package web

import (
	"bytes"
	"encoding/csv"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"math"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"

	root "marmic/servicetrade-toolbox"
	"marmic/servicetrade-toolbox/internal/api"
	"marmic/servicetrade-toolbox/internal/middleware"
)

// UploadResult represents the result of a single file upload
type UploadResult struct {
	JobID    string
	DocName  string
	Success  bool
	Error    string
	Data     map[string]interface{}
	FileSize int64
}

// UploadSession stores upload results for pagination
type UploadSession struct {
	Results            []UploadResult
	TotalJobs          int
	TotalSuccess       int
	TotalFailure       int
	TotalBytesUploaded int64
	TotalTime          time.Duration
	CreatedAt          time.Time
}

// Global map to store upload sessions (in production, use Redis or database)
var uploadSessions = make(map[string]UploadSession)

// DocumentsHandler handles the document upload page
func DocumentsHandler(w http.ResponseWriter, r *http.Request) {
	session, ok := r.Context().Value(middleware.SessionKey).(*api.Session)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	tmpl := root.WebTemplates
	data := map[string]interface{}{
		"Title":   "Document Uploads",
		"Session": session,
	}

	if r.Header.Get("HX-Request") == "true" {
		// For HTMX requests, just send the document_upload partial
		if err := tmpl.ExecuteTemplate(w, "document_upload", data); err != nil {
			log.Printf("Template execution error: %v", err)
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			return
		}
	} else {
		// For full page requests, first render document_upload into a buffer
		var contentBuf bytes.Buffer
		if err := tmpl.ExecuteTemplate(&contentBuf, "document_upload", data); err != nil {
			log.Printf("Template execution error: %v", err)
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			return
		}

		// Add the rendered content to the data for the layout
		data["BodyContent"] = contentBuf.String()

		// Now render the layout with our content
		if err := tmpl.ExecuteTemplate(w, "layout.html", data); err != nil {
			log.Printf("Template execution error: %v", err)
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			return
		}
	}
}

// ProcessCSVHandler processes a CSV file with job numbers
func ProcessCSVHandler(w http.ResponseWriter, r *http.Request) {
	_, ok := r.Context().Value(middleware.SessionKey).(*api.Session)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	// Check if the request method is POST
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	// Parse the multipart form data with a 10MB limit
	if err := r.ParseMultipartForm(10 << 20); err != nil {
		http.Error(w, "Unable to parse form: "+err.Error(), http.StatusBadRequest)
		return
	}

	// Get the file from the form
	file, _, err := r.FormFile("csvFile")
	if err != nil {
		http.Error(w, "Error retrieving file: "+err.Error(), http.StatusBadRequest)
		return
	}
	defer file.Close()

	// Read the CSV data
	csvData, err := csv.NewReader(file).ReadAll()
	if err != nil {
		http.Error(w, "Error reading CSV file: "+err.Error(), http.StatusBadRequest)
		return
	}

	if len(csvData) < 2 {
		http.Error(w, "CSV file must contain at least a header row and one data row", http.StatusBadRequest)
		return
	}

	// Find the index of the 'id' column
	headerRow := csvData[0]
	idColumnIndex := -1
	for i, header := range headerRow {
		if strings.ToLower(strings.TrimSpace(header)) == "id" {
			idColumnIndex = i
			break
		}
	}

	// If 'id' column not found, try the first column
	if idColumnIndex == -1 {
		idColumnIndex = 0
		log.Printf("No 'id' column found in CSV, using first column (header: %s)", headerRow[0])
	} else {
		log.Printf("Found 'id' column at index %d", idColumnIndex)
	}

	// Extract job numbers from the CSV
	var jobNumbers []string
	for rowIndex, row := range csvData {
		// Skip header row
		if rowIndex == 0 {
			continue
		}

		if len(row) > idColumnIndex {
			// Extract and clean up the job ID
			jobID := strings.TrimSpace(row[idColumnIndex])
			if jobID != "" {
				jobNumbers = append(jobNumbers, jobID)
			}
		}
	}

	totalJobs := len(jobNumbers)
	log.Printf("Extracted %d job IDs from CSV", totalJobs)

	if totalJobs == 0 {
		http.Error(w, "No valid job IDs found in the CSV file", http.StatusBadRequest)
		return
	}

	// Create a hidden input with the job IDs
	jobsValue := strings.Join(jobNumbers, ",")

	// Generate HTML for the main response (hidden input for job-ids-container)
	var responseHTML bytes.Buffer
	responseHTML.WriteString(fmt.Sprintf(`<input type="hidden" name="jobNumbers" value="%s">`, jobsValue))
	responseHTML.WriteString(fmt.Sprintf(`<p>Found <strong>%d</strong> job(s) in the CSV file</p>`, totalJobs))

	// Generate out-of-band swap for the preview section - simplified version
	responseHTML.WriteString(fmt.Sprintf(`
		<div id="csv-preview" class="fade-me-out csv-preview-active" hx-swap-oob="true">
			<h4>✓ Jobs Detected</h4>
			<p>Upload to <strong>%d</strong> job(s)</p>
		</div>
	`, totalJobs))

	w.Header().Set("Content-Type", "text/html")
	w.Write(responseHTML.Bytes())
}

// UploadDocumentsHandler handles document uploads to jobs
func UploadDocumentsHandler(w http.ResponseWriter, r *http.Request) {
	startTime := time.Now()

	session, ok := r.Context().Value(middleware.SessionKey).(*api.Session)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	log.Printf("Starting document upload handler with Content-Length: %.2f MB",
		float64(r.ContentLength)/(1024*1024))

	maxMemory := int64(32 << 20) // 32MB in memory, rest to disk
	if err := r.ParseMultipartForm(maxMemory); err != nil {
		log.Printf("Error parsing multipart form: %v", err)
		http.Error(w, "Unable to parse form: "+err.Error(), http.StatusBadRequest)
		return
	}
	defer r.MultipartForm.RemoveAll() // Clean up temporary files

	jobNumbers := r.FormValue("jobNumbers")
	if jobNumbers == "" {
		log.Printf("No job numbers found in hidden 'jobNumbers' input.")
		http.Error(w, "No job numbers provided", http.StatusBadRequest)
		return
	}
	log.Printf("Job numbers: %s", jobNumbers)
	jobs := strings.Split(jobNumbers, ",")
	if len(jobs) == 0 {
		http.Error(w, "No valid job numbers provided", http.StatusBadRequest)
		return
	}

	// Read and parse file metadata from form values
	displayNamesJSON := r.FormValue("file_display_names")
	documentTypesJSON := r.FormValue("file_document_types")
	isActiveFlagsJSON := r.FormValue("file_is_active_flags")

	var displayNames []string
	var documentTypes []string
	var isActiveFlags []bool

	if err := json.Unmarshal([]byte(displayNamesJSON), &displayNames); err != nil {
		log.Printf("Error unmarshalling displayNames: %v. JSON: %s", err, displayNamesJSON)
		http.Error(w, "Error processing file information (display names). Please try again.", http.StatusBadRequest)
		return
	}
	if err := json.Unmarshal([]byte(documentTypesJSON), &documentTypes); err != nil {
		log.Printf("Error unmarshalling documentTypes: %v. JSON: %s", err, documentTypesJSON)
		http.Error(w, "Error processing file information (document types). Please try again.", http.StatusBadRequest)
		return
	}
	if err := json.Unmarshal([]byte(isActiveFlagsJSON), &isActiveFlags); err != nil {
		log.Printf("Error unmarshalling isActiveFlags: %v. JSON: %s", err, isActiveFlagsJSON)
		http.Error(w, "Error processing file information (active flags). Please try again.", http.StatusBadRequest)
		return
	}

	fileHeaders := r.MultipartForm.File["documentFiles"]
	if len(fileHeaders) == 0 {
		// This case might occur if all files were marked inactive on the client,
		// but client still submitted. Or if no files were selected initially.
		log.Println("No document files received in the request.")
		// Depending on desired behavior, could be an error or a silent success if no active files were intended.
		// For now, let user know no files were processed if this path is hit.
		w.Write([]byte("<p>No files were processed. If you selected files, please ensure some are active for upload.</p>"))
		return
	}

	// Validate that the lengths of metadata arrays match the number of files
	if len(fileHeaders) != len(displayNames) || len(fileHeaders) != len(documentTypes) || len(fileHeaders) != len(isActiveFlags) {
		log.Printf("Metadata array length mismatch. Files: %d, Names: %d, Types: %d, ActiveFlags: %d",
			len(fileHeaders), len(displayNames), len(documentTypes), len(isActiveFlags))
		http.Error(w, "Mismatch in file metadata. Please clear selection and try uploading files again.", http.StatusBadRequest)
		return
	}

	type FileToUploadMetadata struct {
		OriginalFilename string
		DisplayName      string
		Type             string
		Content          []byte // Store file content in memory
	}
	var filesToUpload []FileToUploadMetadata

	for i, fileHeader := range fileHeaders {
		if !isActiveFlags[i] {
			log.Printf("Skipping file %s (original index %d) as it's marked inactive.", fileHeader.Filename, i)
			continue // Skip inactive files
		}

		uploadedFile, err := fileHeader.Open()
		if err != nil {
			log.Printf("Error opening uploaded file %s (original index %d): %v. Skipping.", fileHeader.Filename, i, err)
			// No need to close uploadedFile here as it wasn't successfully opened.
			continue
		}

		displayName := displayNames[i]
		docType := documentTypes[i]

		if strings.TrimSpace(displayName) == "" {
			displayName = fileHeader.Filename // Fallback to original filename
			log.Printf("Warning: Empty display name for file %s (original index %d), using original filename.", fileHeader.Filename, i)
		}
		// Basic validation for docType could be added here if necessary, e.g., ensure it's not empty.
		if strings.TrimSpace(docType) == "" {
			docType = "1" // Fallback to a default type
			log.Printf("Warning: Empty document type for file %s (original index %d, display name %s), using default type '1'.", fileHeader.Filename, i, displayName)
		}

		// Read file content into memory
		fileBytes, err := io.ReadAll(uploadedFile)
		if err != nil {
			log.Printf("Error reading content of uploaded file %s (original index %d, display name %s): %v. Skipping.", fileHeader.Filename, i, displayName, err)
			uploadedFile.Close()
			continue
		}
		uploadedFile.Close() // Close the multipart file handle after reading its content

		metadata := FileToUploadMetadata{
			OriginalFilename: fileHeader.Filename,
			DisplayName:      displayName,
			Type:             docType,
			Content:          fileBytes,
		}

		filesToUpload = append(filesToUpload, metadata)
	}

	activeFilesProcessedCount := len(filesToUpload)
	if activeFilesProcessedCount == 0 {
		log.Println("No active files to upload after filtering.")
		// Send a user-friendly message back. The resultHTML later will also reflect this.
		w.Write([]byte("<p>No active files were selected for upload. Please ensure files are selected and not marked as removed.</p>"))
		return
	}
	log.Printf("Total active files prepared for upload: %d", activeFilesProcessedCount)

	const maxConcurrent = 5
	const requestDelay = 300 * time.Millisecond

	totalUploads := len(jobs) * activeFilesProcessedCount
	resultsChan := make(chan UploadResult, totalUploads)
	var wg sync.WaitGroup
	semaphore := make(chan struct{}, maxConcurrent)

	log.Printf("Starting up to %d concurrent upload workers for %d total uploads (%d jobs x %d active files)",
		maxConcurrent, totalUploads, len(jobs), activeFilesProcessedCount)

	for _, jobID := range jobs {
		for _, metadataToUpload := range filesToUpload {
			currentUploadMetadata := metadataToUpload
			wg.Add(1)
			go func(jobID string, meta FileToUploadMetadata) {
				defer wg.Done()
				semaphore <- struct{}{}
				defer func() {
					<-semaphore
					// No temp file to remove here as content is in memory
				}()
				time.Sleep(requestDelay)

				fileNameForUpload := meta.DisplayName
				fileReaderForUpload := io.NopCloser(bytes.NewReader(meta.Content))
				expectedSize := int64(len(meta.Content))

				// Error handling for fileReaderForUpload (e.g. if meta.Content is nil) is implicitly handled by API call failures later
				// but good to be mindful. For now, assume meta.Content is valid if it reached here.

				if len(jobs) > 10 {
					jitter := time.Duration(100+(time.Now().UnixNano()%400)) * time.Millisecond
					time.Sleep(jitter)
				}

				sizeTracker := &readCloserWithSize{reader: fileReaderForUpload, size: 0}
				log.Printf("Goroutine Info: Starting to stream in-memory data (original: %s, uploading as %s, type: %s, size: %.2f MB) to job %s",
					meta.OriginalFilename, fileNameForUpload, meta.Type, float64(expectedSize)/(1024*1024), jobID)

				// Define uploadStart here for per-goroutine timing
				uploadStartGoroutine := time.Now()
				uploadResultData, errUpload := session.UploadAttachmentFile(jobID, fileNameForUpload, meta.Type, sizeTracker)
				uploadDuration := time.Since(uploadStartGoroutine)

				fileSizeUploaded := sizeTracker.Size()
				sizeMatch := true
				if expectedSize > 0 && math.Abs(float64(expectedSize-fileSizeUploaded)) > float64(expectedSize)*0.05 {
					sizeMatch = false
					log.Printf("Goroutine WARNING: Size mismatch for in-memory data (original: %s, uploaded as %s) to job %s. Expected: %d, Uploaded: %d",
						meta.OriginalFilename, fileNameForUpload, jobID, expectedSize, fileSizeUploaded)
				}

				if errUpload != nil {
					log.Printf("Goroutine Error: Uploading in-memory data (original: %s, as %s) to job %s failed after %v: %v",
						meta.OriginalFilename, fileNameForUpload, jobID, uploadDuration, errUpload)
					resultsChan <- UploadResult{
						JobID:    jobID,
						DocName:  fileNameForUpload,
						Success:  false,
						Error:    errUpload.Error(),
						FileSize: fileSizeUploaded,
					}
				} else if !sizeMatch {
					log.Printf("Goroutine Error: Upload of in-memory data (original: %s, as %s) to job %s appears corrupted. API reported success but file sizes mismatch.",
						meta.OriginalFilename, fileNameForUpload, jobID)
					resultsChan <- UploadResult{
						JobID:    jobID,
						DocName:  fileNameForUpload,
						Success:  false,
						Error:    "Upload appears corrupted (file size mismatch)",
						FileSize: fileSizeUploaded,
					}
				} else {
					log.Printf("Goroutine Success: Uploaded in-memory data (original: %s, %.2f MB, as %s, type: %s) to job %s in %v",
						meta.OriginalFilename, float64(fileSizeUploaded)/(1024*1024), fileNameForUpload, meta.Type, jobID, uploadDuration)
					resultsChan <- UploadResult{
						JobID:    jobID,
						DocName:  fileNameForUpload,
						Success:  true,
						Data:     uploadResultData,
						FileSize: fileSizeUploaded,
					}
				}
			}(jobID, currentUploadMetadata)
		}
	}

	go func() {
		wg.Wait()
		close(resultsChan)
		log.Println("All upload goroutines finished.")
	}()

	// Collect all results
	var allResults []UploadResult
	var totalBytesUploaded int64

	for result := range resultsChan {
		log.Printf("Received result: Job %s, File %s, Success: %v, Size: %.2f MB",
			result.JobID, result.DocName, result.Success, float64(result.FileSize)/(1024*1024))
		if result.Success {
			totalBytesUploaded += result.FileSize
		}
		allResults = append(allResults, result)
	}

	// Calculate total duration
	totalDuration := time.Since(startTime)
	log.Printf("All results collected. Total: %d, Total bytes uploaded: %.2f MB, Total time: %v",
		len(allResults), float64(totalBytesUploaded)/(1024*1024), totalDuration)

	// Store results in session for pagination
	sessionID := fmt.Sprintf("upload_%d", time.Now().UnixNano())
	uploadSession := UploadSession{
		Results:            allResults,
		TotalJobs:          len(jobs),
		TotalSuccess:       0,
		TotalFailure:       0,
		TotalBytesUploaded: totalBytesUploaded,
		TotalTime:          totalDuration,
		CreatedAt:          time.Now(),
	}

	// Calculate totals
	for _, result := range allResults {
		if result.Success {
			uploadSession.TotalSuccess++
		} else {
			uploadSession.TotalFailure++
		}
	}

	// Store in global map (in production, use Redis or database)
	uploadSessions[sessionID] = uploadSession

	// Return first page of results
	renderUploadResultsPage(w, sessionID, 1, 20) // Default to page 1, 20 items per page
}

// UploadResultsHandler handles pagination for upload results
func UploadResultsHandler(w http.ResponseWriter, r *http.Request) {
	sessionID := r.URL.Query().Get("session_id")
	if sessionID == "" {
		http.Error(w, "Session ID required", http.StatusBadRequest)
		return
	}

	page, _ := strconv.Atoi(r.URL.Query().Get("page"))
	if page < 1 {
		page = 1
	}

	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
	if limit < 1 {
		limit = 20
	}

	renderUploadResultsPage(w, sessionID, page, limit)
}

// renderUploadResultsPage renders a paginated page of upload results
func renderUploadResultsPage(w http.ResponseWriter, sessionID string, page, limit int) {
	uploadSession, exists := uploadSessions[sessionID]
	if !exists {
		http.Error(w, "Upload session not found", http.StatusNotFound)
		return
	}

	totalResults := len(uploadSession.Results)
	totalPages := (totalResults + limit - 1) / limit // Ceiling division

	if page > totalPages && totalPages > 0 {
		page = totalPages
	}

	startIndex := (page - 1) * limit
	endIndex := startIndex + limit
	if endIndex > totalResults {
		endIndex = totalResults
	}

	// Get results for this page
	var pageResults []UploadResult
	if startIndex < totalResults {
		pageResults = uploadSession.Results[startIndex:endIndex]
	}

	// Calculate pagination info
	startPage := 1
	endPage := totalPages
	if totalPages > 10 {
		if page <= 5 {
			endPage = 10
		} else if page >= totalPages-4 {
			startPage = totalPages - 9
		} else {
			startPage = page - 4
			endPage = page + 5
		}
	}

	data := map[string]interface{}{
		"Results":            pageResults,
		"TotalJobs":          uploadSession.TotalJobs,
		"TotalSuccess":       uploadSession.TotalSuccess,
		"TotalFailure":       uploadSession.TotalFailure,
		"TotalBytesUploaded": uploadSession.TotalBytesUploaded,
		"TotalTime":          uploadSession.TotalTime,
		"TotalResults":       totalResults,
		"TotalPages":         totalPages,
		"CurrentPage":        page,
		"Limit":              limit,
		"StartIndex":         startIndex + 1,
		"EndIndex":           endIndex,
		"StartPage":          startPage,
		"EndPage":            endPage,
		"SessionID":          sessionID,
	}

	tmpl := root.WebTemplates
	if err := tmpl.ExecuteTemplate(w, "upload_results_pagination", data); err != nil {
		log.Printf("Template execution error: %v", err)
		// Don't call http.Error here as the response may have already started
		// Just log the error and return
		return
	}
}

// readCloserWithSize is a custom io.Reader that counts the bytes read
type readCloserWithSize struct {
	reader io.ReadCloser
	size   int64
}

func (r *readCloserWithSize) Read(p []byte) (n int, err error) {
	n, err = r.reader.Read(p)
	r.size += int64(n)
	return n, err
}

func (r *readCloserWithSize) Close() error {
	if r.reader != nil {
		return r.reader.Close()
	}
	return nil // Allow closing nil reader safely
}

// Size returns the current size of data read
func (r *readCloserWithSize) Size() int64 {
	return r.size
}

// DocumentFieldAddHandler and DocumentFieldRemoveHandler are REMOVED
// as they are no longer needed with the multi-file input and new chip UI.