feat: WIP GNO mail (no render)

examples/gno.land/r/demo/mail/DAPP_VS_SYSTEM.txt

@@ -0,0 +1,27 @@
+This is a very specific app.
+
+But the app could also be envisionned to sit on a system instead.
+If mail is a particular type of message, and a mail dapp is a user 
+of a more universal messaging thing, then it brings some advantages.
+
+This mail app would then take just a few lines.
+And it would change the way we do things.
+
+For example, orders in p/demo/releases, DAO orders and so on could be other kind of
+messages. This way, it would be possible to search and have generic tools that
+operate on all point-to-point messages without reimplementing everything all
+the time. 
+
+You could search inside the release notes emitted by a certain user,
+during a certain year. Or searching at the orders emitted by a DAO that contain
+a certain text. You could watch for a certain filter on a certain type of
+message coming from some organization. (While this can end-up being costly, we
+can imagine ways it can be made profitable, or growth-sustainable, instead)
+
+Therefore it would be possible to realize more interoperable systems.
+
+But not all point-to-point system have the same requirements. 
+Some are producer-consumer, some are archive systems with a certain retention.
+Meaning a certain amount of configuration is required for the dapps.
+
+So it's a complex but interesting question.

examples/gno.land/r/demo/mail/DESIGN.md

@@ -0,0 +1,26 @@
+# Design choices
+
+At this point
+
+* mailbox automatically and freely created on both sides when a mail is sent.
+* sender needs to pay stamps, they would go to the realm which will be managed by a DAO to finance new tool
+* mails are unencrypted
+
+I assume people would actually not mind paying for stamps if price is reasonnable. 
+for example it was atom, at 1atom=12usd, I would be okay to pay 0.25$=0.02atom per 
+mail sent (The time spent redacting a mail costs more than the stamps; and
+it would feel less of a waste when I click the button if it costed money).
+
+Do we still need an admin? Yes. Maybe see p/acl
+Is it a public service? I think it can be a DAO. So semi-public?
+
+Encryption is a huge topic for GNO and not possible at the moment.
+
+## Various possible ideas
+
+Things like:
+
+TUI - there is nothing in a Render() now
+Respond to mails
+Mail attachment
+

examples/gno.land/r/demo/mail/README.txt

@@ -0,0 +1,12 @@
+GNO mail
+a demo
+
+📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 
+
+A mailbox connects you to the GNO mail system.
+One day maybe GNO mail v.419 can be 
+used all over the Cosmos.
+
+📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 📪 
+
+

examples/gno.land/r/demo/mail/container.gno

@@ -0,0 +1,27 @@
+package mail
+
+// A private structure to hold mails
+// current impl. is an array
+// RFC Would a ringbuffer with a certain capacity, and a "keep" feature
+//     be better, I wonder.
+
+type container struct {
+	mails []*Mail
+}
+
+func newContainer() *container              { return &container{[]*Mail{}} }
+func newContainerWith(a []*Mail) *container { return &container{a} }
+
+func (ctr *container) push(mail *Mail) {
+	ctr.mails = append(ctr.mails, mail)
+}
+
+func (ctr *container) filter(preds ...Predicate) []*Mail {
+	a := []*Mail{}
+	for _, mail := range ctr.mails {
+		if mail.Satisfies(preds) {
+			a = append(a, mail)
+		}
+	}
+	return a
+}

examples/gno.land/r/demo/mail/files/mail_filetest.gno

@@ -0,0 +1,83 @@
+// PKGPATH: gno.land/r/demo/mail_test
+package mail_test
+
+import (
+	"std"
+	"strconv"
+	"strings"
+	"time"
+
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/testutils"
+	"gno.land/r/demo/mail"
+)
+
+// Send mail, a great movie - SYNOPSIS
+// Starring "dude" (the OrigCaller) and "sanders"
+// ------------------------------------------------------------------
+// Let there be some dude who wants to send mail:
+// .dude gets some money, so he can pay for stamps
+// .dude sent a mail to sanders
+// .now he has a mailbox, so does sanders
+// .mail got received by sanders
+// .mail also gets saved in the outbox
+// .the realm got money from the stamps
+// .sanders still has 0gno
+
+// TODO send more emails.
+// TODO mail.Id is not checked
+
+func init() {}
+
+func main() {
+	var (
+		dude    = testutils.TestAddress("dude")
+		sanders = testutils.TestAddress("sanders")
+		banker  = std.GetBanker(std.BankerTypeReadonly)
+	)
+	std.TestSetOrigCaller(dude)
+	std.TestSetOrigSend(std.Coins{{mail.Fee.Denom, mail.Fee.Amount}}, nil)
+	coinsBefore := banker.GetCoins(std.GetOrigPkgAddr()).AmountOf(mail.Fee.Denom)
+	coins := std.Coins{{mail.Fee.Denom, 10 * mail.Fee.Amount}}
+	std.TestIssueCoins(dude, coins)
+	if banker.GetCoins(dude).AmountOf(mail.Fee.Denom) == 0 {
+		panic(".dude luckily gets some money, so he can pay for stamps")
+	}
+	// ------------------------------------------
+	mail.SendMail(sanders, "hi", "this is the dude")
+	// ------------------------------------------
+	if !mail.HasAddressMailbox(dude) {
+		panic(".now he has a mailbox")
+	}
+	if !mail.HasAddressMailbox(sanders) {
+		panic(".and sanders also has a mailbox")
+	}
+	dudebox := mail.MustMailbox(dude)
+	sandersbox := mail.MustMailbox(sanders)
+	if len(sandersbox.Find(mail.RecipientIs{sanders})) < 1 {
+		panic(".mail got received by sanders")
+	}
+	if len(sandersbox.Find(mail.RecipientIs{sanders}, mail.SenderIs{dude})) < 1 {
+		panic(".mail got received by sanders")
+	}
+	if len(dudebox.Find(mail.SenderIs{dude}, mail.RecipientIs{sanders})) < 1 {
+		panic(".mail to sanders is in large outbox, by date")
+	}
+	if len(sandersbox.ReceivedFrom(dude)) < 1 {
+		panic(".mail got received by sanders")
+	}
+	if len(dudebox.SentTo(sanders)) < 1 {
+		panic(".mail also saved in outbox")
+	}
+	coinsAfter := banker.GetCoins(std.GetOrigPkgAddr()).AmountOf(mail.Fee.Denom)
+	if coinsAfter-coinsBefore != mail.Fee.Amount {
+		panic(".realm received the expected amount from the stamps: recvd=" + strconv.Itoa(int(coinsAfter-coinsBefore)))
+	}
+	if banker.GetCoins(sanders).AmountOf(mail.Fee.Denom) != 0 {
+		panic(".sanders still has 0gno")
+	}
+}
+
+// Output:
+
+// Error:

examples/gno.land/r/demo/mail/mail.gno

@@ -0,0 +1,41 @@
+package mail
+
+import (
+	"std"
+	"strings"
+	"time"
+
+	"gno.land/p/demo/ufmt"
+)
+
+type Mail struct {
+	id        int
+	topic     string
+	body      string
+	time      time.Time
+	sender    std.Address
+	recipient std.Address
+}
+
+func newMail(topic, body string, sender std.Address, recipient std.Address) *Mail {
+	return &Mail{counter + 1, topic, body, time.Now(), sender, recipient}
+}
+
+func (mail *Mail) Satisfies(preds []Predicate) bool {
+	for _, pred := range preds {
+		if !pred.Satisfy(mail) {
+			return false
+		}
+	}
+	return true
+}
+
+func (mail *Mail) Contains(s string) bool {
+	s = strings.ToLower(s)
+	return strings.Contains(strings.ToLower(mail.topic), s) || strings.Contains(strings.ToLower(mail.body), s)
+}
+
+// time key for avl, like 1234567890_<counter>
+func (mail *Mail) GetTimeKey() string {
+	return ufmt.Sprintf("%d_%d", time.Now().Unix(), counter)
+}