package backthink

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

	"git.yeij.top/AskaEth/Cyrene_v2/internal/db"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/agent"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/history"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/loop"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/memory"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/runtime/model"
)

// fakeRecent 是 recentProvider 的 stub，为
// 主会话语境读取返回固定的尾部/错误。
type fakeRecent struct {
	msgs []history.Message
	err  error
}

func (f *fakeRecent) Recent(context.Context, string, int) ([]history.Message, error) {
	return f.msgs, f.err
}

// captureAdapter 是一个 model.Adapter，记录交给它的每个请求，好让
// 测试能对 loop 实际喂给模型的消息做断言。
type captureAdapter struct {
	reqs []model.Request
}

func (c *captureAdapter) Name() string { return "capture" }

func (c *captureAdapter) Chat(_ context.Context, req model.Request, _ model.Options) (model.Response, error) {
	c.reqs = append(c.reqs, req)
	return model.Response{Content: "结论：想陪她聊聊"}, nil
}

func (c *captureAdapter) ChatStream(_ context.Context, req model.Request, _ func(model.StreamEvent)) (model.Response, error) {
	return c.Chat(context.Background(), req, model.Options{})
}

// newThinkLoop 在 ad 之上构建一个真实 loop，并带一条可用的手动记忆抽取
// 路径，好让测试能证明 owner 环境确实生效（extractMemory 只在
// MemWritable=true 时运行）。
func newThinkLoop(t *testing.T, ad model.Adapter) (*loop.Loop, *memory.Store) {
	t.Helper()
	a, err := agent.New("You are Cyrene.", nil, nil, agent.WithModel(ad, nil))
	if err != nil {
		t.Fatalf("agent.New: %v", err)
	}
	store := newMemoryStore(t)
	l := loop.New(loop.Options{
		Agent:     a,
		Memory:    store,
		Extractor: memory.NewManualExtractor("persona-a", "role-a"),
		PersonaID: "persona-a",
	})
	return l, store
}

// newMemoryStore 为单个测试打开一个隔离的内存记忆存储。
func newMemoryStore(t *testing.T) *memory.Store {
	t.Helper()
	d, err := db.Open(context.Background(), ":memory:", nil)
	if err != nil {
		t.Fatalf("db.Open: %v", err)
	}
	t.Cleanup(func() { _ = d.Close() })
	s, err := memory.NewStore(context.Background(), d, discardLog())
	if err != nil {
		t.Fatalf("memory.NewStore: %v", err)
	}
	return s
}

// modelText 返回一条 model 消息各文本片段拼接后的文本。
func modelText(m model.Message) string {
	var b strings.Builder
	for _, c := range m.Content {
		if c.Type == model.ContentTypeText {
			b.WriteString(c.Text)
		}
	}
	return b.String()
}

// TestGuidancePrompt_EncouragesProactiveWithoutSuppression 守护这次改写：
// 引导必须去掉旧的抑制措辞，并推动温暖、有针对性的
// 主动表达（design/20 §2）。
func TestGuidancePrompt_EncouragesProactiveWithoutSuppression(t *testing.T) {
	t.Parallel()
	p := guidancePrompt("heartbeat")
	for _, banned := range []string{"Do not produce a chat-style message", "nothing to report"} {
		if strings.Contains(p, banned) {
			t.Fatalf("guidance prompt still suppresses: contains %q", banned)
		}
	}
	for _, want := range []string{"值得主动告诉", "温暖"} {
		if !strings.Contains(p, want) {
			t.Fatalf("guidance should encourage warm proactive expression, missing %q", want)
		}
	}
}

// TestMainContext_MapsRecentMessages 证明主会话最近尾部被
// 按序转换、角色被映射、图片片段被保留。
func TestMainContext_MapsRecentMessages(t *testing.T) {
	t.Parallel()
	prov := &fakeRecent{msgs: []history.Message{
		{Role: history.RoleUser, Content: "今天有点累"},
		{Role: history.RoleAssistant, Content: "我陪你"},
		{Role: history.RoleUser, Content: "看这张图", Image: "data:image/png;base64,x"},
	}}
	got := mainContext(context.Background(), prov)
	if len(got) != 3 {
		t.Fatalf("len = %d, want 3", len(got))
	}
	if got[0].Role != model.RoleUser || got[0].Content[0].Text != "今天有点累" {
		t.Fatalf("msg[0] = %+v, want user '今天有点累'", got[0])
	}
	if got[1].Role != model.RoleAssistant {
		t.Fatalf("msg[1].Role = %q, want assistant", got[1].Role)
	}
	if got[2].Content[1].Type != model.ContentTypeImage {
		t.Fatalf("msg[2] missing image part: %+v", got[2].Content)
	}
}

// TestMainContext_Degrades 确保提供者为 nil 或读取失败都得到 nil
// 尾部，因此该次思考仅凭引导提示词运行，而不是失败。
func TestMainContext_Degrades(t *testing.T) {
	t.Parallel()
	if got := mainContext(context.Background(), nil); got != nil {
		t.Fatalf("nil provider should yield nil, got %+v", got)
	}
	if got := mainContext(context.Background(), &fakeRecent{err: errors.New("boom")}); got != nil {
		t.Fatalf("failed read should degrade to nil, got %+v", got)
	}
}

// TestThinkInput_AppendsGuidanceLast 验证拼装出的输入是最近
// 语境后跟单个引导回合；状态未知时提示词逐字不变（不注入状态块）。
func TestThinkInput_AppendsGuidanceLast(t *testing.T) {
	t.Parallel()
	in := thinkInput([]model.Message{model.TextMessage(model.RoleUser, "hi")}, "heartbeat", RoundState{})
	if len(in) != 2 {
		t.Fatalf("len = %d, want 2", len(in))
	}
	if in[1].Role != model.RoleUser || !strings.Contains(modelText(in[1]), guidancePrompt("heartbeat")) {
		t.Fatalf("last message is not the guidance prompt: %+v", in[1])
	}
	if strings.Contains(modelText(in[1]), "主人此刻的状态") {
		t.Fatalf("状态未知时不得注入状态块：%s", modelText(in[1]))
	}
}

// TestLoopThinker_Think_UsesMainContextAndOwnerEnv 驱动一次真实思考并
// 断言 design/20 P1 的三件事：模型看到了主会话的最近消息、
// 引导提示词不携带抑制措辞，且该次思考跑在 owner
// 环境之下（手动抽取器只在 MemWritable=true 时持久化）。
func TestLoopThinker_Think_UsesMainContextAndOwnerEnv(t *testing.T) {
	ad := &captureAdapter{}
	l, store := newThinkLoop(t, ad)
	lt := NewLoopThinker(l, &fakeRecent{msgs: []history.Message{
		{Role: history.RoleUser, Content: "记住 她喜欢冰美式"},
	}})

	text, err := lt.Think(context.Background(), "sess-backthink", "heartbeat")
	if err != nil {
		t.Fatalf("Think: %v", err)
	}
	if text != "结论：想陪她聊聊" {
		t.Fatalf("text = %q, want the adapter conclusion", text)
	}

	if len(ad.reqs) == 0 {
		t.Fatal("no model request captured")
	}
	last := ad.reqs[len(ad.reqs)-1]
	var sawContext, sawGuidance bool
	for _, m := range last.Messages {
		txt := modelText(m)
		if strings.Contains(txt, "冰美式") {
			sawContext = true
		}
		if strings.Contains(txt, "无人在旁") {
			sawGuidance = true
		}
	}
	if !sawContext {
		t.Fatalf("input missing the main-session recent message: %+v", last.Messages)
	}
	if !sawGuidance {
		t.Fatalf("input missing the guidance prompt: %+v", last.Messages)
	}

	// 已证明 owner 环境：ManualExtractor 只在 MemWritable=true 时持久化。
	items, err := store.ListByPersona(context.Background(), "persona-a")
	if err != nil {
		t.Fatalf("ListByPersona: %v", err)
	}
	if len(items) == 0 {
		t.Fatal("owner env not in effect: no memory extracted (extractMemory runs only when MemWritable=true)")
	}
	if !strings.Contains(items[0].Content, "冰美式") {
		t.Fatalf("extracted content = %q, want the remembered fact", items[0].Content)
	}
}

// TestLoopThinker_NilHistoryDegrades 保持既有的背压行为：没有
// 历史提供者时该次思考仍会运行（只用引导提示词）且绝不 panic。
func TestLoopThinker_NilHistoryDegrades(t *testing.T) {
	ad := &captureAdapter{}
	l, _ := newThinkLoop(t, ad)
	lt := NewLoopThinker(l, nil)

	if _, err := lt.Think(context.Background(), "sess-backthink", "heartbeat"); err != nil {
		t.Fatalf("Think with nil history: %v", err)
	}
	if len(ad.reqs) == 0 {
		t.Fatal("no model request captured")
	}
	last := ad.reqs[len(ad.reqs)-1]
	// 没有历史提供者时，输入携带引导提示词、不含
	// 主会话消息。（agent 会自行前置一条指令系统消息，
	// 所以我们断言存在性而非精确条数。）
	foundGuidance := false
	for _, m := range last.Messages {
		if strings.Contains(modelText(m), guidancePrompt("heartbeat")) {
			foundGuidance = true
			break
		}
	}
	if !foundGuidance {
		t.Fatalf("degraded think missing the guidance prompt: %+v", last.Messages)
	}
}