package httpd

import (
	"encoding/base64"
	"errors"
	"fmt"
	"html/template"
	"io/ioutil"
	"net/http"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/drakkan/sftpgo/dataprovider"
	"github.com/drakkan/sftpgo/sftpd"
	"github.com/drakkan/sftpgo/utils"
	"github.com/drakkan/sftpgo/vfs"
)

const (
	templateBase           = "base.html"
	templateUsers          = "users.html"
	templateUser           = "user.html"
	templateConnections    = "connections.html"
	templateMessage        = "message.html"
	pageUsersTitle         = "Users"
	pageConnectionsTitle   = "Connections"
	page400Title           = "Bad request"
	page404Title           = "Not found"
	page404Body            = "The page you are looking for does not exist."
	page500Title           = "Internal Server Error"
	page500Body            = "The server is unable to fulfill your request."
	defaultUsersQueryLimit = 500
	webDateTimeFormat      = "2006-01-02 15:04:05" // YYYY-MM-DD HH:MM:SS
)

var (
	templates = make(map[string]*template.Template)
)

type basePage struct {
	Title             string
	CurrentURL        string
	UsersURL          string
	UserURL           string
	APIUserURL        string
	APIConnectionsURL string
	APIQuotaScanURL   string
	ConnectionsURL    string
	UsersTitle        string
	ConnectionsTitle  string
	Version           string
}

type usersPage struct {
	basePage
	Users []dataprovider.User
}

type connectionsPage struct {
	basePage
	Connections []sftpd.ConnectionStatus
}

type userPage struct {
	basePage
	IsAdd                bool
	User                 dataprovider.User
	RootPerms            []string
	Error                string
	ValidPerms           []string
	ValidSSHLoginMethods []string
	RootDirPerms         []string
}

type messagePage struct {
	basePage
	Error   string
	Success string
}

func loadTemplates(templatesPath string) {
	usersPaths := []string{
		filepath.Join(templatesPath, templateBase),
		filepath.Join(templatesPath, templateUsers),
	}
	userPaths := []string{
		filepath.Join(templatesPath, templateBase),
		filepath.Join(templatesPath, templateUser),
	}
	connectionsPaths := []string{
		filepath.Join(templatesPath, templateBase),
		filepath.Join(templatesPath, templateConnections),
	}
	messagePath := []string{
		filepath.Join(templatesPath, templateBase),
		filepath.Join(templatesPath, templateMessage),
	}
	usersTmpl := utils.LoadTemplate(template.ParseFiles(usersPaths...))
	userTmpl := utils.LoadTemplate(template.ParseFiles(userPaths...))
	connectionsTmpl := utils.LoadTemplate(template.ParseFiles(connectionsPaths...))
	messageTmpl := utils.LoadTemplate(template.ParseFiles(messagePath...))

	templates[templateUsers] = usersTmpl
	templates[templateUser] = userTmpl
	templates[templateConnections] = connectionsTmpl
	templates[templateMessage] = messageTmpl
}

func getBasePageData(title, currentURL string) basePage {
	version := utils.GetAppVersion()
	return basePage{
		Title:             title,
		CurrentURL:        currentURL,
		UsersURL:          webUsersPath,
		UserURL:           webUserPath,
		APIUserURL:        userPath,
		APIConnectionsURL: activeConnectionsPath,
		APIQuotaScanURL:   quotaScanPath,
		ConnectionsURL:    webConnectionsPath,
		UsersTitle:        pageUsersTitle,
		ConnectionsTitle:  pageConnectionsTitle,
		Version:           version.GetVersionAsString(),
	}
}

func renderTemplate(w http.ResponseWriter, tmplName string, data interface{}) {
	err := templates[tmplName].ExecuteTemplate(w, tmplName, data)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

func renderMessagePage(w http.ResponseWriter, title, body string, statusCode int, err error, message string) {
	var errorString string
	if len(body) > 0 {
		errorString = body + " "
	}
	if err != nil {
		errorString += err.Error()
	}
	data := messagePage{
		basePage: getBasePageData(title, ""),
		Error:    errorString,
		Success:  message,
	}
	w.WriteHeader(statusCode)
	renderTemplate(w, templateMessage, data)
}

func renderInternalServerErrorPage(w http.ResponseWriter, err error) {
	renderMessagePage(w, page500Title, page400Title, http.StatusInternalServerError, err, "")
}

func renderBadRequestPage(w http.ResponseWriter, err error) {
	renderMessagePage(w, page400Title, "", http.StatusBadRequest, err, "")
}

func renderNotFoundPage(w http.ResponseWriter, err error) {
	renderMessagePage(w, page404Title, page404Body, http.StatusNotFound, err, "")
}

func renderAddUserPage(w http.ResponseWriter, user dataprovider.User, error string) {
	data := userPage{
		basePage:             getBasePageData("Add a new user", webUserPath),
		IsAdd:                true,
		Error:                error,
		User:                 user,
		ValidPerms:           dataprovider.ValidPerms,
		ValidSSHLoginMethods: dataprovider.ValidSSHLoginMethods,
		RootDirPerms:         user.GetPermissionsForPath("/"),
	}
	renderTemplate(w, templateUser, data)
}

func renderUpdateUserPage(w http.ResponseWriter, user dataprovider.User, error string) {
	data := userPage{
		basePage:             getBasePageData("Update user", fmt.Sprintf("%v/%v", webUserPath, user.ID)),
		IsAdd:                false,
		Error:                error,
		User:                 user,
		ValidPerms:           dataprovider.ValidPerms,
		ValidSSHLoginMethods: dataprovider.ValidSSHLoginMethods,
		RootDirPerms:         user.GetPermissionsForPath("/"),
	}
	renderTemplate(w, templateUser, data)
}

func getVirtualFoldersFromPostFields(r *http.Request) []vfs.VirtualFolder {
	var virtualFolders []vfs.VirtualFolder
	formValue := r.Form.Get("virtual_folders")
	for _, cleaned := range getSliceFromDelimitedValues(formValue, "\n") {
		if strings.Contains(cleaned, "::") {
			mapping := strings.Split(cleaned, "::")
			if len(mapping) > 1 {
				virtualFolders = append(virtualFolders, vfs.VirtualFolder{
					VirtualPath: strings.TrimSpace(mapping[0]),
					MappedPath:  strings.TrimSpace(mapping[1]),
				})
			}
		}
	}
	return virtualFolders
}

func getUserPermissionsFromPostFields(r *http.Request) map[string][]string {
	permissions := make(map[string][]string)
	permissions["/"] = r.Form["permissions"]
	subDirsPermsValue := r.Form.Get("sub_dirs_permissions")
	for _, cleaned := range getSliceFromDelimitedValues(subDirsPermsValue, "\n") {
		if strings.Contains(cleaned, "::") {
			dirPerms := strings.Split(cleaned, "::")
			if len(dirPerms) > 1 {
				dir := dirPerms[0]
				dir = strings.TrimSpace(dir)
				perms := []string{}
				for _, p := range strings.Split(dirPerms[1], ",") {
					cleanedPerm := strings.TrimSpace(p)
					if len(cleanedPerm) > 0 {
						perms = append(perms, cleanedPerm)
					}
				}
				if len(dir) > 0 {
					permissions[dir] = perms
				}
			}
		}
	}
	return permissions
}

func getSliceFromDelimitedValues(values, delimiter string) []string {
	result := []string{}
	for _, v := range strings.Split(values, delimiter) {
		cleaned := strings.TrimSpace(v)
		if len(cleaned) > 0 {
			result = append(result, cleaned)
		}
	}
	return result
}

func getFileExtensionsFromPostField(value string, extesionsType int) []dataprovider.ExtensionsFilter {
	var result []dataprovider.ExtensionsFilter
	for _, cleaned := range getSliceFromDelimitedValues(value, "\n") {
		if strings.Contains(cleaned, "::") {
			dirExts := strings.Split(cleaned, "::")
			if len(dirExts) > 1 {
				dir := dirExts[0]
				dir = strings.TrimSpace(dir)
				exts := []string{}
				for _, e := range strings.Split(dirExts[1], ",") {
					cleanedExt := strings.TrimSpace(e)
					if len(cleanedExt) > 0 {
						exts = append(exts, cleanedExt)
					}
				}
				if len(dir) > 0 {
					filter := dataprovider.ExtensionsFilter{
						Path: dir,
					}
					if extesionsType == 1 {
						filter.AllowedExtensions = exts
						filter.DeniedExtensions = []string{}
					} else {
						filter.DeniedExtensions = exts
						filter.AllowedExtensions = []string{}
					}
					result = append(result, filter)
				}
			}
		}
	}
	return result
}

func getFiltersFromUserPostFields(r *http.Request) dataprovider.UserFilters {
	var filters dataprovider.UserFilters
	filters.AllowedIP = getSliceFromDelimitedValues(r.Form.Get("allowed_ip"), ",")
	filters.DeniedIP = getSliceFromDelimitedValues(r.Form.Get("denied_ip"), ",")
	filters.DeniedLoginMethods = r.Form["ssh_login_methods"]
	allowedExtensions := getFileExtensionsFromPostField(r.Form.Get("allowed_extensions"), 1)
	deniedExtensions := getFileExtensionsFromPostField(r.Form.Get("denied_extensions"), 2)
	extensions := []dataprovider.ExtensionsFilter{}
	if len(allowedExtensions) > 0 && len(deniedExtensions) > 0 {
		for _, allowed := range allowedExtensions {
			for _, denied := range deniedExtensions {
				if path.Clean(allowed.Path) == path.Clean(denied.Path) {
					allowed.DeniedExtensions = append(allowed.DeniedExtensions, denied.DeniedExtensions...)
				}
			}
			extensions = append(extensions, allowed)
		}
		for _, denied := range deniedExtensions {
			found := false
			for _, allowed := range allowedExtensions {
				if path.Clean(denied.Path) == path.Clean(allowed.Path) {
					found = true
					break
				}
			}
			if !found {
				extensions = append(extensions, denied)
			}
		}
	} else if len(allowedExtensions) > 0 {
		extensions = append(extensions, allowedExtensions...)
	} else if len(deniedExtensions) > 0 {
		extensions = append(extensions, deniedExtensions...)
	}
	filters.FileExtensions = extensions
	return filters
}

func getFsConfigFromUserPostFields(r *http.Request) (dataprovider.Filesystem, error) {
	var fs dataprovider.Filesystem
	provider, err := strconv.Atoi(r.Form.Get("fs_provider"))
	if err != nil {
		provider = 0
	}
	fs.Provider = provider
	if fs.Provider == 1 {
		fs.S3Config.Bucket = r.Form.Get("s3_bucket")
		fs.S3Config.Region = r.Form.Get("s3_region")
		fs.S3Config.AccessKey = r.Form.Get("s3_access_key")
		fs.S3Config.AccessSecret = r.Form.Get("s3_access_secret")
		fs.S3Config.Endpoint = r.Form.Get("s3_endpoint")
		fs.S3Config.StorageClass = r.Form.Get("s3_storage_class")
		fs.S3Config.KeyPrefix = r.Form.Get("s3_key_prefix")
		fs.S3Config.UploadPartSize, err = strconv.ParseInt(r.Form.Get("s3_upload_part_size"), 10, 64)
		if err != nil {
			return fs, err
		}
		fs.S3Config.UploadConcurrency, err = strconv.Atoi(r.Form.Get("s3_upload_concurrency"))
		if err != nil {
			return fs, err
		}
	} else if fs.Provider == 2 {
		fs.GCSConfig.Bucket = r.Form.Get("gcs_bucket")
		fs.GCSConfig.StorageClass = r.Form.Get("gcs_storage_class")
		fs.GCSConfig.KeyPrefix = r.Form.Get("gcs_key_prefix")
		autoCredentials := r.Form.Get("gcs_auto_credentials")
		if len(autoCredentials) > 0 {
			fs.GCSConfig.AutomaticCredentials = 1
		} else {
			fs.GCSConfig.AutomaticCredentials = 0
		}
		credentials, _, err := r.FormFile("gcs_credential_file")
		if err == http.ErrMissingFile {
			return fs, nil
		}
		if err != nil {
			return fs, err
		}
		defer credentials.Close()
		fileBytes, err := ioutil.ReadAll(credentials)
		if err != nil || len(fileBytes) == 0 {
			if len(fileBytes) == 0 {
				err = errors.New("credentials file size must be greater than 0")
			}
			return fs, err
		}
		fs.GCSConfig.Credentials = base64.StdEncoding.EncodeToString(fileBytes)
		fs.GCSConfig.AutomaticCredentials = 0
	}
	return fs, nil
}

func getUserFromPostFields(r *http.Request) (dataprovider.User, error) {
	var user dataprovider.User
	err := r.ParseMultipartForm(maxRequestSize)
	if err != nil {
		return user, err
	}
	publicKeysFormValue := r.Form.Get("public_keys")
	publicKeys := getSliceFromDelimitedValues(publicKeysFormValue, "\n")
	uid, err := strconv.Atoi(r.Form.Get("uid"))
	if err != nil {
		return user, err
	}
	gid, err := strconv.Atoi(r.Form.Get("gid"))
	if err != nil {
		return user, err
	}
	maxSessions, err := strconv.Atoi(r.Form.Get("max_sessions"))
	if err != nil {
		return user, err
	}
	quotaSize, err := strconv.ParseInt(r.Form.Get("quota_size"), 10, 64)
	if err != nil {
		return user, err
	}
	quotaFiles, err := strconv.Atoi(r.Form.Get("quota_files"))
	if err != nil {
		return user, err
	}
	bandwidthUL, err := strconv.ParseInt(r.Form.Get("upload_bandwidth"), 10, 64)
	if err != nil {
		return user, err
	}
	bandwidthDL, err := strconv.ParseInt(r.Form.Get("download_bandwidth"), 10, 64)
	if err != nil {
		return user, err
	}
	status, err := strconv.Atoi(r.Form.Get("status"))
	if err != nil {
		return user, err
	}
	expirationDateMillis := int64(0)
	expirationDateString := r.Form.Get("expiration_date")
	if len(strings.TrimSpace(expirationDateString)) > 0 {
		expirationDate, err := time.Parse(webDateTimeFormat, expirationDateString)
		if err != nil {
			return user, err
		}
		expirationDateMillis = utils.GetTimeAsMsSinceEpoch(expirationDate)
	}
	fsConfig, err := getFsConfigFromUserPostFields(r)
	if err != nil {
		return user, err
	}
	user = dataprovider.User{
		Username:          r.Form.Get("username"),
		Password:          r.Form.Get("password"),
		PublicKeys:        publicKeys,
		HomeDir:           r.Form.Get("home_dir"),
		VirtualFolders:    getVirtualFoldersFromPostFields(r),
		UID:               uid,
		GID:               gid,
		Permissions:       getUserPermissionsFromPostFields(r),
		MaxSessions:       maxSessions,
		QuotaSize:         quotaSize,
		QuotaFiles:        quotaFiles,
		UploadBandwidth:   bandwidthUL,
		DownloadBandwidth: bandwidthDL,
		Status:            status,
		ExpirationDate:    expirationDateMillis,
		Filters:           getFiltersFromUserPostFields(r),
		FsConfig:          fsConfig,
	}
	return user, err
}

func handleGetWebUsers(w http.ResponseWriter, r *http.Request) {
	limit := defaultUsersQueryLimit
	if _, ok := r.URL.Query()["qlimit"]; ok {
		var err error
		limit, err = strconv.Atoi(r.URL.Query().Get("qlimit"))
		if err != nil {
			limit = defaultUsersQueryLimit
		}
	}
	var users []dataprovider.User
	u, err := dataprovider.GetUsers(dataProvider, limit, 0, "ASC", "")
	users = append(users, u...)
	for len(u) == limit {
		u, err = dataprovider.GetUsers(dataProvider, limit, len(users), "ASC", "")
		if err == nil && len(u) > 0 {
			users = append(users, u...)
		} else {
			break
		}
	}
	if err != nil {
		renderInternalServerErrorPage(w, err)
		return
	}
	data := usersPage{
		basePage: getBasePageData(pageUsersTitle, webUsersPath),
		Users:    users,
	}
	renderTemplate(w, templateUsers, data)
}

func handleWebAddUserGet(w http.ResponseWriter, r *http.Request) {
	renderAddUserPage(w, dataprovider.User{Status: 1}, "")
}

func handleWebUpdateUserGet(userID string, w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(userID, 10, 64)
	if err != nil {
		renderBadRequestPage(w, err)
		return
	}
	user, err := dataprovider.GetUserByID(dataProvider, id)
	if err == nil {
		renderUpdateUserPage(w, user, "")
	} else if _, ok := err.(*dataprovider.RecordNotFoundError); ok {
		renderNotFoundPage(w, err)
	} else {
		renderInternalServerErrorPage(w, err)
	}
}

func handleWebAddUserPost(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxRequestSize)
	user, err := getUserFromPostFields(r)
	if err != nil {
		renderAddUserPage(w, user, err.Error())
		return
	}
	err = dataprovider.AddUser(dataProvider, user)
	if err == nil {
		http.Redirect(w, r, webUsersPath, http.StatusSeeOther)
	} else {
		renderAddUserPage(w, user, err.Error())
	}
}

func handleWebUpdateUserPost(userID string, w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxRequestSize)
	id, err := strconv.ParseInt(userID, 10, 64)
	if err != nil {
		renderBadRequestPage(w, err)
		return
	}
	user, err := dataprovider.GetUserByID(dataProvider, id)
	if _, ok := err.(*dataprovider.RecordNotFoundError); ok {
		renderNotFoundPage(w, err)
		return
	} else if err != nil {
		renderInternalServerErrorPage(w, err)
		return
	}
	updatedUser, err := getUserFromPostFields(r)
	if err != nil {
		renderUpdateUserPage(w, user, err.Error())
		return
	}
	updatedUser.ID = user.ID
	if len(updatedUser.Password) == 0 {
		updatedUser.Password = user.Password
	}
	err = dataprovider.UpdateUser(dataProvider, updatedUser)
	if err == nil {
		http.Redirect(w, r, webUsersPath, http.StatusSeeOther)
	} else {
		renderUpdateUserPage(w, user, err.Error())
	}
}

func handleWebGetConnections(w http.ResponseWriter, r *http.Request) {
	connectionStats := sftpd.GetConnectionsStats()
	data := connectionsPage{
		basePage:    getBasePageData(pageConnectionsTitle, webConnectionsPath),
		Connections: connectionStats,
	}
	renderTemplate(w, templateConnections, data)
}