package handler

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"gcy_hpc_server/internal/model"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

type mockUploadService struct {
	initUploadFn      func(ctx context.Context, req model.InitUploadRequest) (interface{}, error)
	uploadChunkFn     func(ctx context.Context, sessionID int64, chunkIndex int, reader io.Reader, size int64) error
	completeUploadFn  func(ctx context.Context, sessionID int64) (*model.FileResponse, error)
	getUploadStatusFn func(ctx context.Context, sessionID int64) (*model.UploadSessionResponse, error)
	cancelUploadFn    func(ctx context.Context, sessionID int64) error
}

func (m *mockUploadService) InitUpload(ctx context.Context, req model.InitUploadRequest) (interface{}, error) {
	return m.initUploadFn(ctx, req)
}

func (m *mockUploadService) UploadChunk(ctx context.Context, sessionID int64, chunkIndex int, reader io.Reader, size int64) error {
	return m.uploadChunkFn(ctx, sessionID, chunkIndex, reader, size)
}

func (m *mockUploadService) CompleteUpload(ctx context.Context, sessionID int64) (*model.FileResponse, error) {
	return m.completeUploadFn(ctx, sessionID)
}

func (m *mockUploadService) GetUploadStatus(ctx context.Context, sessionID int64) (*model.UploadSessionResponse, error) {
	return m.getUploadStatusFn(ctx, sessionID)
}

func (m *mockUploadService) CancelUpload(ctx context.Context, sessionID int64) error {
	return m.cancelUploadFn(ctx, sessionID)
}

func setupUploadHandler(mock uploadServiceProvider) (*UploadHandler, *gin.Engine) {
	gin.SetMode(gin.TestMode)
	h := &UploadHandler{svc: mock, logger: zap.NewNop()}
	r := gin.New()
	v1 := r.Group("/api/v1")
	uploads := v1.Group("/files/uploads")
	uploads.POST("", h.InitUpload)
	uploads.PUT("/:id/chunks/:index", h.UploadChunk)
	uploads.POST("/:id/complete", h.CompleteUpload)
	uploads.GET("/:id", h.GetUploadStatus)
	uploads.DELETE("/:id", h.CancelUpload)
	return h, r
}

func TestInitUpload_NewSession(t *testing.T) {
	mock := &mockUploadService{
		initUploadFn: func(ctx context.Context, req model.InitUploadRequest) (interface{}, error) {
			return model.UploadSessionResponse{
				ID:             1,
				FileName:       req.FileName,
				FileSize:       req.FileSize,
				ChunkSize:      5 * 1024 * 1024,
				TotalChunks:    2,
				SHA256:         req.SHA256,
				Status:         "pending",
				UploadedChunks: []int{},
				ExpiresAt:      time.Now().Add(24 * time.Hour),
				CreatedAt:      time.Now(),
			}, nil
		},
	}
	_, r := setupUploadHandler(mock)

	body, _ := json.Marshal(model.InitUploadRequest{
		FileName: "test.bin",
		FileSize: 10 * 1024 * 1024,
		SHA256:   "abc123",
	})
	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodPost, "/api/v1/files/uploads", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	r.ServeHTTP(w, req)

	if w.Code != http.StatusCreated {
		t.Fatalf("expected 201, got %d: %s", w.Code, w.Body.String())
	}

	var resp map[string]interface{}
	json.Unmarshal(w.Body.Bytes(), &resp)
	if !resp["success"].(bool) {
		t.Fatal("expected success=true")
	}
	data := resp["data"].(map[string]interface{})
	if data["status"] != "pending" {
		t.Fatalf("expected status=pending, got %v", data["status"])
	}
}

func TestInitUpload_DedupHit(t *testing.T) {
	mock := &mockUploadService{
		initUploadFn: func(ctx context.Context, req model.InitUploadRequest) (interface{}, error) {
			return model.FileResponse{
				ID:        42,
				Name:      req.FileName,
				Size:      req.FileSize,
				SHA256:    req.SHA256,
				MimeType:  "application/octet-stream",
				CreatedAt: time.Now(),
				UpdatedAt: time.Now(),
			}, nil
		},
	}
	_, r := setupUploadHandler(mock)

	body, _ := json.Marshal(model.InitUploadRequest{
		FileName: "existing.bin",
		FileSize: 1024,
		SHA256:   "existinghash",
	})
	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodPost, "/api/v1/files/uploads", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp map[string]interface{}
	json.Unmarshal(w.Body.Bytes(), &resp)
	if !resp["success"].(bool) {
		t.Fatal("expected success=true")
	}
	data := resp["data"].(map[string]interface{})
	if data["sha256"] != "existinghash" {
		t.Fatalf("expected sha256=existinghash, got %v", data["sha256"])
	}
}

func TestInitUpload_MissingFields(t *testing.T) {
	mock := &mockUploadService{
		initUploadFn: func(ctx context.Context, req model.InitUploadRequest) (interface{}, error) {
			return nil, nil
		},
	}
	_, r := setupUploadHandler(mock)

	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodPost, "/api/v1/files/uploads", bytes.NewReader([]byte(`{}`)))
	req.Header.Set("Content-Type", "application/json")
	r.ServeHTTP(w, req)

	if w.Code != http.StatusBadRequest {
		t.Fatalf("expected 400, got %d: %s", w.Code, w.Body.String())
	}
}

func TestUploadChunk_Success(t *testing.T) {
	var receivedSessionID int64
	var receivedChunkIndex int

	mock := &mockUploadService{
		uploadChunkFn: func(ctx context.Context, sessionID int64, chunkIndex int, reader io.Reader, size int64) error {
			receivedSessionID = sessionID
			receivedChunkIndex = chunkIndex
			readBytes, _ := io.ReadAll(reader)
			if len(readBytes) == 0 {
				t.Error("expected non-empty chunk data")
			}
			return nil
		},
	}
	_, r := setupUploadHandler(mock)

	var buf bytes.Buffer
	writer := multipart.NewWriter(&buf)
	part, _ := writer.CreateFormFile("chunk", "test.bin")
	fmt.Fprintf(part, "chunk data here")
	writer.Close()

	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodPut, "/api/v1/files/uploads/1/chunks/0", &buf)
	req.Header.Set("Content-Type", writer.FormDataContentType())
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}
	if receivedSessionID != 1 {
		t.Fatalf("expected session_id=1, got %d", receivedSessionID)
	}
	if receivedChunkIndex != 0 {
		t.Fatalf("expected chunk_index=0, got %d", receivedChunkIndex)
	}
}

func TestCompleteUpload_Success(t *testing.T) {
	mock := &mockUploadService{
		completeUploadFn: func(ctx context.Context, sessionID int64) (*model.FileResponse, error) {
			return &model.FileResponse{
				ID:        10,
				Name:      "completed.bin",
				Size:      2048,
				SHA256:    "completehash",
				MimeType:  "application/octet-stream",
				CreatedAt: time.Now(),
				UpdatedAt: time.Now(),
			}, nil
		},
	}
	_, r := setupUploadHandler(mock)

	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodPost, "/api/v1/files/uploads/5/complete", nil)
	r.ServeHTTP(w, req)

	if w.Code != http.StatusCreated {
		t.Fatalf("expected 201, got %d: %s", w.Code, w.Body.String())
	}

	var resp map[string]interface{}
	json.Unmarshal(w.Body.Bytes(), &resp)
	if !resp["success"].(bool) {
		t.Fatal("expected success=true")
	}
	data := resp["data"].(map[string]interface{})
	if data["name"] != "completed.bin" {
		t.Fatalf("expected name=completed.bin, got %v", data["name"])
	}
}

func TestGetUploadStatus_Success(t *testing.T) {
	mock := &mockUploadService{
		getUploadStatusFn: func(ctx context.Context, sessionID int64) (*model.UploadSessionResponse, error) {
			return &model.UploadSessionResponse{
				ID:             sessionID,
				FileName:       "status.bin",
				FileSize:       4096,
				ChunkSize:      2048,
				TotalChunks:    2,
				SHA256:         "statushash",
				Status:         "uploading",
				UploadedChunks: []int{0},
				ExpiresAt:      time.Now().Add(24 * time.Hour),
				CreatedAt:      time.Now(),
			}, nil
		},
	}
	_, r := setupUploadHandler(mock)

	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodGet, "/api/v1/files/uploads/3", nil)
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	var resp map[string]interface{}
	json.Unmarshal(w.Body.Bytes(), &resp)
	if !resp["success"].(bool) {
		t.Fatal("expected success=true")
	}
	data := resp["data"].(map[string]interface{})
	if data["status"] != "uploading" {
		t.Fatalf("expected status=uploading, got %v", data["status"])
	}
}

func TestCancelUpload_Success(t *testing.T) {
	var receivedSessionID int64

	mock := &mockUploadService{
		cancelUploadFn: func(ctx context.Context, sessionID int64) error {
			receivedSessionID = sessionID
			return nil
		},
	}
	_, r := setupUploadHandler(mock)

	w := httptest.NewRecorder()
	req, _ := http.NewRequest(http.MethodDelete, "/api/v1/files/uploads/7", nil)
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
	}

	if receivedSessionID != 7 {
		t.Fatalf("expected session_id=7, got %d", receivedSessionID)
	}

	var resp map[string]interface{}
	json.Unmarshal(w.Body.Bytes(), &resp)
	data := resp["data"].(map[string]interface{})
	if data["message"] != "upload cancelled" {
		t.Fatalf("expected message='upload cancelled', got %v", data["message"])
	}
}