package main

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/gin-gonic/gin"
)

// --- Mocks ---
type mockLLM struct {
	keywordsResp map[string]interface{}
	disambigID   string
	keywordsErr  error
	disambigErr  error
}

var _ LLMClientAPI = (*mockLLM)(nil)

func (m *mockLLM) ExtractKeywords(ctx context.Context, msg string) (map[string]interface{}, error) {
	return m.keywordsResp, m.keywordsErr
}
func (m *mockLLM) DisambiguateBestMatch(ctx context.Context, msg string, candidates []Visit) (string, error) {
	return m.disambigID, m.disambigErr
}

// --- Test VisitDB ---
type testVisitDB struct {
	candidates []Visit
	findErr    error
	byID       map[string]Visit
}

var _ VisitDBAPI = (*testVisitDB)(nil)

func (db *testVisitDB) FindCandidates(keywords []string) ([]Visit, error) {
	return db.candidates, db.findErr
}
func (db *testVisitDB) FindById(id string) (Visit, error) {
	r, ok := db.byID[id]
	if !ok {
		return Visit{}, context.DeadlineExceeded
	}
	return r, nil
}

// --- Integration tests ---
func TestChatService_MatchFound(t *testing.T) {
	gin.SetMode(gin.TestMode)
	var llm LLMClientAPI = &mockLLM{
		keywordsResp: map[string]interface{}{"keyword": []string{"worms", "deworming"}},
		disambigID:   "deworming",
	}
	visit := Visit{
		ID:         "deworming",
		Procedures: []Procedure{{Name: "Deworming tablet", Price: 30, DurationMin: 10}},
		Notes:      "Bloodwork ensures organs are safe for treatment.",
	}
	var db VisitDBAPI = &testVisitDB{
		candidates: []Visit{visit},
		byID:       map[string]Visit{"deworming": visit},
	}
	var cs ChatServiceAPI = NewChatService(llm, db)
	r := gin.New()
	r.POST("/chat", cs.HandleChat)

	w := httptest.NewRecorder()
	body := map[string]string{"message": "My dog needs deworming"}
	jsonBody, _ := json.Marshal(body)
	req, _ := http.NewRequest("POST", "/chat", httptestNewBody(jsonBody))
	req.Header.Set("Content-Type", "application/json")

	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("Expected 200, got %d", w.Code)
	}
	var resp ChatResponse
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("Invalid response: %v", err)
	}
	if resp.Match == nil || *resp.Match != "deworming" {
		t.Errorf("Expected match 'deworming', got %v", resp.Match)
	}
	if len(resp.Procedures) != 1 || resp.Procedures[0].Name != "Deworming tablet" {
		t.Errorf("Expected procedure 'Deworming tablet', got %+v", resp.Procedures)
	}
	if resp.Notes != visit.Notes {
		t.Errorf("Expected notes '%s', got '%s'", visit.Notes, resp.Notes)
	}
}

func TestChatService_NoMatch(t *testing.T) {
	gin.SetMode(gin.TestMode)
	llm := &mockLLM{
		keywordsResp: map[string]interface{}{"keyword": []string{"unknown"}},
		disambigID:   "",
	}
	db := &testVisitDB{
		candidates: []Visit{},
		byID:       map[string]Visit{},
	}
	cs := NewChatService(llm, db)
	r := gin.New()
	r.POST("/chat", cs.HandleChat)

	w := httptest.NewRecorder()
	body := map[string]string{"message": "No known reason"}
	jsonBody, _ := json.Marshal(body)
	req, _ := http.NewRequest("POST", "/chat", httptestNewBody(jsonBody))
	req.Header.Set("Content-Type", "application/json")

	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("Expected 200, got %d", w.Code)
	}
	var resp ChatResponse
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("Invalid response: %v", err)
	}
	if resp.Match != nil {
		t.Errorf("Expected no match, got %v", resp.Match)
	}
}

func TestChatService_LLMError(t *testing.T) {
	gin.SetMode(gin.TestMode)
	llm := &mockLLM{
		keywordsErr: context.DeadlineExceeded,
	}
	db := &testVisitDB{}
	cs := NewChatService(llm, db)
	r := gin.New()
	r.POST("/chat", cs.HandleChat)

	w := httptest.NewRecorder()
	body := map[string]string{"message": "error"}
	jsonBody, _ := json.Marshal(body)
	req, _ := http.NewRequest("POST", "/chat", httptestNewBody(jsonBody))
	req.Header.Set("Content-Type", "application/json")

	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("Expected 200, got %d", w.Code)
	}
	var resp ChatResponse
	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
		t.Fatalf("Invalid response: %v", err)
	}
	if resp.Match != nil {
		t.Errorf("Expected no match on LLM error, got %v", resp.Match)
	}
}

// --- Helper for request body ---
func httptestNewBody(b []byte) *httptestBody {
	return &httptestBody{b: b}
}

type httptestBody struct {
	b   []byte
	pos int
}

func (r *httptestBody) Read(p []byte) (int, error) {
	if r.pos >= len(r.b) {
		return 0, io.EOF
	}
	n := copy(p, r.b[r.pos:])
	r.pos += n
	return n, nil
}
func (r *httptestBody) Close() error { return nil }