#!/usr/bin/env python3
"""Walk a client directory and emit a release manifest.

Produces canonical-form JSON matching docs/update-manifest.md. Does not sign —
pair with a separate signer that reads the manifest bytes verbatim and emits
a detached Ed25519 signature.

Usage:
    make-manifest.py --source /path/to/client --version 2026.04.14-1 \\
                     [--previous 2026.04.13-3] [--notes "bugfixes"] \\
                     [--launcher Metin2Launcher.exe] [--out manifest.json]

The launcher path is treated specially: its entry appears at the top level
under "launcher", not inside "files". Defaults to "Metin2Launcher.exe"; if
that file does not exist in the source tree, the script refuses to run.
"""

from __future__ import annotations

import argparse
import hashlib
import json
import sys
from dataclasses import dataclass
from datetime import datetime, timezone
from pathlib import Path


# Files and directories that must never appear in a release manifest.
# These are runtime artifacts, build outputs, or developer state.
EXCLUDE_DIRS = {
    ".git",
    ".vs",
    ".updates",
    "log",
    "__pycache__",
}
EXCLUDE_FILES = {
    ".gitignore",
    ".gitattributes",
    "desktop.ini",
    "Thumbs.db",
    ".DS_Store",
}
EXCLUDE_SUFFIXES = {
    ".pdb",         # debug symbols
    ".ilk",         # MSVC incremental link
    ".old",         # rollback copies written by the launcher
    ".log",         # runtime logs, not release content
    ".dxvk-cache",  # DXVK shader cache, per-machine
    ".swp",
    ".tmp",
}


@dataclass
class FileEntry:
    path: str
    sha256: str
    size: int
    platform: str = "all"
    required: bool = True
    executable: bool = False

    def to_dict(self) -> dict:
        out = {
            "path": self.path,
            "sha256": self.sha256,
            "size": self.size,
        }
        if self.platform != "all":
            out["platform"] = self.platform
        if not self.required:
            out["required"] = False
        if self.executable:
            out["executable"] = True
        return out


def sha256_file(path: Path) -> str:
    h = hashlib.sha256()
    with path.open("rb") as f:
        for chunk in iter(lambda: f.read(1 << 20), b""):
            h.update(chunk)
    return h.hexdigest()


def should_skip(rel_path: Path) -> bool:
    for part in rel_path.parts:
        if part in EXCLUDE_DIRS:
            return True
    if rel_path.name in EXCLUDE_FILES:
        return True
    if rel_path.suffix in EXCLUDE_SUFFIXES:
        return True
    return False


def classify_platform(rel_path: Path) -> str:
    """Very simple platform inference. Extend as native Linux build lands."""
    suffix = rel_path.suffix.lower()
    if suffix in {".exe", ".dll"}:
        return "windows"
    return "all"


def walk_client(source: Path, launcher_rel: Path) -> tuple[FileEntry, list[FileEntry]]:
    launcher_entry: FileEntry | None = None
    files: list[FileEntry] = []

    for path in sorted(source.rglob("*")):
        if not path.is_file():
            continue
        rel = path.relative_to(source)
        if should_skip(rel):
            continue

        entry = FileEntry(
            path=rel.as_posix(),
            sha256=sha256_file(path),
            size=path.stat().st_size,
            platform=classify_platform(rel),
        )

        if rel == launcher_rel:
            launcher_entry = entry
        else:
            files.append(entry)

    if launcher_entry is None:
        raise SystemExit(
            f"error: launcher file {launcher_rel} not found under {source}. "
            f"pass --launcher if the launcher is named differently, or create it."
        )

    files.sort(key=lambda e: e.path)
    return launcher_entry, files


def build_manifest(
    version: str,
    created_at: str,
    previous: str | None,
    notes: str | None,
    min_launcher_version: str | None,
    launcher: FileEntry,
    files: list[FileEntry],
) -> dict:
    """Assemble the manifest dict in canonical key order."""
    manifest: dict = {"version": version, "created_at": created_at}
    if previous is not None:
        manifest["previous"] = previous
    if notes is not None:
        manifest["notes"] = notes
    if min_launcher_version is not None:
        manifest["min_launcher_version"] = min_launcher_version
    manifest["launcher"] = launcher.to_dict()
    manifest["files"] = [f.to_dict() for f in files]
    return manifest


def canonical_json(manifest: dict) -> bytes:
    text = json.dumps(manifest, indent=2, ensure_ascii=False)
    return (text + "\n").encode("utf-8")


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    parser.add_argument("--source", required=True, type=Path,
                        help="Path to the client root directory")
    parser.add_argument("--version", required=True,
                        help="Release version, e.g. 2026.04.14-1")
    parser.add_argument("--previous",
                        help="Previous release version, if any")
    parser.add_argument("--notes",
                        help="Release notes (Markdown allowed)")
    parser.add_argument("--min-launcher-version",
                        help="Minimum launcher version that can apply this manifest")
    parser.add_argument("--launcher", default="Metin2Launcher.exe",
                        help="Launcher filename relative to source (default: Metin2Launcher.exe)")
    parser.add_argument("--out", type=Path, default=Path("manifest.json"),
                        help="Output file path (default: ./manifest.json)")
    parser.add_argument("--created-at",
                        help="Override created_at timestamp (default: now, UTC). Useful for reproducible test runs.")
    args = parser.parse_args()

    source: Path = args.source.resolve()
    if not source.is_dir():
        print(f"error: {source} is not a directory", file=sys.stderr)
        return 1

    created_at = args.created_at or datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
    launcher_rel = Path(args.launcher)

    launcher, files = walk_client(source, launcher_rel)

    manifest = build_manifest(
        version=args.version,
        created_at=created_at,
        previous=args.previous,
        notes=args.notes,
        min_launcher_version=args.min_launcher_version,
        launcher=launcher,
        files=files,
    )

    args.out.write_bytes(canonical_json(manifest))

    total_size = launcher.size + sum(f.size for f in files)
    print(
        f"manifest: {args.out}  "
        f"files: {len(files) + 1}  "
        f"total: {total_size / (1024 * 1024):.1f} MiB",
        file=sys.stderr,
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())