package guard

import (
	"context"
	"math/rand/v2"
	"strings"
	"testing"
)

// Found on the PoC: a word held back at one release was dropped at the next,
// when that release had nothing to rewrite and sent the engine's own events.
func TestAWordHeldBackIsNeverLost(t *testing.T) {
	g := gate(t, lib(map[string]Policy{"p": {Output: Rules{PII: map[string]string{"email": "redact"}}}}, "p"))
	got, _, _ := stream(g.Output(context.Background(), Subject{Stream: true}),
		"1", ".", " Red", "\n", "2", ".", " Green", "\n", "3", ".", " Blue")
	if got != "1. Red\n2. Green\n3. Blue" {
		t.Errorf("client got %q", got)
	}
}

// However an answer is cut into tokens, the client is sent exactly the
// whole answer, rewritten.
func TestEverySplitOfAnAnswerArrivesWhole(t *testing.T) {
	g := gate(t, lib(map[string]Policy{"p": {Output: Rules{PII: map[string]string{"email": "redact"}}}}, "p"))
	text := "Hello. Mail bob@example.com or ann@example.org! Lists:\n1. Red\n2. Green and a long tail without stops " +
		strings.Repeat("word ", 50) + "end?"
	want := strings.NewReplacer("bob@example.com", "[EMAIL_1]", "ann@example.org", "[EMAIL_2]").Replace(text)
	rng := rand.New(rand.NewPCG(1, 2))
	for i := range 300 {
		var parts []string
		for rest := text; rest != ""; {
			n := 1 + rng.IntN(8)
			n = min(n, len(rest))
			parts = append(parts, rest[:n])
			rest = rest[n:]
		}
		got, _, _ := stream(g.Output(context.Background(), Subject{Stream: true}), parts...)
		if got != want {
			t.Fatalf("split %d: client got\n%q\nwant\n%q", i, got, want)
		}
	}
}