package web

import (
	"bytes"
	"encoding/csv"
	"fmt"
	"io"
	"log"
	"math"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"time"

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

// 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) {
	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
	}

	// Simple multi-upload: use original filenames as display names and default type "1"
	fileHeaders := r.MultipartForm.File["documentFiles"]
	if len(fileHeaders) == 0 {
		http.Error(w, "No documents selected for upload", http.StatusBadRequest)
		return
	}
	type FileToUploadMetadata struct {
		OriginalFilename string
		DisplayName      string
		Type             string
		TempFile         string
		File             *os.File
	}
	var filesToUpload []FileToUploadMetadata
	for _, fileHeader := range fileHeaders {
		uploadedFile, err := fileHeader.Open()
		if err != nil {
			log.Printf("Error opening uploaded file %s: %v. Skipping.", fileHeader.Filename, err)
			continue
		}
		metadata := FileToUploadMetadata{
			OriginalFilename: fileHeader.Filename,
			DisplayName:      fileHeader.Filename,
			Type:             "1",
		}
		tempFileHandle, err := os.CreateTemp("", "upload-*"+filepath.Ext(fileHeader.Filename))
		if err != nil {
			log.Printf("Error creating temp file for %s: %v. Skipping.", fileHeader.Filename, err)
			uploadedFile.Close()
			continue
		}
		if _, err := io.Copy(tempFileHandle, uploadedFile); err != nil {
			log.Printf("Error copying to temp file for %s: %v. Skipping.", fileHeader.Filename, err)
			uploadedFile.Close()
			tempFileHandle.Close()
			os.Remove(tempFileHandle.Name())
			continue
		}
		uploadedFile.Close()
		if _, err := tempFileHandle.Seek(0, 0); err != nil {
			log.Printf("Error seeking temp file for %s: %v. Skipping.", fileHeader.Filename, err)
			tempFileHandle.Close()
			os.Remove(tempFileHandle.Name())
			continue
		}
		metadata.TempFile = tempFileHandle.Name()
		metadata.File = tempFileHandle
		filesToUpload = append(filesToUpload, metadata)
	}
	activeFilesProcessedCount := len(filesToUpload)
	if activeFilesProcessedCount == 0 {
		log.Println("No files processed for upload.")
		http.Error(w, "No documents were processed for upload.", http.StatusBadRequest)
		return
	}
	log.Printf("Total active files prepared for upload: %d", activeFilesProcessedCount)

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

	type UploadResult struct {
		JobID    string
		DocName  string
		Success  bool
		Error    string
		Data     map[string]interface{}
		FileSize int64
	}

	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 }()
				time.Sleep(requestDelay)

				fileNameForUpload := meta.DisplayName
				fileHandleForUpload, err := os.Open(meta.TempFile)
				if err != nil {
					log.Printf("Goroutine Error: Failed to re-open temp file %s for job %s (uploading as %s): %v",
						meta.TempFile, jobID, fileNameForUpload, err)
					resultsChan <- UploadResult{
						JobID:    jobID,
						DocName:  fileNameForUpload,
						Success:  false,
						Error:    fmt.Sprintf("Error preparing file for upload: %v", err),
						FileSize: 0,
					}
					return
				}
				defer fileHandleForUpload.Close()

				fileInfo, statErr := fileHandleForUpload.Stat()
				var expectedSize int64
				if statErr == nil {
					expectedSize = fileInfo.Size()
				} else {
					log.Printf("Goroutine Warning: Failed to get file info for %s (original: %s, job %s, uploading as %s): %v",
						meta.TempFile, meta.OriginalFilename, jobID, fileNameForUpload, statErr)
				}

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

				sizeTracker := &readCloserWithSize{reader: fileHandleForUpload, size: 0}
				log.Printf("Goroutine Info: Starting to stream file %s (original: %s, uploading as %s, type: %s) to job %s from temp file %s",
					meta.TempFile, meta.OriginalFilename, fileNameForUpload, meta.Type, jobID, meta.TempFile)

				// 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 %s (original: %s, uploaded as %s) to job %s. Expected: %d, Uploaded: %d",
						meta.TempFile, meta.OriginalFilename, fileNameForUpload, jobID, expectedSize, fileSizeUploaded)
				}

				if errUpload != nil {
					log.Printf("Goroutine Error: Uploading %s (original: %s, as %s) to job %s failed after %v: %v",
						meta.TempFile, 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 %s (original: %s, as %s) to job %s appears corrupted. API reported success but file sizes mismatch.",
						meta.TempFile, 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 %s (original: %s, %.2f MB, as %s, type: %s) to job %s in %v",
						meta.TempFile, 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.")
	}()

	results := make(map[string][]UploadResult)
	resultsCount := 0
	var totalBytesUploaded int64

	for result := range resultsChan {
		resultsCount++
		log.Printf("Received result %d/%d: Job %s, File %s, Success: %v, Size: %.2f MB",
			resultsCount, totalUploads, result.JobID, result.DocName, result.Success,
			float64(result.FileSize)/(1024*1024))
		if result.Success {
			totalBytesUploaded += result.FileSize
		}
		if _, exists := results[result.JobID]; !exists {
			results[result.JobID] = []UploadResult{}
		}
		results[result.JobID] = append(results[result.JobID], result)
	}

	log.Printf("All results collected. Total: %d, Total bytes uploaded: %.2f MB",
		resultsCount, float64(totalBytesUploaded)/(1024*1024))

	var resultHTML bytes.Buffer
	var totalSuccess, totalFailure int
	for _, jobResults := range results {
		for _, result := range jobResults {
			if result.Success {
				totalSuccess++
			} else {
				totalFailure++
			}
		}
	}

	resultHTML.WriteString("<div class=\"upload-summary\">")
	resultHTML.WriteString("<h3>Upload Results</h3>")
	resultHTML.WriteString("<div class=\"upload-stats\">")
	resultHTML.WriteString(fmt.Sprintf("<div class=\"stat-box\"><div class=\"stat-value\">%d</div><div class=\"stat-label\">Total Jobs</div></div>", len(results)))
	resultHTML.WriteString(fmt.Sprintf("<div class=\"stat-box success-stat\"><div class=\"stat-value\">%d</div><div class=\"stat-label\">Successful Uploads</div></div>", totalSuccess))
	resultHTML.WriteString(fmt.Sprintf("<div class=\"stat-box error-stat\"><div class=\"stat-value\">%d</div><div class=\"stat-label\">Failed Uploads</div></div>", totalFailure))
	resultHTML.WriteString(fmt.Sprintf("<div class=\"stat-box\"><div class=\"stat-value\">%d</div><div class=\"stat-label\">Files Processed</div></div>", resultsCount))
	resultHTML.WriteString("</div>")

	if totalFailure == 0 && resultsCount > 0 {
		resultHTML.WriteString("<p>All documents were successfully uploaded to ServiceTrade!</p>")
	} else if resultsCount == 0 {
		resultHTML.WriteString("<p>No documents were processed for upload.</p>")
	} else {
		resultHTML.WriteString("<p>Some documents failed to upload. See details below.</p>")
	}
	resultHTML.WriteString("</div>")

	resultHTML.WriteString("<div class=\"job-results\">")
	sortedJobs := make([]string, 0, len(results))
	for jobID := range results {
		sortedJobs = append(sortedJobs, jobID)
	}
	sort.Strings(sortedJobs)

	for _, jobID := range sortedJobs {
		jobResults := results[jobID]
		jobHasSuccess := false
		jobHasFailure := false
		for _, result := range jobResults {
			if result.Success {
				jobHasSuccess = true
			} else {
				jobHasFailure = true
			}
		}
		jobClass := "neutral"
		if jobHasSuccess && !jobHasFailure {
			jobClass = "success"
		} else if jobHasFailure {
			jobClass = "error"
		}
		resultHTML.WriteString(fmt.Sprintf("<div class=\"job-result %s\">", jobClass))
		resultHTML.WriteString(fmt.Sprintf("<div class=\"job-id\">Job ID: %s</div>", jobID))
		if len(jobResults) > 0 {
			resultHTML.WriteString("<div class=\"file-results\">")
			sort.Slice(jobResults, func(i, j int) bool {
				return jobResults[i].DocName < jobResults[j].DocName
			})
			for _, result := range jobResults {
				fileClass := "success"
				icon := "✓"
				message := "Successfully uploaded"
				if !result.Success {
					fileClass = "error"
					icon = "✗"
					message = strings.ReplaceAll(result.Error, "<", "&lt;")
					message = strings.ReplaceAll(message, ">", "&gt;")
				}
				resultHTML.WriteString(fmt.Sprintf("<div class=\"file-result %s\">", fileClass))
				resultHTML.WriteString(fmt.Sprintf("<span class=\"status-icon\">%s</span>", icon))
				resultHTML.WriteString(fmt.Sprintf("<span class=\"file-name\">%s:</span>", result.DocName))
				resultHTML.WriteString(fmt.Sprintf("<span class=\"file-message\">%s</span>", message))
				resultHTML.WriteString("</div>")
			}
			resultHTML.WriteString("</div>")
		} else {
			resultHTML.WriteString("<p>No file upload results for this job.</p>")
		}
		resultHTML.WriteString("</div>")
	}
	resultHTML.WriteString("</div>")
	w.Header().Set("Content-Type", "text/html")
	w.Write(resultHTML.Bytes())
}

// 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.