package main

import (
	"context"
	"encoding/json"
	"errors"
	"testing"
	"time"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

func addedEventBody(t *testing.T, account, folder, messageID string, uid uint32) json.RawMessage {
	t.Helper()
	raw, err := json.Marshal(map[string]any{
		"account": account, "folder": folder, "uid": uid, "uidvalidity": uint32(1),
		"message-id": messageID, "date": "2026-10-20T10:00:00Z",
		"from":    []Person{{Name: "Alice", Address: "alice@example.org"}},
		"subject": "hello", "size": int64(1234), "flags": []string{},
	})
	if err != nil {
		t.Fatal(err)
	}
	return raw
}

// 1518/AC2: an added event is recorded as a waiting mail before the handler returns success.
func TestHearRecordsTheEventAsAWaitingMailBeforeSucceeding(t *testing.T) {
	store := newMemStore()
	now := func() time.Time { return time.Date(2026, 10, 20, 10, 0, 1, 0, time.UTC) }
	raw := addedEventBody(t, "bob", "INBOX", "<msg-1@example.org>", 7)
	if err := Hear(context.Background(), store, raw, now); err != nil {
		t.Fatal(err)
	}
	waiting, err := store.Waiting(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if len(waiting) != 1 {
		t.Fatalf("waiting = %v, want one waiting mail", waiting)
	}
	w := waiting[0]
	if w.Account != "bob" || w.Folder != "INBOX" || w.MessageID != "<msg-1@example.org>" || w.UID != 7 ||
		w.Subject != "hello" || w.Size != 1234 || len(w.From) != 1 || w.From[0].Address != "alice@example.org" {
		t.Fatalf("waiting mail: %+v", w)
	}
}

// 1518/AC2: a store failure is returned unchanged, so the event is redelivered rather than lost.
func TestHearReturnsAStoreFailureSoTheEventIsRedelivered(t *testing.T) {
	store := newMemStore()
	store.failNext = errStoreFake
	raw := addedEventBody(t, "bob", "INBOX", "<msg-2@example.org>", 8)
	err := Hear(context.Background(), store, raw, time.Now)
	if err != errStoreFake {
		t.Fatalf("Hear with a failing store: %v, want %v", err, errStoreFake)
	}
	waiting, _ := store.Waiting(context.Background())
	if len(waiting) != 0 {
		t.Fatalf("waiting = %v, want none (the failed add kept nothing)", waiting)
	}
}

// 1518/AC3: the same event heard twice gives one waiting mail.
func TestHearTwiceGivesOneWaitingMail(t *testing.T) {
	store := newMemStore()
	raw := addedEventBody(t, "bob", "INBOX", "<msg-3@example.org>", 9)
	if err := Hear(context.Background(), store, raw, time.Now); err != nil {
		t.Fatal(err)
	}
	if err := Hear(context.Background(), store, raw, time.Now); err != nil {
		t.Fatal(err)
	}
	waiting, _ := store.Waiting(context.Background())
	if len(waiting) != 1 {
		t.Fatalf("waiting = %v, want exactly one", waiting)
	}
}

// 1518/AC4: waiting mails are handed out in arrival order (the order they were heard), oldest first — not by
// their own date, and regardless of whether reading was healthy when they arrived (Hear never consults
// health; a mail heard while unhealthy is recorded exactly the same way).
func TestHearKeepsArrivalOrder(t *testing.T) {
	store := newMemStore()
	// Heard out of date order: the third mail (by date) arrives first.
	first := addedEventBody(t, "bob", "INBOX", "<a@example.org>", 1)
	second := addedEventBody(t, "bob", "INBOX", "<b@example.org>", 2)
	third := addedEventBody(t, "bob", "INBOX", "<c@example.org>", 3)
	for _, raw := range []json.RawMessage{first, second, third} {
		if err := Hear(context.Background(), store, raw, time.Now); err != nil {
			t.Fatal(err)
		}
	}
	waiting, _ := store.Waiting(context.Background())
	if len(waiting) != 3 {
		t.Fatalf("waiting = %v, want three", waiting)
	}
	wantOrder := []string{"<a@example.org>", "<b@example.org>", "<c@example.org>"}
	for i, w := range waiting {
		if w.MessageID != wantOrder[i] {
			t.Fatalf("waiting[%d].MessageID = %q, want %q (arrival order)", i, w.MessageID, wantOrder[i])
		}
	}
}

// A malformed event is taken and dropped, never redelivered forever (mirrors mesh-mail-notifier's watchWith).
func TestHearDropsAMalformedEvent(t *testing.T) {
	store := newMemStore()
	if err := Hear(context.Background(), store, json.RawMessage(`not json`), time.Now); err != nil {
		t.Fatalf("Hear on a malformed event: %v, want it taken and dropped", err)
	}
	waiting, _ := store.Waiting(context.Background())
	if len(waiting) != 0 {
		t.Fatalf("waiting = %v, want none", waiting)
	}
}

// TestHearLoopRetriesStartingAt250msDoublingToAMinute (issue 1518, fixed per the lead's try feedback on
// bb594652): a subscribe the runtime refuses is retried starting at hearFirstRetryWait (250ms), doubling
// each time, capped at a minute — never mesh-mail-notifier's own 2s start, so a bundle hears within about a
// second of stdio.ServeOn beginning to serve. storeFor is never called: every refusal is the subscribe's own.
func TestHearLoopRetriesStartingAt250msDoublingToAMinute(t *testing.T) {
	var waits []time.Duration
	recordSleep := func(d time.Duration) { waits = append(waits, d) }

	calls := 0
	subscribe := func(string, func(stdio.Envelope) error) error {
		calls++
		if calls <= 4 {
			return errors.New("the runtime refused this subscribe")
		}
		return nil
	}
	storeFor := func(context.Context) (Store, error) {
		t.Fatal("hearLoop must not call storeFor merely to retry a subscribe refusal")
		return nil, nil
	}

	hearLoop(storeFor, subscribe, recordSleep)

	want := []time.Duration{250 * time.Millisecond, 500 * time.Millisecond, time.Second, 2 * time.Second}
	if len(waits) != len(want) {
		t.Fatalf("waited %v, want %v", waits, want)
	}
	for i, w := range want {
		if waits[i] != w {
			t.Fatalf("wait[%d] = %s, want %s", i, waits[i], w)
		}
	}
	if calls != 5 {
		t.Fatalf("subscribe was called %d time(s), want 5 (four refusals, then the one that succeeded)", calls)
	}
}