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chart.go
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chart.go
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package gobarchar
import (
"fmt"
"html"
"math/rand"
"net/http"
"sort"
"strconv"
"strings"
"golang.org/x/exp/slices"
)
var htmlFirstHalf string = `<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="icon" href="data:,">
<title>GoBarChar</title>
<style>
* {
box-sizing: border-box;
}
body {
font-family: sans-serif;
line-height: 1.33;
margin: 0 auto;
max-width: 650px;
padding: 1rem;
}
pre {
overflow: auto;
user-select: all;
}
a {
word-break: break-all;
}
h1 > a, h1 > a:visited {
color: black;
}
</style>
</head>
<body>
<h1><a href="/">GoBarChar</a></h1>
<p><strong>The charting solution that might not suit you 📊</strong></p>
<hr />
<p>What is this? This is a small <a href="https://github.com/usrme/gobarchar">project</a> to generate ASCII bar charts using just query parameters.</p>
<br/>
`
var htmlSecondHalf string = `<hr>
<footer>
<small>Hosted on <a href="https://fly.io">Fly</a>.</small>
</footer>
</body>
</html>`
type entry struct {
Label string
Value float64
}
// Create custom type that implements 'sort.Interface' for easier sorting
type chartData []entry
func (a chartData) Len() int { return len(a) }
func (a chartData) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a chartData) Less(i, j int) bool { return a[i].Value < a[j].Value }
func PresentBarChart(examples string) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// Check if there are any query parameters; if not, add random key-value pairs
if len(r.URL.Query()) == 0 {
encodeRandomQuery(r)
}
chart := createBarChart(r)
// Skip all templating if user is requesting through 'curl' or 'wget'
agent := r.UserAgent()
if strings.HasPrefix(agent, "curl") || strings.HasPrefix(agent, "Wget") {
w.Write([]byte(chart))
return
}
chartUrl := r.URL.String()
html := fmt.Sprintf(
"%s<pre>%s</pre><br/><hr><p>Link used to generate the current chart: <a href='%s'>%s</a></p>%s%s",
htmlFirstHalf, chart, chartUrl, chartUrl, examples, htmlSecondHalf,
)
w.Write([]byte(html))
}
}
func encodeRandomQuery(r *http.Request) {
params := r.URL.Query()
for i := 0; i < 6; i++ {
var month string
for {
month = randomMonth()
if !params.Has(month) {
break
}
}
value := rand.Intn(101)
params.Add(month, strconv.Itoa(value))
}
r.URL.RawQuery = params.Encode()
}
func randomMonth() string {
months := []string{
"January",
"February",
"March",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December",
}
return months[rand.Intn(len(months))]
}
func createBarChart(r *http.Request) string {
// Use custom type to make sorting easier
entries := make([]entry, 0)
maxValue, total := 0.0, 0.0
// Use 'RawQuery' instead of something like 'Query()' or other automatic
// methods to parse query parameters as those get turned into maps that
// then lose their order of appearance in the original query.
//
// The order make intuitive sense when presenting, otherwise every request
// with the same data shows the results with a slightly different order if
// the 'sort' query parameter isn't given.
raw := r.URL.RawQuery
orderedParams := strings.Split(raw, "&")
addSpaces := slices.Contains(orderedParams, "spaces=yes")
var title string
for _, pair := range orderedParams {
kv := strings.Split(pair, "=")
key := kv[0]
// Don't parse certain query parameters as they are not part of the data
switch key {
case "sort", "spaces":
continue
case "title":
title = strings.Replace(kv[1], "%20", " ", -1)
continue
}
count, err := strconv.ParseFloat(kv[1], 64)
if err == nil {
if addSpaces {
key = strings.Replace(key, "%20", " ", -1)
}
entries = append(entries, entry{Label: key, Value: float64(count)})
if count > maxValue {
maxValue = count
}
total += count
}
}
// Only remove the 'sort' query parameter if it was found.
sortOrder := r.URL.Query().Get("sort")
if sortOrder == "asc" {
sort.Sort(chartData(entries))
} else if sortOrder == "desc" {
sort.Sort(sort.Reverse(chartData(entries)))
}
avg := total / float64(len(entries))
entries = append(entries, entry{Label: "Avg.", Value: avg})
orderedParams = append(orderedParams, fmt.Sprintf("%s=%.2f", "Avg.", avg))
entries = append(entries, entry{Label: "Total", Value: total})
orderedParams = append(orderedParams, fmt.Sprintf("%s=%.2f", "Total", total))
increment := maxValue / 25.0
// Find the longest label to determine padding later on
longestLabelLength := 0
for _, entry := range entries {
if len(entry.Label) > longestLabelLength {
longestLabelLength = len(entry.Label)
}
}
longestValueLength := 0
for _, entry := range entries {
valueStr := formatValue(entry.Value)
if len(valueStr) > longestValueLength {
longestValueLength = len(valueStr)
}
}
var chartContent strings.Builder
if title != "" {
chartContent.WriteString(title + "\n\n")
}
maximumBarChunk := 0
for i := range entries {
// Skip parsing the total for now to not interfere with calculating
// the maximum number of bar chunks for all of the labels
if entries[i].Label == "Total" {
continue
}
barChunks := int(entries[i].Value * 8 / increment)
remainder := barChunks % 8
barChunks /= 8
if barChunks > maximumBarChunk {
maximumBarChunk = barChunks
}
bar := calculateBars(barChunks, remainder)
valueStr := formatValue(entries[i].Value)
chartContent.WriteString(
fmt.Sprintf(
"%s %s %s\n",
padRight(entries[i].Label, longestLabelLength), padLeft(valueStr, longestValueLength), bar,
),
)
}
bar := calculateBars(maximumBarChunk, 0)
totalStr := formatValue(total)
chartContent.WriteString(fmt.Sprintf("%s %s %s\n", padRight("Total", longestLabelLength), padLeft(totalStr, longestValueLength), bar))
return html.UnescapeString(chartContent.String())
}
func formatValue(value float64) string {
if value == float64(int(value)) {
return fmt.Sprintf("%4d", int(value))
}
return fmt.Sprintf("%6.2f", value)
}
func calculateBars(count, remainder int) string {
// First draw the full width chunks
bar := strings.Repeat("█", count)
// Then add the fractional part
if remainder > 0 {
bar += string(rune('█' + (8 - remainder)))
}
// If the bar is empty (i.e. a value of 0 was given), add a left one-eighth block
if bar == "" {
bar = "▏"
}
return bar
}
func padRight(str string, length int) string {
if len(str) >= length {
return str
}
return str + strings.Repeat(" ", length-len(str))
}
func padLeft(str string, length int) string {
if len(str) >= length {
return str
}
return strings.Repeat(" ", length-len(str)) + str
}