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poll.go
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poll.go
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// Copyright 2020 Fabian Wenzelmann <fabianwen@posteo.eu>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"bytes"
"errors"
"flag"
"fmt"
"github.com/FabianWe/gopolls"
"html/template"
"io"
"log"
"net/http"
"os"
"path/filepath"
"reflect"
"runtime"
"sync"
"time"
)
const version = "v0.1.0"
var currencyHandler = gopolls.SimpleEuroHandler{}
// used to store the "root" path for static files and templates, avoid passing it around as argument
// should be fine enough in this main file
var templateRoot string
var staticRoot string
var comma rune
var port uint64
var host string
type mainContext struct {
Voters []*gopolls.Voter
PollCollection *gopolls.PollSkeletonCollection
// in case voters were loaded from a file this value is set to the name
VotersSourceFileName string
// in case collection was loaded from a file this value is set to this path
CollectionSourceFileName string
// if you're reading this: don't do this in any live code, it's only here for this app, you would never do that
// because this is a small demonstration that should be used nowhere I think it will be fine
mutex sync.Mutex
}
type renderContext struct {
*mainContext
AdditionalData map[string]interface{}
}
func newRenderContext(mainCtx *mainContext) *renderContext {
return &renderContext{
mainContext: mainCtx,
AdditionalData: make(map[string]interface{}),
}
}
type handlerRes struct {
Status int
Redirect string
ContentType string
FileName string
Err error
}
func newHandlerRes(status int, err error) handlerRes {
return handlerRes{
Status: status,
Redirect: "",
ContentType: "",
Err: err,
}
}
func newRedirectHandlerRes(status int, redirect string) handlerRes {
return handlerRes{
Status: status,
Redirect: redirect,
Err: nil,
}
}
type appHandler interface {
Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes
}
func toHandleFunc(h appHandler, context *mainContext) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
log.Printf("Handler %s called for %s\n",
reflect.TypeOf(h), r.URL)
var buff bytes.Buffer
start := time.Now()
// as mentioned before: never do things this way, just for the sake of this sample demo app
context.mutex.Lock()
defer context.mutex.Unlock()
handlerRes := h.Handle(context, &buff, r)
delta := time.Since(start)
log.Println("Handler done after", delta)
if handlerRes.ContentType != "" {
w.Header().Set("Content-Type", handlerRes.ContentType)
if handlerRes.FileName != "" {
w.Header().Set("Content-Disposition",
fmt.Sprintf("attachment; filename=%s", handlerRes.FileName))
}
}
if err := handlerRes.Err; err != nil {
log.Println("Unable to write to http response", err)
http.Error(w, "Internal error", handlerRes.Status)
return
}
if handlerRes.Redirect != "" {
http.Redirect(w, r, handlerRes.Redirect, handlerRes.Status)
return
}
_, writeErr := io.Copy(w, &buff)
if writeErr != nil {
log.Println("Unable to write to http response", writeErr)
return
}
}
}
func baseTemplates() *template.Template {
funcMap := template.FuncMap{
"inc": func(i int) int {
return i + 1
},
"formatMedianToCurrency": func(val gopolls.MedianUnit) string {
var asCurrency gopolls.CurrencyValue
if val == gopolls.NoMedianUnitValue {
asCurrency = gopolls.NewCurrencyValue(0, "€")
} else {
asCurrency = gopolls.NewCurrencyValue(int(val), "€")
}
return currencyHandler.Format(asCurrency)
},
"formatCurrency": func(val gopolls.CurrencyValue) string {
return currencyHandler.Format(val)
},
// this function lets us print vote result strings more easily
// given two values of type Weight a and b it returns
// "a / b = <PERCENT>%" where PERCENT is the formatted string of (a / b) * 100 (precision is 3)
"voteResult": func(a, b gopolls.Weight) string {
percentage := gopolls.ComputePercentage(a, b)
percentageString := gopolls.FormatPercentage(percentage)
return fmt.Sprintf("%d / %d = %s%%", a, b, percentageString)
},
// similar to voteResult, but only shows the percentage part
"percentage": func(a, b gopolls.Weight) string {
percentage := gopolls.ComputePercentage(a, b)
return gopolls.FormatPercentage(percentage) + "%"
},
"dict": func(values ...interface{}) (map[string]interface{}, error) {
if len(values)%2 != 0 {
return nil, errors.New("invalid dict call")
}
dict := make(map[string]interface{}, len(values)/2)
for i := 0; i < len(values); i += 2 {
key, ok := values[i].(string)
if !ok {
return nil, errors.New("dict keys must be strings")
}
dict[key] = values[i+1]
}
return dict, nil
},
}
basePath := filepath.Join(templateRoot, "base.gohtml")
base := template.Must(template.ParseFiles(basePath))
return base.Funcs(funcMap)
}
func readTemplate(base *template.Template, name string) *template.Template {
templatePath := filepath.Join(templateRoot, name)
return template.Must(template.Must(base.Clone()).ParseFiles(templatePath))
}
func executeTemplate(t *template.Template, context *renderContext, buff *bytes.Buffer) handlerRes {
templateErr := t.Execute(buff, context)
if templateErr != nil {
return newHandlerRes(http.StatusInternalServerError, templateErr)
}
return newHandlerRes(http.StatusOK, nil)
}
type mainHandler struct {
template *template.Template
}
func newMainHandler(base *template.Template) *mainHandler {
t := readTemplate(base, "index.gohtml")
return &mainHandler{t}
}
func (h *mainHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
renderContext := newRenderContext(context)
return executeTemplate(h.template, renderContext, buff)
}
type aboutHandler struct {
template *template.Template
}
func newAboutHandler(base *template.Template) *aboutHandler {
t := readTemplate(base, "about.gohtml")
return &aboutHandler{t}
}
func (h *aboutHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
renderContext := newRenderContext(context)
renderContext.AdditionalData["version"] = version
renderContext.AdditionalData["go_version"] = runtime.Version()
return executeTemplate(h.template, renderContext, buff)
}
type votersHandler struct {
template *template.Template
}
func newVotersHandler(base *template.Template) *votersHandler {
t := readTemplate(base, "voters.gohtml")
return &votersHandler{t}
}
func (h *votersHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
renderContext := newRenderContext(context)
render := func() handlerRes {
return executeTemplate(h.template, renderContext, buff)
}
if r.Method == http.MethodGet {
return render()
}
// already clear voters
context.Voters = make([]*gopolls.Voter, 0, 0)
context.VotersSourceFileName = ""
err := r.ParseMultipartForm(10 << 20)
if err != nil {
return newHandlerRes(http.StatusInternalServerError, err)
}
// Actually check for ErrMissingFile here, but good enough for this
file, handler, formErr := r.FormFile("voters-file")
if formErr != nil {
return newHandlerRes(http.StatusInternalServerError, formErr)
}
defer file.Close()
// now try to parse from file
votersParser := gopolls.NewVotersParser()
voters, votersErr := votersParser.ParseVoters(file)
if votersErr == nil {
// check for duplicate names, if there are any set error to a duplicate error
if name, hasDuplicates := gopolls.HasDuplicateVoters(voters); hasDuplicates {
votersErr = gopolls.NewDuplicateError(fmt.Sprintf("duplicate voter name %s", name))
}
}
if votersErr == nil {
// if it is valid just redirect to voters page again
context.Voters = voters
context.VotersSourceFileName = handler.Filename
log.Printf("Successfuly parsed %d voters from %s\n", len(voters), handler.Filename)
res := newRedirectHandlerRes(http.StatusFound, "/voters")
return res
}
// if an error occurred: if it is an internal gopolls error render it
if errors.Is(votersErr, gopolls.ErrPoll) {
renderContext.AdditionalData["error"] = votersErr
return render()
}
return newHandlerRes(http.StatusInternalServerError, votersErr)
}
type pollsHandler struct {
template *template.Template
}
func newPollsHandler(base *template.Template) *pollsHandler {
t := readTemplate(base, "polls.gohtml")
return &pollsHandler{t}
}
func (h *pollsHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
renderContext := newRenderContext(context)
render := func() handlerRes {
return executeTemplate(h.template, renderContext, buff)
}
if r.Method == http.MethodGet {
return render()
}
// already clear polls
context.PollCollection = gopolls.NewPollSkeletonCollection("dummy")
context.CollectionSourceFileName = ""
err := r.ParseMultipartForm(10 << 20)
if err != nil {
return newHandlerRes(http.StatusInternalServerError, err)
}
// Actually check for ErrMissingFile here, but good enough for this
file, handler, formErr := r.FormFile("polls-file")
if formErr != nil {
return newHandlerRes(http.StatusInternalServerError, formErr)
}
defer file.Close()
// now try to parse
collectionParser := gopolls.NewPollCollectionParser()
collection, collectionErr := collectionParser.ParseCollectionSkeletons(file, currencyHandler)
if collectionErr == nil {
// now check for duplicate names in the polls, if there are any set error to a duplicate error
if name, hasDuplicates := collection.HasDuplicateSkeleton(); hasDuplicates {
collectionErr = gopolls.NewDuplicateError(fmt.Sprintf("duplicate poll name %s", name))
}
}
if collectionErr == nil {
// just redirect to polls page again
context.PollCollection = collection
context.CollectionSourceFileName = handler.Filename
log.Printf("Successfuly parsed %d polls from %s\n", collection.NumSkeletons(), handler.Filename)
res := newRedirectHandlerRes(http.StatusFound, "/polls")
return res
}
// if an error occurred: if it is a gopoll internal error display it
if errors.Is(collectionErr, gopolls.ErrPoll) {
renderContext.AdditionalData["error"] = collectionErr
return render()
}
return newHandlerRes(http.StatusInternalServerError, collectionErr)
}
type evaluationHandler struct {
template *template.Template
evaluationResultsTemplate *template.Template
}
func newEvaluationHandler(base *template.Template) *evaluationHandler {
standardTemplate := readTemplate(base, "evaluate.gohtml")
evaluationResultsTemplate := readTemplate(base, "evaluation_results.gohtml")
return &evaluationHandler{
template: standardTemplate,
evaluationResultsTemplate: evaluationResultsTemplate,
}
}
func (h *evaluationHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
renderContext := newRenderContext(context)
render := func(err error) handlerRes {
if err == nil {
return executeTemplate(h.template, renderContext, buff)
}
if errors.Is(err, gopolls.ErrPoll) {
renderContext.AdditionalData["error"] = err
return executeTemplate(h.template, renderContext, buff)
}
return newHandlerRes(http.StatusInternalServerError, err)
}
if r.Method == http.MethodGet {
return render(nil)
}
if len(context.Voters) == 0 || !context.PollCollection.HasSkeleton() {
// not really nice but well
return render(gopolls.NewPollingSemanticError(nil, "no voters / polls have been uploaded yet"))
}
// try to read the matrix
if err := r.ParseMultipartForm(10 << 20); err != nil {
return newHandlerRes(http.StatusInternalServerError, err)
}
file, handler, formErr := r.FormFile("matrix-file")
if formErr != nil {
return newHandlerRes(http.StatusInternalServerError, formErr)
}
defer file.Close()
// try to parse the matrix
csvReader := gopolls.NewVotesCSVReader(file)
csvReader.Sep = comma
matrix, matrixErr := gopolls.ReadMatrixFromCSV(csvReader)
if matrixErr != nil {
return render(matrixErr)
}
votersMap, votersMapErr := gopolls.VotersToMap(context.Voters)
if votersMapErr != nil {
return render(votersMapErr)
}
pollsMap, pollsMapErr := context.PollCollection.SkeletonsToMap()
if pollsMapErr != nil {
return render(pollsMapErr)
}
polls, pollsErr := gopolls.ConvertSkeletonMapToEmptyPolls(pollsMap,
gopolls.DefaultSkeletonConverter)
if pollsErr != nil {
return render(pollsErr)
}
// next try to parse the results, first generate the parsers
// in the csv we only allow raw cents as input
defaultParsers := gopolls.GenerateDefaultParserTemplateMap()
defaultParsers[gopolls.MedianPollType] = gopolls.NewMedianVoteParser(gopolls.NewRawCentCurrencyParser())
parsers, parsersErr := gopolls.CustomizeParsersToMap(polls, defaultParsers)
if parsersErr != nil {
return render(parsersErr)
}
// parsers are of type ParserCustomizer, we need type VoteParser (this is actually a sub type)
parsersCasted := make(map[string]gopolls.VoteParser, len(parsers))
for name, p := range parsers {
parsersCasted[name] = p
}
// now add all votes
policies := gopolls.GeneratePoliciesMap(gopolls.IgnoreEmptyVote, polls)
_, _, votesErr := matrix.FillPollsWithVotes(polls, votersMap, parsersCasted, policies,
true, false)
if votesErr != nil {
return render(votesErr)
}
// evaluate all polls
tallied, evalErr := evaluatePolls(polls)
if evalErr != nil {
return render(evalErr)
}
renderContext.AdditionalData["source_file_name"] = handler.Filename
renderContext.AdditionalData["evaluation"] = tallied
renderContext.AdditionalData["title"] = context.PollCollection.Title
// prepare polls for nicer handling in templates, we group for each poll together:
// skeleton, poll, result
// we also create this by group
type templatePollEntry struct {
Skel gopolls.AbstractPollSkeleton
Poll gopolls.AbstractPoll
Result interface{}
}
type templateGroup struct {
Title string
Polls []*templatePollEntry
}
results := make([]*templateGroup, context.PollCollection.NumGroups())
for i, group := range context.PollCollection.Groups {
templateGroup := &templateGroup{
Title: group.Title,
Polls: make([]*templatePollEntry, group.NumSkeletons()),
}
results[i] = templateGroup
for j, pollSkell := range group.Skeletons {
name := pollSkell.GetName()
templateGroup.Polls[j] = &templatePollEntry{
Skel: pollSkell,
Poll: polls[name],
Result: tallied[name],
}
}
}
renderContext.AdditionalData["results"] = results
return executeTemplate(h.evaluationResultsTemplate, renderContext, buff)
}
type exportCSVTemplateHandler struct{}
func newExportCSVTemplateHandler() exportCSVTemplateHandler {
return exportCSVTemplateHandler{}
}
func (h exportCSVTemplateHandler) Handle(context *mainContext, buff *bytes.Buffer, r *http.Request) handlerRes {
csvWriter := gopolls.NewVotesCSVWriter(buff)
csvWriter.Sep = comma
// write empty template
writeErr := csvWriter.GenerateEmptyTemplate(context.Voters, context.PollCollection.CollectSkeletons())
if writeErr != nil {
return newHandlerRes(http.StatusInternalServerError, writeErr)
}
res := newHandlerRes(http.StatusOK, nil)
res.ContentType = "text/csv"
res.FileName = "votes.csv"
return res
}
func evaluatePolls(polls gopolls.PollMap) (map[string]interface{}, error) {
res := make(map[string]interface{}, len(polls))
// type used for the channel to communicate
type pollRes struct {
pollName string
res interface{}
err error
}
ch := make(chan pollRes, 1)
// evaluate each poll
for pollName, p := range polls {
go func(name string, poll gopolls.AbstractPoll) {
var evaluated interface{}
var pollErr error
switch typedPoll := poll.(type) {
case *gopolls.BasicPoll:
if truncated := typedPoll.TruncateVoters(); len(truncated) > 0 {
pollErr = errors.New("there were invalid votes for a poll! should not happen")
} else {
evaluated = typedPoll.Tally()
}
case *gopolls.MedianPoll:
if truncated := typedPoll.TruncateVoters(); len(truncated) > 0 {
pollErr = errors.New("there were invalid votes for a poll! should not happen")
} else {
evaluated = typedPoll.Tally(gopolls.NoWeight)
}
case *gopolls.SchulzePoll:
if truncated := typedPoll.TruncateVoters(); len(truncated) > 0 {
pollErr = errors.New("there were invalid votes for a poll! should not happen")
} else {
evaluated = typedPoll.Tally()
}
default:
pollErr = fmt.Errorf("unsupported poll type %s", reflect.TypeOf(poll))
}
ch <- pollRes{
pollName: name,
res: evaluated,
err: pollErr,
}
}(pollName, p)
}
var err error
for i := 0; i < len(polls); i++ {
pollRes := <-ch
if err == nil && pollRes.err != nil {
err = pollRes.err
}
res[pollRes.pollName] = pollRes.res
}
if err != nil {
return nil, err
}
return res, nil
}
func main() {
//pkger.Include("/cmd/poll/templates")
//pkger.Include("/cmd/poll/static")
parseArgs()
base := baseTemplates()
context := mainContext{}
context.PollCollection = gopolls.NewPollSkeletonCollection("dummy")
mainH := newMainHandler(base)
aboutH := newAboutHandler(base)
votersH := newVotersHandler(base)
pollsH := newPollsHandler(base)
csvH := newExportCSVTemplateHandler()
evaluateH := newEvaluationHandler(base)
http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir(staticRoot))))
http.HandleFunc("/voters", toHandleFunc(votersH, &context))
http.HandleFunc("/polls", toHandleFunc(pollsH, &context))
http.HandleFunc("/votes/csv", toHandleFunc(csvH, &context))
http.HandleFunc("/evaluate", toHandleFunc(evaluateH, &context))
http.HandleFunc("/home", toHandleFunc(mainH, &context))
http.HandleFunc("/about", toHandleFunc(aboutH, &context))
addr := fmt.Sprintf("%s:%d", host, port)
log.Printf("Running server on %s\n", addr)
fmt.Printf("Visit http://%s/home in your browser\n", addr)
log.Fatal(http.ListenAndServe(addr, nil))
}
func doesDirExist(path string) bool {
stat, err := os.Stat(path)
if err != nil {
if os.IsExist(err) {
return false
}
log.Fatalf("error accessing assets directory %s: %v", path, err)
}
if !stat.IsDir() {
log.Fatalf("%s is a file, not a directory", path)
}
return true
}
const copyrightStr = `Copyright 2020 Fabian Wenzelmann <fabianwen@posteo.eu>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.`
const projectURL = "https://github.com/FabianWe/gopolls"
func printUsage() {
prog := os.Args[0]
flag.CommandLine.SetOutput(os.Stdout)
// write usage
fmt.Printf("Use \"%s help\" to display this message\n", prog)
fmt.Printf("Use \"%s about\" to print copyright and meta information\n\n", prog)
fmt.Printf("Options for %s:\n\n", prog)
flag.PrintDefaults()
}
func printAbout() {
fmt.Printf("This is gopolls version %s (Go version %s)\n\n", version, runtime.Version())
fmt.Println(copyrightStr)
fmt.Printf("\nAdditional information such as third-party licesnses and usage\ninformation can be found on the project homepage at\n\t%s\n", projectURL)
}
func parseArgs() {
var rootString string
flag.StringVar(&rootString, "assets", "", "Directory in which the assets (templates and static) are, defaults to dir of executable")
var commaVar string
flag.StringVar(&commaVar, "comma", ";", "Comma separator for csv files, for historical reasons defaults to \";\"")
flag.Uint64Var(&port, "port", 8080, "The port to run the web server on, defaults to 8080")
flag.StringVar(&host, "host", "localhost", "The address to run the webserver on, defaults to \"localhost\"")
// test if help was given
if len(os.Args) > 1 && os.Args[1] == "help" {
printUsage()
os.Exit(0)
}
if len(os.Args) > 1 && os.Args[1] == "about" {
printAbout()
os.Exit(0)
}
flag.Parse()
if rootString == "" {
// try to get executable directory
execPath, err := os.Executable()
if err == nil {
rootString = filepath.Dir(execPath)
} else {
rootString = "./"
log.Println("Can't determine executable directory, assuming assets are in ./")
}
}
// check if directories exist
templateDir := filepath.Join(rootString, "templates")
staticDir := filepath.Join(rootString, "static")
if !doesDirExist(templateDir) {
log.Fatalf("template directory does not exist, assumed it to be at %s", templateDir)
}
if !doesDirExist(staticDir) {
log.Fatalf("static directory does not exist, assumed it to be at %s", templateDir)
}
commaRunes := []rune(commaVar)
if len(commaRunes) != 1 {
log.Fatalf("comma separator must be a single character, got \"%s\"\n", commaVar)
}
comma = commaRunes[0]
templateRoot = templateDir
staticRoot = staticDir
}