package history

import (
	"context"
	"errors"
	"strings"
	"testing"
)

// titleOf 返回某个会话已存储的标题，缺失时使测试失败。
func titleOf(t *testing.T, st *Store, id string) string {
	t.Helper()
	sessions, err := st.ListSessions(context.Background())
	if err != nil {
		t.Fatalf("list sessions: %v", err)
	}
	for _, m := range sessions {
		if m.ID == id {
			return m.Title
		}
	}
	t.Fatalf("session %q not found in %+v", id, sessions)
	return ""
}

func TestEnsureTitleFromFirstUserMessage(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	// 主会话初始无名。
	if got := titleOf(t, st, MainSessionID); got != "" {
		t.Fatalf("initial main title = %q, want empty", got)
	}

	// 第一条用户消息为它命名，空白串被折叠。
	if _, err := st.AppendFull(ctx, Message{SessionID: MainSessionID, Role: RoleUser, Content: "  你好\n世界  "}); err != nil {
		t.Fatalf("append first user: %v", err)
	}
	if got := titleOf(t, st, MainSessionID); got != "你好 世界" {
		t.Fatalf("main title = %q, want 你好 世界", got)
	}

	// 之后的用户消息不会覆盖已确定的标题。
	if _, err := st.AppendFull(ctx, Message{SessionID: MainSessionID, Role: RoleUser, Content: "second"}); err != nil {
		t.Fatalf("append second user: %v", err)
	}
	if got := titleOf(t, st, MainSessionID); got != "你好 世界" {
		t.Fatalf("main title after second = %q, want unchanged", got)
	}
}

func TestEnsureTitleTruncatesAndFallsBack(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	// 过长的首条用户消息被截断到 20 个 rune 并加省略号。
	sub, err := st.NewSubSession(ctx, "owner")
	if err != nil {
		t.Fatalf("new sub: %v", err)
	}
	long := strings.Repeat("字", autoTitleMaxRunes+5)
	if _, err := st.AppendFull(ctx, Message{SessionID: sub, Role: RoleUser, Content: long}); err != nil {
		t.Fatalf("append long: %v", err)
	}
	want := strings.Repeat("字", autoTitleMaxRunes) + "…"
	if got := titleOf(t, st, sub); got != want {
		t.Fatalf("sub title = %q, want %q", got, want)
	}

	// 纯空白的首条消息（例如纯图片回合）回退到会话类型标签，子会话与主会话
	// 都是如此。
	blank, err := st.NewSubSession(ctx, "owner")
	if err != nil {
		t.Fatalf("new blank sub: %v", err)
	}
	if _, err := st.AppendFull(ctx, Message{SessionID: blank, Role: RoleUser, Content: " \n\t "}); err != nil {
		t.Fatalf("append blank: %v", err)
	}
	if got := titleOf(t, st, blank); got != titleSubFallback {
		t.Fatalf("blank sub title = %q, want %q", got, titleSubFallback)
	}

	st2 := newStore(t)
	if _, err := st2.AppendFull(ctx, Message{SessionID: MainSessionID, Role: RoleUser, Content: "   "}); err != nil {
		t.Fatalf("append blank main: %v", err)
	}
	if got := titleOf(t, st2, MainSessionID); got != titleMainFallback {
		t.Fatalf("blank main title = %q, want %q", got, titleMainFallback)
	}
}

func TestEnsureTitleOnlyFromFirstUserMessage(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	// 首条是 assistant 消息不会为会话命名。
	sub, err := st.NewSubSession(ctx, "owner")
	if err != nil {
		t.Fatalf("new sub: %v", err)
	}
	if _, err := st.AppendFull(ctx, Message{SessionID: sub, Role: RoleAssistant, Content: "hello"}); err != nil {
		t.Fatalf("append assistant: %v", err)
	}
	if got := titleOf(t, st, sub); got != "" {
		t.Fatalf("sub title after assistant = %q, want empty", got)
	}

	// 其后的第一条用户消息仍会为它命名。
	if _, err := st.AppendFull(ctx, Message{SessionID: sub, Role: RoleUser, Content: "real question"}); err != nil {
		t.Fatalf("append user: %v", err)
	}
	if got := titleOf(t, st, sub); got != "real question" {
		t.Fatalf("sub title after user = %q, want real question", got)
	}
}

func TestRenameSession(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	// 固定主会话可以重命名（与删除不同）。
	if err := st.RenameSession(ctx, MainSessionID, "工作台"); err != nil {
		t.Fatalf("rename main: %v", err)
	}
	if got := titleOf(t, st, MainSessionID); got != "工作台" {
		t.Fatalf("main title = %q, want 工作台", got)
	}

	// 子会话可以重命名，且重命名会覆盖自动标题。
	sub, err := st.NewSubSession(ctx, "owner")
	if err != nil {
		t.Fatalf("new sub: %v", err)
	}
	if _, err := st.AppendFull(ctx, Message{SessionID: sub, Role: RoleUser, Content: "auto"}); err != nil {
		t.Fatalf("append: %v", err)
	}
	if err := st.RenameSession(ctx, sub, "手动标题"); err != nil {
		t.Fatalf("rename sub: %v", err)
	}
	if got := titleOf(t, st, sub); got != "手动标题" {
		t.Fatalf("sub title = %q, want 手动标题", got)
	}

	// 未知 id 报 not found。
	if err := st.RenameSession(ctx, "web:missing", "x"); !errors.Is(err, ErrSessionNotFound) {
		t.Fatalf("rename unknown err = %v, want ErrSessionNotFound", err)
	}
}