guesstimate/server/internal/route/project.go

package route

import (
	"encoding/json"
	"log"
	"net/http"
	"strconv"

	jsonpatch "gopkg.in/evanphx/json-patch.v4"

	"forge.cadoles.com/wpetit/guesstimate/internal/model"
	"forge.cadoles.com/wpetit/guesstimate/internal/storm"
	"github.com/go-chi/chi"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/middleware/container"
)

type projectResponse struct {
	Version uint64         `json:"version"`
	Project *model.Project `json:"project"`
}

func handleGetProject(w http.ResponseWriter, r *http.Request) {
	ctn := container.Must(r.Context())
	db := storm.Must(ctn)

	projectID := getProjectID(r)

	var (
		version uint64
		err     error
	)

	rawVersion := r.URL.Query().Get("version")
	if rawVersion != "" {
		version, err = strconv.ParseUint(rawVersion, 10, 64)
		if err != nil {
			http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)

			return
		}
	}

	tx, err := db.Begin(false)
	if err != nil {
		panic(errors.Wrap(err, "could not start transaction"))
	}

	defer func() {
		if err := tx.Rollback(); err != nil && err != storm.ErrNotInTransaction {
			panic(errors.Wrap(err, "could not rollback transaction"))
		}
	}()

	entry := &model.ProjectEntry{}
	if err := tx.One("ID", projectID, entry); err != nil {
		if err == storm.ErrNotFound {
			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)

			return
		}

		panic(errors.Wrapf(err, "could not find project '%s'", projectID))
	}

	if rawVersion != "" && entry.Version == version {
		http.Error(w, http.StatusText(http.StatusNotModified), http.StatusNotModified)

		return
	}

	if err := writeJSON(w, http.StatusOK, &projectResponse{entry.Version, entry.Project}); err != nil {
		panic(errors.Wrap(err, "could not write json"))
	}
}

type createRequest struct {
	Project *model.Project `json:"project"`
}

func handleCreateProject(w http.ResponseWriter, r *http.Request) {
	ctn := container.Must(r.Context())
	db := storm.Must(ctn)

	projectID := getProjectID(r)

	log.Printf("handling create request for project %s", projectID)

	createReq := &createRequest{}
	if err := parseJSONBody(r, createReq); err != nil {
		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)

		panic(errors.Wrap(err, "could not parse create request"))
	}

	tx, err := db.Begin(true)
	if err != nil {
		panic(errors.Wrap(err, "could not start transaction"))
	}

	defer func() {
		if err := tx.Rollback(); err != nil && err != storm.ErrNotInTransaction {
			panic(errors.Wrap(err, "could not rollback transaction"))
		}
	}()

	entry := &model.ProjectEntry{}

	err = tx.One("ID", projectID, entry)
	if err == nil {
		http.Error(w, http.StatusText(http.StatusConflict), http.StatusConflict)
		return
	}

	if err != storm.ErrNotFound {
		panic(errors.Wrapf(err, "could not check project '%s'", projectID))
	}

	entry.ID = projectID
	entry.Project = createReq.Project
	entry.Version = 0

	if err := tx.Save(entry); err != nil {
		panic(errors.Wrap(err, "could not save project"))
	}

	if err := tx.Commit(); err != nil {
		panic(errors.Wrap(err, "could not commit transaction"))
	}

	if err := writeJSON(w, http.StatusCreated, &projectResponse{entry.Version, entry.Project}); err != nil {
		panic(errors.Wrap(err, "could not write json response"))
	}
}

type patchRequest struct {
	Version uint64          `json:"version"`
	Patch   json.RawMessage `json:"patch"`
}

func handlePatchProject(w http.ResponseWriter, r *http.Request) {
	ctn := container.Must(r.Context())
	db := storm.Must(ctn)

	projectID := getProjectID(r)

	log.Printf("handling patch request for project %s", projectID)

	patchReq := &patchRequest{}
	if err := parseJSONBody(r, patchReq); err != nil {
		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)

		panic(errors.Wrap(err, "could not parse patch request"))
	}

	tx, err := db.Begin(true)
	if err != nil {
		panic(errors.Wrap(err, "could not start transaction"))
	}

	defer func() {
		if err := tx.Rollback(); err != nil && err != storm.ErrNotInTransaction {
			panic(errors.Wrap(err, "could not rollback transaction"))
		}
	}()

	entry := &model.ProjectEntry{}
	if err := tx.One("ID", projectID, entry); err != nil {
		if err == storm.ErrNotFound {
			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)

			return
		}

		panic(errors.Wrapf(err, "could not find project '%s'", projectID))
	}

	if entry.Version != patchReq.Version {
		if err := writeJSON(w, http.StatusConflict, &projectResponse{entry.Version, entry.Project}); err != nil {
			panic(errors.Wrap(err, "could not write json response"))
		}

		return
	}

	projectData, err := json.Marshal(entry.Project)
	if err != nil {
		panic(errors.Wrap(err, "could not marshal project"))
	}

	projectData, err = jsonpatch.MergePatch(projectData, patchReq.Patch)
	if err != nil {
		panic(errors.Wrap(err, "could not merge project patch"))
	}

	newProject := &model.Project{}
	if err := json.Unmarshal(projectData, newProject); err != nil {
		panic(errors.Wrap(err, "could not merge project patch"))
	}

	entry.Version++
	entry.Project = newProject

	if err := tx.Save(entry); err != nil {
		panic(errors.Wrap(err, "could not save project"))
	}

	if err := tx.Commit(); err != nil {
		panic(errors.Wrap(err, "could not commit transaction"))
	}

	if err := writeJSON(w, http.StatusOK, &projectResponse{entry.Version, entry.Project}); err != nil {
		panic(errors.Wrap(err, "could not write json response"))
	}
}

func handleDeleteProject(w http.ResponseWriter, r *http.Request) {

}

func getProjectID(r *http.Request) model.ProjectID {
	return model.ProjectID(chi.URLParam(r, "projectID"))
}

func parseJSONBody(r *http.Request, payload interface{}) (err error) {
	decoder := json.NewDecoder(r.Body)

	defer func() {
		if err = r.Body.Close(); err != nil {
			err = errors.Wrap(err, "could not close request body")
		}
	}()

	if err := decoder.Decode(payload); err != nil {
		return errors.Wrap(err, "could not decode request body")
	}

	return nil
}

func writeJSON(w http.ResponseWriter, statusCode int, data interface{}) error {
	encoder := json.NewEncoder(w)
	encoder.SetIndent("", " ")
	w.WriteHeader(statusCode)
	w.Header().Set("Content-Type", "application/json")

	return encoder.Encode(data)
}