gohorsejobs/backend/internal/handlers/application_handler_test.go

package handlers

import (
	"bytes"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/rede5/gohorsejobs/backend/internal/dto"
	"github.com/rede5/gohorsejobs/backend/internal/models"
	"github.com/stretchr/testify/assert"
)

// mockApplicationService is a mock implementation for testing
type mockApplicationService struct {
	createApplicationFunc       func(req dto.CreateApplicationRequest) (*models.Application, error)
	getApplicationsFunc         func(jobID string) ([]models.Application, error)
	getApplicationByIDFunc      func(id string) (*models.Application, error)
	updateApplicationStatusFunc func(id string, req dto.UpdateApplicationStatusRequest) (*models.Application, error)
}

func (m *mockApplicationService) CreateApplication(req dto.CreateApplicationRequest) (*models.Application, error) {
	if m.createApplicationFunc != nil {
		return m.createApplicationFunc(req)
	}
	return nil, nil
}

func (m *mockApplicationService) GetApplications(jobID string) ([]models.Application, error) {
	if m.getApplicationsFunc != nil {
		return m.getApplicationsFunc(jobID)
	}
	return nil, nil
}

func (m *mockApplicationService) GetApplicationByID(id string) (*models.Application, error) {
	if m.getApplicationByIDFunc != nil {
		return m.getApplicationByIDFunc(id)
	}
	return nil, nil
}

func (m *mockApplicationService) UpdateApplicationStatus(id string, req dto.UpdateApplicationStatusRequest) (*models.Application, error) {
	if m.updateApplicationStatusFunc != nil {
		return m.updateApplicationStatusFunc(id, req)
	}
	return nil, nil
}

// ApplicationServiceInterface defines the interface for application service
type ApplicationServiceInterface interface {
	CreateApplication(req dto.CreateApplicationRequest) (*models.Application, error)
	GetApplications(jobID string) ([]models.Application, error)
	GetApplicationByID(id string) (*models.Application, error)
	UpdateApplicationStatus(id string, req dto.UpdateApplicationStatusRequest) (*models.Application, error)
}

// testableApplicationHandler wraps an interface for testing
type testableApplicationHandler struct {
	service ApplicationServiceInterface
}

func newTestableApplicationHandler(service ApplicationServiceInterface) *testableApplicationHandler {
	return &testableApplicationHandler{service: service}
}

func (h *testableApplicationHandler) CreateApplication(w http.ResponseWriter, r *http.Request) {
	var req dto.CreateApplicationRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	app, err := h.service.CreateApplication(req)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(app)
}

func (h *testableApplicationHandler) GetApplications(w http.ResponseWriter, r *http.Request) {
	jobID := r.URL.Query().Get("jobId")
	apps, err := h.service.GetApplications(jobID)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(apps)
}

func (h *testableApplicationHandler) GetApplicationByID(w http.ResponseWriter, r *http.Request) {
	// In real handler we use path value, here we might need to simulate or just call service
	// For unit test of handler logic usually we mock the router or simply pass arguments if method signature allows.
	// But check original handler: it extracts from r.PathValue("id").
	// In tests using httptest.NewRequest with Go 1.22 routing, we need to set path values.
	id := r.PathValue("id")
	app, err := h.service.GetApplicationByID(id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(app)
}

func (h *testableApplicationHandler) UpdateApplicationStatus(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	var req dto.UpdateApplicationStatusRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	app, err := h.service.UpdateApplicationStatus(id, req)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(app)
}

// =============================================================================
// Test Cases
// =============================================================================

func TestCreateApplication_Success(t *testing.T) {
	name := "John Doe"
	email := "john@example.com"

	mockService := &mockApplicationService{
		createApplicationFunc: func(req dto.CreateApplicationRequest) (*models.Application, error) {
			return &models.Application{
				ID:        "1",
				JobID:     req.JobID,
				Name:      &name,
				Email:     &email,
				Status:    "pending",
				CreatedAt: time.Now(),
				UpdatedAt: time.Now(),
			}, nil
		},
	}

	handler := newTestableApplicationHandler(mockService)

	appReq := dto.CreateApplicationRequest{
		JobID: "1",
		Name:  &name,
		Email: &email,
	}
	body, _ := json.Marshal(appReq)

	req := httptest.NewRequest("POST", "/applications", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.CreateApplication(rr, req)

	assert.Equal(t, http.StatusCreated, rr.Code)

	var app models.Application
	err := json.Unmarshal(rr.Body.Bytes(), &app)
	assert.NoError(t, err)
	assert.Equal(t, "pending", app.Status)
	assert.Equal(t, "1", app.JobID)
}

func TestCreateApplication_InvalidJSON(t *testing.T) {
	mockService := &mockApplicationService{}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("POST", "/applications", bytes.NewReader([]byte("invalid")))
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.CreateApplication(rr, req)

	assert.Equal(t, http.StatusBadRequest, rr.Code)
}

func TestCreateApplication_ServiceError(t *testing.T) {
	mockService := &mockApplicationService{
		createApplicationFunc: func(req dto.CreateApplicationRequest) (*models.Application, error) {
			return nil, assert.AnError
		},
	}

	handler := newTestableApplicationHandler(mockService)

	appReq := dto.CreateApplicationRequest{JobID: "1"}
	body, _ := json.Marshal(appReq)

	req := httptest.NewRequest("POST", "/applications", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.CreateApplication(rr, req)

	assert.Equal(t, http.StatusInternalServerError, rr.Code)
}

func TestGetApplications_Success(t *testing.T) {
	name1 := "John Doe"
	name2 := "Jane Smith"

	mockService := &mockApplicationService{
		getApplicationsFunc: func(jobID string) ([]models.Application, error) {
			return []models.Application{
				{
					ID:        "1",
					JobID:     jobID,
					Name:      &name1,
					Status:    "pending",
					CreatedAt: time.Now(),
				},
				{
					ID:        "2",
					JobID:     jobID,
					Name:      &name2,
					Status:    "reviewed",
					CreatedAt: time.Now(),
				},
			}, nil
		},
	}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("GET", "/applications?jobId=1", nil)
	rr := httptest.NewRecorder()

	handler.GetApplications(rr, req)

	assert.Equal(t, http.StatusOK, rr.Code)

	var apps []models.Application
	err := json.Unmarshal(rr.Body.Bytes(), &apps)
	assert.NoError(t, err)
	assert.Len(t, apps, 2)
}

func TestGetApplications_Empty(t *testing.T) {
	mockService := &mockApplicationService{
		getApplicationsFunc: func(jobID string) ([]models.Application, error) {
			return []models.Application{}, nil
		},
	}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("GET", "/applications?jobId=1", nil)
	rr := httptest.NewRecorder()

	handler.GetApplications(rr, req)

	assert.Equal(t, http.StatusOK, rr.Code)
}

func TestGetApplications_Error(t *testing.T) {
	mockService := &mockApplicationService{
		getApplicationsFunc: func(jobID string) ([]models.Application, error) {
			return nil, assert.AnError
		},
	}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("GET", "/applications?jobId=1", nil)
	rr := httptest.NewRecorder()

	handler.GetApplications(rr, req)

	assert.Equal(t, http.StatusInternalServerError, rr.Code)
}

func TestGetApplicationByID_Success(t *testing.T) {
	name := "John Doe"

	mockService := &mockApplicationService{
		getApplicationByIDFunc: func(id string) (*models.Application, error) {
			return &models.Application{
				ID:        id,
				JobID:     "1",
				Name:      &name,
				Status:    "pending",
				CreatedAt: time.Now(),
			}, nil
		},
	}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("GET", "/applications/1", nil)
	req.SetPathValue("id", "1") // Go 1.22 feature
	rr := httptest.NewRecorder()

	handler.GetApplicationByID(rr, req)

	assert.Equal(t, http.StatusOK, rr.Code)

	var app models.Application
	err := json.Unmarshal(rr.Body.Bytes(), &app)
	assert.NoError(t, err)
	assert.Equal(t, "1", app.ID)
}

func TestGetApplicationByID_NotFound(t *testing.T) {
	mockService := &mockApplicationService{
		getApplicationByIDFunc: func(id string) (*models.Application, error) {
			return nil, assert.AnError
		},
	}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("GET", "/applications/999", nil)
	req.SetPathValue("id", "999")
	rr := httptest.NewRecorder()

	handler.GetApplicationByID(rr, req)

	assert.Equal(t, http.StatusNotFound, rr.Code)
}

func TestUpdateApplicationStatus_Success(t *testing.T) {
	name := "John Doe"

	mockService := &mockApplicationService{
		updateApplicationStatusFunc: func(id string, req dto.UpdateApplicationStatusRequest) (*models.Application, error) {
			return &models.Application{
				ID:        id,
				JobID:     "1",
				Name:      &name,
				Status:    req.Status,
				CreatedAt: time.Now(),
				UpdatedAt: time.Now(),
			}, nil
		},
	}

	handler := newTestableApplicationHandler(mockService)

	statusReq := dto.UpdateApplicationStatusRequest{
		Status: "hired",
	}
	body, _ := json.Marshal(statusReq)

	req := httptest.NewRequest("PUT", "/applications/1/status", bytes.NewReader(body))
	req.SetPathValue("id", "1")
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.UpdateApplicationStatus(rr, req)

	assert.Equal(t, http.StatusOK, rr.Code)

	var app models.Application
	err := json.Unmarshal(rr.Body.Bytes(), &app)
	assert.NoError(t, err)
	assert.Equal(t, "hired", app.Status)
}

func TestUpdateApplicationStatus_InvalidJSON(t *testing.T) {
	mockService := &mockApplicationService{}

	handler := newTestableApplicationHandler(mockService)

	req := httptest.NewRequest("PUT", "/applications/1/status", bytes.NewReader([]byte("invalid")))
	req.SetPathValue("id", "1")
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.UpdateApplicationStatus(rr, req)

	assert.Equal(t, http.StatusBadRequest, rr.Code)
}

func TestUpdateApplicationStatus_Error(t *testing.T) {
	mockService := &mockApplicationService{
		updateApplicationStatusFunc: func(id string, req dto.UpdateApplicationStatusRequest) (*models.Application, error) {
			return nil, assert.AnError
		},
	}

	handler := newTestableApplicationHandler(mockService)

	statusReq := dto.UpdateApplicationStatusRequest{Status: "hired"}
	body, _ := json.Marshal(statusReq)

	req := httptest.NewRequest("PUT", "/applications/1/status", bytes.NewReader(body))
	req.SetPathValue("id", "1")
	req.Header.Set("Content-Type", "application/json")
	rr := httptest.NewRecorder()

	handler.UpdateApplicationStatus(rr, req)

	assert.Equal(t, http.StatusInternalServerError, rr.Code)
}