sklad: preliminary web interface

Only exposing most read operations thus far.
sklad: styling, add a basic view for containers
2019-04-14 10:17:02 +02:00 · 2019-04-14 01:05:05 +02:00 · 2019-04-13 23:54:24 +02:00 · 2019-04-13 22:48:51 +02:00 · 2019-04-13 05:57:43 +02:00 · 2019-04-13 05:43:33 +02:00
8 changed files with 680 additions and 3 deletions
--- a/label-tool/main.go
+++ b/label-tool/main.go
@ -217,10 +217,10 @@ func main() {
 		log.Fatalf("usage: %s ADDRESS BDF-FILE\n", os.Args[0])
 	}

-	address, bdf_path := os.Args[1], os.Args[2]
+	address, bdfPath := os.Args[1], os.Args[2]

 	var err error
-	fi, err := os.Open(bdf_path)
+	fi, err := os.Open(bdfPath)
 	if err != nil {
 		log.Fatalln(err)
 	}
@ -235,5 +235,5 @@ func main() {

 	log.Println("starting server")
 	http.HandleFunc("/", handle)
-	log.Fatal(http.ListenAndServe(address, nil))
+	log.Fatalln(http.ListenAndServe(address, nil))
 }
--- a/sklad/base.tmpl
+++ b/sklad/base.tmpl
@ -0,0 +1,68 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<title>{{ template "Title" . }} - sklad</title>
+	<meta http-equiv=Content-Type content="text/html; charset=utf-8">
+	<meta name=viewport content="width=device-width, initial-scale=1">
+	<style>
+	html, body { min-height: 100vh; }
+	body { padding: 1rem; box-sizing: border-box;
+		margin: 0 auto; max-width: 50rem;
+		border-left: 1px solid #ccc; border-right: 1px solid #ccc;
+		font-family: sans-serif; }
+
+	section { border: 1px outset #ccc; padding: 0 .5rem; margin: 1rem 0; }
+	section > p { margin: 0 0 .5rem 0; }
+
+	header, footer { display: flex; justify-content: space-between;
+		align-items: center; flex-wrap: wrap; padding-top: .5em; }
+	header { margin: 0 -.5rem; padding: .5rem .5rem 0 .5rem;
+		background: linear-gradient(0deg, transparent, #f8f8f8); }
+	body > header { margin: -1rem -1rem 0 -1rem; padding: 1rem 1rem 0 1rem;
+		background: linear-gradient(0deg, transparent, #eeeeee); }
+
+	header *,
+	footer * { display: inline-block; }
+	header > *,
+	footer > * { margin: 0 0 .5rem 0; }
+	header > *:not(:last-child),
+	footer > *:not(:last-child) { margin-right: .5rem; }
+
+	header > h2,
+	header > h3 { flex-grow: 1; }
+
+	/* Don't ask me why this is an improvement on mobile browsers. */
+	input[type=submit], input[type=text], input[type=password],
+	select, textarea { border: 1px inset #ccc; padding: .25rem; }
+	input[type=submit] { border-style: outset; }
+	select { border-style: solid; }
+
+	a { color: inherit; }
+	textarea { padding: .5rem; box-sizing: border-box; width: 100%;
+		font-family: inherit; resize: vertical; }
+	select { max-width: 15rem; }
+	</style>
+</head>
+<body>
+
+<header>
+	<h1>sklad</h1>
+
+{{ block "HeaderControls" . }}
+	<a href=/>Obaly</a>
+	<a href=/series>Řady</a>
+
+	<form method=get action=/search>
+	<input type=text name=q><input type=submit value="Hledat">
+	</form>
+
+	<form method=post action=/logout>
+	<input type=submit value="Odhlásit">
+	</form>
+{{ end }}
+
+</header>
+
+{{ template "Content" . }}
+</body>
+</html>
--- a/sklad/container.tmpl
+++ b/sklad/container.tmpl
@ -0,0 +1,93 @@
+{{ define "Title" }}{{ or .Id "Obaly" }}{{ end }}
+{{ define "Content" }}
+
+{{ if .Id }}
+
+<section>
+<header>
+	<h2>{{ .Id }}</h2>
+	<form method=post action="/label?id={{ .Id }}">
+	<input type=submit value="Vytisknout štítek">
+	</form>
+	<form method=post action="/?id={{ .Id }}&amp;remove">
+	<input type=submit value="Odstranit">
+	</form>
+</header>
+
+<form method=post action="/?id={{ .Id }}">
+<textarea name=description rows=5>
+{{ .Description }}
+</textarea>
+<footer>
+	<div>
+		<label for=series>Řada:</label>
+		<select name=series id=series>
+{{ range $prefix, $desc := .AllSeries }}
+			<option value="{{ $prefix }}"
+				{{ if eq $prefix $.Series }}selected{{ end }}
+				>{{ $prefix }} &mdash; {{ $desc }}</option>
+{{ end }}
+		</select>
+	</div>
+	<div>
+		<label for=parent>Nadobal:</label>
+		<input type=text name=parent id=parent value="{{ .Parent }}">
+	</div>
+	<input type=submit value="Uložit">
+</footer>
+</form>
+</section>
+
+<h2>Podobaly</h3>
+
+{{ else }}
+<section>
+<header>
+	<h2>Nový obal</h2>
+</header>
+<form method=post action="/">
+<textarea name=description rows=5
+	placeholder="Popis obalu nebo jeho obsahu"></textarea>
+<footer>
+	<div>
+		<label for=series>Řada:</label>
+		<select name=series id=series>
+{{ range $prefix, $desc := .AllSeries }}
+			<option value="{{ $prefix }}"
+				{{ if eq $prefix $.Series }}selected{{ end }}
+				>{{ $prefix }} &mdash; {{ $desc }}</option>
+{{ end }}
+		</select>
+	</div>
+	<div>
+		<label for=parent>Nadobal:</label>
+		<input type=text name=parent id=parent value="">
+	</div>
+	<input type=submit value="Uložit">
+</footer>
+</form>
+</section>
+
+<h2>Obaly nejvyšší úrovně</h2>
+{{ end }}
+
+{{ range .Children }}
+<section>
+<header>
+	<h3><a href="/container?id={{ .Id }}">{{ .Id }}</a></h3>
+	<form method=post action="/label?id={{ .Id }}">
+	<input type=submit value="Vytisknout štítek">
+	</form>
+	<form method=post action="/?id={{ .Id }}&amp;remove">
+	<input type=submit value="Odstranit">
+	</form>
+</header>
+{{ if .Description }}
+<p>{{ .Description }}
+{{ end }}
+</section>
+{{ else }}
+<p>Obal je prázdný.
+{{ end }}
+
+{{ end }}
--- a/sklad/db.go
+++ b/sklad/db.go
@ -0,0 +1,157 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"time"
+)
+
+type Series struct {
+	Prefix      string // PK: prefix
+	Description string // what kind of containers this is for
+}
+
+type Container struct {
+	Series      string      // PK: what series does this belong to
+	Number      uint        // PK: order within the series
+	Parent      ContainerId // the container we're in, if any, otherwise ""
+	Description string      // description and/or contents of this container
+}
+
+type ContainerId string
+
+func (c *Container) Id() ContainerId {
+	return ContainerId(fmt.Sprintf("%s%s%d", db.Prefix, c.Series, c.Number))
+}
+
+type Database struct {
+	Password   string       // password for web users
+	Prefix     string       // prefix for all container IDs
+	Series     []*Series    // all known series
+	Containers []*Container // all known containers
+}
+
+var (
+	dbPath string
+	db     Database
+	dbLast Database
+	dbLog  *os.File
+
+	indexSeries    = map[string]*Series{}
+	indexContainer = map[ContainerId]*Container{}
+	indexChildren  = map[ContainerId][]*Container{}
+)
+
+// TODO: Some functions to add, remove and change things in the database.
+// Indexes must be kept valid, just like any invariants.
+
+// TODO: A function for fulltext search in series (1. Prefix, 2. Description).
+
+// TODO: A function for fulltext search in containers (1. Id, 2. Description).
+
+func dbCommit() error {
+	// Write a timestamp.
+	e := json.NewEncoder(dbLog)
+	e.SetIndent("", "  ")
+	if err := e.Encode(time.Now().Format(time.RFC3339)); err != nil {
+		return err
+	}
+
+	// Back up the current database contents.
+	if err := e.Encode(&dbLast); err != nil {
+		return err
+	}
+	if err := dbLog.Sync(); err != nil {
+		return err
+	}
+
+	// Atomically replace the current database file.
+	tempPath := dbPath + ".new"
+	temp, err := os.OpenFile(tempPath, os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	defer temp.Close()
+
+	e = json.NewEncoder(temp)
+	e.SetIndent("", "  ")
+	if err := e.Encode(&db); err != nil {
+		return err
+	}
+
+	if err := os.Rename(tempPath, dbPath); err != nil {
+		return err
+	}
+
+	dbLast = db
+	return nil
+}
+
+// loadDatabase loads the database from a simple JSON file. We do not use
+// any SQL stuff or even external KV storage because there is no real need
+// for our trivial use case, with our general amount of data.
+func loadDatabase() error {
+	dbFile, err := os.Open(dbPath)
+	if err != nil {
+		return err
+	}
+	if err := json.NewDecoder(dbFile).Decode(&db); err != nil {
+		return err
+	}
+
+	// Further validate the database.
+	if db.Prefix == "" {
+		return errors.New("misconfigured prefix")
+	}
+
+	// Construct indexes for primary keys, validate against duplicates.
+	for _, pv := range db.Series {
+		if _, ok := indexSeries[pv.Prefix]; ok {
+			return fmt.Errorf("duplicate series: %s", pv.Prefix)
+		}
+		indexSeries[pv.Prefix] = pv
+	}
+	for _, pv := range db.Containers {
+		id := pv.Id()
+		if _, ok := indexContainer[id]; ok {
+			return fmt.Errorf("duplicate container: %s", id)
+		}
+		indexContainer[id] = pv
+	}
+
+	// Construct an index that goes from parent containers to their children.
+	for _, pv := range db.Containers {
+		if pv.Parent != "" {
+			if _, ok := indexContainer[pv.Parent]; !ok {
+				return fmt.Errorf("container %s has a nonexistent parent %s",
+					pv.Id(), pv.Parent)
+			}
+		}
+		indexChildren[pv.Parent] = append(indexChildren[pv.Parent], pv)
+	}
+
+	// Validate that no container is a parent of itself on any level.
+	// This could probably be optimized but it would stop being obvious.
+	for _, pv := range db.Containers {
+		parents := map[ContainerId]bool{pv.Id(): true}
+		for pv.Parent != "" {
+			if parents[pv.Parent] {
+				return fmt.Errorf("%s contains itself", pv.Parent)
+			}
+			parents[pv.Parent] = true
+			pv = indexContainer[pv.Parent]
+		}
+	}
+
+	// Open database log file for appending.
+	if dbLog, err = os.OpenFile(dbPath+".log",
+		os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644); err != nil {
+		return err
+	}
+
+	// Remember the current state of the database.
+	dbLast = db
+	return nil
+}
--- a/sklad/login.tmpl
+++ b/sklad/login.tmpl
@ -0,0 +1,17 @@
+{{ define "Title" }}Přihlášení{{ end }}
+{{ define "HeaderControls" }}<!-- text/template requires content -->{{ end }}
+{{ define "Content" }}
+
+<h2>Přihlášení</h2>
+
+<form method=post>
+<label for=password>Heslo:</label>
+<input type=password name=password id=password
+><input type=submit value="Přihlásit">
+</form>
+
+{{ if .IncorrectPassword }}
+<p>Bylo zadáno nesprávné heslo.
+{{ end }}
+
+{{ end }}
--- a/sklad/main.go
+++ b/sklad/main.go
@ -0,0 +1,233 @@
+package main
+
+import (
+	"html/template"
+	"io"
+	"log"
+	"math/rand"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+var templates = map[string]*template.Template{}
+
+func executeTemplate(name string, w io.Writer, data interface{}) {
+	if err := templates[name].Execute(w, data); err != nil {
+		panic(err)
+	}
+}
+
+func wrap(inner func(http.ResponseWriter, *http.Request)) func(
+	http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if err := r.ParseForm(); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		if r.Method == http.MethodGet {
+			w.Header().Set("Cache-Control", "no-store")
+		}
+		inner(w, r)
+	}
+}
+
+func handleLogin(w http.ResponseWriter, r *http.Request) {
+	redirect := r.FormValue("redirect")
+	if redirect == "" {
+		redirect = "/"
+	}
+
+	session := sessionGet(w, r)
+	if session.LoggedIn {
+		http.Redirect(w, r, redirect, http.StatusSeeOther)
+		return
+	}
+
+	params := struct {
+		IncorrectPassword bool
+	}{}
+
+	switch r.Method {
+	case http.MethodGet:
+		// We're just going to render the template.
+	case http.MethodPost:
+		if r.FormValue("password") == db.Password {
+			session.LoggedIn = true
+			http.Redirect(w, r, redirect, http.StatusSeeOther)
+			return
+		}
+		params.IncorrectPassword = true
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	executeTemplate("login.tmpl", w, &params)
+}
+
+func handleLogout(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	session := r.Context().Value(sessionContextKey{}).(*Session)
+	session.LoggedIn = false
+	http.Redirect(w, r, "/", http.StatusSeeOther)
+}
+
+func handleContainer(w http.ResponseWriter, r *http.Request) {
+	if r.Method == http.MethodPost {
+		// TODO
+	}
+	if r.Method != http.MethodGet {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	allSeries := map[string]string{}
+	for _, s := range indexSeries {
+		allSeries[s.Prefix] = s.Description
+	}
+
+	children := []*Container{}
+	id := ContainerId(r.FormValue("id"))
+	description := ""
+	series := ""
+	parent := ContainerId("")
+
+	if id == "" {
+		children = indexChildren[id]
+	} else if container, ok := indexContainer[id]; ok {
+		children = indexChildren[id]
+		description = container.Description
+		series = container.Series
+		parent = container.Parent
+	}
+
+	params := struct {
+		Id          ContainerId
+		Description string
+		Children    []*Container
+		Series      string
+		Parent      ContainerId
+		AllSeries   map[string]string
+	}{
+		Id:          id,
+		Description: description,
+		Children:    children,
+		Series:      series,
+		Parent:      parent,
+		AllSeries:   allSeries,
+	}
+
+	executeTemplate("container.tmpl", w, &params)
+}
+
+func handleSeries(w http.ResponseWriter, r *http.Request) {
+	if r.Method == http.MethodPost {
+		// TODO
+	}
+	if r.Method != http.MethodGet {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	allSeries := map[string]string{}
+	for _, s := range indexSeries {
+		allSeries[s.Prefix] = s.Description
+	}
+
+	prefix := r.FormValue("prefix")
+	description := ""
+
+	if prefix == "" {
+	} else if series, ok := indexSeries[prefix]; ok {
+		description = series.Description
+	}
+
+	params := struct {
+		Prefix      string
+		Description string
+		AllSeries   map[string]string
+	}{
+		Prefix:      prefix,
+		Description: description,
+		AllSeries:   allSeries,
+	}
+
+	executeTemplate("series.tmpl", w, &params)
+}
+
+func handleSearch(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	query := r.FormValue("q")
+	_ = query
+
+	// TODO: Query the database for exact matches and fulltext.
+
+	params := struct{}{}
+
+	executeTemplate("search.tmpl", w, &params)
+}
+
+func handleLabel(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		return
+	}
+
+	id := r.FormValue("id")
+	_ = id
+
+	// TODO: See if such a container exists, print a label on the printer.
+
+	params := struct{}{}
+
+	executeTemplate("label.tmpl", w, &params)
+}
+
+func main() {
+	// Randomize the RNG for session string generation.
+	rand.Seed(time.Now().UnixNano())
+
+	if len(os.Args) != 3 {
+		log.Fatalf("Usage: %s ADDRESS DATABASE-FILE\n", os.Args[0])
+	}
+
+	var address string
+	address, dbPath = os.Args[1], os.Args[2]
+
+	// Load database.
+	if err := loadDatabase(); err != nil {
+		log.Fatalln(err)
+	}
+
+	// Load HTML templates from the current working directory.
+	m, err := filepath.Glob("*.tmpl")
+	if err != nil {
+		log.Fatalln(err)
+	}
+	for _, name := range m {
+		templates[name] = template.Must(template.ParseFiles("base.tmpl", name))
+	}
+
+	// TODO: Eventually we will need to load a font file for label printing.
+	//  - The path might be part of configuration, or implicit by filename.
+
+	http.HandleFunc("/login", wrap(handleLogin))
+	http.HandleFunc("/logout", sessionWrap(wrap(handleLogout)))
+
+	http.HandleFunc("/", sessionWrap(wrap(handleContainer)))
+	http.HandleFunc("/series", sessionWrap(wrap(handleSeries)))
+	http.HandleFunc("/search", sessionWrap(wrap(handleSearch)))
+	http.HandleFunc("/label", sessionWrap(wrap(handleLabel)))
+
+	log.Fatalln(http.ListenAndServe(address, nil))
+}
--- a/sklad/series.tmpl
+++ b/sklad/series.tmpl
@ -0,0 +1,43 @@
+{{ define "Title" }}{{ or .Prefix "Řady" }}{{ end }}
+{{ define "Content" }}
+
+{{ if .Prefix }}
+<h2>{{ .Prefix }}</h2>
+
+{{ if .Description }}
+<p>{{ .Description }}
+{{ end }}
+{{ else }}
+
+<section>
+<form method=post action="/series">
+<header>
+	<h3>Nová řada</h3>
+	<input type=text name=prefix placeholder="Prefix řady">
+	<input type=text name=description placeholder="Popis řady"
+	><input type=submit value="Uložit">
+	</form>
+</header>
+</form>
+</section>
+
+{{ range $prefix, $desc := .AllSeries }}
+<section>
+<header>
+	<h3><a href="/series?prefix={{ $prefix }}">{{ $prefix }}</a></h3>
+	<form method=post action="/series?prefix={{ $prefix }}">
+	<input type=text name=description value="{{ $desc }}"
+	><input type=submit value="Uložit">
+	</form>
+	<form method=post action="/series?prefix={{ $prefix }}&amp;remove">
+	<input type=submit value="Odstranit">
+	</form>
+</header>
+</section>
+{{ else }}
+<p>Nejsou žádné řady.
+{{ end }}
+
+{{ end }}
+
+{{ end }}
--- a/sklad/session.go
+++ b/sklad/session.go
@ -0,0 +1,66 @@
+package main
+
+import (
+	"context"
+	"encoding/hex"
+	"math/rand"
+	"net/http"
+	"net/url"
+)
+
+// session storage indexed by a random UUID
+var sessions = map[string]*Session{}
+
+type Session struct {
+	LoggedIn bool // may access the DB
+}
+
+type sessionContextKey struct{}
+
+func sessionGenId() string {
+	u := make([]byte, 16)
+	if _, err := rand.Read(u); err != nil {
+		panic("cannot generate random bytes")
+	}
+	return hex.EncodeToString(u)
+}
+
+// TODO: We don't want to keep an unlimited amount of cookies in the storage.
+//  - The essential question is: how do we avoid DoS?
+//  - Which cookies are worth keeping?
+//     - Definitely logged-in users, only one person should know the password.
+//  - Evict by FIFO? LRU?
+func sessionGet(w http.ResponseWriter, r *http.Request) (session *Session) {
+	if c, _ := r.Cookie("sessionid"); c != nil {
+		session, _ = sessions[c.Value]
+	}
+	if session == nil {
+		id := sessionGenId()
+		session = &Session{LoggedIn: false}
+		sessions[id] = session
+		http.SetCookie(w, &http.Cookie{Name: "sessionid", Value: id})
+	}
+	return
+}
+
+func sessionWrap(inner func(http.ResponseWriter, *http.Request)) func(
+	http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		// We might also try no-cache with an ETag for the whole database,
+		// though I don't expect any substantial improvements of anything.
+		w.Header().Set("Cache-Control", "no-store")
+
+		redirect := "/login"
+		if r.RequestURI != "/" {
+			redirect += "?redirect=" + url.QueryEscape(r.RequestURI)
+		}
+
+		session := sessionGet(w, r)
+		if !session.LoggedIn {
+			http.Redirect(w, r, redirect, http.StatusSeeOther)
+			return
+		}
+		inner(w, r.WithContext(
+			context.WithValue(r.Context(), sessionContextKey{}, session)))
+	}
+}
Author	SHA1	Message	Date
Přemysl Eric Janouch	e003427f9f	sklad: preliminary web interface Only exposing most read operations thus far.	2019-04-14 10:17:02 +02:00
Přemysl Eric Janouch	7eb84cd937	sklad: styling, add a basic view for containers	2019-04-14 01:05:05 +02:00
Přemysl Eric Janouch	bcfb9fbc2b	sklad: implement login and logout So far there are no other pages, and nothing links to the logout.	2019-04-13 23:54:24 +02:00
Přemysl Eric Janouch	f5790dbff9	sklad: write timestamps to the DB log	2019-04-13 22:48:51 +02:00
Přemysl Eric Janouch	401ed71323	sklad: sync the database log	2019-04-13 05:57:43 +02:00
Přemysl Eric Janouch	8c3aaa8261	sklad: move the database into its own file	2019-04-13 05:43:33 +02:00
Přemysl Eric Janouch	3fe6d7d071	label-tool: cleanup	2019-04-13 05:38:58 +02:00
Přemysl Eric Janouch	fd347fa1eb	sklad: initial commit for the web application	2019-04-13 05:16:16 +02:00