		}
		println("If this is unexpected, please log in with password and setup Gitea under another user.")
		return nil
	}

	verb, args := parseCmd(cmd)

	var lfsVerb string
	if verb == lfsAuthenticateVerb {
		if !setting.LFS.StartServer {
			fail("Unknown git command", "LFS authentication request over SSH denied, LFS support is disabled")
		}

		argsSplit := strings.Split(args, " ")
		if len(argsSplit) >= 2 {
			args = strings.TrimSpace(argsSplit[0])
			lfsVerb = strings.TrimSpace(argsSplit[1])
		}
	}

	repoPath := strings.ToLower(strings.Trim(args, "'"))
	rr := strings.SplitN(repoPath, "/", 2)
	if len(rr) != 2 {
		fail("Invalid repository path", "Invalid repository path: %v", args)
	}

	username := strings.ToLower(rr[0])
	reponame := strings.ToLower(strings.TrimSuffix(rr[1], ".git"))

	if alphaDashDotPattern.MatchString(reponame) {
		fail("Invalid repo name", "Invalid repo name: %s", reponame)
	}

	if setting.EnablePprof || c.Bool("enable-pprof") {
		if err := os.MkdirAll(setting.PprofDataPath, os.ModePerm); err != nil {
			fail("Error while trying to create PPROF_DATA_PATH", "Error while trying to create PPROF_DATA_PATH: %v", err)
		}

		stopCPUProfiler, err := pprof.DumpCPUProfileForUsername(setting.PprofDataPath, username)
		if err != nil {
			fail("Internal Server Error", "Unable to start CPU profile: %v", err)
		}
		defer func() {
			stopCPUProfiler()
			err := pprof.DumpMemProfileForUsername(setting.PprofDataPath, username)
			if err != nil {
				fail("Internal Server Error", "Unable to dump Mem Profile: %v", err)
			}
		}()
	}

	requestedMode, has := allowedCommands[verb]
	if !has {
		fail("Unknown git command", "Unknown git command %s", verb)
	}

	if verb == lfsAuthenticateVerb {
		if lfsVerb == "upload" {
			requestedMode = models.AccessModeWrite
		} else if lfsVerb == "download" {
			requestedMode = models.AccessModeRead
		} else {
			fail("Unknown LFS verb", "Unknown lfs verb %s", lfsVerb)
		}
	}

	results, err := private.ServCommand(keyID, username, reponame, requestedMode, verb, lfsVerb)
	if err != nil {
		if private.IsErrServCommand(err) {
			errServCommand := err.(private.ErrServCommand)
			if errServCommand.StatusCode != http.StatusInternalServerError {
				fail("Unauthorized", "%s", errServCommand.Error())
			} else {
				fail("Internal Server Error", "%s", errServCommand.Error())
			}
		}
		fail("Internal Server Error", "%s", err.Error())
	}
	os.Setenv(models.EnvRepoIsWiki, strconv.FormatBool(results.IsWiki))
	os.Setenv(models.EnvRepoName, results.RepoName)
	os.Setenv(models.EnvRepoUsername, results.OwnerName)
	os.Setenv(models.EnvPusherName, results.UserName)
	os.Setenv(models.EnvPusherID, strconv.FormatInt(results.UserID, 10))
	os.Setenv(models.ProtectedBranchRepoID, strconv.FormatInt(results.RepoID, 10))
	os.Setenv(models.ProtectedBranchPRID, fmt.Sprintf("%d", 0))
	os.Setenv(models.EnvIsDeployKey, fmt.Sprintf("%t", results.IsDeployKey))
	os.Setenv(models.EnvKeyID, fmt.Sprintf("%d", results.KeyID))

	//LFS token authentication
	if verb == lfsAuthenticateVerb {
		url := fmt.Sprintf("%s%s/%s.git/info/lfs", setting.AppURL, url.PathEscape(results.OwnerName), url.PathEscape(results.RepoName))

		now := time.Now()
		claims := jwt.MapClaims{
			"repo": results.RepoID,
			"op":   lfsVerb,
			"exp":  now.Add(setting.LFS.HTTPAuthExpiry).Unix(),
			"nbf":  now.Unix(),
			"user": results.UserID,
		}
		token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

		// Sign and get the complete encoded token as a string using the secret
		tokenString, err := token.SignedString(setting.LFS.JWTSecretBytes)
		if err != nil {
			fail("Internal error", "Failed to sign JWT token: %v", err)
		}

		tokenAuthentication := &models.LFSTokenResponse{
			Header: make(map[string]string),
			Href:   url,
		}
		tokenAuthentication.Header["Authorization"] = fmt.Sprintf("Bearer %s", tokenString)

		enc := json.NewEncoder(os.Stdout)
		err = enc.Encode(tokenAuthentication)
		if err != nil {
			fail("Internal error", "Failed to encode LFS json response: %v", err)
		}
		return nil
	}

	// Special handle for Windows.
	if setting.IsWindows {
		verb = strings.Replace(verb, "-", " ", 1)
	}

	var gitcmd *exec.Cmd
	verbs := strings.Split(verb, " ")
	if len(verbs) == 2 {
		gitcmd = exec.Command(verbs[0], verbs[1], repoPath)
	} else {
		gitcmd = exec.Command(verb, repoPath)
	}

	gitcmd.Dir = setting.RepoRootPath
	gitcmd.Stdout = os.Stdout
	gitcmd.Stdin = os.Stdin
	gitcmd.Stderr = os.Stderr
	if err = gitcmd.Run(); err != nil {
		fail("Internal error", "Failed to execute git command: %v", err)
	}

	// Update user key activity.
	if results.KeyID > 0 {
		if err = private.UpdatePublicKeyInRepo(results.KeyID, results.RepoID); err != nil {
			fail("Internal error", "UpdatePublicKeyInRepo: %v", err)
		}
	}

	return nil
}