gno.land/r/moul/x/daily/counter/v0⧉

1// Package counter implements "Counter Club": a single shared integer counter2// with a rolling history of the last 20 mutations. Anyone may Inc, Dec, or3// Reset the value; every change records the caller, the delta applied, the4// resulting value, and the block height it happened at.5package counter67import (8	"chain"9	"chain/runtime"10	"chain/runtime/unsafe"11	"strconv"12	"strings"13)1415// maxHistory is the number of recent changes kept in the log.16const maxHistory = 201718// change is a single recorded mutation of the counter.19type change struct {20	caller address // who triggered the change21	delta  int     // how much the value moved (+1, -1, or reset amount)22	value  int     // the resulting counter value after the change23	height int64   // block height at which it occurred24}2526// value is the current shared counter.27var value int2829// total counts every mutation ever applied (not capped, unlike history).30var total int3132// history holds the last maxHistory changes, oldest first.33var history []change3435// record appends a change to the history, trimming to the last maxHistory.36func record(delta, newValue int) {37	c := change{38		caller: unsafe.PreviousRealm().Address(),39		delta:  delta,40		value:  newValue,41		height: runtime.ChainHeight(),42	}43	history = append(history, c)44	if len(history) > maxHistory {45		history = history[len(history)-maxHistory:]46	}47	total++48	chain.Emit(49		"CounterChange",50		"delta", strconv.Itoa(delta),51		"value", strconv.Itoa(newValue),52	)53}5455// Inc adds one to the shared counter and logs the change.56func Inc(cur realm) int {57	value++58	record(1, value)59	return value60}6162// Dec subtracts one from the shared counter and logs the change.63func Dec(cur realm) int {64	value--65	record(-1, value)66	return value67}6869// Reset sets the shared counter back to zero and logs the change. The recorded70// delta is the amount required to bring the previous value to zero.71func Reset(cur realm) int {72	delta := -value73	value = 074	record(delta, value)75	return value76}7778// Value returns the current counter value (read-only helper).79func Value() int {80	return value81}8283// Total returns the total number of mutations ever applied.84func Total() int {85	return total86}8788// Render produces a Markdown view: the big current value, the total number of89// changes, and a table of the most recent changes (newest first).90func Render(path string) string {91	var b strings.Builder9293	b.WriteString("# Counter Club\n\n")94	b.WriteString("A shared counter anyone can Inc, Dec, or Reset. ")95	b.WriteString("The last ")96	b.WriteString(strconv.Itoa(maxHistory))97	b.WriteString(" changes are logged below.\n\n")9899	// Big current value.100	b.WriteString("## Current value\n\n")101	b.WriteString("# ")102	b.WriteString(strconv.Itoa(value))103	b.WriteString("\n\n")104105	b.WriteString("**Total changes:** ")106	b.WriteString(strconv.Itoa(total))107	b.WriteString("\n\n")108109	// Recent history, newest first.110	b.WriteString("## Recent history\n\n")111	if len(history) == 0 {112		b.WriteString("_No changes yet — be the first to count!_\n")113		return b.String()114	}115116	b.WriteString("| # | Caller | Delta | New value | Height |\n")117	b.WriteString("|---|--------|-------|-----------|--------|\n")118	n := len(history)119	for i := n - 1; i >= 0; i-- {120		c := history[i]121		b.WriteString("| ")122		b.WriteString(strconv.Itoa(n - i))123		b.WriteString(" | ")124		b.WriteString(c.caller.String())125		b.WriteString(" | ")126		b.WriteString(signed(c.delta))127		b.WriteString(" | ")128		b.WriteString(strconv.Itoa(c.value))129		b.WriteString(" | ")130		b.WriteString(strconv.FormatInt(c.height, 10))131		b.WriteString(" |\n")132	}133134	return b.String()135}136137// signed formats an int with an explicit leading sign for non-negative values.138func signed(n int) string {139	if n >= 0 {140		return "+" + strconv.Itoa(n)141	}142	return strconv.Itoa(n)143}144