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 is a recentProvider stub returning a fixed tail/error for the
// main-session context read.
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 is a model.Adapter that records every request it is handed so a
// test can assert on the messages the loop actually fed to the model.
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 builds a real loop over ad with a working manual memory-extraction
// path so a test can prove the owner environment is in effect (extractMemory runs
// only when MemWritable=true).
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 opens an isolated in-memory memory store for one test.
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 returns the concatenated text of a model message's text parts.
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 guards the rewrite:
// the guidance must drop the old suppression phrases and push warm, targeted
// proactive expression (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 proves the recent main-session tail is
// converted in order with roles mapped and image parts preserved.
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 ensures a nil provider or a failed read yields a nil
// tail so the think runs on the guidance prompt alone rather than failing.
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 verifies the assembled input is the recent
// context followed by a single guidance turn.
func TestThinkInput_AppendsGuidanceLast(t *testing.T) {
	t.Parallel()
	in := thinkInput([]model.Message{model.TextMessage(model.RoleUser, "hi")}, "heartbeat")
	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])
	}
}

// TestLoopThinker_Think_UsesMainContextAndOwnerEnv drives a real think and asserts
// three things from design/20 P1: the model saw the main-session recent message,
// the guidance prompt carries no suppression, and the think ran under the owner
// environment (the manual extractor persists only when MemWritable=true).
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)
	}

	// Owner env proved: ManualExtractor only persists under MemWritable=true.
	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 keeps the pre-existing backpressure: with no
// history provider the think still runs (guidance prompt only) and never panics.
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]
	// With no history provider the input carries the guidance prompt and no
	// main-session messages. (The agent prepends its own instruction system message,
	// so we assert presence rather than an exact count.)
	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)
	}
}