package session

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

	"agent-native/runtime/llm"
)

func appendMsgs(t *testing.T, s *Store, msgs ...llm.Message) {
	t.Helper()
	for _, m := range msgs {
		if err := s.Append(m); err != nil {
			t.Fatal(err)
		}
	}
}

func TestLoadSkipsCrashResidueTail(t *testing.T) {
	dir := t.TempDir()
	s, err := Open(filepath.Join(dir, "t.jsonl"))
	if err != nil {
		t.Fatal(err)
	}
	appendMsgs(t, s,
		llm.Message{Role: llm.RoleSystem, Content: "sys"},
		llm.Message{Role: llm.RoleUser, Content: "hi"},
	)
	// 模拟崩溃半行：无换行结尾的残缺 JSON。
	f, _ := os.OpenFile(s.Path(), os.O_APPEND|os.O_WRONLY, 0o644)
	_, _ = f.WriteString(`{"role":"assistant","content":"trunca`)
	_ = f.Close()

	msgs, err := s.Load()
	if err != nil {
		t.Fatalf("crash residue must not poison the session: %v", err)
	}
	if len(msgs) != 2 || msgs[0].Role != llm.RoleSystem || msgs[1].Content != "hi" {
		t.Fatalf("want sys+hi, got %+v", msgs)
	}
}

func TestLoadStillFailsOnMidFileCorruption(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "t.jsonl")
	if err := os.WriteFile(path, []byte("{\"bad json}\n{\"role\":\"user\",\"content\":\"ok\"}\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	s := &Store{path: path}
	if _, err := s.Load(); err == nil {
		t.Fatal("mid-file corruption must still error")
	}
}

func TestStatsAndMeta(t *testing.T) {
	dir := t.TempDir()
	s, _ := Open(filepath.Join(dir, "t.jsonl"))
	appendMsgs(t, s,
		llm.Message{Role: llm.RoleSystem, Content: "sys"},
		llm.Message{Role: llm.RoleUser, Content: "q"},
	)
	st := s.Stats()
	if st.Lines != 2 || st.Bytes <= 0 {
		t.Fatalf("stats wrong: %+v", st)
	}
	if err := s.SaveMeta(map[string]string{"model": "m1"}); err != nil {
		t.Fatal(err)
	}
	meta := s.ReadMeta()
	if meta == nil || meta["model"] != "m1" {
		t.Fatalf("meta roundtrip failed: %v", meta)
	}
	if other := (&Store{path: filepath.Join(dir, "missing.jsonl")}).ReadMeta(); other != nil {
		t.Fatalf("missing meta must return nil, got %v", other)
	}
}

func TestCompactRewritesTranscript(t *testing.T) {
	dir := t.TempDir()
	s, _ := Open(filepath.Join(dir, "t.jsonl"))
	appendMsgs(t, s, llm.Message{Role: llm.RoleSystem, Content: "sys"})
	for i := 0; i < 10; i++ {
		appendMsgs(t, s,
			llm.Message{Role: llm.RoleUser, Content: "early" + string(rune('a'+i))},
			llm.Message{Role: llm.RoleAssistant, Content: "reply"},
		)
	}
	var seenHead []llm.Message
	done, err := s.Compact(3, func(messages []llm.Message) (string, error) {
		seenHead = messages
		return "这是摘要", nil
	})
	if err != nil || !done {
		t.Fatalf("compact failed: %v done=%v", err, done)
	}
	if len(seenHead) != 17 { // 20 - system - 3 tail
		t.Fatalf("summarizer should receive 17 head messages, got %d", len(seenHead))
	}
	msgs, err := s.Load()
	if err != nil {
		t.Fatal(err)
	}
	if len(msgs) != 5 { // system + summary + 3 tail
		t.Fatalf("want 5 messages after compact, got %d", len(msgs))
	}
	if msgs[0].Role != llm.RoleSystem {
		t.Fatal("system message must be preserved")
	}
	if !strings.Contains(msgs[1].Content, "[conversation summary]") || !strings.Contains(msgs[1].Content, "这是摘要") {
		t.Fatalf("summary message wrong: %+v", msgs[1])
	}
	if msgs[2].Content != "reply" || msgs[3].Content != "earlyj" || msgs[4].Content != "reply" {
		t.Fatalf("tail order wrong: %+v", msgs[2:])
	}
	entries, err := s.Entries()
	if err != nil {
		t.Fatal(err)
	}
	if len(entries) <= 5 {
		t.Fatalf("compaction must append, not rewrite; got %d entries", len(entries))
	}
}

func TestCompactNoopWhenShort(t *testing.T) {
	dir := t.TempDir()
	s, _ := Open(filepath.Join(dir, "t.jsonl"))
	appendMsgs(t, s,
		llm.Message{Role: llm.RoleSystem, Content: "sys"},
		llm.Message{Role: llm.RoleUser, Content: "q"},
	)
	done, err := s.Compact(8, func([]llm.Message) (string, error) { return "x", nil })
	if err != nil || done {
		t.Fatalf("short transcript must be a no-op: %v %v", done, err)
	}
	msgs, _ := s.Load()
	if len(msgs) != 2 {
		t.Fatal("no-op compact must not touch the file")
	}
}

func TestCompactSummarizerErrorAborts(t *testing.T) {
	dir := t.TempDir()
	s, _ := Open(filepath.Join(dir, "t.jsonl"))
	appendMsgs(t, s, llm.Message{Role: llm.RoleSystem, Content: "sys"})
	for i := 0; i < 6; i++ {
		appendMsgs(t, s, llm.Message{Role: llm.RoleUser, Content: "m"})
	}
	done, err := s.Compact(2, func([]llm.Message) (string, error) { return "", errStringT("boom") })
	if err == nil || done {
		t.Fatal("summarizer error must abort compaction")
	}
	msgs, _ := s.Load()
	if len(msgs) != 7 {
		t.Fatal("failed compaction must leave the transcript untouched")
	}
}

type errStringT string

func (e errStringT) Error() string { return string(e) }