package fingerprint_test

import (
	"strings"
	"testing"

	"git.wntrmute.dev/kyle/crossbar/internal/fingerprint"
)

const conv1 = `{"model":"m","messages":[{"role":"system","content":"You are the project A assistant."},{"role":"user","content":"Add a config loader."},{"role":"assistant","content":"Sure."},{"role":"user","content":"Now tests."}]}`
const conv1later = `{"model":"m","messages":[{"role":"system","content":"You are the project A assistant."},{"role":"user","content":"Add a config loader."},{"role":"assistant","content":"Sure."},{"role":"user","content":"Now tests."},{"role":"assistant","content":"Done."},{"role":"user","content":"And docs."}]}`
const conv2 = `{"model":"m","messages":[{"role":"system","content":"You are the project A assistant."},{"role":"user","content":"Fix the flaky test."}]}`
const conv3 = `{"model":"m","messages":[{"role":"system","content":"You are the project B assistant."},{"role":"user","content":"Add a config loader."}]}`

func TestSameConversationSameKey(t *testing.T) {
	a := fingerprint.Of([]byte(conv1))
	b := fingerprint.Of([]byte(conv1later))
	if a == "" || a != b {
		t.Errorf("later turns of one conversation must keep the key: %q vs %q", a, b)
	}
	if len(a) != 64 || strings.Trim(a, "0123456789abcdef") != "" {
		t.Errorf("key must be lowercase hex sha256 (64 chars), got %q", a)
	}
}

func TestDifferentConversationsDifferentKeys(t *testing.T) {
	a, b, c := fingerprint.Of([]byte(conv1)), fingerprint.Of([]byte(conv2)), fingerprint.Of([]byte(conv3))
	if a == b {
		t.Errorf("different first user message must change the key")
	}
	if a == c {
		t.Errorf("different system prompt must change the key")
	}
}

func TestNoUserMessageIsEmpty(t *testing.T) {
	for _, body := range []string{
		`{"model":"m","messages":[{"role":"system","content":"only a system prompt"}]}`,
		`{"model":"m","messages":[]}`,
		`{"model":"m"}`,
		`{"input":"an embeddings request"}`,
		`not json at all`,
		``,
	} {
		if got := fingerprint.Of([]byte(body)); got != "" {
			t.Errorf("Of(%q) = %q, want empty", body, got)
		}
	}
}

func TestOnlyTheFirstFourKiBCount(t *testing.T) {
	long := strings.Repeat("x", 5000)
	a := `{"messages":[{"role":"user","content":"` + long + `A"}]}`
	b := `{"messages":[{"role":"user","content":"` + long + `B"}]}`
	if fingerprint.Of([]byte(a)) != fingerprint.Of([]byte(b)) {
		t.Errorf("bytes after the first 4 KiB of a message must not change the key")
	}
	c := `{"messages":[{"role":"user","content":"A` + long + `"}]}`
	if fingerprint.Of([]byte(a)) == fingerprint.Of([]byte(c)) {
		t.Errorf("bytes inside the first 4 KiB must change the key")
	}
}

func TestContentPartsAreFlattened(t *testing.T) {
	plain := `{"messages":[{"role":"user","content":"hello world"}]}`
	parts := `{"messages":[{"role":"user","content":[{"type":"text","text":"hello world"}]}]}`
	if fingerprint.Of([]byte(plain)) != fingerprint.Of([]byte(parts)) {
		t.Errorf("a content array of text parts must fingerprint like the joined text")
	}
}