package native

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"agent-native/exec"
	"agent-native/runtime/llm"
)

func TestBackendCompactBeforeRun(t *testing.T) {
	dir := t.TempDir()
	// 预置一份超阈值的长转录（系统消息 + 12 条历史）。
	transcript := filepath.Join(dir, ".agentx", "transcript.jsonl")
	if err := os.MkdirAll(filepath.Dir(transcript), 0o755); err != nil {
		t.Fatal(err)
	}
	var b strings.Builder
	b.WriteString(`{"role":"system","content":"sys"}` + "\n")
	for i := 0; i < 12; i++ {
		b.WriteString(`{"role":"user","content":"` + strings.Repeat("x", 400) + `"}` + "\n")
	}
	if err := os.WriteFile(transcript, []byte(b.String()), 0o644); err != nil {
		t.Fatal(err)
	}

	var sawSummary bool
	// 注入式捕获：验证 Run 收到的消息里有摘要标记。
	bk2 := New(Options{
		ModelOptions: ModelOptions{
			Model:  "fake",
			Stream: captureFirstStream(&sawSummary),
		},
		SessionOptions: SessionOptions{
			Compact: &CompactConfig{ThresholdChars: 1000, KeepLastN: 3, Summarizer: func(ctx context.Context, messages []llm.Message) (string, error) {
				return "预置历史摘要", nil
			}},
		},
	})
	res, err := bk2.Execute(context.Background(), exec.Request{
		WorkDir: dir, Prompt: "继续", Targets: []string{"output.md"},
		ToolProfile: exec.ToolProfileReasoning,
	})
	if err != nil {
		t.Fatal(err)
	}
	if res.Success && !sawSummary {
		t.Fatal("compaction should have run before the loop")
	}
	data, _ := os.ReadFile(transcript)
	if !strings.Contains(string(data), "预置历史摘要") || !strings.Contains(string(data), `"type":"compaction"`) {
		t.Fatalf("transcript should keep history and append a compaction entry, got:\n%.400s", data)
	}
	if !strings.Contains(string(data), `"role":"system"`) {
		t.Fatal("compaction must not rewrite the original transcript")
	}
}

func captureFirstStream(saw *bool) llm.StreamFunc {
	return func(ctx context.Context, model string, messages []llm.Message, decls []llm.ToolDecl, opts llm.StreamOptions) <-chan llm.Event {
		for _, m := range messages {
			if strings.Contains(m.Content, "[conversation summary]") {
				*saw = true
			}
		}
		ch := make(chan llm.Event, 4)
		go func() {
			defer close(ch)
			ch <- llm.Event{Kind: llm.KindMessageEnd, Message: llm.Message{Role: llm.RoleAssistant, Content: "压缩后续写完成", StopReason: llm.StopEnd}}
		}()
		return ch
	}
}