package vtt

import (
	"bufio"
	"fmt"
	"os"
	"regexp"
	"strconv"
	"strings"
	"time"

	"sub-cli/internal/model"
)

// Constants for VTT format
const (
	VTTHeader = "WEBVTT"
)

// Parse parses a WebVTT file into our intermediate Subtitle representation
func Parse(filePath string) (model.Subtitle, error) {
	subtitle := model.NewSubtitle()
	subtitle.Format = "vtt"
	
	// Ensure maps are initialized
	if subtitle.Styles == nil {
		subtitle.Styles = make(map[string]string)
	}

	file, err := os.Open(filePath)
	if err != nil {
		return subtitle, fmt.Errorf("error opening VTT file: %w", err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	
	// First line must be WEBVTT
	if !scanner.Scan() {
		return subtitle, fmt.Errorf("empty VTT file")
	}
	
	header := scanner.Text()
	if !strings.HasPrefix(header, VTTHeader) {
		return subtitle, fmt.Errorf("invalid VTT file, missing WEBVTT header")
	}

	// Get metadata from header
	if strings.Contains(header, " - ") {
		subtitle.Title = strings.TrimSpace(strings.TrimPrefix(header, VTTHeader+" - "))
	}

	// Process file content
	var currentEntry model.SubtitleEntry
	var inCue bool
	var inStyle bool
	var styleBuffer strings.Builder
	var cueTextBuffer strings.Builder
	
	lineNum := 0
	prevLine := ""
	
	for scanner.Scan() {
		lineNum++
		line := scanner.Text()
		
		// Check for style blocks
		if strings.HasPrefix(line, "STYLE") {
			inStyle = true
			continue
		}
		
		if inStyle {
			if strings.TrimSpace(line) == "" {
				inStyle = false
				subtitle.Styles["css"] = styleBuffer.String()
				styleBuffer.Reset()
			} else {
				styleBuffer.WriteString(line)
				styleBuffer.WriteString("\n")
			}
			continue
		}
		
		// Skip empty lines, but handle end of cue
		if strings.TrimSpace(line) == "" {
			if inCue && cueTextBuffer.Len() > 0 {
				// End of a cue
				currentEntry.Text = strings.TrimSpace(cueTextBuffer.String())
				subtitle.Entries = append(subtitle.Entries, currentEntry)
				inCue = false
				cueTextBuffer.Reset()
				currentEntry = model.SubtitleEntry{} // Reset to zero value
			}
			continue
		}
		
		// Check for NOTE comments
		if strings.HasPrefix(line, "NOTE") {
			comment := strings.TrimSpace(strings.TrimPrefix(line, "NOTE"))
			subtitle.Comments = append(subtitle.Comments, comment)
			continue
		}
		
		// Check for REGION definitions
		if strings.HasPrefix(line, "REGION") {
			// Process region definitions if needed
			continue
		}
		
		// Check for cue timing line
		if strings.Contains(line, " --> ") {
			inCue = true
			
			// If we already have a populated currentEntry, save it
			if currentEntry.Text != "" {
				subtitle.Entries = append(subtitle.Entries, currentEntry)
				cueTextBuffer.Reset()
			}
			
			// Start a new entry
			currentEntry = model.NewSubtitleEntry()
			
			// Use the previous line as cue identifier if it's a number
			if prevLine != "" && !inCue {
				if index, err := strconv.Atoi(strings.TrimSpace(prevLine)); err == nil {
					currentEntry.Index = index
				}
			}
			
			// Parse timestamps
			timestamps := strings.Split(line, " --> ")
			if len(timestamps) != 2 {
				return subtitle, fmt.Errorf("invalid timestamp format at line %d: %s", lineNum, line)
			}
			
			startTimeStr := strings.TrimSpace(timestamps[0])
			endTimeAndSettings := strings.TrimSpace(timestamps[1])
			
			// Extract cue settings if any
			endTimeStr := endTimeAndSettings
			settings := ""
			
			if spaceIndex := strings.IndexByte(endTimeAndSettings, ' '); spaceIndex > 0 {
				endTimeStr = endTimeAndSettings[:spaceIndex]
				settings = endTimeAndSettings[spaceIndex+1:]
			}
			
			// Set timestamps
			currentEntry.StartTime = parseVTTTimestamp(startTimeStr)
			currentEntry.EndTime = parseVTTTimestamp(endTimeStr)
			
			// Initialize the styles map
			currentEntry.Styles = make(map[string]string)
			currentEntry.FormatData = make(map[string]interface{})
			
			// Parse cue settings
			if settings != "" {
				settingPairs := strings.Split(settings, " ")
				for _, pair := range settingPairs {
					if pair == "" {
						continue
					}
					
					if strings.Contains(pair, ":") {
						parts := strings.Split(pair, ":")
						if len(parts) == 2 {
							currentEntry.Styles[strings.TrimSpace(parts[0])] = strings.TrimSpace(parts[1])
						}
					} else {
						// Handle non-key-value settings if any
						currentEntry.FormatData["setting_"+pair] = true
					}
				}
			}
			
			cueTextBuffer.Reset()
			continue
		}
		
		// If we're in a cue, add the line to the text buffer
		if inCue {
			if cueTextBuffer.Len() > 0 {
				cueTextBuffer.WriteString("\n")
			}
			cueTextBuffer.WriteString(line)
		}
		
		prevLine = line
	}
	
	// Don't forget the last entry
	if inCue && cueTextBuffer.Len() > 0 {
		currentEntry.Text = strings.TrimSpace(cueTextBuffer.String())
		subtitle.Entries = append(subtitle.Entries, currentEntry)
	}
	
	// Ensure all entries have sequential indices if they don't already
	for i := range subtitle.Entries {
		if subtitle.Entries[i].Index == 0 {
			subtitle.Entries[i].Index = i + 1
		}
		
		// Ensure styles map is initialized for all entries
		if subtitle.Entries[i].Styles == nil {
			subtitle.Entries[i].Styles = make(map[string]string)
		}
		
		// Ensure formatData map is initialized for all entries
		if subtitle.Entries[i].FormatData == nil {
			subtitle.Entries[i].FormatData = make(map[string]interface{})
		}
	}
	
	if err := scanner.Err(); err != nil {
		return subtitle, fmt.Errorf("error reading VTT file: %w", err)
	}
	
	// Process cue text to extract styling
	processVTTCueTextStyling(&subtitle)

	return subtitle, nil
}

// parseVTTTimestamp parses a VTT timestamp string into our Timestamp model
func parseVTTTimestamp(timeStr string) model.Timestamp {
	// VTT timestamps format: 00:00:00.000
	re := regexp.MustCompile(`(\d+):(\d+):(\d+)\.(\d+)|\d+:(\d+)\.(\d+)`)
	matches := re.FindStringSubmatch(timeStr)
	
	var hours, minutes, seconds, milliseconds int
	
	if len(matches) >= 5 && matches[1] != "" {
		// Full format: 00:00:00.000
		hours, _ = strconv.Atoi(matches[1])
		minutes, _ = strconv.Atoi(matches[2])
		seconds, _ = strconv.Atoi(matches[3])
		
		msStr := matches[4]
		// Ensure milliseconds are treated correctly
		switch len(msStr) {
		case 1:
			milliseconds, _ = strconv.Atoi(msStr + "00")
		case 2:
			milliseconds, _ = strconv.Atoi(msStr + "0")
		case 3:
			milliseconds, _ = strconv.Atoi(msStr)
		default:
			if len(msStr) > 3 {
				milliseconds, _ = strconv.Atoi(msStr[:3])
			}
		}
	} else if len(matches) >= 7 && matches[5] != "" {
		// Short format: 00:00.000
		minutes, _ = strconv.Atoi(matches[5])
		seconds, _ = strconv.Atoi(matches[6])
		
		msStr := matches[7]
		// Ensure milliseconds are treated correctly
		switch len(msStr) {
		case 1:
			milliseconds, _ = strconv.Atoi(msStr + "00")
		case 2:
			milliseconds, _ = strconv.Atoi(msStr + "0")
		case 3:
			milliseconds, _ = strconv.Atoi(msStr)
		default:
			if len(msStr) > 3 {
				milliseconds, _ = strconv.Atoi(msStr[:3])
			}
		}
	} else {
		// Try another approach with time.Parse
		layout := "15:04:05.000"
		t, err := time.Parse(layout, timeStr)
		if err == nil {
			hours = t.Hour()
			minutes = t.Minute()
			seconds = t.Second()
			milliseconds = t.Nanosecond() / 1000000
		}
	}
	
	return model.Timestamp{
		Hours:        hours,
		Minutes:      minutes,
		Seconds:      seconds,
		Milliseconds: milliseconds,
	}
}

// processVTTCueTextStyling processes the cue text to extract styling tags
func processVTTCueTextStyling(subtitle *model.Subtitle) {
	for i, entry := range subtitle.Entries {
		// Look for basic HTML tags in the text and extract them to styling attributes
		text := entry.Text
		
		// Process <b>, <i>, <u>, etc. tags to collect styling information
		// For simplicity, we'll just note that styling exists, but we won't modify the text
		if strings.Contains(text, "<") && strings.Contains(text, ">") {
			entry.FormatData["has_html_tags"] = true
		}
		
		// Update the entry
		subtitle.Entries[i] = entry
	}
}

// Generate generates a WebVTT file from our intermediate Subtitle representation
func Generate(subtitle model.Subtitle, filePath string) error {
	file, err := os.Create(filePath)
	if err != nil {
		return fmt.Errorf("error creating VTT file: %w", err)
	}
	defer file.Close()

	// Write header
	if subtitle.Title != "" {
		fmt.Fprintf(file, "%s - %s\n\n", VTTHeader, subtitle.Title)
	} else {
		fmt.Fprintf(file, "%s\n\n", VTTHeader)
	}

	// Write styles if any
	if cssStyle, ok := subtitle.Styles["css"]; ok && cssStyle != "" {
		fmt.Fprintln(file, "STYLE")
		fmt.Fprintln(file, cssStyle)
		fmt.Fprintln(file)
	}

	// Write regions if any
	for _, region := range subtitle.Regions {
		fmt.Fprintf(file, "REGION %s:", region.ID)
		for key, value := range region.Settings {
			fmt.Fprintf(file, " %s=%s", key, value)
		}
		fmt.Fprintln(file)
	}

	// Write comments if any
	for _, comment := range subtitle.Comments {
		fmt.Fprintf(file, "NOTE %s\n", comment)
	}
	if len(subtitle.Comments) > 0 {
		fmt.Fprintln(file)
	}

	// Write cues
	for i, entry := range subtitle.Entries {
		// Write identifier if available
		if identifier, ok := entry.Metadata["identifier"]; ok && identifier != "" {
			fmt.Fprintln(file, identifier)
		} else if entry.Index > 0 {
			fmt.Fprintln(file, entry.Index)
		} else {
			fmt.Fprintln(file, i+1)
		}

		// Write timestamps and settings
		fmt.Fprintf(file, "%s --> %s", formatVTTTimestamp(entry.StartTime), formatVTTTimestamp(entry.EndTime))
		
		// Add cue settings
		for key, value := range entry.Styles {
			fmt.Fprintf(file, " %s:%s", key, value)
		}
		fmt.Fprintln(file)

		// Write cue text
		fmt.Fprintln(file, entry.Text)
		fmt.Fprintln(file)
	}

	return nil
}

// formatVTTTimestamp formats a Timestamp struct as a VTT timestamp string
func formatVTTTimestamp(ts model.Timestamp) string {
	return fmt.Sprintf("%02d:%02d:%02d.%03d", 
		ts.Hours, 
		ts.Minutes, 
		ts.Seconds, 
		ts.Milliseconds)
}

// Format standardizes and formats a VTT file
func Format(filePath string) error {
	// Parse the file
	subtitle, err := Parse(filePath)
	if err != nil {
		return fmt.Errorf("error parsing VTT file: %w", err)
	}

	// Standardize entry numbering
	for i := range subtitle.Entries {
		subtitle.Entries[i].Index = i + 1
	}

	// Write back the formatted content
	return Generate(subtitle, filePath)
}

// ConvertToSubtitle converts VTT entries to our intermediate Subtitle structure
func ConvertToSubtitle(filePath string) (model.Subtitle, error) {
	return Parse(filePath)
}

// ConvertFromSubtitle converts our intermediate Subtitle to VTT format
func ConvertFromSubtitle(subtitle model.Subtitle, filePath string) error {
	return Generate(subtitle, filePath)
}