#!/usr/bin/env python3
"""Maintain zipped render sequences for Git hooks.

Default mode scans `Renders/`, produces ZIP archives under `Renders/_zipped/`,
and stages any updated archives so commits only track compact files. Switch to
`--mode expand` to inflate the tracked archives back into the ignored working
directories after checkouts or pulls.
"""

from __future__ import annotations

import argparse
import json
import os
import platform
import shutil
import subprocess
import sys
import tempfile
import time
from concurrent.futures import ThreadPoolExecutor, as_completed
from pathlib import Path
from typing import Iterator, Sequence

# Try to import psutil for cross-platform RAM detection
try:
    import psutil
    HAS_PSUTIL = True
except ImportError:
    HAS_PSUTIL = False
    # For Windows fallback
    if platform.system() == "Windows":
        try:
            import ctypes
            HAS_CTYPES = True
        except ImportError:
            HAS_CTYPES = False
    else:
        HAS_CTYPES = False


RENDER_ROOT = Path("Renders")
ARCHIVE_ROOT = RENDER_ROOT / "_zipped"
SEQUENCE_EXTENSIONS = {
    ".png",
    ".jpg",
    ".jpeg",
    ".tif",
    ".tiff",
    ".exr",
}
STATE_SUFFIX = ".meta.json"
DEFAULT_CONFIG = {
    "zipper": "7z",
    "compression": 9,
    "dailyFormat": "daily_YYMMDD",
    "Max7zInst": 0,  # Maximum concurrent 7z instances (0 = auto-calculate)
}


def load_config() -> dict:
    # First try to load from project's .config folder (current working directory)
    # Then fall back to ProjectStructure repo config (next to zip_sequences.py)
    cwd = Path.cwd()
    project_config = cwd / ".config" / "config.json"
    repo_config = Path(__file__).resolve().with_name("config.json")
    
    config_paths = [
        ("project", project_config),
        ("repo", repo_config),
    ]
    
    for source, config_path in config_paths:
        try:
            if config_path.exists():
                text = config_path.read_text(encoding="utf-8")
                try:
                    data = json.loads(text)
                    if isinstance(data, dict):
                        merged = DEFAULT_CONFIG.copy()
                        merged.update(data)
                        return merged
                except json.JSONDecodeError:
                    continue
        except OSError:
            continue
    
    # If no config found, return defaults
    return DEFAULT_CONFIG.copy()


CONFIG = load_config()
zipper_val = CONFIG.get("zipper", "7z")
# Handle both old boolean format and new string format
if isinstance(zipper_val, bool):
    ZIPPER_TYPE = "7z" if zipper_val else "zip"
else:
    ZIPPER_TYPE = str(zipper_val).lower()

COMPRESSION_LEVEL = CONFIG.get("compression", 9)
if isinstance(COMPRESSION_LEVEL, str):
    try:
        COMPRESSION_LEVEL = int(COMPRESSION_LEVEL)
    except ValueError:
        COMPRESSION_LEVEL = 9
if not isinstance(COMPRESSION_LEVEL, int):
    COMPRESSION_LEVEL = 9
COMPRESSION_LEVEL = max(0, min(9, COMPRESSION_LEVEL))

MAX_7Z_INSTANCES = CONFIG.get("Max7zInst", 0)
if MAX_7Z_INSTANCES is not None:
    if isinstance(MAX_7Z_INSTANCES, str):
        try:
            MAX_7Z_INSTANCES = int(MAX_7Z_INSTANCES)
        except ValueError:
            MAX_7Z_INSTANCES = 0
    if not isinstance(MAX_7Z_INSTANCES, int) or MAX_7Z_INSTANCES < 1:
        MAX_7Z_INSTANCES = 0
# Treat 0 as None (auto-calculate)
if MAX_7Z_INSTANCES == 0:
    MAX_7Z_INSTANCES = None

SEVEN_Z_EXE: str | None = None
if ZIPPER_TYPE == "7z":
    SEVEN_Z_EXE = shutil.which("7z") or shutil.which("7za")


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Sync render sequences with zipped archives.")
    parser.add_argument(
        "--mode",
        choices=("zip", "expand"),
        default="zip",
        help="zip sequences for commit (default) or expand tracked archives",
    )
    parser.add_argument("--jobs", type=int, help="max parallel workers")
    parser.add_argument("--verbose", action="store_true", help="print extra progress details")
    return parser.parse_args()


def get_available_ram() -> int | None:
    """Get available RAM in bytes, reserving 20% for system.
    
    Returns:
        Available RAM in bytes, or None if detection fails.
    """
    try:
        if HAS_PSUTIL:
            # Use psutil for cross-platform RAM detection
            mem = psutil.virtual_memory()
            # Reserve 20% for system, use 80% for compression jobs
            available = int(mem.total * 0.8)
            return available
        elif HAS_CTYPES and platform.system() == "Windows":
            # Windows fallback using ctypes
            class MEMORYSTATUSEX(ctypes.Structure):
                _fields_ = [
                    ("dwLength", ctypes.c_ulong),
                    ("dwMemoryLoad", ctypes.c_ulong),
                    ("ullTotalPhys", ctypes.c_ulonglong),
                    ("ullAvailPhys", ctypes.c_ulonglong),
                    ("ullTotalPageFile", ctypes.c_ulonglong),
                    ("ullAvailPageFile", ctypes.c_ulonglong),
                    ("ullTotalVirtual", ctypes.c_ulonglong),
                    ("ullAvailVirtual", ctypes.c_ulonglong),
                    ("ullAvailExtendedVirtual", ctypes.c_ulonglong),
                ]
            
            kernel32 = ctypes.windll.kernel32
            kernel32.GlobalMemoryStatusEx.argtypes = [ctypes.POINTER(MEMORYSTATUSEX)]
            kernel32.GlobalMemoryStatusEx.restype = ctypes.c_bool
            
            mem_status = MEMORYSTATUSEX()
            mem_status.dwLength = ctypes.sizeof(MEMORYSTATUSEX)
            
            if kernel32.GlobalMemoryStatusEx(ctypes.byref(mem_status)):
                # Reserve 20% for system, use 80% for compression jobs
                available = int(mem_status.ullTotalPhys * 0.8)
                return available
    except Exception:
        pass
    
    return None


def estimate_ram_per_job(seq_dir: Path, seq_state: dict) -> int:
    """Estimate RAM usage per compression job based on folder size.
    
    Args:
        seq_dir: Path to the sequence directory
        seq_state: State dictionary containing file information
        
    Returns:
        Estimated RAM usage in bytes
    """
    # Calculate total folder size from seq_state
    total_bytes = sum(entry.get("size", 0) for entry in seq_state.get("files", []))
    
    if ZIPPER_TYPE == "7z":
        # Base RAM: 500MB per job
        base_ram = 500 * 1024 * 1024  # 500 MB
        
        # Compression factor: 7z can use significant RAM, especially for large files
        # Use 0.15x factor (conservative estimate accounting for 7z's 80% usage)
        compression_factor = 0.15
        
        # For very large folders (>10GB), cap at 8GB per job
        max_ram_per_job = 8 * 1024 * 1024 * 1024  # 8 GB
        large_folder_threshold = 10 * 1024 * 1024 * 1024  # 10 GB
        
        if total_bytes > large_folder_threshold:
            estimated_ram = max_ram_per_job
        else:
            estimated_ram = max(base_ram, int(total_bytes * compression_factor))
            estimated_ram = min(estimated_ram, max_ram_per_job)
        
        return estimated_ram
    else:
        # zip compression is more memory-efficient
        # Conservative estimate: 1GB per job
        return 1024 * 1024 * 1024  # 1 GB


def max_workers(
    requested: int | None,
    work_items: list[tuple[Path, Path, Path, dict]] | None = None,
    *,
    verbose: bool = False
) -> tuple[int, int | None]:
    """Calculate maximum worker count based on CPU and RAM constraints.
    
    Args:
        requested: User-requested worker count (from --jobs)
        work_items: List of work items (seq_dir, zip_path, state_path, seq_state)
        verbose: Whether to log RAM-based calculations
        
    Returns:
        Tuple of (worker_count, per_job_memory_limit_bytes)
        per_job_memory_limit_bytes is None if not using 7z or RAM detection failed
    """
    cpu = os.cpu_count() or 1
    cpu_limit = max(1, min(8, cpu))
    if requested and requested > 0:
        cpu_limit = min(requested, max(1, cpu))
    
    # If no work items provided, return CPU-based limit
    if work_items is None or len(work_items) == 0:
        return (cpu_limit, None)
    
    # Try to calculate RAM-based limit
    available_ram = get_available_ram()
    
    if available_ram is None:
        # RAM detection failed, fall back to CPU limit
        if verbose:
            log("zip", "RAM detection failed, using CPU-based worker limit", verbose_only=True, verbose=verbose)
        return (cpu_limit, None)
    
    # For 7z: use fixed dictionary size and calculate workers
    if ZIPPER_TYPE == "7z":
        # Fixed dictionary size: 1GB (1024MB)
        FIXED_DICT_SIZE_MB = 1024
        fixed_dict_size_bytes = FIXED_DICT_SIZE_MB * 1024 * 1024
        
        # Check if Max7zInst is configured
        if MAX_7Z_INSTANCES is not None:
            # Use configured maximum instances, but still respect user's --jobs
            final_limit = MAX_7Z_INSTANCES
            if requested and requested > 0:
                final_limit = min(final_limit, requested)
            
            if verbose:
                log(
                    "zip",
                    f"Using Max7zInst={MAX_7Z_INSTANCES} from config → "
                    f"requested: {requested}, final: {final_limit}",
                    verbose_only=True,
                    verbose=verbose
                )
            
            return (final_limit, fixed_dict_size_bytes)
        
        # Auto-calculate based on RAM if Max7zInst not configured
        if available_ram is not None:
            # 7z uses ~2-3x dictionary size in RAM, but with overhead use 8x for safety
            # This accounts for 7z's internal buffers, OS overhead, and other processes
            FIXED_RAM_PER_JOB = FIXED_DICT_SIZE_MB * 8 * 1024 * 1024  # 8GB per job
            
            # available_ram is already 80% of total (20% reserved for system)
            # Use only 40% of that for compression jobs (very conservative to prevent swapping)
            compression_ram = int(available_ram * 0.4)
            
            # Calculate worker limit based on fixed per-job RAM
            ram_limit = max(1, compression_ram // FIXED_RAM_PER_JOB)
            
            # Use RAM limit directly (no CPU limit)
            final_limit = ram_limit
            if requested and requested > 0:
                final_limit = min(final_limit, requested)
            
            if verbose:
                ram_gb = available_ram / (1024 ** 3)
                compression_ram_gb = compression_ram / (1024 ** 3)
                ram_per_job_gb = FIXED_RAM_PER_JOB / (1024 ** 3)
                log(
                    "zip",
                    f"RAM: {ram_gb:.1f}GB available (80% of total), {compression_ram_gb:.1f}GB for compression (40%), {ram_per_job_gb:.1f}GB per job (dict: {FIXED_DICT_SIZE_MB}MB) → "
                    f"RAM limit: {ram_limit}, requested: {requested}, final: {final_limit}",
                    verbose_only=True,
                    verbose=verbose
                )
            
            return (final_limit, fixed_dict_size_bytes)
        
        # RAM detection failed, use a safe default (no CPU limit)
        if verbose:
            log("zip", "RAM detection failed and Max7zInst not set, using default worker limit of 4", verbose_only=True, verbose=verbose)
        default_limit = 4
        if requested and requested > 0:
            default_limit = requested
        return (default_limit, fixed_dict_size_bytes)
    
    # For zip compression, use existing estimation-based approach
    # Estimate RAM per job for each work item
    ram_estimates = []
    for seq_dir, zip_path, state_path, seq_state in work_items:
        try:
            estimated_ram = estimate_ram_per_job(seq_dir, seq_state)
            ram_estimates.append(estimated_ram)
        except Exception:
            # If estimation fails, use fallback estimate
            ram_estimates.append(1024 * 1024 * 1024)  # 1GB fallback for zip
    
    if not ram_estimates:
        return (cpu_limit, None)
    
    max_ram_per_job = max(ram_estimates)
    ram_limit = max(1, available_ram // max_ram_per_job)
    ram_limit = min(ram_limit, 6)  # Conservative limit for zip
    final_limit = min(cpu_limit, ram_limit)
    
    if verbose:
        ram_gb = available_ram / (1024 ** 3)
        max_ram_gb = max_ram_per_job / (1024 ** 3)
        log(
            "zip",
            f"RAM: {ram_gb:.1f}GB available, ~{max_ram_gb:.1f}GB per job → "
            f"RAM limit: {ram_limit}, CPU limit: {cpu_limit}, final: {final_limit}",
            verbose_only=True,
            verbose=verbose
        )
    
    return (final_limit, None)


def log(mode: str, message: str, *, verbose_only: bool = False, verbose: bool = False) -> None:
    if verbose_only and not verbose:
        return
    print(f"[{mode}] {message}")


def is_archive_path(path: Path) -> bool:
    return any(part in ("_archive", "_CURRENT") for part in path.parts)


def find_sequence_dirs(root: Path) -> Iterator[Path]:
    for dirpath, dirnames, filenames in os.walk(root):
        path = Path(dirpath)
        dirnames[:] = [d for d in dirnames if d not in ("_archive", "_CURRENT")]
        if is_archive_path(path):
            continue
        has_frames = any(Path(dirpath, f).suffix.lower() in SEQUENCE_EXTENSIONS for f in filenames)
        if has_frames:
            yield path


def iter_sequence_files(seq_dir: Path) -> Iterator[Path]:
    for dirpath, dirnames, filenames in os.walk(seq_dir):
        path = Path(dirpath)
        dirnames[:] = [d for d in dirnames if d not in ("_archive", "_CURRENT")]
        if is_archive_path(path):
            continue
        for filename in filenames:
            yield path / filename


def compute_state(seq_dir: Path) -> dict:
    entries = []
    files = sorted(
        iter_sequence_files(seq_dir),
        key=lambda p: p.relative_to(seq_dir).as_posix(),
    )
    for file_path in files:
        stat = file_path.stat()
        entries.append(
            {
                "path": file_path.relative_to(seq_dir).as_posix(),
                "size": stat.st_size,
                "mtime_ns": stat.st_mtime_ns,
            }
        )
    return {"files": entries}


def current_state(seq_dir: Path) -> dict:
    if not seq_dir.exists() or not seq_dir.is_dir():
        return {"files": []}
    return compute_state(seq_dir)


def load_state(state_path: Path) -> dict | None:
    if not state_path.exists():
        return None
    try:
        return json.loads(state_path.read_text())
    except json.JSONDecodeError:
        return None


def state_changed(seq_state: dict, stored_state: dict | None) -> bool:
    if stored_state is None:
        return True
    return seq_state != stored_state


def archive_path_for(seq_dir: Path) -> Path:
    rel = seq_dir.relative_to(RENDER_ROOT)
    suffix = ".7z" if ZIPPER_TYPE == "7z" else ".zip"
    return (ARCHIVE_ROOT / rel).with_suffix(suffix)


def sequence_dir_for(zip_path: Path) -> Path:
    rel = zip_path.relative_to(ARCHIVE_ROOT)
    return (RENDER_ROOT / rel).with_suffix("")


def state_path_for(zip_path: Path) -> Path:
    return zip_path.with_suffix(zip_path.suffix + STATE_SUFFIX)


def zip_sequence(seq_dir: Path, zip_path: Path, per_job_memory_limit: int | None = None) -> None:
    if ZIPPER_TYPE == "7z":
        if SEVEN_Z_EXE is None:
            raise RuntimeError(
                "7z compression requested but 7z executable not found in PATH. "
                "Please install 7z (e.g., via Chocolatey: choco install 7zip) "
                "or set zipper to 'zip' in config.json"
            )
        zip_path.parent.mkdir(parents=True, exist_ok=True)
        
        # If creating a .7z file, remove any existing .zip file for the same sequence
        if zip_path.suffix == ".7z":
            old_zip_path = zip_path.with_suffix(".zip")
            if old_zip_path.exists():
                old_zip_path.unlink(missing_ok=True)
                old_state_path = state_path_for(old_zip_path)
                if old_state_path.exists():
                    old_state_path.unlink(missing_ok=True)
        
        # Build list of files to archive with relative paths
        file_list = []
        for file_path in iter_sequence_files(seq_dir):
            rel_path = file_path.relative_to(seq_dir).as_posix()
            file_list.append(rel_path)
        
        if not file_list:
            raise RuntimeError(f"No files found to archive in {seq_dir}")
        
        # Create zip in temporary location first to avoid issues with corrupted existing files
        temp_zip = None
        list_file_path = None
        try:
            # Create temporary archive file path (but don't create the file - let 7z create it)
            temp_zip_path = tempfile.mktemp(suffix=".7z", dir=zip_path.parent)
            temp_zip = Path(temp_zip_path)
            
            # Create list file with absolute path
            fd, temp_path = tempfile.mkstemp(suffix=".lst", text=True)
            list_file_path = Path(temp_path)
            with os.fdopen(fd, "w", encoding="utf-8") as list_file:
                for rel_path in file_list:
                    list_file.write(rel_path + "\n")
                list_file.flush()
                os.fsync(list_file.fileno())  # Ensure data is written to disk
            # File is closed here by context manager, small delay to ensure OS releases handle
            time.sleep(0.1)
            
            # Use absolute paths for both list file and temp zip
            list_file_abs = list_file_path.resolve()
            temp_zip_abs = temp_zip.resolve()
            # Create archive in temp location first (7z will create it fresh)
            cmd = [
                SEVEN_Z_EXE,
                "a",
                "-y",
                "-bb0",  # Suppress progress output
                f"-mx={COMPRESSION_LEVEL}",
                "-t7z",  # Use 7z format, not zip
            ]
            
            # Add fixed dictionary size if specified (7z memory usage is controlled by dictionary size)
            if per_job_memory_limit is not None:
                # per_job_memory_limit is actually the fixed dictionary size in bytes
                dict_size_mb = per_job_memory_limit // (1024 * 1024)
                cmd.append(f"-md={dict_size_mb}m")
            
            cmd.extend([
                str(temp_zip_abs),
                f"@{list_file_abs}",
            ])
            result = subprocess.run(
                cmd,
                cwd=seq_dir,
                check=False,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
                text=True,
            )
            if result.returncode != 0:
                error_msg = result.stderr.strip() if result.stderr else "Unknown error"
                if result.stdout:
                    error_msg += f"\nstdout: {result.stdout.strip()}"
                raise RuntimeError(f"7z compression failed: {error_msg}")
            
            # Move temp zip to final location, replacing any existing file
            if zip_path.exists():
                zip_path.unlink()
            temp_zip.replace(zip_path)
            temp_zip = None  # Mark as moved so we don't delete it
        finally:
            # Clean up temp zip if it wasn't moved
            if temp_zip and temp_zip.exists():
                try:
                    temp_zip.unlink(missing_ok=True)
                except OSError:
                    pass
            # Clean up list file, with retry in case 7z still has it open
            if list_file_path and list_file_path.exists():
                for attempt in range(3):
                    try:
                        list_file_path.unlink(missing_ok=True)
                        break
                    except PermissionError:
                        if attempt < 2:
                            time.sleep(0.1)  # Wait 100ms before retry
                        else:
                            # Last attempt failed, just log and continue
                            # The temp file will be cleaned up by the OS eventually
                            pass
        return

    # Use zipfile (only if ZIPPER_TYPE == "zip")
    if ZIPPER_TYPE == "zip":
        from zipfile import ZIP_DEFLATED, ZIP_STORED, ZipFile

        zip_path.parent.mkdir(parents=True, exist_ok=True)
        if COMPRESSION_LEVEL <= 0:
            compression = ZIP_STORED
            zip_kwargs = {}
        else:
            compression = ZIP_DEFLATED
            zip_kwargs = {"compresslevel": COMPRESSION_LEVEL}

        with ZipFile(zip_path, "w", compression=compression, **zip_kwargs) as archive:
            for file_path in iter_sequence_files(seq_dir):
                archive.write(file_path, arcname=file_path.relative_to(seq_dir).as_posix())
        return

    # Unknown ZIPPER_TYPE - fail with clear error
    raise RuntimeError(
        f"Unsupported ZIPPER_TYPE: {ZIPPER_TYPE!r}. "
        f"Expected '7z' or 'zip'. "
        f"Config zipper value: {CONFIG.get('zipper', 'not set')!r}"
    )


def expand_sequence(zip_path: Path, seq_state: dict) -> None:
    target_dir = sequence_dir_for(zip_path)
    if target_dir.exists():
        shutil.rmtree(target_dir)
    target_dir.mkdir(parents=True, exist_ok=True)

    if ZIPPER_TYPE == "7z":
        if SEVEN_Z_EXE is None:
            raise RuntimeError(
                "7z extraction requested but 7z executable not found in PATH. "
                "Please install 7z or set zipper to 'zip' in config.json"
            )
        cmd = [
            SEVEN_Z_EXE,
            "x",
            "-y",
            str(zip_path),
            f"-o{target_dir}",
        ]
        result = subprocess.run(
            cmd,
            check=False,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True,
        )
        if result.returncode != 0:
            error_msg = result.stderr.strip() if result.stderr else "Unknown error"
            if result.stdout:
                error_msg += f"\nstdout: {result.stdout.strip()}"
            raise RuntimeError(f"7z extraction failed: {error_msg}")
    elif ZIPPER_TYPE == "zip":
        from zipfile import ZipFile

        with ZipFile(zip_path, "r") as archive:
            archive.extractall(target_dir)
    else:
        raise RuntimeError(
            f"Unsupported ZIPPER_TYPE: {ZIPPER_TYPE!r}. "
            f"Expected '7z' or 'zip'. "
            f"Config zipper value: {CONFIG.get('zipper', 'not set')!r}"
        )

    for entry in seq_state.get("files", []):
        file_path = target_dir / entry["path"]
        if file_path.exists():
            os.utime(file_path, ns=(entry["mtime_ns"], entry["mtime_ns"]))


def process_zip(seq_dir: Path, zip_path: Path, state_path: Path, seq_state: dict, per_job_memory_limit: int | None, *, verbose: bool) -> Sequence[Path]:
    log("zip", f"{seq_dir} -> {zip_path}", verbose_only=True, verbose=verbose)
    zip_sequence(seq_dir, zip_path, per_job_memory_limit)
    state_path.write_text(json.dumps(seq_state, indent=2))
    return (zip_path, state_path)


def process_expand(zip_path: Path, state: dict, *, verbose: bool) -> None:
    log("expand", f"{zip_path} -> {sequence_dir_for(zip_path)}", verbose_only=True, verbose=verbose)
    expand_sequence(zip_path, state)


def run_zip(requested_workers: int | None, *, verbose: bool) -> int:
    work_items: list[tuple[Path, Path, Path, dict]] = []

    if RENDER_ROOT.exists():
        for seq_dir in find_sequence_dirs(RENDER_ROOT):
            # Get the target archive path (will be .7z if ZIPPER_TYPE is "7z")
            zip_path = archive_path_for(seq_dir)
            state_path = state_path_for(zip_path)
            
            # Quick check: if archive exists, load stored state first (fast)
            stored_state = load_state(state_path)
            
            # Check if we need to upgrade from .zip to .7z
            old_zip_path = None
            old_stored_state = None
            if ZIPPER_TYPE == "7z":
                old_zip_path = zip_path.with_suffix(".zip")
                if old_zip_path.exists():
                    old_state_path = state_path_for(old_zip_path)
                    old_stored_state = load_state(old_state_path)
                    # If old .zip exists and .7z doesn't, use old .zip's state for comparison
                    if not zip_path.exists() and old_stored_state is not None:
                        stored_state = old_stored_state
            
            # If .7z archive exists and we have stored state, do quick check before computing full state
            if zip_path.exists() and stored_state is not None:
                # Quick check: if directory mtime is older than archive, likely unchanged
                try:
                    dir_mtime = seq_dir.stat().st_mtime_ns
                    archive_mtime = zip_path.stat().st_mtime_ns
                    # If directory wasn't modified since archive was created, skip state computation
                    if dir_mtime <= archive_mtime:
                        # Still need to check for old .zip cleanup (we have .7z, so .zip is obsolete)
                        if old_zip_path and old_zip_path.exists():
                            old_zip_path.unlink(missing_ok=True)
                            old_state_path = state_path_for(old_zip_path)
                            if old_state_path.exists():
                                old_state_path.unlink(missing_ok=True)
                        continue
                except OSError:
                    # If stat fails, fall through to full state computation
                    pass
            
            # Compute current state only if we need to
            seq_state = compute_state(seq_dir)
            if not seq_state["files"]:
                continue
            
            # Check if state changed
            if stored_state is not None and not state_changed(seq_state, stored_state):
                # Metadata matches stored state
                if zip_path.exists():
                    # .7z exists and is up to date, clean up old .zip if it exists
                    if old_zip_path and old_zip_path.exists():
                        old_zip_path.unlink(missing_ok=True)
                        old_state_path = state_path_for(old_zip_path)
                        if old_state_path.exists():
                            old_state_path.unlink(missing_ok=True)
                elif old_zip_path and old_zip_path.exists() and old_stored_state is not None:
                    # .7z doesn't exist, but .zip exists and metadata matches
                    # Keep the .zip file, don't create .7z
                    continue
                else:
                    # No archive exists, but state matches (shouldn't happen, but be safe)
                    continue

            work_items.append((seq_dir, zip_path, state_path, seq_state))

    if not work_items:
        if not RENDER_ROOT.exists():
            log("zip", "Render root 'Renders' not found; nothing to zip.")
        else:
            log("zip", "Archives already up to date; no sequences needed zipping.")
        return 0

    # Calculate RAM-aware worker count based on work items
    worker_count, per_job_memory_limit = max_workers(requested_workers, work_items, verbose=verbose)

    updated_paths: list[Path] = []

    total = len(work_items)
    completed = 0

    with ThreadPoolExecutor(max_workers=worker_count) as executor:
        future_map = {
            executor.submit(process_zip, seq_dir, zip_path, state_path, seq_state, per_job_memory_limit, verbose=verbose): seq_dir
            for seq_dir, zip_path, state_path, seq_state in work_items
        }

        for future in as_completed(future_map):
            updated_paths.extend(future.result())
            completed += 1
            seq_dir = future_map[future]
            rel = seq_dir.relative_to(RENDER_ROOT)
            log("zip", f"{completed}/{total} {rel}")

    updated_count = len(updated_paths) // 2
    log("zip", f"Updated {updated_count} sequence archive(s).", verbose=verbose)
    if updated_paths:
        log(
            "zip",
            "Archives updated. Stage manually with `git add Renders/_zipped`, if desired.",
            verbose_only=True,
            verbose=verbose,
        )

    removed = cleanup_orphan_archives(verbose=verbose)
    if removed:
        log("zip", f"Removed {removed} orphan archive(s).", verbose=verbose)

    return updated_count


def run_expand(worker_count: int, *, verbose: bool) -> int:
    if not ARCHIVE_ROOT.exists():
        log("expand", "No archives to expand (missing 'Renders/_zipped').")
        return 0

    work_items: list[tuple[Path, dict]] = []

    # Look for both .zip and .7z archives
    archive_patterns = ["*.zip", "*.7z"]
    for pattern in archive_patterns:
        for zip_path in ARCHIVE_ROOT.rglob(pattern):
            state_path = state_path_for(zip_path)
            seq_state = load_state(state_path)
            if seq_state is None:
                log("expand", f"Skipping {zip_path} (missing metadata)")
                continue

            target_dir = sequence_dir_for(zip_path)
            if current_state(target_dir) == seq_state:
                continue

            work_items.append((zip_path, seq_state))

    if not work_items:
        log("expand", "Working folders already match archives; nothing to expand.")
        return 0

    total = len(work_items)
    completed = 0

    with ThreadPoolExecutor(max_workers=worker_count) as executor:
        future_map = {
            executor.submit(process_expand, zip_path, seq_state, verbose=verbose): zip_path
            for zip_path, seq_state in work_items
        }

        for future in as_completed(future_map):
            future.result()
            completed += 1
            zip_path = future_map[future]
            rel = zip_path.relative_to(ARCHIVE_ROOT)
            log("expand", f"{completed}/{total} {rel}")

    log("expand", f"Refreshed {len(work_items)} sequence folder(s).", verbose=verbose)
    return len(work_items)


def cleanup_orphan_archives(*, verbose: bool) -> int:
    if not ARCHIVE_ROOT.exists():
        return 0

    removed: list[Path] = []

    # Look for both .zip and .7z archives
    archive_patterns = ["*.zip", "*.7z"]
    for pattern in archive_patterns:
        for zip_path in ARCHIVE_ROOT.rglob(pattern):
            seq_dir = sequence_dir_for(zip_path)
            if seq_dir.exists():
                continue

            rel = zip_path.relative_to(ARCHIVE_ROOT)
            log("zip", f"Removing orphan archive {rel}", verbose_only=True, verbose=verbose)

            zip_path.unlink(missing_ok=True)
            state_path = state_path_for(zip_path)
            if state_path.exists():
                state_path.unlink()
            removed.append(zip_path)

    if not removed:
        return 0

    for parent in sorted({p.parent for p in removed}, key=lambda p: len(p.parts), reverse=True):
        if not parent.exists():
            continue
        while parent != ARCHIVE_ROOT and not any(parent.iterdir()):
            parent.rmdir()
            parent = parent.parent

    return len(removed)


def main() -> int:
    args = parse_args()

    if args.mode == "expand":
        # For expand mode, use simple CPU-based worker calculation
        workers, _ = max_workers(args.jobs, work_items=None, verbose=args.verbose)
        run_expand(workers, verbose=args.verbose)
        return 0

    # For zip mode, work items will be calculated in run_zip
    updated = run_zip(args.jobs, verbose=args.verbose)
    return 0 if updated >= 0 else 1


if __name__ == "__main__":
    try:
        raise SystemExit(main())
    except Exception as exc:  # broad to surface unexpected errors cleanly
        print(f"Sequence sync failed: {exc}", file=sys.stderr)
        raise