#!/usr/bin/env python3
"""Replace a stopped RustProxy source tree, preserving old code, data and .env."""
from __future__ import annotations
import argparse
import json
import os
from pathlib import Path
import shutil
import sys
import uuid

MANAGED = ["build.rs", "langs", "deploy", "debian", "grafana", "make_zip.py", "src", "tests", "scripts", "nagios", "docker-agent", "migrations", "examples", "docs", ".github", ".cargo",
           "Cargo.toml", "Cargo.lock", "rust-toolchain.toml", "dev.sh", "upgrade.sh", "install.sh", "update.sh",
           "README.md", "ROADMAP.md", "CHANGELOG.md", "AGENTS.md", "SHA256SUMS",
           ".env.example", ".gitignore"]


def upgrade(source: Path, target: Path, *, stopped: bool, data_dir: Path | None = None) -> Path:
    source = source.resolve()
    if target.is_symlink():
        raise ValueError("Target must not be a symlink.")
    target = target.resolve()
    if not stopped:
        raise ValueError("Stop RustProxy and pass --stopped. Source replacement is not a live-update operation.")
    if target == source or target in source.parents or source in target.parents:
        raise ValueError("Source and destination must be separate, non-nested directories.")
    manifest = target / "Cargo.toml"
    if not manifest.is_file() or 'name = "rust-proxy"' not in manifest.read_text(encoding="utf-8"):
        raise ValueError("Target is not an existing RustProxy source directory.")
    locks = []
    try:
        if os.name == "posix":
            import fcntl
            for directory in {target / "data", data_dir or target / "data"}:
                path = directory / "process.lock"
                if path.exists():
                    if path.is_symlink():
                        raise ValueError("Refusing a symlinked process lock.")
                    stream = path.open("r+")
                    try:
                        fcntl.flock(stream, fcntl.LOCK_EX | fcntl.LOCK_NB)
                    except OSError:
                        stream.close()
                        raise ValueError("A RustProxy server still owns the data directory. Stop it first.") from None
                    locks.append(stream)
        for name in MANAGED:
            if (target / name).is_symlink():
                raise ValueError(f"Managed target {name} is a symlink; refusing to replace it.")
        backup = target / ".upgrade-backup" / ("before-0.27.2-" + uuid.uuid4().hex[:12])
        backup.mkdir(parents=True, mode=0o700)
        installed: list[str] = []
        moved: list[str] = []
        try:
            for name in MANAGED:
                old, new = target / name, source / name
                if old.exists():
                    old.rename(backup / name)
                    moved.append(name)
                if new.is_dir():
                    installed.append(name)
                    shutil.copytree(new, old)
                    if name == "langs" and (backup / name).is_dir():
                        # Preserve additional site language packs; bundled packs are
                        # updated, with their previous bytes retained in the backup.
                        for pack in (backup / name).glob("*.json"):
                            if pack.is_symlink():
                                raise ValueError("Language packs must not be symlinks.")
                            if not (old / pack.name).exists():
                                shutil.copy2(pack, old / pack.name)
                elif new.is_file():
                    installed.append(name)
                    shutil.copy2(new, old)
            # Old renewal observations were diagnostic scheduler state only;
            # certificates, accounts and renewal profiles live elsewhere. 0.19.1
            # has no runtime JSON importer. Validate the obsolete sidecar now,
            # write the completed source-upgrade manifest, then remove the file
            # as the final fallible operation. SQLite observations are rebuilt by
            # the normal renewal scheduler. No second legacy copy is retained.
            runtime_data = (data_dir or (target / "data")).resolve()
            certs_dir = runtime_data / "certs"
            if certs_dir.is_symlink():
                raise ValueError("Certificate data directory must not be a symlink during legacy cleanup.")
            legacy = certs_dir / "renewals.json"
            remove_legacy = legacy.exists()
            if remove_legacy and (legacy.is_symlink() or not legacy.is_file()):
                raise ValueError("Obsolete renewal observation sidecar must be a regular file.")
            (backup / "upgrade.json").write_text(json.dumps({"from_directory":str(target), "to_version":"0.27.2", "managed_paths":MANAGED, "removed_obsolete_runtime_state": remove_legacy}, indent=2)+"\n", encoding="utf-8")
            if remove_legacy:
                legacy.unlink()
        except BaseException:
            for name in reversed(installed):
                path = target / name
                if path.is_dir():
                    shutil.rmtree(path)
                elif path.exists():
                    path.unlink()
            for name in moved:
                (backup / name).rename(target / name)
            raise
        return backup
    finally:
        for stream in locks:
            stream.close()


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("target", type=Path)
    parser.add_argument("--stopped", action="store_true")
    parser.add_argument("--data-dir", type=Path, help="also check the process lock when data lives outside target/data")
    args = parser.parse_args()
    os.umask(0o077)
    data_dir = args.data_dir or (Path(os.environ["RUST_PROXY_DATA_DIR"]) if os.environ.get("RUST_PROXY_DATA_DIR") else None)
    try:
        backup = upgrade(Path(__file__).resolve().parents[1], args.target, stopped=args.stopped, data_dir=data_dir)
    except (OSError, ValueError) as error:
        parser.exit(2, f"Upgrade refused or rolled back: {error}\n")
    print(f"Installed RustProxy 0.27.2. Previous managed source files: {backup}")
    print("Preserved data, .env, .git, target and other unmanaged files. No database migration was run.")
    print(f"Next: cd {args.target}; ./dev.sh test; ./dev.sh")


if __name__ == "__main__":
    main()