You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: get_upgrade_notes.go
    path of file: ./repos/porter/api/server/handlers/v1/template
    
    the code of the file until where you have to start completion: package template

import (
	"context"
	"fmt"
	"net/http"
	"strings"

	"github.com/porter-dev/porter/api/server/handlers"
	"github.com/porter-dev/porter/api/server/shared"
	"github.com/porter-dev/porter/api/server/shared/apierrors"
	"github.com/porter-dev/porter/api/server/shared/config"
	"github.com/porter-dev/porter/api/server/shared/requestutils"
	"github.com/porter-dev/porter/api/types"
	"github.com/porter-dev/porter/internal/helm/loader"
	"github.com/porter-dev/porter/internal/helm/repo"
	"github.com/porter-dev/porter/internal/helm/upgrade"
	"github.com/porter-dev/porter/internal/models"
)

type TemplateGetUpgradeNotesHandler struct {
	handlers.PorterHandlerReadWriter
}

func NewTemplateGetUpgradeNotesHandler(
	config *config.Config,
	decoderValidator shared.RequestDecoderValidator,
	writer shared.ResultWriter,
) *TemplateGetUpgradeNotesHandler {
	return &TemplateGetUpgradeNotesHandler{
		PorterHandl
    
func (t *TemplateGetUpgradeNotesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	project, _ := r.Context().Value(types.ProjectScope).(*models.Project)

	request := &types.GetTemplateUpgradeNotesRequest{}

	ok := t.DecodeAndValidate(w, r, request)

	if !ok {
		return
	}

	hrs, err := t.Repo().HelmRepo().ListHelmReposByProjectID(project.ID)
	if err != nil {
		t.HandleAPIError(w, r, apierrors.NewErrInternal(err))
		return
	}

	isValid := repo.ValidateRepoURL(t.Config().ServerConf.DefaultAddonHelmRepoURL, t.Config().ServerConf.DefaultApplicationHelmRepoURL, hrs, request.RepoURL)

	if !isValid {
		t.HandleAPIError(w, r, apierrors.NewErrPassThroughToClient(
			fmt.Errorf("invalid repo_url parameter"),
			http.StatusBadRequest,
		))

		return
	}

	name, _ := requestutils.GetURLParamString(r, types.URLParamTemplateName)

	if name == "" {
		t.HandleAPIError(w, r, apierrors.NewErrPassThroughToClient(
			fmt.Errorf("template name is required"),
			http.StatusBadRequest,
		))

		return
	}

	version, _ := requestutils.GetURLParamString(r, types.URLParamTemplateVersion)

	// if version passed as latest, pass empty string to loader to get latest
	if version == "latest" {
		version = ""
	}

	prevVersion := request.PrevVersion

	if prevVersion == "" {
		prevVersion = "v0.0.0"
	}

	chart, err := loader.LoadChartPublic(context.Background(), request.RepoURL, name, version)
	if err != nil {
		t.HandleAPIError(w, r, apierrors.NewErrInternal(err))
		return
	}

	res := &upgrade.UpgradeFile{}

	for _, file := range chart.Files {
		if strings.Contains(file.Name, "upgrade.yaml") {
			upgradeFile, err := upgrade.ParseUpgradeFileFromBytes(file.Data)
			if err != nil {
				break
			}

			upgradeFile, err = upgradeFile.GetUpgradeFileBetweenVersions(prevVersion, version)

			if err != nil {
				break
			}

			res = upgradeFile
		}
	}

	t.WriteResult(w, r, res)
}