"""
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 logging
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]

log = logging.getLogger(__name__)

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

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

[hub]
url      = "https://meshbay.org"
username = "myusername"

[node]
quic_port = 19010  # QUIC (MNP) — LAN, port-forwarded, hub-less direct access
ui_port  = 18000   # local admin UI (127.0.0.1 only)

# One-time codes. An invitation waits for someone to read their messages; an
# operator pairing code is typed during the SSH session that printed it.
invite_ttl_hours = 168   # 7 days
pair_ttl_hours   = 24
# How long a new device may wait for one of your existing devices to approve it.
device_request_ttl_minutes = 60

# How many people may watch a video at once. One ffmpeg runs per viewer for as
# long as they watch — it remuxes rather than re-encodes, so it costs little CPU
# and around 50 MB of memory, and spends most of the film idle. Past this, a
# viewer is told the server is busy. Raise it on a machine with memory to spare;
# lower it on a Pi.
max_concurrent_streams = 8

# Browser and native clients reach this node over WebRTC DataChannel via hub
# signaling — no inbound port to open. QUIC is the optional direct path.

# Multiple groups — each with one or more named directories ("roots").
#
# A root's name is the directory's basename, and it becomes the first segment of
# every path members see: /home/user/Media appears to everyone as "Media/".
# Two roots cannot share a name (compared without regard to case), and no root
# may sit inside another. Exactly one root receives uploads.
[[groups]]
id          = ""    # set after joining
name        = "My Media"
quic_port   = 19010

  [[groups.roots]]
  path   = "/home/user/Media"
  upload = true

  [[groups.roots]]
  path = "/run/media/user/USB/Musique"   # an external drive is fine: if it is
  kind = "audio"                         # unplugged the root goes unavailable
                                         # and its files stay in the index,
                                         # rather than looking deleted

# upload_dir: a separate directory for uploads. Files land directly in it,
# not in an "uploads" subdirectory. It appears as its own root in the index.
# upload_dir = "/home/user/Incoming"

# The single-directory form still works and means the same thing — one root,
# named after the directory, receiving uploads.
[[groups]]
id          = ""
name        = "Public Archive"
shared_dir  = "/home/user/Archive"
quic_port   = 19012
visibility  = "public"       # discoverable on the hub
# join_policy = "open"       # anyone the hub says is a member gets the group key,
                             # with no pairing code. Only for groups where that is
                             # genuinely intended: it means the hub can join too.

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

# Operator authority is not configured here. Run `meshbay-node operator pair` and
# enter the code in your browser: the node pins that browser's key, and invites
# and file deletion are signed with it.
"""


@dataclass
class HubConfig:
    url:      str = "https://meshbay.org"
    username: str = ""


@dataclass
class NodeConfig:
    quic_port:  int = 19010
    ui_port:    int = 18000
    # How long a one-time code stays usable. Invitations travel through a human
    # conversation and are answered days later; operator pairing happens during
    # the SSH session that printed it.
    invite_ttl_hours: int = 168   # 7 days
    pair_ttl_hours:   int = 24
    # A device-add code is read off one screen and typed into another, in one
    # sitting. Comfort rather than security: the code is bound to the requesting
    # keys by its hash, so a longer window widens nothing an attacker can use.
    device_request_ttl_minutes: int = 60
    # How many people may watch a video at the same time. One ffmpeg runs per
    # viewer for as long as they watch, so this is the knob that decides when
    # the node answers "server busy" — see MAX_CONCURRENT_TRANSCODES in
    # transport/webrtc_server.py for what one costs.
    max_concurrent_streams: int = 8


@dataclass
class RootSpec:
    """One named directory inside a group. See `meshbay_node/roots.py`."""
    path:   str = ""
    name:   str = ""          # empty → the directory's basename, derived at load
    kind:   str = "generic"   # generic|video|audio|photo — a view hint, unused for now
    upload: bool = False      # exactly one root per group receives uploads
    direct: bool = False      # uploads land at root path, not in a subdirectory


@dataclass
class GroupConfig:
    id:         str = ""
    name:       str = ""
    # A group's content is several named roots. `shared_dir` is the single-root
    # form and is still read: it becomes one root named after its basename, which
    # is why every path gained a segment. See roots.py for why there is no
    # unprefixed shape.
    roots:      list[RootSpec] = field(default_factory=list)
    shared_dir: str = ""      # legacy single-root form, migrated at load
    upload_dir: str = ""      # separate filesystem path for uploads
    visibility: str = "private"   # public|private — discoverability, not admission
    # Admission. "invite" (default) means a newcomer needs a one-time pairing code
    # before the node wraps the group key for them; "open" means the node pins
    # whoever turns up first (TOFU) and serves them.
    #
    # Deliberately read from THIS file and never from the hub: a hub that could
    # declare a group open would walk into any group it liked. Being findable
    # (`visibility`) and being open (`join_policy`) are different questions.
    join_policy: str = "invite"   # invite|open
    quic_port:  int = 19010       # QUIC MNP port

    def __post_init__(self) -> None:
        """
        The single-directory form becomes one root, whoever built this.

        On the dataclass rather than in the TOML reader, because a GroupConfig is
        also built by the CLI, by `group attach` and by tests. Putting the
        migration in the parser alone left every one of those paths with a group
        that had no directory at all — and it presented as "skipping group",
        which reads like configuration rather than a bug.
        """
        if not self.roots and self.shared_dir.strip():
            self.roots = [RootSpec(path=self.shared_dir.strip(), upload=True)]
        if self.upload_dir.strip():
            for r in self.roots:
                r.upload = False
            self.roots.append(RootSpec(
                path=self.upload_dir.strip(), upload=True, direct=True))


@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)
    groups:   list[GroupConfig] = field(default_factory=list)
    keystore: KeystoreConfig = field(default_factory=KeystoreConfig)
    data_dir: Path = field(default_factory=lambda: Path.home() / ".local" / "share" / "meshbay")

    # Back-compat: single-group access
    @property
    def group(self) -> GroupConfig:
        return self.groups[0] if self.groups else GroupConfig()


def _positive(value: object, default: int, name: str) -> int:
    """A count that must be at least one, or the default with a word about it.

    Zero is the dangerous one: `asyncio.Semaphore(0)` is not "no limit", it is
    a node where no video ever plays and nothing in the log says why.
    """
    # bool before int: TOML `true` is a bool, and `int(True)` is 1 — a node
    # where exactly one person may watch, arrived at by a typo and announced
    # nowhere.
    if isinstance(value, bool) or not isinstance(value, (int, str)):
        log.warning("%s = %r is not a count — using %d", name, value, default)
        return default
    try:
        n = int(value)
    except (TypeError, ValueError):
        log.warning("%s = %r is not a number — using %d", name, value, default)
        return default
    if n < 1:
        log.warning("%s = %d would stop the feature entirely — using %d",
                    name, n, default)
        return default
    return n


def _read_roots(group: dict) -> list[RootSpec]:
    """
    A group's roots, from `[[groups.roots]]` or from the legacy `shared_dir`.

    Both forms are accepted and `shared_dir` is not deprecated for a single
    directory — it is the same thing said shorter. Naming both is refused rather
    than merged: which one receives uploads would be a guess, and a wrong guess
    is discovered weeks later.
    """
    specs = [
        RootSpec(
            path=str(r.get("path", "")),
            name=str(r.get("name", "")),
            kind=str(r.get("kind", "generic")),
            upload=bool(r.get("upload", False)),
        )
        for r in group.get("roots", []) or []
    ]
    legacy = str(group.get("shared_dir", "") or "").strip()
    if specs and legacy:
        log.warning(
            "group %r declares both shared_dir and [[groups.roots]] — using "
            "roots and ignoring shared_dir = %s",
            group.get("name", ""), legacy)
    # A bare shared_dir needs no handling here: GroupConfig.__post_init__ turns
    # it into one root for every construction path, not just this one.
    return specs


def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
    """
    Load config from TOML file. Supports both single [group] and
    multiple [[groups]] sections. 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", {})
        # `port` (TCP+TLS) and `http_port` no longer exist — both listeners were removed
        # in Phase 11.5 (findings C1, C6). Regenerate node.toml with `meshbay-node init`.
        cfg.node.quic_port = nd.get("quic_port", cfg.node.quic_port)
        cfg.node.ui_port   = nd.get("ui_port",   cfg.node.ui_port)
        cfg.node.invite_ttl_hours = int(
            nd.get("invite_ttl_hours", cfg.node.invite_ttl_hours))
        cfg.node.pair_ttl_hours = int(
            nd.get("pair_ttl_hours", cfg.node.pair_ttl_hours))
        cfg.node.device_request_ttl_minutes = int(
            nd.get("device_request_ttl_minutes",
                   cfg.node.device_request_ttl_minutes))
        cfg.node.max_concurrent_streams = _positive(
            nd.get("max_concurrent_streams", cfg.node.max_concurrent_streams),
            cfg.node.max_concurrent_streams, "max_concurrent_streams")

        # Multi-group: [[groups]] array
        if "groups" in raw:
            for g in raw["groups"]:
                cfg.groups.append(GroupConfig(
                    id=g.get("id", ""),
                    name=g.get("name", ""),
                    roots=_read_roots(g),
                    # Ignored when roots are given explicitly (warned about in
                    # _read_roots); otherwise __post_init__ migrates it.
                    shared_dir="" if _read_roots(g) else g.get("shared_dir", ""),
                    upload_dir=g.get("upload_dir", ""),
                    visibility=g.get("visibility", "private"),
                    join_policy=g.get("join_policy", "invite"),
                    quic_port=g.get("quic_port", cfg.node.quic_port),
                ))
        # Back-compat: single [group] section
        elif "group" in raw:
            grp = raw["group"]
            cfg.groups.append(GroupConfig(
                id=grp.get("id", ""),
                name=grp.get("name", ""),
            ))

        if "data_dir" in raw:
            cfg.data_dir = Path(raw["data_dir"]).expanduser().resolve()

        if "admin_pk_ed25519" in raw:
            # Removed, not merely unused: a key named here granted operator
            # authority, and dropping it silently would refuse invites and file
            # deletion with a signature error that looks like something else.
            log.warning(
                "admin_pk_ed25519 in %s is ignored — operator authority now comes "
                "from the roster. Run `meshbay-node operator pair` and delete the "
                "line.", path)

        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 port := os.environ.get("MESHBAY_QUIC_PORT"):
        cfg.node.quic_port = int(port)
    if streams := os.environ.get("MESHBAY_MAX_CONCURRENT_STREAMS"):
        cfg.node.max_concurrent_streams = _positive(
            streams, cfg.node.max_concurrent_streams,
            "MESHBAY_MAX_CONCURRENT_STREAMS")

    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)