package agent

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestReasoningStreamSeparatesThinkingFromAnswer(t *testing.T) {
	for _, field := range []string{"reasoning_content", "reasoning"} {
		t.Run(field, func(t *testing.T) {
			stream := fmt.Sprintf("data: {\"choices\":[{\"delta\":{%q:\"先确认设备。\"}}]}\n\ndata: {\"choices\":[{\"delta\":{%q:\"再检查页面。\",\"content\":\"设备在线。\"},\"finish_reason\":\"stop\"}]}\n\ndata: [DONE]\n\n", field, field)
			var answer, thought strings.Builder
			step, err := readToolStream(strings.NewReader(stream), "", func(delta string) { answer.WriteString(delta) }, func(delta string) { thought.WriteString(delta) })
			if err != nil || step.Text != "设备在线。" || answer.String() != step.Text || step.Reasoning != "先确认设备。再检查页面。" || thought.String() != step.Reasoning {
				t.Fatalf("reasoning/answer mixed or lost: %+v %q %q %v", step, answer.String(), thought.String(), err)
			}
		})
	}
}

func TestReasoningInterruptedStreamRetainsReceivedThought(t *testing.T) {
	stream := "data: {\"choices\":[{\"delta\":{\"reasoning_content\":\"尚未完成的思考\"}}]}\n\n"
	var received strings.Builder
	step, err := readToolStream(strings.NewReader(stream), "", nil, func(delta string) { received.WriteString(delta) })
	if err == nil || step.Reasoning != "尚未完成的思考" || received.String() != step.Reasoning || step.Text != "" {
		t.Fatalf("partial reasoning lost: %+v %v", step, err)
	}
}

func TestReasoningEventResultAndConversationRoundTrip(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		fmt.Fprint(w, "data: {\"choices\":[{\"delta\":{\"reasoning_content\":\"先核对预算。\"}}]}\n\ndata: {\"choices\":[{\"delta\":{\"content\":\"预算3500元。\"},\"finish_reason\":\"stop\"}]}\n\ndata: [DONE]\n\n")
	}))
	defer server.Close()
	s, secrets := testService(t)
	if _, err := s.SaveModelConfig(ModelConfigInput{Config: testConfig(server.URL), APIKey: "key"}); err != nil {
		t.Fatal(err)
	}
	session, err := s.CreateConversation()
	if err != nil {
		t.Fatal(err)
	}
	var thought, answer strings.Builder
	s.emitDelta = func(delta ChatDelta) {
		if delta.RequestID != "reasoning-request" {
			t.Errorf("wrong request ID: %s", delta.RequestID)
		}
		thought.WriteString(delta.ReasoningDelta)
		answer.WriteString(delta.Delta)
	}
	result, err := s.ChatStream(context.Background(), "reasoning-request", session.ID, "预算多少？")
	if err != nil || result["reasoning"] != "先核对预算。" || thought.String() != result["reasoning"] || answer.String() != result["content"] {
		t.Fatalf("reasoning not delivered: %v %v", result, err)
	}
	session.Messages = []ConversationMessage{{ID: "u1", Role: "user", Content: "预算多少？", CreatedAt: 1}, {ID: "a1", Role: "assistant", Content: result["content"], Reasoning: result["reasoning"], CreatedAt: 2, Status: "complete"}}
	if _, err = s.SaveConversation(session); err != nil {
		t.Fatal(err)
	}
	loaded, err := newService(s.configPath, secrets).GetConversation(session.ID)
	if err != nil || loaded.Messages[1].Reasoning != result["reasoning"] {
		t.Fatalf("reasoning lost on reopen: %+v %v", loaded, err)
	}
	raw, _ := json.Marshal(s.history[session.ID])
	if strings.Contains(string(raw), "先核对预算") {
		t.Fatal("display reasoning leaked into legacy history")
	}
}

func TestNonStreamReasoningFromModelAndToolStep(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		fmt.Fprint(w, `{"choices":[{"message":{"content":"回答","reasoning_content":"思考"},"finish_reason":"stop"}]}`)
	}))
	defer server.Close()
	var thought string
	text, err := complete(testConfig(server.URL), "key", nil, func(delta string) { thought += delta })
	if err != nil || text != "回答" || thought != "思考" {
		t.Fatalf("non-stream reasoning missing: %q %q %v", text, thought, err)
	}
	step, err := modelToolStep(context.Background(), testConfig(server.URL), "key", nil, nil, nil)
	if err != nil || step.Reasoning != "思考" || step.Text != "回答" {
		t.Fatalf("tool step reasoning missing: %+v %v", step, err)
	}
}