render.gno

  1package gnosplit
  2
  3import (
  4	"encoding/base64"
  5	"html"
  6	"strconv"
  7	"strings"
  8	"time"
  9
 10	"gno.land/p/nym-alexiscolin000/gnosplit/ledger/v0"
 11	"gno.land/p/nt/markdown/sanitize/v0"
 12)
 13
 14// categories are an expense's kinds, in the order ByCat counts them. The last
 15// one is the default. A form sends the name.
 16var categories = []struct{ Name, Icon, Color string }{
 17	{"Food", "🍽", "#4e79a7"},
 18	{"Groceries", "🛒", "#f28e2b"},
 19	{"Transport", "🚗", "#59a14f"},
 20	{"Lodging", "🏠", "#e15759"},
 21	{"Activities", "🎟", "#76b7b2"},
 22	{"Shopping", "🛍", "#edc948"},
 23	{"Bills", "🧾", "#b07aa1"},
 24	{"Other", "📦", "#9c755f"},
 25}
 26
 27func categoryOf(name string) int {
 28	name = strings.ToLower(strings.TrimSpace(name))
 29	if name == "" {
 30		return len(categories) - 1
 31	}
 32	for i, c := range categories {
 33		if strings.ToLower(c.Name) == name {
 34			return i
 35		}
 36	}
 37	panic("gnosplit: no category " + name)
 38}
 39
 40const (
 41	pageSize = 25 // entries per history page
 42	latest   = 8  // entries on a group's page
 43)
 44
 45// Render serves "" (home), "u/<address>" (a wallet's groups) and a group's
 46// pages: "<id>", then "/add", "/settle", "/settle/<from>/<to>/<cents>",
 47// "/members", "/stats", "/history[/<page>]", "/e/<entry>" and "/csv".
 48func Render(path string) string {
 49	if path == "" {
 50		return renderHome()
 51	}
 52	if strings.HasPrefix(path, "u/") {
 53		return renderWallet(address(strings.TrimPrefix(path, "u/")))
 54	}
 55	parts := strings.Split(path, "/")
 56	g := getGroup(parts[0])
 57	if g == nil {
 58		return "# Not found\n\nNo group " + sanitize.InlineText(parts[0]) + ". [Back home](" + hub + ")\n"
 59	}
 60	page := ""
 61	if len(parts) > 1 {
 62		page = parts[1]
 63	}
 64	switch {
 65	case page == "" && len(parts) == 1:
 66		return renderGroup(g)
 67	case page == "add" && len(parts) == 2:
 68		return renderAdd(g)
 69	case page == "settle" && len(parts) == 2:
 70		return renderSettle(g, -1, -1, 0)
 71	case page == "settle" && len(parts) == 5:
 72		f, t, c := atoi(parts[2]), atoi(parts[3]), atoi(parts[4])
 73		if f >= 0 && t >= 0 && f < len(g.Members) && t < len(g.Members) && c > 0 {
 74			return renderSettle(g, f, t, int64(c))
 75		}
 76	case page == "members" && len(parts) == 2:
 77		return renderMembers(g)
 78	case page == "stats" && len(parts) == 2:
 79		return renderStats(g)
 80	case page == "history" && len(parts) <= 3:
 81		n := 1
 82		if len(parts) == 3 {
 83			n = atoi(parts[2])
 84		}
 85		if n >= 1 {
 86			return renderHistory(g, n)
 87		}
 88	case page == "e" && len(parts) == 3:
 89		if v := g.Entries.Get(key(atoi(parts[2]))); v != nil {
 90			return renderEntry(g, v.(*Entry))
 91		}
 92	case page == "csv" && len(parts) == 2:
 93		return header(g, "Export") + "Every member and entry, as CSV.\n\n" + sanitize.CodeBlock(Export(parts[0]))
 94	}
 95	return "# Not found\n\n[Back to the group](" + link(g, "") + ")\n"
 96}
 97
 98func renderHome() string {
 99	var b strings.Builder
100	b.WriteString("# gnosplit\n\n")
101	b.WriteString("**Share expenses with friends, then settle up in as few transfers as possible.** ")
102	b.WriteString("Trips, flatshares, dinners: like Tricount, on gno.land, with no account and no ads.\n\n")
103	b.WriteString("<gno-columns>\n### 1. Create a group\nName it, pick a currency, list your friends. They don't need a wallet.\n")
104	b.WriteString("<gno-columns-sep />\n### 2. Add expenses\nWho paid, for whom: split equally, by shares or by exact amounts. Foreign currencies too.\n")
105	b.WriteString("<gno-columns-sep />\n### 3. Settle up\ngnosplit works out who pays whom, in the fewest transfers. Friends with a wallet get notified.\n")
106	b.WriteString("</gno-columns>\n\n")
107	b.WriteString("## Create a group\n\n")
108	b.WriteString("<gno-form exec=\"CreateGroup\">\n")
109	b.WriteString(input("name", "Group name, like Ski trip", "", true))
110	b.WriteString(input("currency", "Currency, like € or CHF", "€", true))
111	b.WriteString(input("you", "Your name in the group", "", true))
112	b.WriteString(input("others", "Your friends, comma-separated: Alice, Bob", "", false))
113	b.WriteString("</gno-form>\n\n")
114	b.WriteString("> [!NOTE] Everything is public\n> A group lives on gno.land: anyone with its link can read it. ")
115	b.WriteString("Use first names, and keep private details out of titles.\n\n")
116	b.WriteString("## Your groups\n\nOpen `" + hub + ":u/<your address>` to list the groups your wallet is in. ")
117	b.WriteString(plural(groups.Size(), "group") + " so far.\n")
118	return b.String()
119}
120
121func renderWallet(a address) string {
122	if !a.IsValid() {
123		return "# Not found\n\nNot an address. [Back home](" + hub + ")\n"
124	}
125	var b strings.Builder
126	b.WriteString("# Your groups\n\n" + a.String() + "\n\n")
127	n := 0
128	byAddr.Iterate(a.String()+"/", a.String()+"0", func(k string, _ any) bool {
129		g := groups.Get(k[strings.LastIndex(k, "/")+1:]).(*Group)
130		m := g.Members[g.editor(a)]
131		if n == 0 {
132			b.WriteString("| Group | You | Your balance |\n|---|---|---:|\n")
133		}
134		b.WriteString("| [" + cellText(g.Name) + "](" + link(g, "") + ") | " + sanitize.TableCell(m.Name) +
135			" | " + ledger.Signed(m.Bal) + " " + g.Currency + " |\n")
136		n++
137		return false
138	})
139	if n == 0 {
140		b.WriteString("This wallet is in no group yet. [Create one](" + hub + ")\n")
141	}
142	return b.String()
143}
144
145func renderGroup(g *Group) string {
146	var b strings.Builder
147	b.WriteString(header(g, ""))
148	b.WriteString("<gno-columns>\n## Balances\n\n| Member | | Balance |\n|---|---|---:|\n")
149	var max int64
150	for _, m := range g.Members {
151		if abs(m.Bal) > max {
152			max = abs(m.Bal)
153		}
154	}
155	for _, m := range g.Members {
156		b.WriteString("| " + sanitize.TableCell(m.Name) + " | " + balanceBar(m.Bal, max) + " | **" + g.money(m.Bal) + "** |\n")
157	}
158	b.WriteString("\n<gno-columns-sep />\n## Settle up\n\n")
159	b.WriteString(transfers(g, true))
160	b.WriteString("</gno-columns>\n\n## Latest\n\n")
161	if g.Entries.Size() == 0 {
162		b.WriteString("No expense yet. [Add the first one](" + link(g, "/add") + ")\n")
163		return b.String()
164	}
165	b.WriteString(entryTable(g, 0, latest))
166	if g.Entries.Size() > latest {
167		b.WriteString("\n[All " + plural(g.Entries.Size(), "entry") + " →](" + link(g, "/history") + ")\n")
168	}
169	return b.String()
170}
171
172// transfers lists the payments that settle the group, each with a link that
173// fills in the form to record it.
174func transfers(g *Group, short bool) string {
175	bal := make([]int64, len(g.Members))
176	for i, m := range g.Members {
177		bal[i] = m.Bal
178	}
179	ts := ledger.Settle(bal)
180	if len(ts) == 0 {
181		return "> [!SUCCESS] All settled up\n> Nobody owes anything.\n\n"
182	}
183	var b strings.Builder
184	b.WriteString("| Who | Pays | Amount | |\n|---|---|---:|---|\n")
185	for _, t := range ts {
186		b.WriteString("| " + sanitize.TableCell(g.Members[t.From].Name) + " | " + sanitize.TableCell(g.Members[t.To].Name) +
187			" | " + g.money(t.Amount) + " | [Record](" + link(g, "/settle/"+itoa(t.From)+"/"+itoa(t.To)+"/"+strconv.FormatInt(t.Amount, 10)) + ") |\n")
188	}
189	if short {
190		b.WriteString("\n" + plural(len(ts), "transfer") + " settle everything. [Settle up →](" + link(g, "/settle") + ")\n")
191	}
192	return b.String()
193}
194
195func renderAdd(g *Group) string {
196	var b strings.Builder
197	b.WriteString(header(g, "Add"))
198	if g.Moved {
199		return b.String()
200	}
201	b.WriteString("Amounts are like `42.50`. Paid in another currency? Write `50 USD x0.92`: 50 dollars at 0.92 " +
202		g.Currency + " each.\n\n")
203
204	b.WriteString("## Split equally\n\n<gno-form exec=\"AddExpense\">\n")
205	b.WriteString(groupField(g) + input("title", "What, like Groceries", "", true) + input("amount", "Amount", "", true))
206	b.WriteString(memberSelect(g, "paidBy", "Paid by", -1))
207	b.WriteString(memberChecks(g, "forWhom", "For whom"))
208	b.WriteString(categorySelect())
209	b.WriteString("</gno-form>\n\n")
210
211	var shares, amounts []string
212	for _, m := range g.Members {
213		shares = append(shares, m.Name+":1")
214		amounts = append(amounts, m.Name+":")
215	}
216	b.WriteString("## Split by shares\n\nGive each a number of shares: `Alice:2, Bob:1` makes Alice pay two thirds. Leave out who is not in.\n\n")
217	b.WriteString("<gno-form exec=\"AddByShares\">\n")
218	b.WriteString(groupField(g) + input("title", "What", "", true) + input("amount", "Amount", "", true))
219	b.WriteString(memberSelect(g, "paidBy", "Paid by", -1))
220	b.WriteString(input("shares", "Shares", strings.Join(shares, ", "), true))
221	b.WriteString(categorySelect())
222	b.WriteString("</gno-form>\n\n")
223
224	b.WriteString("## Split by amounts\n\nWrite each one's exact part: `Alice:12.50, Bob:7.50`. The expense is their sum.\n\n")
225	b.WriteString("<gno-form exec=\"AddByAmounts\">\n")
226	b.WriteString(groupField(g) + input("title", "What", "", true))
227	b.WriteString(memberSelect(g, "paidBy", "Paid by", -1))
228	b.WriteString(input("amounts", "Amounts, like "+strings.Join(amounts, "12.50, ")+"12.50", "", true))
229	b.WriteString(categorySelect())
230	b.WriteString("</gno-form>\n\n")
231
232	b.WriteString("## Money received\n\nA refund, a deposit returned: who received it, and for whom.\n\n")
233	b.WriteString("<gno-form exec=\"AddIncome\">\n")
234	b.WriteString(groupField(g) + input("title", "What, like Deposit back", "", true) + input("amount", "Amount", "", true))
235	b.WriteString(memberSelect(g, "receivedBy", "Received by", -1))
236	b.WriteString(memberChecks(g, "forWhom", "For whom"))
237	b.WriteString("</gno-form>\n")
238	return b.String()
239}
240
241func renderSettle(g *Group, from, to int, amount int64) string {
242	var b strings.Builder
243	b.WriteString(header(g, "Settle up"))
244	if from < 0 {
245		b.WriteString(transfers(g, false) + "\n")
246	}
247	if g.Moved {
248		return b.String()
249	}
250	b.WriteString("## Record a payment\n\nA payment made outside gnosplit, by bank transfer or in cash.\n\n")
251	b.WriteString("<gno-form exec=\"AddTransfer\">\n" + groupField(g))
252	if to < 0 && len(g.Members) > 1 {
253		to = 1 // a blank form starts on two different members
254	}
255	b.WriteString(memberSelect(g, "from", "From", from))
256	b.WriteString(memberSelect(g, "to", "To", to))
257	amt := ""
258	if amount > 0 {
259		amt = cents(amount)
260	}
261	b.WriteString(input("amount", "Amount", amt, true))
262	b.WriteString("</gno-form>\n\n")
263	if from >= 0 {
264		return b.String()
265	}
266	var debtors []int
267	for i, m := range g.Members {
268		if m.Bal < 0 && m.Addr != "" {
269			debtors = append(debtors, i)
270		}
271	}
272	if len(debtors) > 0 {
273		b.WriteString("## Send a reminder\n\nA notification to a member who owes, at most one every 12 hours.\n\n")
274		b.WriteString("<gno-form exec=\"Remind\">\n" + groupField(g))
275		for k, i := range debtors {
276			b.WriteString(selectOpt("member", g.Members[i].Name, first(k, "Who"), k == 0))
277		}
278		b.WriteString("</gno-form>\n")
279	}
280	return b.String()
281}
282
283func renderMembers(g *Group) string {
284	var b strings.Builder
285	b.WriteString(header(g, "Members"))
286	b.WriteString("| Member | Wallet | Paid | Share | Balance |\n|---|---|---:|---:|---:|\n")
287	var free []int
288	for i, m := range g.Members {
289		w := "—"
290		if m.Addr != "" {
291			w = "[" + short(m.Addr) + "](" + hub + ":u/" + m.Addr.String() + ")"
292		} else {
293			free = append(free, i)
294		}
295		b.WriteString("| " + sanitize.TableCell(m.Name) + " | " + w + " | " + g.money(m.Paid) + " | " +
296			g.money(m.Share) + " | **" + g.money(m.Bal) + "** |\n")
297	}
298	b.WriteString("\nMembers with a wallet can add and change entries, and get notified. ")
299	b.WriteString("To turn notifications on, open [gnotif](https://gnotif.xyz) with your address.\n\n")
300	if g.Moved {
301		return b.String()
302	}
303	b.WriteString("## Add a member\n\n<gno-form exec=\"AddMember\">\n" + groupField(g))
304	b.WriteString(input("name", "Name", "", true) + input("addr", "Their g1 address, if they have a wallet", "", false))
305	b.WriteString("</gno-form>\n\n")
306	if len(free) > 0 && len(g.Members) > 0 {
307		b.WriteString("## Link a wallet\n\nA friend got a wallet: link it to their name. A linked wallet is never replaced.\n\n")
308		b.WriteString("<gno-form exec=\"LinkMember\">\n" + groupField(g))
309		for k, i := range free {
310			b.WriteString(selectOpt("name", g.Members[i].Name, first(k, "Member"), k == 0))
311		}
312		b.WriteString(input("addr", "Their g1 address", "", true))
313		b.WriteString("</gno-form>\n")
314	}
315	return b.String()
316}
317
318func renderStats(g *Group) string {
319	var b strings.Builder
320	b.WriteString(header(g, "Stats"))
321	var total int64
322	for _, c := range g.ByCat {
323		total += c
324	}
325	if total <= 0 {
326		b.WriteString("No expense yet.\n")
327		return b.String()
328	}
329	b.WriteString("## By category\n\n" + categoryBar(g.ByCat, total) + "\n\n")
330	b.WriteString("| | Category | Spent | Share |\n|---|---|---:|---:|\n")
331	for i, c := range categories {
332		if g.ByCat[i] == 0 {
333			continue
334		}
335		b.WriteString("| " + swatch(c.Color) + " | " + c.Icon + " " + c.Name + " | " + g.money(g.ByCat[i]) +
336			" | " + percent(g.ByCat[i], total) + " |\n")
337	}
338	b.WriteString("\n## By member\n\nWhat each one paid, and what their part of the expenses came to.\n\n")
339	b.WriteString("| Member | Paid | Share | Of all paid |\n|---|---:|---:|---:|\n")
340	for _, m := range g.Members {
341		b.WriteString("| " + sanitize.TableCell(m.Name) + " | " + g.money(m.Paid) + " | " + g.money(m.Share) +
342			" | " + percent(m.Paid, g.Spent) + " |\n")
343	}
344	return b.String()
345}
346
347func renderHistory(g *Group, page int) string {
348	var b strings.Builder
349	b.WriteString(header(g, "History"))
350	n := g.Entries.Size()
351	pages := (n + pageSize - 1) / pageSize
352	if n == 0 || page > pages {
353		b.WriteString("Nothing here.\n")
354		return b.String()
355	}
356	b.WriteString(entryTable(g, (page-1)*pageSize, pageSize) + "\n")
357	if page > 1 {
358		b.WriteString("[← Newer](" + link(g, "/history/"+itoa(page-1)) + ") ")
359	}
360	if page < pages {
361		b.WriteString("[Older →](" + link(g, "/history/"+itoa(page+1)) + ")")
362	}
363	b.WriteString("\n\nPage " + itoa(page) + " of " + itoa(pages) + " · [Export as CSV](" + link(g, "/csv") + ")\n")
364	return b.String()
365}
366
367func renderEntry(g *Group, e *Entry) string {
368	var b strings.Builder
369	b.WriteString(header(g, "Entry"))
370	b.WriteString("## " + entryIcon(e) + " " + sanitize.InlineText(e.Title) + "\n\n")
371	total := abs(e.Total)
372	b.WriteString("**" + g.money(total) + "**")
373	if e.Note != "" {
374		b.WriteString(" (" + e.Note + ")")
375	}
376	b.WriteString(" · " + verb(e) + " **" + sanitize.InlineText(g.Members[e.Payer].Name) + "** · " + date(e.At, "Mon Jan 2, 2006"))
377	b.WriteString("\n\nRecorded by " + e.By.String() + "\n\n")
378	if e.Kind != KindTransfer {
379		b.WriteString("| Member | Part |\n|---|---:|\n")
380		for i, m := range e.Who {
381			b.WriteString("| " + sanitize.TableCell(g.Members[m].Name) + " | " + g.money(abs(e.Owe[i])) + " |\n")
382		}
383		b.WriteString("\n")
384	}
385	if g.Moved {
386		return b.String()
387	}
388	b.WriteString("## Delete\n\nRemoves the entry and undoes it on every balance.\n\n")
389	b.WriteString("<gno-form exec=\"Delete\">\n" + groupField(g) + readonly("entry", "Entry", itoa(e.ID)) + "</gno-form>\n")
390	return b.String()
391}
392
393// entryTable writes count entries, newest first, from offset.
394func entryTable(g *Group, offset, count int) string {
395	var b strings.Builder
396	b.WriteString("| Date | What | Paid by | For | Amount |\n|---|---|---|---|---:|\n")
397	g.Entries.ReverseIterateByOffset(offset, count, func(_ string, v any) bool {
398		e := v.(*Entry)
399		title := "[" + cellText(e.Title) + "](" + link(g, "/e/"+itoa(e.ID)) + ")"
400		amount := g.money(abs(e.Total))
401		if e.Kind == KindIncome {
402			amount = "−" + amount
403		}
404		b.WriteString("| " + date(e.At, "Jan 2") + " | " + entryIcon(e) + " " + title + " | " +
405			sanitize.TableCell(g.Members[e.Payer].Name) + " | " + forWhom(g, e) + " | " + amount + " |\n")
406		return false
407	})
408	return b.String()
409}
410
411func header(g *Group, page string) string {
412	var b strings.Builder
413	if page == "" {
414		b.WriteString("# " + sanitize.InlineText(g.Name) + "\n\n")
415	} else {
416		b.WriteString("# [" + sanitize.InlineText(g.Name) + "](" + link(g, "") + ") · " + page + "\n\n")
417	}
418	b.WriteString(plural(len(g.Members), "member") + " · **" + g.money(g.Spent) + "** spent · ")
419	b.WriteString("[Add](" + link(g, "/add") + ") · [Settle up](" + link(g, "/settle") + ") · [Members](" +
420		link(g, "/members") + ") · [Stats](" + link(g, "/stats") + ") · [History](" + link(g, "/history") + ")\n\n")
421	if g.Moved {
422		b.WriteString("> [!WARNING] This group moved\n> It is kept read-only here. Its new home is [" + successor + "](" +
423			strings.TrimPrefix(successor, "gno.land") + ":" + itoa(g.ID) + ").\n\n")
424	}
425	return b.String()
426}
427
428// Export writes a group as CSV: its members, then every entry, oldest first.
429// MoveOut hands it to the successor, and the /csv page shows it.
430func Export(group string) string {
431	g := mustGroup(group)
432	var b strings.Builder
433	b.WriteString("member,address,balance,paid,share\n")
434	for _, m := range g.Members {
435		b.WriteString(csv(m.Name) + "," + m.Addr.String() + "," + cents(m.Bal) + "," + cents(m.Paid) + "," + cents(m.Share) + "\n")
436	}
437	b.WriteString("\nentry,kind,time,title,category,payer,total,note,split\n")
438	g.Entries.Iterate("", "", func(_ string, v any) bool {
439		e := v.(*Entry)
440		split := make([]string, len(e.Who))
441		for i, m := range e.Who {
442			split[i] = g.Members[m].Name + ":" + cents(e.Owe[i])
443		}
444		b.WriteString(itoa(e.ID) + "," + [...]string{"expense", "income", "transfer"}[e.Kind] + "," +
445			date(e.At, "2006-01-02T15:04:05Z") + "," + csv(e.Title) + "," + categories[e.Cat].Name + "," +
446			csv(g.Members[e.Payer].Name) + "," + cents(e.Total) + "," + csv(e.Note) + "," + csv(strings.Join(split, ";")) + "\n")
447		return false
448	})
449	return b.String()
450}
451
452// Form fields. Every value is escaped for the attribute it lands in; a form's
453// fields are in the order of its function's parameters, since gnoweb passes
454// them by position.
455
456func input(name, placeholder, value string, required bool) string {
457	s := `<gno-input name="` + name + `" placeholder="` + attr(placeholder) + `"`
458	if value != "" {
459		s += ` value="` + attr(value) + `"`
460	}
461	if required {
462		s += ` required="true"`
463	}
464	return s + " />\n"
465}
466
467func readonly(name, placeholder, value string) string {
468	return `<gno-input name="` + name + `" placeholder="` + placeholder + `" value="` + attr(value) + `" readonly="true" />` + "\n"
469}
470
471func groupField(g *Group) string { return readonly("group", "Group", itoa(g.ID)) }
472
473// selectOpt is one option of a select; gnoweb reads the description off
474// the first one, so only that one carries it.
475func selectOpt(name, value, description string, selected bool) string {
476	s := `<gno-select name="` + name + `" value="` + attr(value) + `"`
477	if description != "" {
478		s += ` description="` + attr(description) + `"`
479	}
480	if selected {
481		s += ` selected="true"`
482	}
483	return s + " />\n"
484}
485
486func memberSelect(g *Group, name, description string, selected int) string {
487	var b strings.Builder
488	if selected < 0 {
489		selected = 0
490	}
491	for i, m := range g.Members {
492		b.WriteString(selectOpt(name, m.Name, first(i, description), i == selected))
493	}
494	return b.String()
495}
496
497// first is s for the first item of a list, "" after.
498func first(i int, s string) string {
499	if i == 0 {
500		return s
501	}
502	return ""
503}
504
505func memberChecks(g *Group, name, description string) string {
506	var b strings.Builder
507	for i, m := range g.Members {
508		s := `<gno-input type="checkbox" name="` + name + `" value="` + attr(m.Name) + `" checked="true"`
509		if i == 0 {
510			s += ` description="` + description + `"`
511		}
512		b.WriteString(s + " />\n")
513	}
514	return b.String()
515}
516
517func categorySelect() string {
518	var b strings.Builder
519	for i, c := range categories {
520		b.WriteString(selectOpt("category", c.Name, first(i, "Category"), i == len(categories)-1))
521	}
522	return b.String()
523}
524
525// Pictures: small SVGs as data URIs, the one image source gnoweb always shows.
526
527// balanceBar draws a balance against the largest one: right and teal when the
528// group owes the member, left and orange when they owe.
529func balanceBar(v, max int64) string {
530	w := 0
531	if max > 0 {
532		w = int(abs(v) * 56 / max)
533		if w == 0 && v != 0 {
534			w = 1
535		}
536	}
537	x, color := 60, "#1a9e8f"
538	if v < 0 {
539		x, color = 60-w, "#e07b39"
540	}
541	return svg(120, 14, `<rect x="59.5" y="0" width="1" height="14" fill="#8b8f98"/><rect x="`+itoa(x)+
542		`" y="2" width="`+itoa(w)+`" height="10" rx="2" fill="`+color+`"/>`)
543}
544
545// categoryBar is one bar split by category, in the table's order.
546func categoryBar(byCat []int64, total int64) string {
547	const w = 600
548	var s strings.Builder
549	x := 0
550	for i, c := range byCat {
551		if c <= 0 {
552			continue
553		}
554		cw := int(c * w / total)
555		if x+cw > w {
556			cw = w - x
557		}
558		s.WriteString(`<rect x="` + itoa(x) + `" y="0" width="` + itoa(cw) + `" height="24" fill="` + categories[i].Color + `"/>`)
559		x += cw
560	}
561	return svg(w, 24, s.String())
562}
563
564func swatch(color string) string {
565	return svg(12, 12, `<rect width="12" height="12" rx="3" fill="`+color+`"/>`)
566}
567
568func svg(w, h int, body string) string {
569	doc := `<svg xmlns="http://www.w3.org/2000/svg" width="` + itoa(w) + `" height="` + itoa(h) +
570		`" viewBox="0 0 ` + itoa(w) + ` ` + itoa(h) + `">` + body + `</svg>`
571	return "![](data:image/svg+xml;base64," + base64.StdEncoding.EncodeToString([]byte(doc)) + ")"
572}
573
574// Small helpers.
575
576func link(g *Group, page string) string { return hub + ":" + itoa(g.ID) + page }
577
578func entryIcon(e *Entry) string {
579	switch e.Kind {
580	case KindIncome:
581		return "↩"
582	case KindTransfer:
583		return "⇄"
584	}
585	return categories[e.Cat].Icon
586}
587
588func verb(e *Entry) string {
589	if e.Kind == KindIncome {
590		return "received by"
591	}
592	return "paid by"
593}
594
595func forWhom(g *Group, e *Entry) string {
596	if e.Kind == KindTransfer {
597		return sanitize.TableCell(g.Members[e.Who[0]].Name)
598	}
599	if len(e.Who) == len(g.Members) {
600		return "everyone"
601	}
602	var names []string
603	for i, m := range e.Who {
604		if i == 3 {
605			return sanitize.TableCell(strings.Join(names, ", ")) + " +" + itoa(len(e.Who)-3)
606		}
607		names = append(names, g.Members[m].Name)
608	}
609	return sanitize.TableCell(strings.Join(names, ", "))
610}
611
612func date(unix int64, layout string) string { return time.Unix(unix, 0).UTC().Format(layout) }
613
614func short(a address) string {
615	s := a.String()
616	if len(s) < 12 {
617		return s
618	}
619	return s[:6] + "…" + s[len(s)-4:]
620}
621
622func percent(part, whole int64) string {
623	if whole <= 0 {
624		return "—"
625	}
626	return strconv.FormatInt((part*100+whole/2)/whole, 10) + "%"
627}
628
629func plural(n int, word string) string {
630	if n == 1 {
631		return "1 " + word
632	}
633	if strings.HasSuffix(word, "y") {
634		return itoa(n) + " " + word[:len(word)-1] + "ies"
635	}
636	return itoa(n) + " " + word + "s"
637}
638
639// cents writes an amount for CSV: "42.50", no thousands separator.
640func cents(c int64) string { return strings.ReplaceAll(ledger.Format(c), ",", "") }
641
642func csv(s string) string {
643	if !strings.ContainsAny(s, ",\"\n;") {
644		return s
645	}
646	return `"` + strings.ReplaceAll(s, `"`, `""`) + `"`
647}
648
649func attr(s string) string { return html.EscapeString(s) }
650
651// cellText is link text inside a table cell: InlineText leaves "|" alone,
652// and a bare one would end the cell.
653func cellText(s string) string { return strings.ReplaceAll(sanitize.InlineText(s), "|", `\|`) }
654
655func abs(v int64) int64 {
656	if v < 0 {
657		return -v
658	}
659	return v
660}
661
662// atoi is a non-negative number, -1 for anything else.
663func atoi(s string) int {
664	n, err := strconv.Atoi(s)
665	if err != nil || n < 0 {
666		return -1
667	}
668	return n
669}