wsb 0.155.49

use anyhow::{Context, Result};
use rayon::prelude::*;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use walkdir::{DirEntry, WalkDir};

use super::{
    cli::{Args, Mode, OutputFormat},
    collision_detector::{CollisionDetector, CollisionType},
    file_ops::FileOperations,
    patterns_file::PatternPair,
    progress::{ProgressTracker, SimpleOutput},
};
use crate::{utils, ItemType, RenameConfig, RenameItem, RenameStats};

/// Detailed information about changes to a specific file/directory
#[derive(Debug, Clone)]
pub struct FileChangeReport {
    pub path: PathBuf,
    pub content_changes: Option<usize>, // Number of content occurrences to replace
    pub rename_target: Option<PathBuf>, // New path if being renamed
    pub item_type: ItemType,
}

/// Organized summary of all changes, grouped and sorted by location
#[derive(Debug, Clone)]
pub struct DetailedChangeReport {
    pub file_changes: Vec<FileChangeReport>,
    pub total_stats: RenameStats,
}

/// Structured validation error with location and context information
#[derive(Debug, Clone)]
pub struct ValidationError {
    pub location: PathBuf,
    pub error_type: ValidationErrorType,
    pub message: String,
    pub suggestion: Option<String>,
}

#[derive(Debug, Clone)]
pub enum ValidationErrorType {
    FileNotFound,
    PermissionDenied,
    EncodingError,
    NotAFile,
    NotADirectory,
    ReadOnlyFile,
    TargetExists,
    ParentDirectoryError,
    ContentNotFound,
    EmptyDirectoryIssue,
}

/// Main engine for executing rename operations
pub struct RenameEngine {
    config: RenameConfig,
    /// All pattern/substitute pairs to apply. For single-pair mode this has one entry.
    pairs: Vec<PatternPair>,
    mode: Mode,
    file_ops: FileOperations,
    progress: Option<ProgressTracker>,
    simple_output: Option<SimpleOutput>,
    thread_count: usize,
    output_format: OutputFormat,
    max_depth: Option<usize>,
    include_patterns: Vec<String>,
    exclude_patterns: Vec<String>,
    ignore_case: bool,
    use_regex: bool,
    include_hidden: bool,
    binary_names: bool,
}

impl RenameEngine {
    pub fn new(args: Args) -> Result<Self> {
        Self::new_with_pairs(args, Vec::new())
    }

    /// Construct engine with explicit pattern pairs (from --patterns-file or positional args).
    /// If `pairs` is empty, falls back to extracting from args.pattern/args.substitute.
    pub fn new_with_pairs(args: Args, pairs: Vec<PatternPair>) -> Result<Self> {
        args.validate().map_err(|e| anyhow::anyhow!(e))?;

        let pairs = if pairs.is_empty() {
            let pattern = args
                .pattern
                .clone()
                .ok_or_else(|| anyhow::anyhow!("Pattern is required"))?;
            let substitute = args
                .substitute
                .clone()
                .ok_or_else(|| anyhow::anyhow!("Substitute is required"))?;
            vec![PatternPair {
                pattern,
                substitute,
            }]
        } else {
            pairs
        };

        // Config uses first pair for root_dir canonicalization and flags.
        // The actual pattern/substitute come from self.pairs, not config.
        let config = RenameConfig::new(
            &args.root_dir,
            pairs[0].pattern.clone(),
            pairs[0].substitute.clone(),
        )?
        .with_assume_yes(args.assume_yes)
        .with_verbose(args.verbose)
        .with_follow_symlinks(args.follow_symlinks)
        .with_backup(args.backup);

        let show_progress = match args.progress {
            super::cli::ProgressMode::Always => true,
            super::cli::ProgressMode::Never => false,
            super::cli::ProgressMode::Auto => atty::is(atty::Stream::Stdout),
        };

        let (progress, simple_output) = if show_progress && args.format == OutputFormat::Human {
            (Some(ProgressTracker::new(true, args.verbose)), None)
        } else {
            (None, Some(SimpleOutput::new(args.verbose)))
        };

        Ok(Self {
            config,
            pairs,
            mode: args.get_mode(),
            file_ops: FileOperations::new().with_backup(args.backup),
            progress,
            simple_output,
            thread_count: args.get_thread_count(),
            output_format: args.format,
            max_depth: if args.max_depth > 0 {
                Some(args.max_depth)
            } else {
                None
            },
            include_patterns: args.include_patterns,
            exclude_patterns: args.exclude_patterns,
            ignore_case: args.ignore_case,
            use_regex: args.use_regex,
            include_hidden: args.include_hidden,
            binary_names: args.binary_names,
        })
    }

    /// Execute the rename operation
    pub fn execute(&self) -> Result<()> {
        self.print_header()?;

        // Phase 1: Discovery
        self.print_info("Phase 1: Discovering files and directories...")?;
        let (content_files, rename_items) = self.discover_items()?;

        // Phase 2: Collision Detection
        self.print_info("Phase 2: Checking for naming collisions...")?;
        self.check_collisions(&rename_items)?;

        // Phase 3: Mandatory Validation (Dry-Run)
        self.print_info("Phase 3: Validating all operations...")?;
        self.validate_all_operations(&content_files, &rename_items)?;

        // Phase 4: Summary and Confirmation
        let stats = self.show_summary(&content_files, &rename_items)?;
        if stats.total_changes() == 0 {
            self.print_success("No changes needed.")?;
            return Ok(());
        }

        // Phase 4.5: Show diff preview for content changes
        if !content_files.is_empty() && self.output_format == OutputFormat::Human {
            self.show_diff_preview(&content_files)?;
        }

        if !self.confirm_changes()? {
            self.print_info("Operation cancelled by user.")?;
            return Ok(());
        }

        // Phase 5: Execute Changes
        self.execute_changes(&content_files, &rename_items)?;

        // Phase 5: Final Report
        self.show_final_report(&stats)?;

        Ok(())
    }

    /// Discover files for content replacement and items for renaming.
    /// Walks the directory tree once. For multi-pair mode, checks all pairs
    /// and computes the final destination path by applying all pairs sequentially
    /// to each path component.
    fn discover_items(&self) -> Result<(Vec<PathBuf>, Vec<RenameItem>)> {
        let mut content_files = Vec::new();
        let mut rename_items = Vec::new();

        if let Some(progress) = &self.progress {
            progress.init_main_progress(0, "Scanning files and directories...");
        }

        let walker = WalkDir::new(&self.config.root_dir)
            .follow_links(self.config.follow_symlinks)
            .max_depth(self.max_depth.unwrap_or(usize::MAX))
            .into_iter()
            .filter_entry(|e| self.should_process_entry(e));

        for entry in walker {
            let entry = entry.with_context(|| "Failed to read directory entry")?;
            let path = entry.path();

            if path == self.config.root_dir {
                continue;
            }

            if !self.matches_patterns(path)? {
                continue;
            }

            // Check for content replacement in files
            if self.should_process_content() && self.should_process_files() && path.is_file() {
                if self.file_needs_content_replacement(path)? {
                    content_files.push(path.to_path_buf());
                }
            }

            // Check for renaming
            if self.should_process_names() {
                if let Some(rename_item) = self.create_rename_item(path)? {
                    rename_items.push(rename_item);
                }
            }

            if let Some(progress) = &self.progress {
                progress.update_main(&format!("Scanned: {}", path.display()));
            }
        }

        // Sort: files first (deepest first), then directories (deepest first).
        // This ensures children are renamed before parents so paths stay valid.
        rename_items.sort_by(|a, b| match (&a.item_type, &b.item_type) {
            (ItemType::File, ItemType::Directory) => std::cmp::Ordering::Less,
            (ItemType::Directory, ItemType::File) => std::cmp::Ordering::Greater,
            (ItemType::File, ItemType::File) => b.depth.cmp(&a.depth),
            (ItemType::Directory, ItemType::Directory) => b.depth.cmp(&a.depth),
        });

        if let Some(progress) = &self.progress {
            progress.finish_main("Discovery complete");
        }

        Ok((content_files, rename_items))
    }

    /// Check if an entry should be processed
    fn should_process_entry(&self, entry: &DirEntry) -> bool {
        let path = entry.path();

        // Don't skip the root directory itself, even if it's hidden
        if path == self.config.root_dir {
            return true;
        }

        // Skip hidden files unless explicitly included
        if let Some(name) = path.file_name() {
            if let Some(name_str) = name.to_str() {
                if name_str.starts_with('.') {
                    // Check if include_hidden flag is set
                    if self.include_hidden {
                        // Include hidden files when flag is set
                    } else {
                        // Original logic: check include patterns
                        let should_include = self
                            .include_patterns
                            .iter()
                            .any(|p| p == ".*" || p.contains("*"));
                        if !should_include {
                            return false;
                        }
                    }
                }
            }
        }

        // Check file type restrictions
        match self.mode {
            Mode::FilesOnly => path.is_file(),
            Mode::DirsOnly => path.is_dir(),
            _ => true,
        }
    }

    /// Check if a path matches include/exclude patterns
    fn matches_patterns(&self, path: &Path) -> Result<bool> {
        // If there are include patterns, the file must match at least one
        if !self.include_patterns.is_empty() {
            let matches = self
                .include_patterns
                .iter()
                .any(|pattern| self.path_matches_pattern(path, pattern));
            if !matches {
                return Ok(false);
            }
        }

        // If there are exclude patterns, the file must not match any
        if !self.exclude_patterns.is_empty() {
            let excluded = self
                .exclude_patterns
                .iter()
                .any(|pattern| self.path_matches_pattern(path, pattern));
            if excluded {
                return Ok(false);
            }
        }

        Ok(true)
    }

    /// Check if a path matches a glob pattern
    fn path_matches_pattern(&self, path: &Path, pattern: &str) -> bool {
        // Simple glob matching - could be enhanced with a proper glob library
        let file_name = path.file_name().and_then(|n| n.to_str()).unwrap_or("");
        let pattern_str = if self.ignore_case {
            pattern.to_lowercase()
        } else {
            pattern.to_string()
        };
        let compare_str = if self.ignore_case {
            file_name.to_lowercase()
        } else {
            file_name.to_string()
        };

        if self.use_regex {
            // Use regex matching
            if let Ok(regex) = regex::Regex::new(&pattern_str) {
                return regex.is_match(&compare_str);
            }
        }

        // Special case for ".*" pattern to match hidden files
        if pattern_str == ".*" {
            return compare_str.starts_with('.');
        }

        // Simple glob-style matching
        if pattern_str.contains('*') {
            let parts: Vec<&str> = pattern_str.split('*').collect();
            if parts.len() == 2 {
                return compare_str.starts_with(parts[0]) && compare_str.ends_with(parts[1]);
            }
        }

        compare_str.contains(&pattern_str)
    }

    /// Check if a file needs content replacement by any of the pairs.
    /// We check whether the file contains ANY pair's pattern. Note that a later pair's
    /// pattern might only appear after an earlier pair's substitution transforms the content,
    /// but we can't know that without actually doing the replacement. So we also include
    /// files that contain any pair's substitute when there are subsequent pairs, since
    /// an earlier pair could produce text that a later pair matches.
    ///
    /// For correctness without over-reading, we check if the file contains any pattern
    /// from any pair. If pair 1 produces text that pair 2 matches, pair 2's pattern won't
    /// be in the original file — but pair 1's pattern WILL be. So the file gets picked up
    /// for content processing. During execution, replace_content_multi applies all pairs
    /// sequentially and handles the cascade.
    fn file_needs_content_replacement(&self, path: &Path) -> Result<bool> {
        if !self.file_ops.is_text_file(path)? {
            return Ok(false);
        }

        let search_strings: Vec<&str> = self
            .pairs
            .iter()
            .map(|p| {
                if self.ignore_case {
                    // This is a simplification — proper case-insensitive needs regex
                    p.pattern.as_str()
                } else {
                    p.pattern.as_str()
                }
            })
            .collect();

        self.file_ops
            .file_contains_any_string(path, &search_strings)
    }

    /// Apply all pattern pairs sequentially to a name string, returning the final name.
    fn apply_pairs_to_name(&self, name: &str) -> String {
        let mut result = name.to_string();
        for pair in &self.pairs {
            if self.ignore_case {
                // Case-insensitive: match against lowercased, replace in the lowercased string
                result = result
                    .to_lowercase()
                    .replace(&pair.pattern.to_lowercase(), &pair.substitute);
            } else {
                result = result.replace(&pair.pattern, &pair.substitute);
            }
        }
        result
    }

    /// Create a rename item if the path needs renaming after applying all pairs.
    fn create_rename_item(&self, path: &Path) -> Result<Option<RenameItem>> {
        let file_name = path
            .file_name()
            .and_then(|n| n.to_str())
            .ok_or_else(|| anyhow::anyhow!("Invalid file name: {}", path.display()))?;

        // Apply all pairs to this entry's own name. If the name doesn't change,
        // this entry doesn't need a rename item (parent renames are separate items).
        let final_name = self.apply_pairs_to_name(file_name);

        if final_name == file_name {
            return Ok(None);
        }

        // Check binary file handling for files
        if path.is_file() {
            match self.file_ops.is_text_file(path) {
                Ok(false) => {
                    if !self.binary_names {
                        return Ok(None);
                    }
                }
                Err(_) => {
                    if !self.binary_names {
                        return Ok(None);
                    }
                }
                Ok(true) => {}
            }
        }

        // Apply type restrictions
        let item_type = if path.is_file() {
            if !self.should_process_files() {
                return Ok(None);
            }
            ItemType::File
        } else {
            if !self.should_process_dirs() {
                return Ok(None);
            }
            ItemType::Directory
        };

        let depth = utils::calculate_depth(path, &self.config.root_dir);

        // For the rename item, the new_path is the final computed path.
        // But we only rename this entry's own name, not its parents (parents get their
        // own rename items). So new_path should only change THIS entry's name component,
        // keeping the original parent path — the parent's rename item handles the parent.
        let new_path = path.with_file_name(&final_name);

        Ok(Some(RenameItem {
            original_path: path.to_path_buf(),
            new_path,
            item_type,
            depth,
        }))
    }

    /// Check for collisions in the rename operations
    fn check_collisions(&self, rename_items: &[RenameItem]) -> Result<()> {
        if rename_items.is_empty() {
            return Ok(());
        }

        let mut detector = CollisionDetector::new();

        // Scan existing paths
        detector.scan_existing_paths(&self.config.root_dir)?;

        // Add rename operations
        detector.add_renames(rename_items);

        // Detect collisions
        let collisions = detector.detect_collisions()?;

        if !collisions.is_empty() {
            self.print_error("Naming collisions detected!")?;

            for collision in &collisions {
                match collision.collision_type {
                    CollisionType::SourceEqualsTarget => {
                        // Skip no-op renames
                        continue;
                    }
                    _ => {
                        self.print_error(&collision.description)?;
                    }
                }
            }

            let serious_collisions: Vec<_> = collisions
                .iter()
                .filter(|c| c.collision_type != CollisionType::SourceEqualsTarget)
                .collect();

            if !serious_collisions.is_empty() {
                anyhow::bail!(
                    "Cannot proceed due to {} naming collision(s)",
                    serious_collisions.len()
                );
            }
        }

        Ok(())
    }

    /// Generate detailed report of all changes organized by file/directory
    fn generate_detailed_report(
        &self,
        content_files: &[PathBuf],
        rename_items: &[RenameItem],
    ) -> Result<DetailedChangeReport> {
        use std::collections::HashMap;

        let mut file_changes_map: HashMap<PathBuf, FileChangeReport> = HashMap::new();
        let mut stats = RenameStats::default();

        // Process content changes
        for file_path in content_files {
            // Count total occurrences across all pairs by simulating the sequential replacement
            let content_count = match std::fs::read_to_string(file_path) {
                Ok(content) => {
                    let mut total = 0;
                    let mut current = content;
                    for pair in &self.pairs {
                        let count = current.matches(&pair.pattern).count();
                        total += count;
                        if count > 0 {
                            current = current.replace(&pair.pattern, &pair.substitute);
                        }
                    }
                    total
                }
                Err(_) => 0,
            };

            file_changes_map.insert(
                file_path.clone(),
                FileChangeReport {
                    path: file_path.clone(),
                    content_changes: Some(content_count),
                    rename_target: None,
                    item_type: ItemType::File,
                },
            );
            stats.files_with_content_changes += 1;
        }

        // Process rename operations
        for item in rename_items {
            let entry = file_changes_map
                .entry(item.original_path.clone())
                .or_insert_with(|| FileChangeReport {
                    path: item.original_path.clone(),
                    content_changes: None,
                    rename_target: None,
                    item_type: item.item_type.clone(),
                });

            entry.rename_target = Some(item.new_path.clone());
            entry.item_type = item.item_type.clone();

            match item.item_type {
                ItemType::File => stats.files_renamed += 1,
                ItemType::Directory => stats.directories_renamed += 1,
            }
        }

        // Convert to sorted vector (by path for consistent ordering)
        let mut file_changes: Vec<FileChangeReport> = file_changes_map.into_values().collect();
        file_changes.sort_by(|a, b| a.path.cmp(&b.path));

        Ok(DetailedChangeReport {
            file_changes,
            total_stats: stats,
        })
    }

    /// Show detailed summary of changes organized by file/directory
    fn show_summary(
        &self,
        content_files: &[PathBuf],
        rename_items: &[RenameItem],
    ) -> Result<RenameStats> {
        let report = self.generate_detailed_report(content_files, rename_items)?;

        match self.output_format {
            OutputFormat::Json => {
                let json_report = serde_json::json!({
                    "summary": {
                        "content_changes": report.total_stats.files_with_content_changes,
                        "file_renames": report.total_stats.files_renamed,
                        "directory_renames": report.total_stats.directories_renamed,
                        "total_changes": report.total_stats.total_changes()
                    },
                    "file_changes": report.file_changes.iter().map(|fc| {
                        serde_json::json!({
                            "path": fc.path,
                            "content_changes": fc.content_changes,
                            "rename_target": fc.rename_target,
                            "item_type": format!("{:?}", fc.item_type)
                        })
                    }).collect::<Vec<_>>()
                });
                println!("{}", serde_json::to_string_pretty(&json_report)?);
            }
            OutputFormat::Plain => {
                println!(
                    "Content changes: {}",
                    report.total_stats.files_with_content_changes
                );
                println!("File renames: {}", report.total_stats.files_renamed);
                println!(
                    "Directory renames: {}",
                    report.total_stats.directories_renamed
                );
                println!("Total changes: {}", report.total_stats.total_changes());
            }
            OutputFormat::Human => {
                self.print_info("=== PLANNED CHANGES ===")?;
                self.print_info(&format!(
                    "Total files/directories affected: {}",
                    report.file_changes.len()
                ))?;
                self.print_info(&format!(
                    "Content modifications: {} file(s)",
                    report.total_stats.files_with_content_changes
                ))?;
                self.print_info(&format!(
                    "File renames:         {} file(s)",
                    report.total_stats.files_renamed
                ))?;
                self.print_info(&format!(
                    "Directory renames:    {} directory(ies)",
                    report.total_stats.directories_renamed
                ))?;
                self.print_info("")?;

                if !report.file_changes.is_empty() {
                    self.print_info("=== DETAILED CHANGES BY LOCATION ===")?;

                    for change in &report.file_changes {
                        let relative_path = change
                            .path
                            .strip_prefix(&self.config.root_dir)
                            .unwrap_or(&change.path);

                        self.print_info(&format!("📁 {}", relative_path.display()))?;

                        // Show content changes
                        if let Some(count) = change.content_changes {
                            if self.pairs.len() == 1 {
                                self.print_verbose(&format!(
                                    "   Content: {} occurrence(s) of '{}' → '{}'",
                                    count, self.pairs[0].pattern, self.pairs[0].substitute
                                ))?;
                            } else {
                                self.print_verbose(&format!(
                                    "   Content: {} total replacement(s) across {} pairs",
                                    count,
                                    self.pairs.len()
                                ))?;
                            }
                        }

                        // Show rename operation
                        if let Some(target) = &change.rename_target {
                            let relative_target =
                                target.strip_prefix(&self.config.root_dir).unwrap_or(target);
                            self.print_verbose(&format!(
                                "   Rename:  {} → {}",
                                relative_path.display(),
                                relative_target.display()
                            ))?;
                        }
                    }
                }
            }
        }

        Ok(report.total_stats)
    }

    /// Show diff preview for content changes with colored +/- lines
    fn show_diff_preview(&self, content_files: &[PathBuf]) -> Result<()> {
        self.print_info("=== DIFF PREVIEW ===")?;

        for (i, file_path) in content_files.iter().enumerate() {
            if i >= 5 {
                // Limit preview to first 5 files to avoid overwhelming output
                self.print_info(&format!("... and {} more files", content_files.len() - i))?;
                break;
            }

            let relative_path = file_path
                .strip_prefix(&self.config.root_dir)
                .unwrap_or(file_path);

            // Read file content
            let content = match std::fs::read_to_string(file_path) {
                Ok(content) => content,
                Err(_) => {
                    self.print_warning(&format!(
                        "⚠️  Cannot preview {}: unable to read file",
                        relative_path.display()
                    ))?;
                    continue;
                }
            };

            self.print_info(&format!("\n⏺ Update({})", relative_path.display()))?;

            // Count replacements across all pairs
            let mut total_replacements = 0;
            let mut simulated = content.clone();
            for pair in &self.pairs {
                let count = simulated.matches(&pair.pattern).count();
                total_replacements += count;
                if count > 0 {
                    simulated = simulated.replace(&pair.pattern, &pair.substitute);
                }
            }

            self.print_verbose(&format!(
                "  ⎿  Updated {} with {} replacement(s)",
                relative_path.display(),
                total_replacements
            ))?;

            // Show context around changes
            self.show_diff_context(&content, file_path)?;
        }

        self.print_info("")?; // Empty line for spacing
        Ok(())
    }

    /// Show diff context with colored +/- lines for a specific file.
    /// Applies all pairs sequentially to each changed line.
    fn show_diff_context(&self, content: &str, _file_path: &Path) -> Result<()> {
        use colored::*;

        let lines: Vec<&str> = content.lines().collect();
        let mut changes_shown = 0;
        const MAX_CHANGES_TO_SHOW: usize = 3;

        for (i, line) in lines.iter().enumerate() {
            if changes_shown >= MAX_CHANGES_TO_SHOW {
                break;
            }

            // Check if any pair's pattern matches this line
            let line_matches = self.pairs.iter().any(|p| line.contains(&p.pattern));
            if !line_matches {
                continue;
            }

            let start_context = i.saturating_sub(2);
            let end_context = std::cmp::min(i + 3, lines.len());

            for j in start_context..i {
                let line_num = j + 1;
                println!(
                    "      {}        {}",
                    line_num.to_string().dimmed(),
                    lines[j]
                );
            }

            let line_num = i + 1;
            println!(
                "      {} {}      {}",
                line_num.to_string().dimmed(),
                "-".red().bold(),
                line.white().on_bright_red()
            );

            // Apply all pairs sequentially to get the final line
            let mut new_line = line.to_string();
            for pair in &self.pairs {
                new_line = new_line.replace(&pair.pattern, &pair.substitute);
            }

            println!(
                "      {} {}      {}",
                line_num.to_string().dimmed(),
                "+".green().bold(),
                new_line.white().on_bright_green()
            );

            for j in (i + 1)..end_context {
                let line_num = j + 1;
                println!(
                    "      {}        {}",
                    line_num.to_string().dimmed(),
                    lines[j]
                );
            }

            changes_shown += 1;

            if changes_shown < MAX_CHANGES_TO_SHOW && i + 3 < lines.len() {
                println!("      ...");
            }
        }

        Ok(())
    }

    /// Confirm changes with the user
    fn confirm_changes(&self) -> Result<bool> {
        if self.config.assume_yes {
            return Ok(true);
        }

        match self.output_format {
            OutputFormat::Json => Ok(true), // No confirmation in JSON mode
            OutputFormat::Plain | OutputFormat::Human => {
                self.print_warning("This operation will modify your files and directories.")?;

                let confirmation = if let Some(progress) = &self.progress {
                    progress.suspend(|| {
                        dialoguer::Confirm::new()
                            .with_prompt("Do you want to proceed?")
                            .default(false)
                            .interact()
                    })
                } else {
                    dialoguer::Confirm::new()
                        .with_prompt("Do you want to proceed?")
                        .default(false)
                        .interact()
                };

                confirmation.with_context(|| "Failed to get user confirmation")
            }
        }
    }

    /// Execute the actual changes
    fn execute_changes(
        &self,
        content_files: &[PathBuf],
        rename_items: &[RenameItem],
    ) -> Result<()> {
        // Phase 1: Content replacement
        if !content_files.is_empty() && self.should_process_content() {
            self.execute_content_changes(content_files)?;
        }

        // Phase 2: Rename items (directories first, then files)
        if !rename_items.is_empty() && self.should_process_names() {
            self.execute_renames(rename_items)?;
        }

        Ok(())
    }

    /// Execute content changes — applies all pairs sequentially per file, reading and writing once.
    fn execute_content_changes(&self, content_files: &[PathBuf]) -> Result<()> {
        self.print_info("Replacing content in files...")?;

        if let Some(progress) = &self.progress {
            progress.init_content_progress(content_files.len() as u64);
        }

        let errors = Arc::new(Mutex::new(Vec::new()));
        let file_ops_ref = &self.file_ops;
        let config_ref = &self.config;
        let pairs_tuples: Vec<(String, String)> = self
            .pairs
            .iter()
            .map(|p| (p.pattern.clone(), p.substitute.clone()))
            .collect();
        let errors_ref = Arc::clone(&errors);

        if self.thread_count > 1 {
            let pairs_ref = &pairs_tuples;
            content_files.par_iter().for_each(|file_path| {
                if !file_path.exists() {
                    errors_ref
                        .lock()
                        .unwrap()
                        .push(format!("File no longer exists: {}", file_path.display()));
                    return;
                }

                let result = file_ops_ref.replace_content_multi(file_path, pairs_ref);

                match result {
                    Ok(_) => {}
                    Err(e) => {
                        errors_ref.lock().unwrap().push(format!(
                            "Failed to modify {}: {}",
                            file_path.display(),
                            e
                        ));
                    }
                }
            });
        } else {
            for file_path in content_files {
                if !file_path.exists() {
                    self.print_error(&format!("File no longer exists: {}", file_path.display()))?;
                    if let Some(progress) = &self.progress {
                        progress.update_content(&file_path.display().to_string());
                    }
                    continue;
                }

                let result = file_ops_ref.replace_content_multi(file_path, &pairs_tuples);

                match result {
                    Ok(modified) => {
                        if modified && config_ref.verbose {
                            self.print_verbose(&format!("Modified: {}", file_path.display()))?;
                        }
                    }
                    Err(e) => {
                        self.print_error(&format!(
                            "Failed to modify {}: {}",
                            file_path.display(),
                            e
                        ))?;
                    }
                }

                if let Some(progress) = &self.progress {
                    progress.update_content(&file_path.display().to_string());
                }
            }
        }

        let errors = errors.lock().unwrap();
        for error in errors.iter() {
            self.print_error(error)?;
        }

        if let Some(progress) = &self.progress {
            progress.finish_content(&format!(
                "Content replacement complete ({} files)",
                content_files.len()
            ));
        }

        Ok(())
    }

    /// Execute rename operations with proper ordering and error handling
    fn execute_renames(&self, rename_items: &[RenameItem]) -> Result<()> {
        self.print_info("Renaming files and directories...")?;

        if let Some(progress) = &self.progress {
            progress.init_rename_progress(rename_items.len() as u64);
        }

        let mut errors = Vec::new();
        let mut successful_renames = Vec::new();

        // Process renames sequentially to maintain ordering (files before directories)
        for item in rename_items {
            // Skip no-op renames
            if item.original_path == item.new_path {
                if let Some(progress) = &self.progress {
                    progress.update_rename(&item.original_path.display().to_string());
                }
                continue;
            }

            // Validate that source still exists (in case of race conditions, including broken symlinks)
            let source_exists =
                item.original_path.exists() || item.original_path.symlink_metadata().is_ok();
            if !source_exists {
                errors.push(format!(
                    "Source path no longer exists: {}",
                    item.original_path.display()
                ));
                if let Some(progress) = &self.progress {
                    progress.update_rename(&item.original_path.display().to_string());
                }
                continue;
            }

            // Ensure target directory exists
            if let Some(parent) = item.new_path.parent() {
                if let Err(e) = self.file_ops.create_dir_all(parent) {
                    errors.push(format!(
                        "Failed to create parent directory for {}: {}",
                        item.new_path.display(),
                        e
                    ));
                    if let Some(progress) = &self.progress {
                        progress.update_rename(&item.original_path.display().to_string());
                    }
                    continue;
                }
            }

            let result = self.file_ops.move_item(&item.original_path, &item.new_path);

            match result {
                Ok(()) => {
                    successful_renames.push((item.original_path.clone(), item.new_path.clone()));
                    if self.config.verbose {
                        self.print_verbose(&format!(
                            "Renamed: {} → {}",
                            item.original_path.display(),
                            item.new_path.display()
                        ))?;
                    }
                }
                Err(e) => {
                    errors.push(format!(
                        "Failed to rename {} to {}: {}",
                        item.original_path.display(),
                        item.new_path.display(),
                        e
                    ));
                }
            }

            if let Some(progress) = &self.progress {
                progress.update_rename(&item.original_path.display().to_string());
            }
        }

        // Report errors
        for error in &errors {
            self.print_error(error)?;
        }

        if !errors.is_empty() {
            self.print_warning(&format!(
                "{} rename operation(s) failed out of {}",
                errors.len(),
                rename_items.len()
            ))?;
        }

        if let Some(progress) = &self.progress {
            progress.finish_rename(&format!(
                "Rename complete ({} successful, {} failed)",
                successful_renames.len(),
                errors.len()
            ));
        }

        Ok(())
    }

    /// Validate all operations before execution (mandatory validation phase)
    /// This catches all potential issues before making any changes
    fn validate_all_operations(
        &self,
        content_files: &[PathBuf],
        rename_items: &[RenameItem],
    ) -> Result<()> {
        let mut validation_errors = Vec::new();

        // Validate content replacement operations
        for file_path in content_files {
            self.validate_content_file(file_path, &mut validation_errors);
        }

        // Validate rename operations
        for item in rename_items {
            self.validate_rename_item(item, &mut validation_errors);
        }

        // Validate that operation will not leave empty directories
        self.validate_no_empty_directories_remain(rename_items, &mut validation_errors)?;

        // Report all validation errors with enhanced formatting
        if !validation_errors.is_empty() {
            self.report_validation_errors(&validation_errors)?;

            // Create a more descriptive error message that includes error types
            let error_types: std::collections::HashSet<&str> = validation_errors
                .iter()
                .map(|e| match e.error_type {
                    ValidationErrorType::FileNotFound => "missing files",
                    ValidationErrorType::PermissionDenied => "permission issues",
                    ValidationErrorType::EncodingError => "encoding issues",
                    ValidationErrorType::ReadOnlyFile => "read-only files",
                    ValidationErrorType::TargetExists => "target conflicts",
                    ValidationErrorType::ParentDirectoryError => "directory issues",
                    ValidationErrorType::ContentNotFound => "content issues",
                    ValidationErrorType::EmptyDirectoryIssue => "directory structure issues",
                    _ => "other issues",
                })
                .collect();

            let error_summary = error_types.into_iter().collect::<Vec<_>>().join(", ");
            anyhow::bail!(
                "Operation cannot proceed due to {} validation error(s): {}",
                validation_errors.len(),
                error_summary
            );
        }

        self.print_info("Validation passed: All operations can be performed safely.")?;
        Ok(())
    }

    /// Validate a single content file for replacement operations
    fn validate_content_file(
        &self,
        file_path: &PathBuf,
        validation_errors: &mut Vec<ValidationError>,
    ) {
        let relative_path = file_path
            .strip_prefix(&self.config.root_dir)
            .unwrap_or(file_path);

        if !file_path.exists() {
            validation_errors.push(ValidationError {
                location: file_path.clone(),
                error_type: ValidationErrorType::FileNotFound,
                message: format!("Content file does not exist: {}", relative_path.display()),
                suggestion: Some("Check if the file was moved or deleted".to_string()),
            });
            return;
        }

        if !file_path.is_file() {
            validation_errors.push(ValidationError {
                location: file_path.clone(),
                error_type: ValidationErrorType::NotAFile,
                message: format!("Content target is not a file: {}", relative_path.display()),
                suggestion: Some(
                    "Content replacement only works on files, not directories".to_string(),
                ),
            });
            return;
        }

        // Check if file is readable and writable
        if let Err(e) = std::fs::OpenOptions::new()
            .read(true)
            .write(true)
            .open(file_path)
        {
            let error_type = if e.kind() == std::io::ErrorKind::PermissionDenied {
                ValidationErrorType::PermissionDenied
            } else {
                ValidationErrorType::PermissionDenied
            };

            validation_errors.push(ValidationError {
                location: file_path.clone(),
                error_type,
                message: format!("Cannot access file {}: {}", relative_path.display(), e),
                suggestion: Some(
                    "Check file permissions or if file is locked by another process".to_string(),
                ),
            });
            return;
        }

        // Check if file is binary before attempting to read as text
        match self.file_ops.is_text_file(file_path) {
            Ok(false) => {
                // Binary file - skip validation (should not have been included in content_files)
                if self.config.verbose {
                    eprintln!("WARNING: Binary file {} was included in content validation - this may indicate a discovery phase issue", relative_path.display());
                }
                return; // Binary files are skipped during content processing
            }
            Err(e) => {
                validation_errors.push(ValidationError {
                    location: file_path.clone(),
                    error_type: ValidationErrorType::EncodingError,
                    message: format!(
                        "Cannot determine if file {} is binary or text: {}",
                        relative_path.display(),
                        e
                    ),
                    suggestion: Some(
                        "Use --exclude patterns to exclude problematic files".to_string(),
                    ),
                });
                return;
            }
            Ok(true) => {
                // File is text, continue with validation
            }
        }

        // Validate that file can be read and contains at least one pair's pattern
        let search_strings: Vec<&str> = self.pairs.iter().map(|p| p.pattern.as_str()).collect();
        match self
            .file_ops
            .file_contains_any_string(file_path, &search_strings)
        {
            Ok(contains_any) => {
                if !contains_any {
                    validation_errors.push(ValidationError {
                        location: file_path.clone(),
                        error_type: ValidationErrorType::ContentNotFound,
                        message: format!(
                            "File {} does not contain any target pattern",
                            relative_path.display()
                        ),
                        suggestion: Some(
                            "File may have been modified since discovery phase".to_string(),
                        ),
                    });
                }
            }
            Err(e) => {
                validation_errors.push(ValidationError {
                    location: file_path.clone(),
                    error_type: ValidationErrorType::EncodingError,
                    message: format!(
                        "Cannot read file {} with detected encoding: {}",
                        relative_path.display(),
                        e
                    ),
                    suggestion: Some("Use --exclude patterns to exclude this file".to_string()),
                });
            }
        }
    }

    /// Validate a single rename operation
    fn validate_rename_item(
        &self,
        item: &RenameItem,
        validation_errors: &mut Vec<ValidationError>,
    ) {
        let relative_source = item
            .original_path
            .strip_prefix(&self.config.root_dir)
            .unwrap_or(&item.original_path);
        let relative_target = item
            .new_path
            .strip_prefix(&self.config.root_dir)
            .unwrap_or(&item.new_path);

        // Skip no-op renames
        if item.original_path == item.new_path {
            return;
        }

        // Check source exists (including broken symlinks)
        let source_exists =
            item.original_path.exists() || item.original_path.symlink_metadata().is_ok();
        if !source_exists {
            validation_errors.push(ValidationError {
                location: item.original_path.clone(),
                error_type: ValidationErrorType::FileNotFound,
                message: format!(
                    "Rename source does not exist: {}",
                    relative_source.display()
                ),
                suggestion: Some(
                    "Source may have been moved or deleted since discovery".to_string(),
                ),
            });
            return;
        }

        // Check target doesn't already exist (unless it's the same as source)
        if item.new_path.exists() && item.new_path != item.original_path {
            validation_errors.push(ValidationError {
                location: item.new_path.clone(),
                error_type: ValidationErrorType::TargetExists,
                message: format!(
                    "Rename target already exists: {}",
                    relative_target.display()
                ),
                suggestion: Some(
                    "Target was created since discovery phase, or there's a naming collision"
                        .to_string(),
                ),
            });
            return;
        }

        // Check parent directory exists or can be created
        if let Some(parent) = item.new_path.parent() {
            if !parent.exists() {
                match std::fs::create_dir_all(parent) {
                    Ok(_) => {
                        // Remove the directory we just created for validation
                        let _ = std::fs::remove_dir_all(parent);
                    }
                    Err(e) => {
                        validation_errors.push(ValidationError {
                            location: parent.to_path_buf(),
                            error_type: ValidationErrorType::ParentDirectoryError,
                            message: format!(
                                "Cannot create parent directory for {}: {}",
                                relative_target.display(),
                                e
                            ),
                            suggestion: Some("Check permissions on parent directories".to_string()),
                        });
                        return;
                    }
                }
            }
        }

        // Check permissions on source (use symlink_metadata to handle broken symlinks)
        match item.original_path.symlink_metadata() {
            Ok(metadata) => {
                if metadata.permissions().readonly() {
                    validation_errors.push(ValidationError {
                        location: item.original_path.clone(),
                        error_type: ValidationErrorType::ReadOnlyFile,
                        message: format!("Source is read-only: {}", relative_source.display()),
                        suggestion: Some(
                            "Change file permissions or exclude read-only files".to_string(),
                        ),
                    });
                }
            }
            Err(e) => {
                validation_errors.push(ValidationError {
                    location: item.original_path.clone(),
                    error_type: ValidationErrorType::PermissionDenied,
                    message: format!(
                        "Cannot read metadata for {}: {}",
                        relative_source.display(),
                        e
                    ),
                    suggestion: Some("Check file permissions and access rights".to_string()),
                });
            }
        }
    }

    /// Report validation errors with enhanced formatting and organization
    fn report_validation_errors(&self, validation_errors: &[ValidationError]) -> Result<()> {
        self.print_error("=== VALIDATION FAILED ===")?;
        self.print_error(&format!(
            "Found {} issue(s) that prevent safe execution:",
            validation_errors.len()
        ))?;
        self.print_error("")?;

        // Group errors by type for better organization
        use std::collections::HashMap;
        let mut errors_by_type: HashMap<String, Vec<&ValidationError>> = HashMap::new();

        for error in validation_errors {
            let type_name = match error.error_type {
                ValidationErrorType::FileNotFound => "Missing Files/Directories",
                ValidationErrorType::PermissionDenied => "Permission Issues",
                ValidationErrorType::EncodingError => "Encoding/Binary File Issues",
                ValidationErrorType::NotAFile => "File Type Issues",
                ValidationErrorType::ReadOnlyFile => "Read-Only Files",
                ValidationErrorType::TargetExists => "Target Conflicts",
                ValidationErrorType::ParentDirectoryError => "Directory Creation Issues",
                ValidationErrorType::ContentNotFound => "Content Issues",
                ValidationErrorType::EmptyDirectoryIssue => "Directory Structure Issues",
                _ => "Other Issues",
            };

            errors_by_type
                .entry(type_name.to_string())
                .or_insert_with(Vec::new)
                .push(error);
        }

        // Report errors grouped by type
        for (error_type, errors) in errors_by_type {
            self.print_error(&format!("📋 {}: ({} issue(s))", error_type, errors.len()))?;

            for error in errors {
                let relative_path = error
                    .location
                    .strip_prefix(&self.config.root_dir)
                    .unwrap_or(&error.location);

                self.print_error(&format!("   📍 Location: {}", relative_path.display()))?;
                self.print_error(&format!("      Problem: {}", error.message))?;

                if let Some(suggestion) = &error.suggestion {
                    self.print_error(&format!("      Suggestion: {}", suggestion))?;
                }
                self.print_error("")?;
            }
        }

        self.print_error("❌ Cannot proceed until these issues are resolved.")?;
        Ok(())
    }

    /// Validate that the rename operations will not leave empty directories
    /// This is a critical test - if it fails, our operation ordering is wrong
    fn validate_no_empty_directories_remain(
        &self,
        rename_items: &[RenameItem],
        validation_errors: &mut Vec<ValidationError>,
    ) -> Result<()> {
        use std::collections::{HashMap, HashSet};

        // Build a map of all directories and what they contain
        let mut directory_contents: HashMap<PathBuf, HashSet<PathBuf>> = HashMap::new();

        // Scan the existing directory structure
        for entry in walkdir::WalkDir::new(&self.config.root_dir) {
            let entry = entry?;
            let path = entry.path();

            if let Some(parent) = path.parent() {
                directory_contents
                    .entry(parent.to_path_buf())
                    .or_insert_with(HashSet::new)
                    .insert(path.to_path_buf());
            }
        }

        // Simulate the rename operations
        for item in rename_items {
            if item.original_path == item.new_path {
                continue; // No-op
            }

            // Remove from old parent
            if let Some(old_parent) = item.original_path.parent() {
                if let Some(contents) = directory_contents.get_mut(old_parent) {
                    contents.remove(&item.original_path);
                }
            }

            // Add to new parent
            if let Some(new_parent) = item.new_path.parent() {
                directory_contents
                    .entry(new_parent.to_path_buf())
                    .or_insert_with(HashSet::new)
                    .insert(item.new_path.clone());
            }
        }

        // Check for directories that would become empty (excluding directories being renamed themselves)
        let renamed_dirs: HashSet<PathBuf> = rename_items
            .iter()
            .filter(|item| item.item_type == crate::ItemType::Directory)
            .map(|item| item.original_path.clone())
            .collect();

        for (dir_path, contents) in &directory_contents {
            // Skip root directory
            if dir_path == &self.config.root_dir {
                continue;
            }

            // Skip directories that are being renamed (they should become empty)
            if renamed_dirs.contains(dir_path) {
                continue;
            }

            // Check if directory would become empty
            if contents.is_empty() {
                let relative_path = dir_path
                    .strip_prefix(&self.config.root_dir)
                    .unwrap_or(dir_path);

                validation_errors.push(ValidationError {
                    location: dir_path.clone(),
                    error_type: ValidationErrorType::EmptyDirectoryIssue,
                    message: format!("CRITICAL: Directory would become empty after operation: {}. This indicates incorrect operation ordering.", 
                                   relative_path.display()),
                    suggestion: Some("This is a logic error in operation ordering - files should be processed before directories".to_string()),
                });
            }
        }

        Ok(())
    }

    /// Show final report
    fn show_final_report(&self, stats: &RenameStats) -> Result<()> {
        match self.output_format {
            OutputFormat::Json => {
                let report = serde_json::json!({
                    "result": "success",
                    "stats": {
                        "content_changes": stats.files_with_content_changes,
                        "file_renames": stats.files_renamed,
                        "directory_renames": stats.directories_renamed,
                        "total_changes": stats.total_changes(),
                        "errors": stats.errors.len()
                    },
                });
                println!("{}", serde_json::to_string_pretty(&report)?);
            }
            OutputFormat::Plain => {
                println!("Operation completed successfully.");
                println!("Total changes: {}", stats.total_changes());
            }
            OutputFormat::Human => {
                self.print_success("=== OPERATION COMPLETE ===")?;
                self.print_success("Operation completed successfully!")?;
                self.print_info(&format!("Total changes applied: {}", stats.total_changes()))?;

                if !stats.errors.is_empty() {
                    self.print_warning(&format!("{} error(s) occurred:", stats.errors.len()))?;
                    for error in &stats.errors {
                        self.print_error(error)?;
                    }
                }
            }
        }

        Ok(())
    }

    /// Print header information
    fn print_header(&self) -> Result<()> {
        if self.output_format != OutputFormat::Human {
            return Ok(());
        }

        if self.pairs.len() == 1 {
            self.print_success("=== WORKSPACE REFAC TOOL ===")?;
            self.print_info(&format!("Pattern: '{}'", self.pairs[0].pattern))?;
            self.print_info(&format!("Substitute: '{}'", self.pairs[0].substitute))?;
        } else {
            self.print_success(&format!(
                "=== WORKSPACE REFAC TOOL ({} pairs) ===",
                self.pairs.len()
            ))?;
            for (i, pair) in self.pairs.iter().enumerate() {
                self.print_info(&format!(
                    "  Pair {}: '{}' → '{}'",
                    i + 1,
                    pair.pattern,
                    pair.substitute
                ))?;
            }
        }
        self.print_info(&format!(
            "Root directory: {}",
            self.config.root_dir.display()
        ))?;
        self.print_info(&format!("Mode: {:?}", self.mode))?;

        if self.config.backup {
            self.print_info("Backup mode: Enabled")?;
        }

        Ok(())
    }

    // Utility methods for printing
    fn print_info(&self, message: &str) -> Result<()> {
        if let Some(progress) = &self.progress {
            progress.print_info(message);
        } else if let Some(output) = &self.simple_output {
            output.print_info(message);
        }
        Ok(())
    }

    fn print_error(&self, message: &str) -> Result<()> {
        if let Some(progress) = &self.progress {
            progress.print_error(message);
        } else if let Some(output) = &self.simple_output {
            output.print_error(message);
        }
        Ok(())
    }

    fn print_warning(&self, message: &str) -> Result<()> {
        if let Some(progress) = &self.progress {
            progress.print_warning(message);
        } else if let Some(output) = &self.simple_output {
            output.print_warning(message);
        }
        Ok(())
    }

    fn print_success(&self, message: &str) -> Result<()> {
        if let Some(progress) = &self.progress {
            progress.print_success(message);
        } else if let Some(output) = &self.simple_output {
            output.print_success(message);
        }
        Ok(())
    }

    fn print_verbose(&self, message: &str) -> Result<()> {
        if let Some(progress) = &self.progress {
            progress.print_verbose(message);
        } else if let Some(output) = &self.simple_output {
            output.print_verbose(message);
        }
        Ok(())
    }

    // Mode checking methods
    fn should_process_files(&self) -> bool {
        self.mode.should_process_files()
    }

    fn should_process_dirs(&self) -> bool {
        self.mode.should_process_dirs()
    }

    fn should_process_content(&self) -> bool {
        !matches!(self.mode, Mode::NamesOnly)
    }

    fn should_process_names(&self) -> bool {
        !matches!(self.mode, Mode::ContentOnly)
    }
}

// Extension traits to add methods to the Mode and Config types
trait ModeExt {
    fn should_process_files(&self) -> bool;
    fn should_process_dirs(&self) -> bool;
}

impl ModeExt for Mode {
    fn should_process_files(&self) -> bool {
        matches!(
            self,
            Mode::Full | Mode::FilesOnly | Mode::ContentOnly | Mode::NamesOnly
        )
    }

    fn should_process_dirs(&self) -> bool {
        matches!(self, Mode::Full | Mode::DirsOnly | Mode::NamesOnly)
    }
}