use std::fs;
use std::io::{Read, Seek, SeekFrom, Write};
use std::path::{Path, PathBuf};

use rand::Rng;
use rayon::prelude::*;
use std::os::unix::fs::PermissionsExt;

use crate::compression;
use crate::crypto;
use crate::format::{self, Header, TocEntry, HEADER_SIZE};

/// Processed file data collected during Pass 1 of pack.
struct ProcessedFile {
    name: String,
    entry_type: u8,    // 0x00 = file, 0x01 = directory
    permissions: u16,   // Lower 12 bits of POSIX mode_t
    original_size: u32,
    compressed_size: u32,
    encrypted_size: u32,
    iv: [u8; 16],
    hmac: [u8; 32],
    sha256: [u8; 32],
    compression_flag: u8,
    ciphertext: Vec<u8>,
    padding_after: u16,
    padding_bytes: Vec<u8>,
}

/// Collected entry from the directory walk (before crypto processing).
///
/// Separates the fast sequential path-collection phase from the
/// parallelizable crypto-processing phase.
enum CollectedEntry {
    Dir {
        name: String,
        permissions: u16,
    },
    File {
        path: PathBuf,
        name: String,
        permissions: u16,
    },
}

/// Read and de-obfuscate archive header and TOC entries.
///
/// Handles XOR header bootstrapping (FORMAT.md Section 10 steps 1-3),
/// optional salt reading (between header and TOC), and TOC decryption
/// (Section 10 step 4) automatically.
/// Used by both unpack() and inspect().
///
/// When `key` is `None` and the TOC is encrypted, returns `Ok((header, vec![], salt))`.
/// The caller can check `header.flags & 0x02` to determine if entries were omitted.
fn read_archive_metadata(file: &mut fs::File, key: Option<&[u8; 32]>) -> anyhow::Result<(Header, Vec<TocEntry>, Option<[u8; 16]>)> {
    // Step 1-3: Read header with XOR bootstrapping
    let header = format::read_header_auto(file)?;

    // Read salt if present (between header and TOC)
    let salt = format::read_salt(file, &header)?;

    // Step 4: Read TOC (possibly encrypted)
    file.seek(SeekFrom::Start(header.toc_offset as u64))?;
    let mut toc_raw = vec![0u8; header.toc_size as usize];
    file.read_exact(&mut toc_raw)?;

    let entries = if header.flags & 0x02 != 0 {
        // TOC is encrypted
        if let Some(k) = key {
            // Decrypt with toc_iv, then parse
            let toc_plaintext = crypto::decrypt_data(&toc_raw, k, &header.toc_iv)?;
            format::read_toc_from_buf(&toc_plaintext, header.file_count)?
        } else {
            // No key provided: cannot decrypt TOC
            vec![]
        }
    } else {
        // TOC is plaintext: parse directly
        format::read_toc_from_buf(&toc_raw, header.file_count)?
    };

    Ok((header, entries, salt))
}

/// Read just the salt from an archive (for password-based key derivation before full unpack).
pub fn read_archive_salt(archive: &Path) -> anyhow::Result<Option<[u8; 16]>> {
    let mut file = fs::File::open(archive)?;
    let header = format::read_header_auto(&mut file)?;
    format::read_salt(&mut file, &header)
}

/// Get Unix permission bits (lower 12 bits of mode_t) for a path.
fn get_permissions(path: &Path) -> anyhow::Result<u16> {
    let metadata = fs::metadata(path)?;
    Ok((metadata.permissions().mode() & 0o7777) as u16)
}

/// Process a single file through the crypto pipeline, returning a ProcessedFile.
///
/// Thread-safe: creates a thread-local RNG instead of accepting an external one.
fn process_file(
    file_path: &Path,
    name: String,
    permissions: u16,
    no_compress: &[String],
    key: &[u8; 32],
) -> anyhow::Result<ProcessedFile> {
    let data = fs::read(file_path)?;

    // Validate file size <= u32::MAX
    anyhow::ensure!(
        data.len() <= u32::MAX as usize,
        "File too large: {} ({} bytes exceeds 4 GB limit)",
        file_path.display(),
        data.len()
    );

    // Step 1: SHA-256 of original data
    let sha256 = crypto::sha256_hash(&data);

    // Step 2: Determine compression and compress if needed
    let should_compress = compression::should_compress(&name, no_compress);
    let (compressed_data, compression_flag) = if should_compress {
        let compressed = compression::compress(&data)?;
        (compressed, 1u8)
    } else {
        (data.clone(), 0u8)
    };

    let original_size = data.len() as u32;
    let compressed_size = compressed_data.len() as u32;

    // Step 3: Generate random IV
    let iv = crypto::generate_iv();

    // Step 4: Encrypt
    let ciphertext = crypto::encrypt_data(&compressed_data, key, &iv);
    let encrypted_size = ciphertext.len() as u32;

    // Step 5: Compute HMAC over IV || ciphertext
    let hmac = crypto::compute_hmac(key, &iv, &ciphertext);

    // Step 6: Generate decoy padding (FORMAT.md Section 9.3)
    let mut rng = rand::rng();
    let padding_after: u16 = rng.random_range(64..=4096);
    let mut padding_bytes = vec![0u8; padding_after as usize];
    rand::Fill::fill(&mut padding_bytes[..], &mut rng);

    Ok(ProcessedFile {
        name,
        entry_type: 0,
        permissions,
        original_size,
        compressed_size,
        encrypted_size,
        iv,
        hmac,
        sha256,
        compression_flag,
        ciphertext,
        padding_after,
        padding_bytes,
    })
}

/// Create a ProcessedFile for a directory entry (no data block).
fn make_directory_entry(name: String, permissions: u16) -> ProcessedFile {
    ProcessedFile {
        name,
        entry_type: 1,
        permissions,
        original_size: 0,
        compressed_size: 0,
        encrypted_size: 0,
        iv: [0u8; 16],
        hmac: [0u8; 32],
        sha256: [0u8; 32],
        compression_flag: 0,
        ciphertext: Vec::new(),
        padding_after: 0,
        padding_bytes: Vec::new(),
    }
}

/// Recursively collect paths from a directory (no crypto processing).
///
/// Entries are emitted in parent-before-child order (DFS preorder).
/// The base_name is the top-level directory name used as prefix for all relative paths.
fn collect_directory_paths(
    dir_path: &Path,
    base_name: &str,
) -> anyhow::Result<Vec<CollectedEntry>> {
    let mut entries = Vec::new();

    // Add the directory itself first (parent-before-child)
    let dir_perms = get_permissions(dir_path)?;
    entries.push(CollectedEntry::Dir {
        name: base_name.to_string(),
        permissions: dir_perms,
    });

    // Collect children sorted by name for deterministic ordering
    let mut children: Vec<fs::DirEntry> = fs::read_dir(dir_path)?
        .collect::<Result<Vec<_>, _>>()?;
    children.sort_by_key(|e| e.file_name());

    for child in children {
        let child_path = child.path();
        let child_name = format!(
            "{}/{}",
            base_name,
            child.file_name().to_str()
                .ok_or_else(|| anyhow::anyhow!("Non-UTF-8 filename: {}", child_path.display()))?
        );

        // Use symlink_metadata to avoid following symlinks.
        // is_dir()/is_file() follow symlinks, which can cause infinite
        // recursion or massively inflated entry counts with symlink farms
        // (e.g., pnpm node_modules with hundreds of directory symlinks).
        let meta = fs::symlink_metadata(&child_path)?;

        if meta.file_type().is_symlink() {
            eprintln!(
                "Warning: skipping symlink: {}",
                child_path.display()
            );
            continue;
        } else if meta.is_dir() {
            // Recurse into real subdirectory (not a symlink)
            let sub_entries = collect_directory_paths(
                &child_path,
                &child_name,
            )?;
            entries.extend(sub_entries);
        } else {
            // Collect file path for later parallel processing
            let file_perms = (meta.permissions().mode() & 0o7777) as u16;
            entries.push(CollectedEntry::File {
                path: child_path,
                name: child_name,
                permissions: file_perms,
            });
        }
    }

    Ok(entries)
}

/// Collect all entry paths from input paths (files and directories).
///
/// Returns a list of CollectedEntry items in deterministic order,
/// ready for parallel processing of file entries.
fn collect_paths(inputs: &[PathBuf]) -> anyhow::Result<Vec<CollectedEntry>> {
    let mut collected = Vec::new();

    for input_path in inputs {
        // Check for symlinks at top level too
        let meta = fs::symlink_metadata(input_path)?;
        if meta.file_type().is_symlink() {
            eprintln!(
                "Warning: skipping symlink: {}",
                input_path.display()
            );
            continue;
        }

        if meta.is_dir() {
            // Get the directory's own name for the archive prefix
            let dir_name = input_path
                .file_name()
                .ok_or_else(|| anyhow::anyhow!("Invalid directory path: {}", input_path.display()))?
                .to_str()
                .ok_or_else(|| anyhow::anyhow!("Non-UTF-8 directory name: {}", input_path.display()))?
                .to_string();

            let dir_entries = collect_directory_paths(input_path, &dir_name)?;
            collected.extend(dir_entries);
        } else {
            // Single file: use just the filename
            let name = input_path
                .file_name()
                .ok_or_else(|| anyhow::anyhow!("Invalid file path: {}", input_path.display()))?
                .to_str()
                .ok_or_else(|| anyhow::anyhow!("Non-UTF-8 filename: {}", input_path.display()))?
                .to_string();

            let file_perms = get_permissions(input_path)?;
            collected.push(CollectedEntry::File {
                path: input_path.clone(),
                name,
                permissions: file_perms,
            });
        }
    }

    Ok(collected)
}

/// Pack files and directories into an encrypted archive.
///
/// Two-pass algorithm with full obfuscation and parallel file processing:
///   Pass 1a: Walk directory tree sequentially, collect paths in deterministic order.
///   Pass 1b: Process file entries in parallel (read, hash, compress, encrypt, padding).
///            Directory entries become zero-length entries (no processing needed).
///   Pass 2:  Encrypt TOC, compute offsets, XOR header, write archive sequentially.
pub fn pack(files: &[PathBuf], output: &Path, no_compress: &[String], key: &[u8; 32], salt: Option<&[u8; 16]>) -> anyhow::Result<()> {
    anyhow::ensure!(!files.is_empty(), "No input files specified");

    // --- Pass 1a: Collect paths sequentially (fast, deterministic) ---
    let collected = collect_paths(files)?;

    anyhow::ensure!(!collected.is_empty(), "No entries to archive");

    // Guard against u16 overflow: file_count field in header is u16 (max 65535)
    anyhow::ensure!(
        collected.len() <= u16::MAX as usize,
        "Too many entries: {} exceeds maximum of {} (u16 file_count limit)",
        collected.len(),
        u16::MAX
    );

    // --- Pass 1b: Process files in parallel, directories inline ---
    // We use par_iter on the collected entries while preserving their order.
    // Each entry is processed independently; file entries go through the full
    // crypto pipeline in parallel, directory entries are trivially converted.
    let processed: Vec<ProcessedFile> = collected
        .into_par_iter()
        .map(|entry| match entry {
            CollectedEntry::Dir { name, permissions } => {
                Ok(make_directory_entry(name, permissions))
            }
            CollectedEntry::File { path, name, permissions } => {
                process_file(&path, name, permissions, no_compress, key)
            }
        })
        .collect::<anyhow::Result<Vec<_>>>()?;

    // Count files and directories
    let file_count = processed.iter().filter(|pf| pf.entry_type == 0).count();
    let dir_count = processed.iter().filter(|pf| pf.entry_type == 1).count();

    // --- Pass 2: Compute offsets and write archive ---

    // Determine flags byte: bit 0 if any file is compressed, bits 1-3 for obfuscation
    let any_compressed = processed.iter().any(|pf| pf.compression_flag == 1);
    let mut flags: u8 = if any_compressed { 0x01 } else { 0x00 };
    // Enable all three obfuscation features
    flags |= 0x02; // bit 1: TOC encrypted
    flags |= 0x04; // bit 2: XOR header
    flags |= 0x08; // bit 3: decoy padding
    // Set KDF salt flag if password-derived key
    if salt.is_some() {
        flags |= format::FLAG_KDF_SALT; // bit 4: KDF salt present
    }

    // Build TOC entries (with placeholder data_offset=0, will be set after toc_size known)
    let toc_entries: Vec<TocEntry> = processed
        .iter()
        .map(|pf| TocEntry {
            name: pf.name.clone(),
            entry_type: pf.entry_type,
            permissions: pf.permissions,
            original_size: pf.original_size,
            compressed_size: pf.compressed_size,
            encrypted_size: pf.encrypted_size,
            data_offset: 0, // placeholder
            iv: pf.iv,
            hmac: pf.hmac,
            sha256: pf.sha256,
            compression_flag: pf.compression_flag,
            padding_after: pf.padding_after,
        })
        .collect();

    // Serialize TOC to get plaintext size, then encrypt to get final toc_size
    let toc_plaintext = format::serialize_toc(&toc_entries)?;

    // Generate TOC IV and encrypt
    let toc_iv = crypto::generate_iv();
    let encrypted_toc = crypto::encrypt_data(&toc_plaintext, key, &toc_iv);
    let encrypted_toc_size = encrypted_toc.len() as u32;

    let toc_offset = if salt.is_some() {
        HEADER_SIZE + format::SALT_SIZE
    } else {
        HEADER_SIZE
    };

    // Compute data offsets (accounting for encrypted TOC size and padding)
    // Directory entries are skipped (no data block).
    let data_block_start = toc_offset + encrypted_toc_size;
    let mut data_offsets: Vec<u32> = Vec::with_capacity(processed.len());
    let mut current_offset = data_block_start;
    for pf in &processed {
        if pf.entry_type == 1 {
            // Directory: no data block, offset is 0
            data_offsets.push(0);
        } else {
            data_offsets.push(current_offset);
            current_offset += pf.encrypted_size + pf.padding_after as u32;
        }
    }

    // Now re-serialize TOC with correct data_offsets
    let final_toc_entries: Vec<TocEntry> = processed
        .iter()
        .enumerate()
        .map(|(i, pf)| TocEntry {
            name: pf.name.clone(),
            entry_type: pf.entry_type,
            permissions: pf.permissions,
            original_size: pf.original_size,
            compressed_size: pf.compressed_size,
            encrypted_size: pf.encrypted_size,
            data_offset: data_offsets[i],
            iv: pf.iv,
            hmac: pf.hmac,
            sha256: pf.sha256,
            compression_flag: pf.compression_flag,
            padding_after: pf.padding_after,
        })
        .collect();

    let final_toc_plaintext = format::serialize_toc(&final_toc_entries)?;
    let final_encrypted_toc = crypto::encrypt_data(&final_toc_plaintext, key, &toc_iv);
    let final_encrypted_toc_size = final_encrypted_toc.len() as u32;

    // Sanity check: encrypted TOC size should not change (same plaintext length)
    assert_eq!(
        encrypted_toc_size, final_encrypted_toc_size,
        "TOC encrypted size changed unexpectedly"
    );

    // Create header
    let header = Header {
        version: format::VERSION,
        flags,
        file_count: processed.len() as u16,
        toc_offset,
        toc_size: final_encrypted_toc_size,
        toc_iv,
        reserved: [0u8; 8],
    };

    // Serialize header to buffer and XOR
    let mut header_buf = format::write_header_to_buf(&header);
    format::xor_header_buf(&mut header_buf);

    // Open output file
    let mut out_file = fs::File::create(output)?;

    // Write XOR'd header
    out_file.write_all(&header_buf)?;

    // Write salt if present (between header and TOC)
    if let Some(s) = salt {
        format::write_salt(&mut out_file, s)?;
    }

    // Write encrypted TOC
    out_file.write_all(&final_encrypted_toc)?;

    // Write data blocks with interleaved decoy padding (skip directory entries)
    for pf in &processed {
        if pf.entry_type == 1 {
            continue; // directories have no data block
        }
        out_file.write_all(&pf.ciphertext)?;
        out_file.write_all(&pf.padding_bytes)?;
    }

    let total_bytes = current_offset;
    println!(
        "Packed {} entries ({} files, {} directories) into {} ({} bytes)",
        processed.len(),
        file_count,
        dir_count,
        output.display(),
        total_bytes
    );

    Ok(())
}

/// Inspect archive metadata.
///
/// Without a key: displays header fields only (version, flags, file_count, etc.).
/// If the TOC is encrypted and no key is provided, prints a message indicating
/// that a key is needed to see the entry listing.
///
/// With a key: decrypts TOC and displays full entry listing (file names, sizes, etc.).
pub fn inspect(archive: &Path, key: Option<&[u8; 32]>) -> anyhow::Result<()> {
    let mut file = fs::File::open(archive)?;

    // Read header and TOC (TOC may be empty if encrypted and no key provided)
    let (header, entries, _salt) = read_archive_metadata(&mut file, key)?;

    // Print header info
    let filename = archive
        .file_name()
        .map(|s| s.to_string_lossy().to_string())
        .unwrap_or_else(|| archive.display().to_string());

    println!("Archive: {}", filename);
    println!("Version: {}", header.version);
    println!("Flags: 0x{:02X}", header.flags);
    println!("Entries: {}", header.file_count);
    println!("TOC offset: {}", header.toc_offset);
    println!("TOC size: {}", header.toc_size);
    println!();

    // Check if TOC was encrypted but we had no key
    if entries.is_empty() && header.file_count > 0 && header.flags & 0x02 != 0 && key.is_none() {
        println!("TOC is encrypted, provide a key to see entry listing");
        return Ok(());
    }

    // Print each entry
    let mut total_original: u64 = 0;
    for (i, entry) in entries.iter().enumerate() {
        let type_str = if entry.entry_type == 1 { "dir" } else { "file" };
        let perms_str = format!("{:04o}", entry.permissions);

        println!("[{}] {} ({}, {})", i, entry.name, type_str, perms_str);
        println!("    Permissions: {}", perms_str);

        if entry.entry_type == 0 {
            // File entry: show size and crypto details
            let compression_str = if entry.compression_flag == 1 {
                "yes"
            } else {
                "no"
            };

            println!("    Original: {} bytes", entry.original_size);
            println!("    Compressed: {} bytes", entry.compressed_size);
            println!("    Encrypted: {} bytes", entry.encrypted_size);
            println!("    Offset: {}", entry.data_offset);
            println!("    Compression: {}", compression_str);
            println!("    Padding after: {} bytes", entry.padding_after);
            println!(
                "    IV: {}",
                entry.iv.iter().map(|b| format!("{:02x}", b)).collect::<String>()
            );
            println!(
                "    HMAC: {}",
                entry.hmac.iter().map(|b| format!("{:02x}", b)).collect::<String>()
            );
            println!(
                "    SHA-256: {}",
                entry.sha256.iter().map(|b| format!("{:02x}", b)).collect::<String>()
            );

            total_original += entry.original_size as u64;
        }
    }

    println!();
    println!("Total original size: {} bytes", total_original);

    Ok(())
}

/// Data read from the archive for a single entry, ready for parallel processing.
enum ReadEntry {
    /// Directory entry: just needs creation and permission setting.
    Dir {
        name: String,
        permissions: u16,
    },
    /// File entry: ciphertext has been read, ready for verify/decrypt/decompress/write.
    File {
        entry: TocEntry,
        ciphertext: Vec<u8>,
    },
    /// Entry with unsafe name that was skipped during reading.
    Skipped {
        _name: String,
    },
}

/// Result of processing a single file entry during parallel unpack.
enum UnpackResult {
    /// File extracted successfully.
    Ok { name: String, original_size: u32 },
    /// File had a verification error but was still written (SHA-256 mismatch).
    Written { name: String, original_size: u32 },
    /// File processing failed (HMAC, decryption, or decompression error).
    Error { name: String, message: String },
}

/// Unpack an encrypted archive, extracting all files and directories with
/// HMAC and SHA-256 verification, and Unix permission restoration.
///
/// Uses parallel processing for the verify/decrypt/decompress/write pipeline:
///   1. Read header and TOC sequentially (single file handle).
///   2. Create all directories sequentially (ensures parent dirs exist).
///   3. Read all file ciphertexts sequentially from the archive.
///   4. Process and write files in parallel (HMAC, decrypt, decompress, SHA-256, write).
pub fn unpack(archive: &Path, output_dir: &Path, key: &[u8; 32]) -> anyhow::Result<()> {
    let mut file = fs::File::open(archive)?;

    // Read header and TOC with full de-obfuscation
    let (_header, entries, _salt) = read_archive_metadata(&mut file, Some(key))?;

    // Create output directory
    fs::create_dir_all(output_dir)?;

    let entry_count = entries.len();

    // --- Phase 1: Sequential read of all entry data ---
    // Separate directories from files, read ciphertexts for files.
    let mut read_entries: Vec<ReadEntry> = Vec::with_capacity(entry_count);

    for entry in entries {
        // Sanitize filename: reject directory traversal
        if entry.name.starts_with('/') || entry.name.contains("..") {
            eprintln!(
                "Skipping entry with unsafe name: {} (directory traversal attempt)",
                entry.name
            );
            read_entries.push(ReadEntry::Skipped { _name: entry.name.clone() });
            continue;
        }

        if entry.entry_type == 1 {
            read_entries.push(ReadEntry::Dir {
                name: entry.name.clone(),
                permissions: entry.permissions,
            });
        } else {
            // Seek to data_offset and read ciphertext into memory
            file.seek(SeekFrom::Start(entry.data_offset as u64))?;
            let mut ciphertext = vec![0u8; entry.encrypted_size as usize];
            file.read_exact(&mut ciphertext)?;

            read_entries.push(ReadEntry::File {
                entry,
                ciphertext,
            });
        }
    }

    // --- Phase 2: Create directories sequentially (parent-before-child order) ---
    let mut dir_count: usize = 0;
    for re in &read_entries {
        if let ReadEntry::Dir { name, permissions } = re {
            let output_path = output_dir.join(name);
            fs::create_dir_all(&output_path)?;
            fs::set_permissions(
                &output_path,
                fs::Permissions::from_mode(*permissions as u32),
            )?;
            println!("Created directory: {}", name);
            dir_count += 1;
        }
    }

    // --- Phase 3: Process and write files in parallel ---
    // Count skipped entries from phase 1
    let skipped_count = read_entries.iter()
        .filter(|re| matches!(re, ReadEntry::Skipped { .. }))
        .count();

    // Collect only file entries for parallel processing
    let file_entries: Vec<(&TocEntry, &Vec<u8>)> = read_entries.iter()
        .filter_map(|re| {
            if let ReadEntry::File { entry, ciphertext } = re {
                Some((entry, ciphertext))
            } else {
                None
            }
        })
        .collect();

    // Process all files in parallel: HMAC verify, decrypt, decompress, SHA-256, write
    let results: Vec<UnpackResult> = file_entries
        .par_iter()
        .map(|(entry, ciphertext)| {
            let output_path = output_dir.join(&entry.name);

            // Create parent directories if name contains path separators
            if let Some(parent) = output_path.parent() {
                if let Err(e) = fs::create_dir_all(parent) {
                    return UnpackResult::Error {
                        name: entry.name.clone(),
                        message: format!("Failed to create parent directory: {}", e),
                    };
                }
            }

            // Step 1: Verify HMAC FIRST (encrypt-then-MAC)
            if !crypto::verify_hmac(key, &entry.iv, ciphertext, &entry.hmac) {
                return UnpackResult::Error {
                    name: entry.name.clone(),
                    message: "HMAC verification failed".to_string(),
                };
            }

            // Step 2: Decrypt
            let decrypted = match crypto::decrypt_data(ciphertext, key, &entry.iv) {
                Ok(data) => data,
                Err(e) => {
                    return UnpackResult::Error {
                        name: entry.name.clone(),
                        message: format!("Decryption failed: {}", e),
                    };
                }
            };

            // Step 3: Decompress if compressed
            let decompressed = if entry.compression_flag == 1 {
                match compression::decompress(&decrypted) {
                    Ok(data) => data,
                    Err(e) => {
                        return UnpackResult::Error {
                            name: entry.name.clone(),
                            message: format!("Decompression failed: {}", e),
                        };
                    }
                }
            } else {
                decrypted
            };

            // Step 4: Verify SHA-256
            let computed_sha256 = crypto::sha256_hash(&decompressed);
            let sha256_ok = computed_sha256 == entry.sha256;

            // Step 5: Write file (even if SHA-256 mismatch, per spec)
            if let Err(e) = fs::write(&output_path, &decompressed) {
                return UnpackResult::Error {
                    name: entry.name.clone(),
                    message: format!("Write failed: {}", e),
                };
            }

            // Step 6: Set file permissions
            if let Err(e) = fs::set_permissions(
                &output_path,
                fs::Permissions::from_mode(entry.permissions as u32),
            ) {
                return UnpackResult::Error {
                    name: entry.name.clone(),
                    message: format!("Failed to set permissions: {}", e),
                };
            }

            if sha256_ok {
                UnpackResult::Ok {
                    name: entry.name.clone(),
                    original_size: entry.original_size,
                }
            } else {
                UnpackResult::Written {
                    name: entry.name.clone(),
                    original_size: entry.original_size,
                }
            }
        })
        .collect();

    // --- Phase 4: Report results (sequential for deterministic output) ---
    let mut final_error_count = skipped_count;
    let mut final_success_count = dir_count;

    for result in &results {
        match result {
            UnpackResult::Ok { name, original_size } => {
                println!("Extracted: {} ({} bytes)", name, original_size);
                final_success_count += 1;
            }
            UnpackResult::Written { name, original_size } => {
                eprintln!("SHA-256 mismatch for {} (data may be corrupted)", name);
                println!("Extracted: {} ({} bytes)", name, original_size);
                final_error_count += 1;
                // Original code increments both error_count AND success_count for
                // SHA-256 mismatch (file is still written and counted as extracted).
                final_success_count += 1;
            }
            UnpackResult::Error { name, message } => {
                eprintln!("{} for {}, skipping", message, name);
                final_error_count += 1;
            }
        }
    }

    println!(
        "Extracted {}/{} entries",
        final_success_count, entry_count
    );

    if final_error_count > 0 {
        anyhow::bail!("{} entry(ies) had verification errors", final_error_count);
    }

    Ok(())
}