soma-core 2.0.0

// src/cli/advanced_preview.rs
// Issue #18: AdvancedPreviewSystem - Split-pane Live Editor with Real-time Preview

use crate::edit_control::{EditModificationInterface, EditModification};
use crate::cli::preview::{EditPreviewBuilder, PreviewResult};
use crossterm::{
    cursor,
    event::{self, Event, KeyCode, KeyEvent, KeyModifiers},
    execute,
    style::{Color, ResetColor, SetForegroundColor},
    terminal::{self, ClearType, size},
};
use std::io::{self, stdout, Write};
use std::time::{Duration, Instant};

/// AdvancedPreviewSystem for Issue #18
/// Provides split-pane live editor with real-time preview capabilities
pub struct AdvancedPreviewSystem {
    interface: EditModificationInterface,
    editor_pane: EditorPane,
    preview_pane: PreviewPane,
    layout: SplitLayout,
    active_pane: ActivePane,
    auto_preview: bool,
    preview_delay: Duration,
    last_edit: Instant,
}

#[derive(Debug, Clone)]
pub struct EditorPane {
    content: Vec<String>,
    cursor_row: usize,
    cursor_col: usize,
    scroll_offset: usize,
    syntax_highlighting: bool,
    show_line_numbers: bool,
    width: u16,
    height: u16,
}

impl EditorPane {
    pub fn content(&self) -> &Vec<String> {
        &self.content
    }

    pub fn syntax_highlighting(&self) -> bool {
        self.syntax_highlighting
    }

    pub fn show_line_numbers(&self) -> bool {
        self.show_line_numbers
    }

    pub fn width(&self) -> u16 {
        self.width
    }

    pub fn height(&self) -> u16 {
        self.height
    }
}

#[derive(Debug)]
pub struct PreviewPane {
    preview_result: Option<PreviewResult>,
    scroll_offset: usize,
    auto_refresh: bool,
    width: u16,
    height: u16,
    last_update: Instant,
}

impl PreviewPane {
    pub fn auto_refresh(&self) -> bool {
        self.auto_refresh
    }

    pub fn width(&self) -> u16 {
        self.width
    }

    pub fn height(&self) -> u16 {
        self.height
    }
}

#[derive(Debug, Clone, PartialEq)]
pub enum SplitLayout {
    Horizontal,    // Left-Right split
    Vertical,      // Top-Bottom split
    EditorOnly,    // Editor takes full screen
    PreviewOnly,   // Preview takes full screen
}

#[derive(Debug, Clone, PartialEq)]
pub enum ActivePane {
    Editor,
    Preview,
}

impl AdvancedPreviewSystem {
    /// Create new AdvancedPreviewSystem from EditModificationInterface
    pub fn new(interface: EditModificationInterface) -> Self {
        let (terminal_width, terminal_height) = size().unwrap_or((80, 24));
        
        let editor_content: Vec<String> = interface
            .modifiable_edit
            .compute_final_code()
            .lines()
            .map(|s| s.to_string())
            .collect();

        let editor_pane = EditorPane {
            content: editor_content,
            cursor_row: 0,
            cursor_col: 0,
            scroll_offset: 0,
            syntax_highlighting: true,
            show_line_numbers: true,
            width: terminal_width / 2,
            height: terminal_height.saturating_sub(6), // Account for header/footer
        };

        let preview_pane = PreviewPane {
            preview_result: None,
            scroll_offset: 0,
            auto_refresh: true,
            width: terminal_width / 2,
            height: terminal_height.saturating_sub(6),
            last_update: Instant::now(),
        };

        Self {
            interface,
            editor_pane,
            preview_pane,
            layout: SplitLayout::Horizontal,
            active_pane: ActivePane::Editor,
            auto_preview: true,
            preview_delay: Duration::from_millis(500), // 0.5s delay for auto-refresh
            last_edit: Instant::now(),
        }
    }

    /// Getter methods for demo access
    pub fn layout(&self) -> &SplitLayout {
        &self.layout
    }

    pub fn active_pane(&self) -> &ActivePane {
        &self.active_pane
    }

    pub fn auto_preview(&self) -> bool {
        self.auto_preview
    }

    pub fn preview_delay(&self) -> Duration {
        self.preview_delay
    }

    pub fn editor_pane(&self) -> &EditorPane {
        &self.editor_pane
    }

    pub fn preview_pane(&self) -> &PreviewPane {
        &self.preview_pane
    }

    pub fn interface(&self) -> &EditModificationInterface {
        &self.interface
    }

    pub fn interface_mut(&mut self) -> &mut EditModificationInterface {
        &mut self.interface
    }

    /// Main interactive editing loop with live preview
    pub fn edit_with_live_preview(&mut self) -> io::Result<Option<EditModificationInterface>> {
        terminal::enable_raw_mode()?;

        // Initial preview generation
        self.update_preview();

        let result = loop {
            self.render()?;

            // Auto-refresh preview if needed
            if self.auto_preview && self.should_refresh_preview() {
                self.update_preview();
            }

            if let Event::Key(key_event) = event::read()? {
                match self.handle_key(key_event)? {
                    PreviewAction::Exit => {
                        break Ok(None);
                    }
                    PreviewAction::Save => {
                        break Ok(Some(self.interface.clone()));
                    }
                    PreviewAction::Continue => {}
                }
            }
        };

        terminal::disable_raw_mode()?;
        result
    }

    /// Render the split-pane interface
    fn render(&self) -> io::Result<()> {
        execute!(
            stdout(),
            terminal::Clear(ClearType::All),
            cursor::MoveTo(0, 0)
        )?;

        // Header
        self.render_header()?;

        match self.layout {
            SplitLayout::Horizontal => self.render_horizontal_split()?,
            SplitLayout::Vertical => self.render_vertical_split()?,
            SplitLayout::EditorOnly => self.render_editor_only()?,
            SplitLayout::PreviewOnly => self.render_preview_only()?,
        }

        // Footer
        self.render_footer()?;

        // Position cursor
        self.position_cursor()?;

        stdout().flush()
    }

    fn render_header(&self) -> io::Result<()> {
        execute!(stdout(), SetForegroundColor(Color::Cyan))?;
        println!("🔄 SOMA AdvancedPreviewSystem v1.0 - Issue #18 - Split-Pane Live Editor");
        execute!(stdout(), ResetColor)?;
        
        println!(
            "📁 {} | Layout: {:?} | Active: {:?} | Auto-preview: {} | Changes: {}",
            self.interface.modifiable_edit.base_edit.file,
            self.layout,
            self.active_pane,
            if self.auto_preview { "ON" } else { "OFF" },
            self.interface.modification_count()
        );

        println!(); // Separator
        Ok(())
    }

    fn render_horizontal_split(&self) -> io::Result<()> {
        let (terminal_width, _) = size().unwrap_or((80, 24));
        let split_pos = terminal_width / 2;

        // Split header
        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
        print!("┌");
        for _ in 0..split_pos.saturating_sub(2) {
            print!("─");
        }
        print!("┬");
        for _ in split_pos..terminal_width.saturating_sub(1) {
            print!("─");
        }
        println!("┐");

        print!("│");
        execute!(stdout(), SetForegroundColor(Color::Green))?;
        let editor_title = if self.active_pane == ActivePane::Editor { "► Editor" } else { "  Editor" };
        print!("{:^width$}", editor_title, width = split_pos.saturating_sub(2) as usize);
        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
        print!("│");
        execute!(stdout(), SetForegroundColor(Color::Blue))?;
        let preview_title = if self.active_pane == ActivePane::Preview { "► Live Preview" } else { "  Live Preview" };
        print!("{:^width$}", preview_title, width = (terminal_width - split_pos - 1) as usize);
        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
        println!("│");

        print!("├");
        for _ in 0..split_pos.saturating_sub(2) {
            print!("─");
        }
        print!("┼");
        for _ in split_pos..terminal_width.saturating_sub(1) {
            print!("─");
        }
        println!("┤");
        execute!(stdout(), ResetColor)?;

        // Content area
        let content_height = self.editor_pane.height.min(self.preview_pane.height) as usize;
        for row in 0..content_height {
            // Editor side
            print!("│");
            self.render_editor_line(row, split_pos.saturating_sub(2) as usize)?;
            print!("│");
            
            // Preview side
            self.render_preview_line(row, (terminal_width - split_pos - 1) as usize)?;
            println!("│");
        }

        // Bottom border
        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
        print!("└");
        for _ in 0..split_pos.saturating_sub(2) {
            print!("─");
        }
        print!("┴");
        for _ in split_pos..terminal_width.saturating_sub(1) {
            print!("─");
        }
        println!("┘");
        execute!(stdout(), ResetColor)?;

        Ok(())
    }

    fn render_vertical_split(&self) -> io::Result<()> {
        let (terminal_width, terminal_height) = size().unwrap_or((80, 24));
        let split_pos = terminal_height / 2;

        // Editor section (top)
        execute!(stdout(), SetForegroundColor(Color::Green))?;
        let editor_title = if self.active_pane == ActivePane::Editor { "► Editor" } else { "  Editor" };
        println!("┌─ {} {}", editor_title, "─".repeat(terminal_width.saturating_sub(12) as usize));
        execute!(stdout(), ResetColor)?;

        for row in 0..split_pos.saturating_sub(4) as usize {
            self.render_editor_line(row, terminal_width as usize)?;
            println!();
        }

        // Separator
        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
        println!("{}", "─".repeat(terminal_width as usize));
        execute!(stdout(), ResetColor)?;

        // Preview section (bottom)
        execute!(stdout(), SetForegroundColor(Color::Blue))?;
        let preview_title = if self.active_pane == ActivePane::Preview { "► Live Preview" } else { "  Live Preview" };
        println!("└─ {} {}", preview_title, "─".repeat(terminal_width.saturating_sub(17) as usize));
        execute!(stdout(), ResetColor)?;

        for row in 0..(terminal_height - split_pos - 2) as usize {
            self.render_preview_line(row, terminal_width as usize)?;
            println!();
        }

        Ok(())
    }

    fn render_editor_only(&self) -> io::Result<()> {
        let (terminal_width, terminal_height) = size().unwrap_or((80, 24));
        
        execute!(stdout(), SetForegroundColor(Color::Green))?;
        println!("┌─ ► Full Editor Mode {}", "─".repeat(terminal_width.saturating_sub(21) as usize));
        execute!(stdout(), ResetColor)?;

        for row in 0..terminal_height.saturating_sub(6) as usize {
            self.render_editor_line(row, terminal_width as usize)?;
            println!();
        }

        Ok(())
    }

    fn render_preview_only(&self) -> io::Result<()> {
        let (terminal_width, terminal_height) = size().unwrap_or((80, 24));
        
        execute!(stdout(), SetForegroundColor(Color::Blue))?;
        println!("┌─ ► Full Preview Mode {}", "─".repeat(terminal_width.saturating_sub(22) as usize));
        execute!(stdout(), ResetColor)?;

        for row in 0..terminal_height.saturating_sub(6) as usize {
            self.render_preview_line(row, terminal_width as usize)?;
            println!();
        }

        Ok(())
    }

    fn render_editor_line(&self, row: usize, width: usize) -> io::Result<()> {
        let content_row = row + self.editor_pane.scroll_offset;
        
        if content_row < self.editor_pane.content.len() {
            let line = &self.editor_pane.content[content_row];
            let cursor_marker = if content_row == self.editor_pane.cursor_row { ">" } else { " " };
            
            let display_text = if self.editor_pane.show_line_numbers {
                format!("{:3}:{} {}", content_row + 1, cursor_marker, line)
            } else {
                format!("{} {}", cursor_marker, line)
            };

            if self.editor_pane.syntax_highlighting && self.active_pane == ActivePane::Editor {
                self.render_syntax_highlighted(&display_text, width)?;
            } else {
                print!("{:width$}", display_text.chars().take(width).collect::<String>(), width = width);
            }
        } else {
            print!("{:width$}", "~", width = width);
        }

        Ok(())
    }

    fn render_preview_line(&self, row: usize, width: usize) -> io::Result<()> {
        if let Some(ref preview) = self.preview_pane.preview_result {
            let preview_text = self.get_preview_line(preview, row);
            print!("{:width$}", preview_text.chars().take(width).collect::<String>(), width = width);
        } else {
            execute!(stdout(), SetForegroundColor(Color::DarkGrey))?;
            print!("{:width$}", "Preview updating...", width = width);
            execute!(stdout(), ResetColor)?;
        }

        Ok(())
    }

    fn get_preview_line(&self, preview: &PreviewResult, row: usize) -> String {
        let content_row = row + self.preview_pane.scroll_offset;
        let mut line_index = 0;

        for section in &preview.sections {
            let section_lines: Vec<&str> = section.content.lines().collect();
            
            if content_row == line_index {
                return format!("╔═ {} ═╗", section.title);
            }
            line_index += 1;

            for (i, line) in section_lines.iter().enumerate() {
                if content_row == line_index {
                    return if i == section_lines.len() - 1 {
                        format!("╚ {} ╝", line)
                    } else {
                        format!("║ {} ║", line)
                    };
                }
                line_index += 1;
            }

            if content_row == line_index {
                return "║".to_string();
            }
            line_index += 1;
        }

        "".to_string()
    }

    fn render_syntax_highlighted(&self, text: &str, width: usize) -> io::Result<()> {
        // Simple syntax highlighting for Rust-like code
        let mut in_string = false;
        let mut in_comment = false;
        
        for (i, ch) in text.chars().enumerate() {
            if i >= width { break; }
            
            if in_comment {
                execute!(stdout(), SetForegroundColor(Color::DarkGreen))?;
                print!("{}", ch);
            } else if in_string {
                execute!(stdout(), SetForegroundColor(Color::Yellow))?;
                print!("{}", ch);
                if ch == '"' {
                    in_string = false;
                    execute!(stdout(), ResetColor)?;
                }
            } else {
                match ch {
                    '/' if text.chars().nth(i + 1) == Some('/') => {
                        in_comment = true;
                        execute!(stdout(), SetForegroundColor(Color::DarkGreen))?;
                        print!("{}", ch);
                    }
                    '"' => {
                        in_string = true;
                        execute!(stdout(), SetForegroundColor(Color::Yellow))?;
                        print!("{}", ch);
                    }
                    _ => {
                        if text[..i].ends_with("fn ") || text[..i].ends_with("let ") || text[..i].ends_with("pub ") {
                            execute!(stdout(), SetForegroundColor(Color::Blue))?;
                        } else {
                            execute!(stdout(), ResetColor)?;
                        }
                        print!("{}", ch);
                    }
                }
            }
        }
        
        // Pad remaining width
        for _ in text.chars().count()..width {
            print!(" ");
        }
        
        execute!(stdout(), ResetColor)?;
        Ok(())
    }

    fn render_footer(&self) -> io::Result<()> {
        execute!(stdout(), SetForegroundColor(Color::Cyan))?;
        println!("─────────────────────────────────────────────────────────────────────────");
        execute!(stdout(), ResetColor)?;
        
        println!(
            "Cursor: {}:{} | Undo: {} | Redo: {} | Last Update: {:.1}s ago | Tab: Switch Pane",
            self.editor_pane.cursor_row + 1,
            self.editor_pane.cursor_col + 1,
            if self.interface.can_undo() { "✓" } else { "✗" },
            if self.interface.can_redo() { "✓" } else { "✗" },
            self.preview_pane.last_update.elapsed().as_secs_f32()
        );

        println!("Ctrl+S: Save | Ctrl+Q: Quit | Ctrl+L: Layout | Ctrl+A: Auto-preview | Ctrl+R: Refresh");

        Ok(())
    }

    fn position_cursor(&self) -> io::Result<()> {
        if self.active_pane == ActivePane::Editor {
            let header_offset = 6; // Account for header and split decorations
            let display_row = header_offset + self.editor_pane.cursor_row - self.editor_pane.scroll_offset;
            let display_col = match self.layout {
                SplitLayout::Horizontal => {
                    let line_num_offset = if self.editor_pane.show_line_numbers { 6 } else { 2 };
                    1 + line_num_offset + self.editor_pane.cursor_col
                }
                _ => {
                    let line_num_offset = if self.editor_pane.show_line_numbers { 6 } else { 2 };
                    line_num_offset + self.editor_pane.cursor_col
                }
            };
            
            execute!(
                stdout(),
                cursor::MoveTo(display_col as u16, display_row as u16)
            )?;
        }
        
        Ok(())
    }

    /// Enhanced key handling for split-pane interface
    fn handle_key(&mut self, key: KeyEvent) -> io::Result<PreviewAction> {
        match (key.code, key.modifiers) {
            // Core actions
            (KeyCode::Char('q'), KeyModifiers::CONTROL) => Ok(PreviewAction::Exit),
            (KeyCode::Char('s'), KeyModifiers::CONTROL) => {
                self.save_editor_changes();
                Ok(PreviewAction::Save)
            },
            
            // Layout controls
            (KeyCode::Char('l'), KeyModifiers::CONTROL) => {
                self.cycle_layout();
                Ok(PreviewAction::Continue)
            },
            (KeyCode::Tab, _) => {
                self.switch_active_pane();
                Ok(PreviewAction::Continue)
            },
            
            // Preview controls
            (KeyCode::Char('a'), KeyModifiers::CONTROL) => {
                self.auto_preview = !self.auto_preview;
                Ok(PreviewAction::Continue)
            },
            (KeyCode::Char('r'), KeyModifiers::CONTROL) => {
                self.update_preview();
                Ok(PreviewAction::Continue)
            },
            
            // Undo/Redo
            (KeyCode::Char('z'), KeyModifiers::CONTROL) => {
                if self.interface.undo() {
                    self.update_editor_from_interface();
                    if self.auto_preview {
                        self.update_preview();
                    }
                }
                Ok(PreviewAction::Continue)
            },
            (KeyCode::Char('y'), KeyModifiers::CONTROL) => {
                if self.interface.redo() {
                    self.update_editor_from_interface();
                    if self.auto_preview {
                        self.update_preview();
                    }
                }
                Ok(PreviewAction::Continue)
            },
            
            // Editor navigation (when editor is active)
            _ if self.active_pane == ActivePane::Editor => {
                self.handle_editor_key(key)
            },
            
            // Preview navigation (when preview is active)
            _ if self.active_pane == ActivePane::Preview => {
                self.handle_preview_key(key)
            },
            
            _ => Ok(PreviewAction::Continue),
        }
    }

    fn handle_editor_key(&mut self, key: KeyEvent) -> io::Result<PreviewAction> {
        match key.code {
            KeyCode::Up => {
                if self.editor_pane.cursor_row > 0 {
                    self.editor_pane.cursor_row -= 1;
                    self.adjust_editor_scroll();
                    self.adjust_cursor_bounds();
                }
            }
            KeyCode::Down => {
                if self.editor_pane.cursor_row < self.editor_pane.content.len().saturating_sub(1) {
                    self.editor_pane.cursor_row += 1;
                    self.adjust_editor_scroll();
                    self.adjust_cursor_bounds();
                }
            }
            KeyCode::Left => {
                if self.editor_pane.cursor_col > 0 {
                    self.editor_pane.cursor_col -= 1;
                } else if self.editor_pane.cursor_row > 0 {
                    self.editor_pane.cursor_row -= 1;
                    self.editor_pane.cursor_col = self.editor_pane.content
                        .get(self.editor_pane.cursor_row)
                        .map(|s| s.len())
                        .unwrap_or(0);
                    self.adjust_editor_scroll();
                }
            }
            KeyCode::Right => {
                let line_len = self.editor_pane.content
                    .get(self.editor_pane.cursor_row)
                    .map(|s| s.len())
                    .unwrap_or(0);
                
                if self.editor_pane.cursor_col < line_len {
                    self.editor_pane.cursor_col += 1;
                } else if self.editor_pane.cursor_row < self.editor_pane.content.len().saturating_sub(1) {
                    self.editor_pane.cursor_row += 1;
                    self.editor_pane.cursor_col = 0;
                    self.adjust_editor_scroll();
                }
            }
            KeyCode::Home => {
                self.editor_pane.cursor_col = 0;
            }
            KeyCode::End => {
                self.editor_pane.cursor_col = self.editor_pane.content
                    .get(self.editor_pane.cursor_row)
                    .map(|s| s.len())
                    .unwrap_or(0);
            }
            KeyCode::Enter => {
                self.insert_newline();
                self.mark_editor_changed();
            }
            KeyCode::Char(c) => {
                self.insert_char(c);
                self.mark_editor_changed();
            }
            KeyCode::Backspace => {
                self.delete_char();
                self.mark_editor_changed();
            }
            KeyCode::Delete => {
                self.delete_char_forward();
                self.mark_editor_changed();
            }
            _ => {}
        }

        Ok(PreviewAction::Continue)
    }

    fn handle_preview_key(&mut self, key: KeyEvent) -> io::Result<PreviewAction> {
        match key.code {
            KeyCode::Up => {
                if self.preview_pane.scroll_offset > 0 {
                    self.preview_pane.scroll_offset -= 1;
                }
            }
            KeyCode::Down => {
                self.preview_pane.scroll_offset += 1;
            }
            KeyCode::PageUp => {
                self.preview_pane.scroll_offset = self.preview_pane.scroll_offset.saturating_sub(10);
            }
            KeyCode::PageDown => {
                self.preview_pane.scroll_offset += 10;
            }
            KeyCode::Home => {
                self.preview_pane.scroll_offset = 0;
            }
            _ => {}
        }

        Ok(PreviewAction::Continue)
    }

    fn cycle_layout(&mut self) {
        self.layout = match self.layout {
            SplitLayout::Horizontal => SplitLayout::Vertical,
            SplitLayout::Vertical => SplitLayout::EditorOnly,
            SplitLayout::EditorOnly => SplitLayout::PreviewOnly,
            SplitLayout::PreviewOnly => SplitLayout::Horizontal,
        };
        self.update_pane_dimensions();
    }

    fn switch_active_pane(&mut self) {
        self.active_pane = match self.active_pane {
            ActivePane::Editor => ActivePane::Preview,
            ActivePane::Preview => ActivePane::Editor,
        };
    }

    fn update_pane_dimensions(&mut self) {
        let (terminal_width, terminal_height) = size().unwrap_or((80, 24));
        let content_height = terminal_height.saturating_sub(6);

        match self.layout {
            SplitLayout::Horizontal => {
                self.editor_pane.width = terminal_width / 2;
                self.editor_pane.height = content_height;
                self.preview_pane.width = terminal_width / 2;
                self.preview_pane.height = content_height;
            }
            SplitLayout::Vertical => {
                self.editor_pane.width = terminal_width;
                self.editor_pane.height = content_height / 2;
                self.preview_pane.width = terminal_width;
                self.preview_pane.height = content_height / 2;
            }
            SplitLayout::EditorOnly => {
                self.editor_pane.width = terminal_width;
                self.editor_pane.height = content_height;
            }
            SplitLayout::PreviewOnly => {
                self.preview_pane.width = terminal_width;
                self.preview_pane.height = content_height;
            }
        }
    }

    fn should_refresh_preview(&self) -> bool {
        self.last_edit.elapsed() >= self.preview_delay
    }

    pub fn update_preview(&mut self) {
        let preview_builder = EditPreviewBuilder::new()
            .with_diff(true)
            .with_risk_assessment(true)
            .with_syntax_highlighting(true);
        
        let preview = preview_builder.build();
        self.preview_pane.preview_result = Some(preview.generate_preview(&self.interface.modifiable_edit));
        self.preview_pane.last_update = Instant::now();
    }

    fn mark_editor_changed(&mut self) {
        self.last_edit = Instant::now();
    }

    fn save_editor_changes(&mut self) {
        let new_content = self.editor_pane.content.join("\n");
        let old_content = self.interface.modifiable_edit.compute_final_code();
        
        if new_content != old_content {
            self.interface.add_modification(
                EditModification::CodeChange {
                    line: 0,
                    old: old_content,
                    new: new_content,
                },
                "Live editor changes".to_string(),
            );
            self.update_preview();
        }
    }

    fn update_editor_from_interface(&mut self) {
        let new_content = self.interface.modifiable_edit.compute_final_code();
        self.editor_pane.content = new_content.lines().map(|s| s.to_string()).collect();
    }

    fn adjust_cursor_bounds(&mut self) {
        if let Some(line) = self.editor_pane.content.get(self.editor_pane.cursor_row) {
            if self.editor_pane.cursor_col > line.len() {
                self.editor_pane.cursor_col = line.len();
            }
        }
    }

    fn adjust_editor_scroll(&mut self) {
        let visible_lines = self.editor_pane.height as usize;
        
        if self.editor_pane.cursor_row < self.editor_pane.scroll_offset {
            self.editor_pane.scroll_offset = self.editor_pane.cursor_row;
        } else if self.editor_pane.cursor_row >= self.editor_pane.scroll_offset + visible_lines {
            self.editor_pane.scroll_offset = self.editor_pane.cursor_row - visible_lines + 1;
        }
    }

    fn insert_char(&mut self, c: char) {
        if self.editor_pane.cursor_row < self.editor_pane.content.len() {
            self.editor_pane.content[self.editor_pane.cursor_row].insert(self.editor_pane.cursor_col, c);
            self.editor_pane.cursor_col += 1;
        }
    }

    fn insert_newline(&mut self) {
        if self.editor_pane.cursor_row < self.editor_pane.content.len() {
            let current_line = self.editor_pane.content[self.editor_pane.cursor_row].clone();
            let (left, right) = current_line.split_at(self.editor_pane.cursor_col);

            self.editor_pane.content[self.editor_pane.cursor_row] = left.to_string();
            self.editor_pane.content.insert(self.editor_pane.cursor_row + 1, right.to_string());

            self.editor_pane.cursor_row += 1;
            self.editor_pane.cursor_col = 0;
            self.adjust_editor_scroll();
        }
    }

    fn delete_char(&mut self) {
        if self.editor_pane.cursor_col > 0 && self.editor_pane.cursor_row < self.editor_pane.content.len() {
            self.editor_pane.content[self.editor_pane.cursor_row].remove(self.editor_pane.cursor_col - 1);
            self.editor_pane.cursor_col -= 1;
        } else if self.editor_pane.cursor_row > 0 {
            // Merge with previous line
            let current_line = self.editor_pane.content.remove(self.editor_pane.cursor_row);
            self.editor_pane.cursor_row -= 1;
            self.editor_pane.cursor_col = self.editor_pane.content[self.editor_pane.cursor_row].len();
            self.editor_pane.content[self.editor_pane.cursor_row].push_str(&current_line);
            self.adjust_editor_scroll();
        }
    }

    fn delete_char_forward(&mut self) {
        if self.editor_pane.cursor_row < self.editor_pane.content.len() {
            let line_len = self.editor_pane.content[self.editor_pane.cursor_row].len();
            if self.editor_pane.cursor_col < line_len {
                self.editor_pane.content[self.editor_pane.cursor_row].remove(self.editor_pane.cursor_col);
            } else if self.editor_pane.cursor_row < self.editor_pane.content.len() - 1 {
                // Merge with next line
                let next_line = self.editor_pane.content.remove(self.editor_pane.cursor_row + 1);
                self.editor_pane.content[self.editor_pane.cursor_row].push_str(&next_line);
            }
        }
    }
}

#[derive(Debug)]
enum PreviewAction {
    Continue,
    Save,
    Exit,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::agents::gpt4_agent::ProposedEdit;
    use crate::edit_control::ModifiableEdit;

    fn create_test_interface() -> EditModificationInterface {
        let proposed = ProposedEdit {
            file: "test.rs".to_string(),
            line_range: (10, 15),
            new_code: "fn test() {\n    println!(\"Hello, World!\");\n    return 42;\n}".to_string(),
            reason: "Test function for AdvancedPreviewSystem".to_string(),
            confidence: 0.9,
        };
        let modifiable = ModifiableEdit::from_proposed_edit(proposed);
        EditModificationInterface::new(modifiable)
    }

    #[test]
    fn test_advanced_preview_system_creation() {
        let interface = create_test_interface();
        let preview_system = AdvancedPreviewSystem::new(interface);

        assert_eq!(preview_system.layout, SplitLayout::Horizontal);
        assert_eq!(preview_system.active_pane, ActivePane::Editor);
        assert!(preview_system.auto_preview);
        assert_eq!(preview_system.editor_pane.content.len(), 4); // 4 lines in test code
        assert_eq!(preview_system.editor_pane.cursor_row, 0);
        assert_eq!(preview_system.editor_pane.cursor_col, 0);
    }

    #[test]
    fn test_layout_cycling() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        assert_eq!(preview_system.layout, SplitLayout::Horizontal);
        
        preview_system.cycle_layout();
        assert_eq!(preview_system.layout, SplitLayout::Vertical);
        
        preview_system.cycle_layout();
        assert_eq!(preview_system.layout, SplitLayout::EditorOnly);
        
        preview_system.cycle_layout();
        assert_eq!(preview_system.layout, SplitLayout::PreviewOnly);
        
        preview_system.cycle_layout();
        assert_eq!(preview_system.layout, SplitLayout::Horizontal);
    }

    #[test]
    fn test_pane_switching() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        assert_eq!(preview_system.active_pane, ActivePane::Editor);
        
        preview_system.switch_active_pane();
        assert_eq!(preview_system.active_pane, ActivePane::Preview);
        
        preview_system.switch_active_pane();
        assert_eq!(preview_system.active_pane, ActivePane::Editor);
    }

    #[test]
    fn test_editor_text_insertion() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        let initial_line = preview_system.editor_pane.content[0].clone();
        
        preview_system.insert_char('X');
        assert_eq!(preview_system.editor_pane.cursor_col, 1);
        assert!(preview_system.editor_pane.content[0].starts_with('X'));
        assert_ne!(preview_system.editor_pane.content[0], initial_line);
    }

    #[test]
    fn test_editor_newline_insertion() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        let initial_lines = preview_system.editor_pane.content.len();
        
        preview_system.insert_newline();
        assert_eq!(preview_system.editor_pane.content.len(), initial_lines + 1);
        assert_eq!(preview_system.editor_pane.cursor_row, 1);
        assert_eq!(preview_system.editor_pane.cursor_col, 0);
    }

    #[test]
    fn test_cursor_movement() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        // Test right movement
        let initial_col = preview_system.editor_pane.cursor_col;
        preview_system.editor_pane.cursor_col = 5;
        preview_system.adjust_cursor_bounds();
        assert!(preview_system.editor_pane.cursor_col >= initial_col);

        // Test down movement
        preview_system.editor_pane.cursor_row = 1;
        preview_system.adjust_cursor_bounds();
        assert!(preview_system.editor_pane.cursor_row <= preview_system.editor_pane.content.len());
    }

    #[test]
    fn test_scroll_adjustment() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        // Simulate moving cursor beyond visible area
        preview_system.editor_pane.cursor_row = 50;
        preview_system.editor_pane.height = 20; // Visible height
        preview_system.adjust_editor_scroll();

        // Scroll offset should adjust to keep cursor visible
        assert!(preview_system.editor_pane.scroll_offset > 0);
        assert!(preview_system.editor_pane.cursor_row >= preview_system.editor_pane.scroll_offset);
    }

    #[test]
    fn test_auto_preview_timing() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        // Initially should not need refresh
        assert!(!preview_system.should_refresh_preview());

        // Simulate passage of time by setting a very short delay
        preview_system.preview_delay = Duration::from_nanos(1);
        std::thread::sleep(Duration::from_millis(1));

        // Now should need refresh
        assert!(preview_system.should_refresh_preview());
    }

    #[test]
    fn test_preview_line_extraction() {
        let interface = create_test_interface();
        let mut preview_system = AdvancedPreviewSystem::new(interface);

        preview_system.update_preview();
        
        if let Some(ref preview) = preview_system.preview_pane.preview_result {
            let line = preview_system.get_preview_line(preview, 0);
            assert!(!line.is_empty());
            // Should contain section header format
            assert!(line.contains("╔═") || line.contains("║") || line.is_empty());
        }
    }
}