"""
MeshBay Node configuration.

Config file: ~/.config/meshbay/node.toml
All values have sensible defaults and can be overridden by env vars
prefixed with MESHBAY_ (e.g. MESHBAY_HUB_URL).
"""

import os
from dataclasses import dataclass, field
from pathlib import Path

try:
    import tomllib   # Python 3.11+
except ImportError:
    import tomli as tomllib   # type: ignore[no-redef]

DEFAULT_CONFIG_PATH = Path.home() / ".config" / "meshbay" / "node.toml"

EXAMPLE_CONFIG = """\
# MeshBay Node configuration
# See: https://meshbay.org/docs/node-config

[hub]
url      = "http://meshbay.org"
username = "myusername"
# password stored separately via keystore

[node]
port        = 19000
ui_port     = 18000
shared_dirs = ["/home/user/MeshBay"]

[group]
id   = ""   # set after joining a group
name = ""

[keystore]
# unlock_file = "~/.config/meshbay/unlock.key"
# or set MESHBAY_UNLOCK_KEY env var
"""


@dataclass
class HubConfig:
    url:      str = "http://meshbay.org"
    username: str = ""
    password: str = ""   # loaded from keystore or env; never written to TOML


@dataclass
class NodeConfig:
    port:        int = 19000
    ui_port:     int = 18000
    shared_dirs: list[str] = field(default_factory=list)


@dataclass
class GroupConfig:
    id:   str = ""
    name: str = ""


@dataclass
class KeystoreConfig:
    path:        Path = field(default_factory=lambda: DEFAULT_CONFIG_PATH.parent / "keystore.enc")
    unlock_file: Path | None = None


@dataclass
class Config:
    hub:      HubConfig      = field(default_factory=HubConfig)
    node:     NodeConfig     = field(default_factory=NodeConfig)
    group:    GroupConfig    = field(default_factory=GroupConfig)
    keystore: KeystoreConfig = field(default_factory=KeystoreConfig)


def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
    """
    Load config from TOML file. Missing file returns defaults.
    Env vars override file values.
    """
    cfg = Config()

    if path.exists():
        raw = tomllib.loads(path.read_text())
        hub = raw.get("hub", {})
        cfg.hub.url      = hub.get("url",      cfg.hub.url)
        cfg.hub.username = hub.get("username", cfg.hub.username)

        nd = raw.get("node", {})
        cfg.node.port        = nd.get("port",        cfg.node.port)
        cfg.node.ui_port     = nd.get("ui_port",     cfg.node.ui_port)
        cfg.node.shared_dirs = nd.get("shared_dirs", cfg.node.shared_dirs)

        grp = raw.get("group", {})
        cfg.group.id   = grp.get("id",   cfg.group.id)
        cfg.group.name = grp.get("name", cfg.group.name)

        ks = raw.get("keystore", {})
        if "path" in ks:
            cfg.keystore.path = Path(ks["path"]).expanduser()
        if "unlock_file" in ks:
            cfg.keystore.unlock_file = Path(ks["unlock_file"]).expanduser()

    # Env var overrides
    if url := os.environ.get("MESHBAY_HUB_URL"):
        cfg.hub.url = url
    if user := os.environ.get("MESHBAY_USERNAME"):
        cfg.hub.username = user
    if pwd := os.environ.get("MESHBAY_PASSWORD"):
        cfg.hub.password = pwd
    if port := os.environ.get("MESHBAY_PORT"):
        cfg.node.port = int(port)

    return cfg


def write_example_config(path: Path = DEFAULT_CONFIG_PATH) -> None:
    """Write an example config file if none exists."""
    if not path.exists():
        path.parent.mkdir(parents=True, exist_ok=True)
        path.write_text(EXAMPLE_CONFIG)