CIiP-WS-2021-2022-Projektarbeit_Lithium/main.go

package main

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"

	"github.com/geplauder/lithium/middlewares"
	"github.com/geplauder/lithium/pipelines"
	"github.com/geplauder/lithium/settings"
	"github.com/geplauder/lithium/storage"
	"github.com/gorilla/mux"
	"github.com/spf13/afero"
)

const Name string = "Lithium"
const Version string = "0.1.0"

var GitCommit string

type Metadata struct {
	Name       string `json:"name"`
	Version    string `json:"version"`
	CommitHash string `json:"commit_hash"`
}

func PipelineHandler(pipeline pipelines.IPipeline, storageProvider storage.IStorageProvider, w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	err := json.NewEncoder(w).Encode(pipeline)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
	}
}

func IndexHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	err := json.NewEncoder(w).Encode(Metadata{Name, Version, GitCommit})
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
	}
}

func writeError(w http.ResponseWriter, status int, errStr string) {
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(struct {
		Error string `json:"error"`
	}{errStr})
}

func UploadHandler(w http.ResponseWriter, r *http.Request, pipes []pipelines.IPipeline, storageProvider storage.IStorageProvider) {
	// open file handler
	formFile, handler, err := r.FormFile("file")
	if err != nil {
		writeError(w, http.StatusUnprocessableEntity, err.Error())
		return
	}

	defer formFile.Close()

	// check pipelines form param
	formPipeline := r.FormValue("pipeline")
	if formPipeline == "" {
		writeError(w, http.StatusUnprocessableEntity, "pipeline parameter missing")
		return
	}

	var execPipe pipelines.IPipeline
	for _, pipe := range pipes {
		if formPipeline == pipe.GetSlug() {
			execPipe = pipe
			break
		}
	}

	if execPipe == nil {
		writeError(w, http.StatusUnprocessableEntity, "pipeline not found")
		return
	}

	bucket := r.FormValue("bucket")
	if bucket == "" {
		writeError(w, http.StatusUnprocessableEntity, "bucket parameter missing")
		return
	}

	// open file
	file, err := handler.Open()
	if err != nil {
		writeError(w, http.StatusInternalServerError, "error reading uploaded file")
		return
	}

	defer file.Close()

	// read file to buffer
	buf := bytes.NewBuffer(nil)
	_, err = io.Copy(buf, file)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "error reading file from buffer")
		return
	}

	// store uploaded file
	_, err = storageProvider.StoreRaw(bucket, "source.jpg", buf.Bytes())
	if err != nil {
		return
	}

	// execute pipeline
	output, err := execPipe.Run("source.jpg", bucket, storageProvider)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "error executing pipeline")
		return
	}

	w.Header().Set("Content-Type", "application/json")

	err = json.NewEncoder(w).Encode(struct {
		Message     string   `json:"message"`
		OutputFiles []string `json:"output_files"`
	}{"ok", []string{output}})

	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
	}
}

func RegisterRoutes(r *mux.Router, pipelines []pipelines.IPipeline, storageProvider storage.IStorageProvider) {
	r.HandleFunc("/", IndexHandler).Methods("GET")
	r.HandleFunc("/upload", func(w http.ResponseWriter, r *http.Request) {
		UploadHandler(w, r, pipelines, storageProvider)
	}).Methods("POST")
	r.HandleFunc("/pipelines/{pipeline}", func(w http.ResponseWriter, r *http.Request) {
		for _, pipeline := range pipelines {
			if pipeline.GetSlug() == mux.Vars(r)["pipeline"] {
				PipelineHandler(pipeline, storageProvider, w, r)
				return
			}
		}

		w.WriteHeader(404)
	}).Methods("GET")
}

func main() {
	appSettings, err := settings.LoadSettings(afero.NewOsFs())
	if err != nil {
		panic(err)
	}

	var storageProvider storage.IStorageProvider

	if appSettings.StorageProvider.Type == 0 {
		storageProvider = storage.GetFileSystemStorageProvider(appSettings.StorageProvider.BasePath, "")
	} else {
		panic("Invalid file system provided!")
	}

	pipes := pipelines.LoadPipelines()

	r := mux.NewRouter()

	if appSettings.Authentication.Enabled {
		authMiddleware := middlewares.CreateAuthenticationMiddleware(appSettings.Authentication.Token)

		r.Use(authMiddleware.Middleware)
	}

	if appSettings.RateLimiter.Enabled {
		rateLimiterMiddleware, err := middlewares.CreateRateLimiterMiddleware(appSettings.RateLimiter.RequestsPerMinute, appSettings.RateLimiter.AllowedBurst)
		if err != nil {
			panic(err)
		}

		r.Use(rateLimiterMiddleware.Middleware)
	}

	RegisterRoutes(r, pipes, storageProvider)

	err = http.ListenAndServe(appSettings.Endpoint, r)
	if err != nil {
		panic(err)
	}
}