feat: add TunnelConfig dataclass and YAML I/O

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/autossh_mgr/config.py

@@ -0,0 +1,71 @@
+import os
+from dataclasses import dataclass, asdict, field
+from pathlib import Path
+from typing import Optional
+
+import click
+import yaml
+
+
+def get_config_dir() -> Path:
+    env = os.environ.get("AUTOSSH_MGR_CONFIG_DIR")
+    if env:
+        return Path(env)
+    return Path.home() / ".config" / "autossh-mgr"
+
+
+@dataclass
+class TunnelConfig:
+    name: str
+    host: str
+    user: str
+    local_port: int
+    remote_port: int
+    port: int = 22
+    identity_file: str = "~/.ssh/id_ed25519"
+    local_host: str = "127.0.0.1"
+    remote_host: str = "0.0.0.0"
+    ssh_options: str = ""
+
+
+_DEFAULTS = TunnelConfig(
+    name="", host="", user="", local_port=0, remote_port=0
+)
+
+
+def ensure_dirs(config_dir: Path) -> None:
+    config_dir.mkdir(parents=True, exist_ok=True)
+    (config_dir / "pids").mkdir(exist_ok=True)
+    (config_dir / "logs").mkdir(exist_ok=True)
+    tunnels_file = config_dir / "tunnels.yaml"
+    if not tunnels_file.exists():
+        tunnels_file.write_text("tunnels: []\n")
+
+
+def load_tunnels(config_dir: Path) -> list[TunnelConfig]:
+    tunnels_file = config_dir / "tunnels.yaml"
+    if not tunnels_file.exists():
+        return []
+    data = yaml.safe_load(tunnels_file.read_text()) or {}
+    return [TunnelConfig(**entry) for entry in data.get("tunnels", [])]
+
+
+def save_tunnels(config_dir: Path, tunnels: list[TunnelConfig]) -> None:
+    rows = []
+    for t in tunnels:
+        d = asdict(t)
+        # Omit optional fields that are at their default values
+        for key in ("port", "identity_file", "local_host", "remote_host", "ssh_options"):
+            if d[key] == getattr(_DEFAULTS, key):
+                del d[key]
+        rows.append(d)
+    tmp = config_dir / "tunnels.yaml.tmp"
+    tmp.write_text(yaml.dump({"tunnels": rows}, default_flow_style=False))
+    tmp.replace(config_dir / "tunnels.yaml")
+
+
+def get_tunnel(config_dir: Path, name: str) -> TunnelConfig:
+    for t in load_tunnels(config_dir):
+        if t.name == name:
+            return t
+    raise click.ClickException(f"No tunnel named '{name}'")