// Init implements cmd.Command.Init. It will return an error satisfying
// errors.BadRequest if you give it an incorrect number of arguments.
func (c *ShowServiceCommand) Init(args []string) error {
	if len(args) == 0 {
		return errors.NewBadRequest(nil, "missing service name")
	}
	c.target = args[0]
	if err := cmd.CheckEmpty(args[1:]); err != nil {
		return errors.NewBadRequest(err, "")
	}
	return nil
}

func (h *charmsHandler) serveGet(w http.ResponseWriter, r *http.Request) error {
	// TODO (bug #1499338 2015/09/24) authenticate this.
	st, err := h.ctxt.stateForRequestUnauthenticated(r)
	if err != nil {
		return errors.Trace(err)
	}
	// Retrieve or list charm files.
	// Requires "url" (charm URL) and an optional "file" (the path to the
	// charm file) to be included in the query.
	charmArchivePath, filePath, err := h.processGet(r, st)
	if err != nil {
		// An error occurred retrieving the charm bundle.
		if errors.IsNotFound(err) {
			return errors.Trace(err)
		}
		return errors.NewBadRequest(err, "")
	}
	var sender bundleContentSenderFunc
	switch filePath {
	case "":
		// The client requested the list of charm files.
		sender = h.manifestSender
	case "*":
		// The client requested the archive.
		sender = h.archiveSender
	default:
		// The client requested a specific file.
		sender = h.archiveEntrySender(filePath)
	}
	if err := h.sendBundleContent(w, r, charmArchivePath, sender); err != nil {
		return errors.Trace(err)
	}
	return nil
}

func (h *toolsDownloadHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	st, err := h.ctxt.stateForRequestUnauthenticated(r)
	if err != nil {
		if err := sendError(w, err); err != nil {
			logger.Errorf("%v", err)
		}
		return
	}

	switch r.Method {
	case "GET":
		tarball, err := h.processGet(r, st)
		if err != nil {
			logger.Errorf("GET(%s) failed: %v", r.URL, err)
			if err := sendError(w, errors.NewBadRequest(err, "")); err != nil {
				logger.Errorf("%v", err)
			}
			return
		}
		if err := h.sendTools(w, http.StatusOK, tarball); err != nil {
			logger.Errorf("%v", err)
		}
	default:
		if err := sendError(w, errors.MethodNotAllowedf("unsupported method: %q", r.Method)); err != nil {
			logger.Errorf("%v", err)
		}
	}
}

// RestoreError makes a best effort at converting the given error
// back into an error originally converted by ServerError(). If the
// error could not be converted then false is returned.
func RestoreError(err error) (error, bool) {
	err = errors.Cause(err)

	if apiErr, ok := err.(*params.Error); !ok {
		return err, false
	} else if apiErr == nil {
		return nil, true
	}
	if params.ErrCode(err) == "" {
		return err, false
	}
	msg := err.Error()

	if singleton, ok := singletonError(err); ok {
		return singleton, true
	}

	// TODO(ericsnow) Support the other error types handled by ServerError().
	switch {
	case params.IsCodeUnauthorized(err):
		return errors.NewUnauthorized(nil, msg), true
	case params.IsCodeNotFound(err):
		// TODO(ericsnow) UnknownModelError should be handled here too.
		// ...by parsing msg?
		return errors.NewNotFound(nil, msg), true
	case params.IsCodeAlreadyExists(err):
		return errors.NewAlreadyExists(nil, msg), true
	case params.IsCodeNotAssigned(err):
		return errors.NewNotAssigned(nil, msg), true
	case params.IsCodeHasAssignedUnits(err):
		// TODO(ericsnow) Handle state.HasAssignedUnitsError here.
		// ...by parsing msg?
		return err, false
	case params.IsCodeNoAddressSet(err):
		// TODO(ericsnow) Handle isNoAddressSetError here.
		// ...by parsing msg?
		return err, false
	case params.IsCodeNotProvisioned(err):
		return errors.NewNotProvisioned(nil, msg), true
	case params.IsCodeUpgradeInProgress(err):
		// TODO(ericsnow) Handle state.UpgradeInProgressError here.
		// ...by parsing msg?
		return err, false
	case params.IsCodeMachineHasAttachedStorage(err):
		// TODO(ericsnow) Handle state.HasAttachmentsError here.
		// ...by parsing msg?
		return err, false
	case params.IsCodeNotSupported(err):
		return errors.NewNotSupported(nil, msg), true
	case params.IsBadRequest(err):
		return errors.NewBadRequest(nil, msg), true
	case params.IsMethodNotAllowed(err):
		return errors.NewMethodNotAllowed(nil, msg), true
	case params.ErrCode(err) == params.CodeDischargeRequired:
		// TODO(ericsnow) Handle DischargeRequiredError here.
		return err, false
	default:
		return err, false
	}
}

// sendTools streams the tools tarball to the client.
func (h *toolsDownloadHandler) sendTools(w http.ResponseWriter, statusCode int, tarball []byte) {
	w.Header().Set("Content-Type", "application/x-tar-gz")
	w.Header().Set("Content-Length", fmt.Sprint(len(tarball)))
	w.WriteHeader(statusCode)
	if _, err := w.Write(tarball); err != nil {
		sendError(w, errors.NewBadRequest(errors.Annotatef(err, "failed to write tools"), ""))
		return
	}
}

// processPost handles a tools upload POST request after authentication.
func (h *toolsUploadHandler) processPost(r *http.Request, st *state.State) (*tools.Tools, error) {
	query := r.URL.Query()

	binaryVersionParam := query.Get("binaryVersion")
	if binaryVersionParam == "" {
		return nil, errors.BadRequestf("expected binaryVersion argument")
	}
	toolsVersion, err := version.ParseBinary(binaryVersionParam)
	if err != nil {
		return nil, errors.NewBadRequest(err, fmt.Sprintf("invalid tools version %q", binaryVersionParam))
	}

	// Make sure the content type is x-tar-gz.
	contentType := r.Header.Get("Content-Type")
	if contentType != "application/x-tar-gz" {
		return nil, errors.BadRequestf("expected Content-Type: application/x-tar-gz, got: %v", contentType)
	}

	// Get the server root, so we know how to form the URL in the Tools returned.
	serverRoot, err := h.getServerRoot(r, query, st)
	if err != nil {
		return nil, errors.NewBadRequest(err, "cannot to determine server root")
	}

	// We'll clone the tools for each additional series specified.
	var cloneSeries []string
	if seriesParam := query.Get("series"); seriesParam != "" {
		cloneSeries = strings.Split(seriesParam, ",")
	}
	logger.Debugf("request to upload tools: %s", toolsVersion)
	logger.Debugf("additional series: %s", cloneSeries)

	toolsVersions := []version.Binary{toolsVersion}
	for _, series := range cloneSeries {
		if series != toolsVersion.Series {
			v := toolsVersion
			v.Series = series
			toolsVersions = append(toolsVersions, v)
		}
	}
	return h.handleUpload(r.Body, toolsVersions, serverRoot, st)
}

func (h *charmsHandler) servePost(w http.ResponseWriter, r *http.Request) error {
	st, _, err := h.ctxt.stateForRequestAuthenticatedUser(r)
	if err != nil {
		return errors.Trace(err)
	}
	// Add a charm to the store provider.
	charmURL, err := h.processPost(r, st)
	if err != nil {
		return errors.NewBadRequest(err, "")
	}
	sendStatusAndJSON(w, http.StatusOK, &params.CharmsResponse{CharmURL: charmURL.String()})
	return nil
}

func getGUIComboPath(rootDir, query string) (string, error) {
	k := strings.SplitN(query, "=", 2)[0]
	fname, err := url.QueryUnescape(k)
	if err != nil {
		return "", errors.NewBadRequest(err, fmt.Sprintf("invalid file name %q", k))
	}
	// Ignore pat injected queries.
	if strings.HasPrefix(fname, ":") {
		return "", nil
	}
	// The Juju GUI references its combined files starting from the
	// "static/gui/build" directory.
	fname = filepath.Clean(fname)
	if fname == ".." || strings.HasPrefix(fname, "../") {
		return "", errors.BadRequestf("forbidden file path %q", k)
	}
	return filepath.Join(rootDir, "static", "gui", "build", fname), nil
}

func (h *charmsHandler) ServeGet(w http.ResponseWriter, r *http.Request) error {
	if r.Method != "GET" {
		return errors.Trace(emitUnsupportedMethodErr(r.Method))
	}

	st, _, err := h.ctxt.stateForRequestAuthenticated(r)
	if err != nil {
		return errors.Trace(err)
	}
	// Retrieve or list charm files.
	// Requires "url" (charm URL) and an optional "file" (the path to the
	// charm file) to be included in the query. Optionally also receives an
	// "icon" query for returning the charm icon or a default one in case the
	// charm has no icon.
	charmArchivePath, fileArg, serveIcon, err := h.processGet(r, st)
	if err != nil {
		// An error occurred retrieving the charm bundle.
		if errors.IsNotFound(err) {
			return errors.Trace(err)
		}

		return errors.NewBadRequest(err, "")
	}
	defer os.Remove(charmArchivePath)

	var sender bundleContentSenderFunc
	switch fileArg {
	case "":
		// The client requested the list of charm files.
		sender = h.manifestSender
	case "*":
		// The client requested the archive.
		sender = h.archiveSender
	default:
		// The client requested a specific file.
		sender = h.archiveEntrySender(fileArg, serveIcon)
	}

	return errors.Trace(sendBundleContent(w, r, charmArchivePath, sender))
}

// Init implements cmd.Command.Init. It will return an error satisfying
// errors.BadRequest if you give it an incorrect number of arguments.
func (c *UploadCommand) Init(args []string) error {
	switch len(args) {
	case 0:
		return errors.BadRequestf("missing application name")
	case 1:
		return errors.BadRequestf("no resource specified")
	}

	service := args[0]
	if service == "" { // TODO(ericsnow) names.IsValidApplication
		return errors.NewNotValid(nil, "missing application name")
	}
	c.service = service

	if err := c.addResourceFile(args[1]); err != nil {
		return errors.Trace(err)
	}
	if err := cmd.CheckEmpty(args[2:]); err != nil {
		return errors.NewBadRequest(err, "")
	}

	return nil
}

// handlePut is used to switch to a specific Juju GUI version.
func (h *guiVersionHandler) handlePut(w http.ResponseWriter, req *http.Request) error {
	// Validate the request.
	if ctype := req.Header.Get("Content-Type"); ctype != params.ContentTypeJSON {
		return errors.BadRequestf("invalid content type %q: expected %q", ctype, params.ContentTypeJSON)
	}

	// Authenticate the request and retrieve the Juju state.
	st, _, err := h.ctxt.stateForRequestAuthenticatedUser(req)
	if err != nil {
		return errors.Annotate(err, "cannot open state")
	}

	var selected params.GUIVersionRequest
	decoder := json.NewDecoder(req.Body)
	if err := decoder.Decode(&selected); err != nil {
		return errors.NewBadRequest(err, "invalid request body")
	}

	// Switch to the provided GUI version.
	if err = st.GUISetVersion(selected.Version); err != nil {
		return errors.Trace(err)
	}
	return nil
}

// processPost handles a charm upload POST request after authentication.
func (h *charmsHandler) processPost(r *http.Request, st *state.State) (*charm.URL, error) {
	query := r.URL.Query()
	schema := query.Get("schema")
	if schema == "" {
		schema = "local"
	}

	series := query.Get("series")
	if series != "" {
		if err := charm.ValidateSeries(series); err != nil {
			return nil, errors.NewBadRequest(err, "")
		}
	}

	// Make sure the content type is zip.
	contentType := r.Header.Get("Content-Type")
	if contentType != "application/zip" {
		return nil, errors.BadRequestf("expected Content-Type: application/zip, got: %v", contentType)
	}

	charmFileName, err := writeCharmToTempFile(r.Body)
	if err != nil {
		return nil, errors.Trace(err)
	}
	defer os.Remove(charmFileName)

	err = h.processUploadedArchive(charmFileName)
	if err != nil {
		return nil, err
	}
	archive, err := charm.ReadCharmArchive(charmFileName)
	if err != nil {
		return nil, errors.BadRequestf("invalid charm archive: %v", err)
	}

	name := archive.Meta().Name
	if err := charm.ValidateName(name); err != nil {
		return nil, errors.NewBadRequest(err, "")
	}

	// We got it, now let's reserve a charm URL for it in state.
	curl := &charm.URL{
		Schema:   schema,
		Name:     archive.Meta().Name,
		Revision: archive.Revision(),
		Series:   series,
	}
	if schema == "local" {
		curl, err = st.PrepareLocalCharmUpload(curl)
		if err != nil {
			return nil, errors.Trace(err)
		}
	} else {
		// "cs:" charms may only be uploaded into models which are
		// being imported during model migrations. There's currently
		// no other time where it makes sense to accept charm store
		// charms through this endpoint.
		if isImporting, err := modelIsImporting(st); err != nil {
			return nil, errors.Trace(err)
		} else if !isImporting {
			return nil, errors.New("cs charms may only be uploaded during model migration import")
		}

		// If a revision argument is provided, it takes precedence
		// over the revision in the charm archive. This is required to
		// handle the revision differences between unpublished and
		// published charms in the charm store.
		revisionStr := query.Get("revision")
		if revisionStr != "" {
			curl.Revision, err = strconv.Atoi(revisionStr)
			if err != nil {
				return nil, errors.NewBadRequest(errors.NewNotValid(err, "revision"), "")
			}
		}
		if _, err := st.PrepareStoreCharmUpload(curl); err != nil {
			return nil, errors.Trace(err)
		}
	}

	// Now we need to repackage it with the reserved URL, upload it to
	// provider storage and update the state.
	err = h.repackageAndUploadCharm(st, archive, curl)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return curl, nil
}