"""A group's directories: adding, removing, changing and ejecting them."""

from __future__ import annotations

import logging
from dataclasses import asdict
from pathlib import Path

from meshbay_node.config import DEFAULT_CONFIG_PATH
from meshbay_node.ops.core import OpError, _config, _group_ctx, _roster
from meshbay_node.ops.node_toml import _insert_roots_block, _remove_roots_block, _update_root_field
from meshbay_node.roots import RootError, RootSet, off_disk

log = logging.getLogger("meshbay_node.ops")


async def add_root(state: dict, group_id: str, path: str, *,
                   name: str = "", kind: str = "generic",
                   writable: bool = False,
                   removable: bool = False) -> dict:
    """
    Add a directory to a group, refusing anything ambiguous.

    Validated against the group's existing roots *before* being written, so a
    config that would be refused at startup is refused here instead — where the
    operator is watching and can fix it.
    """
    config = _config(state)
    cfg = next((g for g in config.groups if g.id == group_id), None)
    if cfg is None:
        raise OpError("Group not configured on this node", status=404)

    specs = [asdict(r) for r in cfg.roots]
    specs.append({"path": path, "name": name, "kind": kind,
                  "writable": writable, "removable": removable})
    try:
        built = RootSet.build(specs)
    except RootError as e:
        raise OpError(str(e)) from e

    added = built.roots[-1]

    try:
        added.path.mkdir(parents=True, exist_ok=True)
    except OSError as e:
        raise OpError(f"Cannot create {added.path}: {e}") from e

    conf_path = Path(state.get("config_path") or DEFAULT_CONFIG_PATH)
    root_block = f'  [[groups.roots]]\n  path   = "{added.path.as_posix()}"'
    if name:
        root_block += f'\n  name   = "{added.name}"'
    if kind != "generic":
        root_block += f'\n  kind   = "{added.kind}"'
    if writable:
        root_block += '\n  writable = true'
    if removable:
        root_block += '\n  removable = true'
    _insert_roots_block(conf_path, group_id, root_block)

    from meshbay_node.config import RootSpec
    cfg.roots.append(RootSpec(
        path=str(added.path), name=added.name, kind=added.kind,
        writable=added.writable, removable=added.removable))

    # Deliberately *not* mutating the live RootSet in place.
    #
    # `DirectoryIndexer.retarget` decides what to scan by diffing the names it
    # already has against the ones it is given — so handing it the same object,
    # edited, means the new root is in both sides of the comparison and is
    # never scanned. It would appear in the table and stay permanently empty.
    # `_reload_config_inner` diffs the same way and would likewise conclude
    # nothing changed. The caller reloads instead, which builds a fresh set
    # from the file this just wrote.
    #
    # `built` is that set, computed here only to validate and to answer with;
    # what the node serves comes from the reload.
    log.info("Root added: %s → group %s", added.name, group_id[:8])
    return {"status": "added", "name": added.name, "path": str(added.path),
            "group_id": group_id, "roots": built.describe()}


async def remove_root(state: dict, group_id: str, root_name: str) -> dict:
    """Remove a named root from a group. At least one root must remain."""
    config = _config(state)
    cfg = next((g for g in config.groups if g.id == group_id), None)
    if cfg is None:
        raise OpError("Group not configured on this node", status=404)

    from meshbay_common.paths import fold

    from meshbay_node.roots import derive_name
    target = fold(root_name)
    match_idx = None
    for i, r in enumerate(cfg.roots):
        try:
            rname = r.name or derive_name(Path(r.path).expanduser().resolve())
        except Exception:
            continue
        if fold(rname) == target:
            match_idx = i
            break

    if match_idx is None:
        raise OpError(f"No root named {root_name!r} in this group", status=404)
    if len(cfg.roots) < 2:
        raise OpError("Cannot remove the only root", status=400)

    removed = cfg.roots[match_idx]
    resolved = str(Path(removed.path).expanduser().resolve())

    conf_path = Path(state.get("config_path") or DEFAULT_CONFIG_PATH)
    _remove_roots_block(conf_path, group_id, resolved)

    cfg.roots.pop(match_idx)

    # Not mutating the live set here either — see `add_root`. Dropping the
    # root from it would leave `retarget` unable to tell that its entries
    # should go, so the removed directory's files would stay in the index.
    #
    # Built from the config this just edited, and never returned empty: an
    # empty list is a *valid answer* meaning "this group has no directories",
    # which the client cannot tell from "the node could not say" — it would
    # blank the operator's table on an op that succeeded.
    result_roots = RootSet.build([asdict(r) for r in cfg.roots]).describe()

    log.info("Root removed: %s from group %s", root_name, group_id[:8])
    return {"status": "removed", "name": root_name, "group_id": group_id,
            "roots": result_roots}


async def update_root(state: dict, group_id: str, root_name: str, *,
                      writable: bool | None = None,
                      removable: bool | None = None) -> dict:
    """Toggle writable/removable on an existing root without removing it."""
    config = _config(state)
    cfg = next((g for g in config.groups if g.id == group_id), None)
    if cfg is None:
        raise OpError("Group not configured on this node", status=404)

    from meshbay_common.paths import fold

    from meshbay_node.roots import RootSet
    target = fold(root_name)
    match = None
    for r in cfg.roots:
        rname = r.name or str(Path(r.path).name)
        if fold(rname) == target:
            match = r
            break
    if match is None:
        raise OpError(f"No root named {root_name!r} in this group", status=404)

    changed = False
    if writable is not None and match.writable != writable:
        match.writable = writable
        changed = True
    if removable is not None and match.removable != removable:
        match.removable = removable
        changed = True

    if not changed:
        specs = [asdict(r) for r in cfg.roots]
        built = RootSet.build(specs)
        return {"status": "unchanged", "name": root_name, "group_id": group_id,
                "roots": built.describe()}

    conf_path = Path(state.get("config_path") or DEFAULT_CONFIG_PATH)
    _update_root_field(conf_path, group_id, str(Path(match.path).expanduser().resolve()),
                       writable=match.writable, removable=match.removable)

    # Update the live RootSet so GET /api/groups returns correct data
    # immediately, without waiting for the async reload to finish.
    live_roots: RootSet | None = state.get("groups_ctx", {}).get(
        group_id, {}).get("roots")
    if live_roots:
        for lr in live_roots.roots:
            lr_name = lr.name or str(Path(lr.path).name)
            if fold(lr_name) == target:
                if writable is not None:
                    lr.writable = writable
                if removable is not None:
                    lr.removable = removable
                break

    # Built from config when there is no live set, never returned empty: an
    # empty list is a *valid answer* meaning "this group has no directories",
    # and the client cannot tell it from "the node could not say". It would
    # blank the operator's table on an op that succeeded.
    result_roots = (live_roots.describe() if live_roots
                    else RootSet.build([asdict(r) for r in cfg.roots]).describe())

    log.info("Root updated: %s (writable=%s, removable=%s) in group %s",
             root_name, match.writable, match.removable, group_id[:8])
    return {"status": "updated", "name": root_name, "group_id": group_id,
            "roots": result_roots}


async def eject_root(state: dict, group_id: str, root_name: str) -> dict:
    """Mark a removable root as ejected so the operator can safely unplug."""
    config = _config(state)
    cfg = next((g for g in config.groups if g.id == group_id), None)
    if cfg is None:
        raise OpError("Group not configured on this node", status=404)

    from meshbay_common.paths import fold
    target = fold(root_name)
    ctx = _group_ctx(state, group_id)
    roots: RootSet | None = ctx.get("roots")
    if not roots:
        raise OpError("Group has no roots", status=503)

    root = None
    for r in roots:
        if fold(r.name) == target:
            root = r
            break
    if root is None:
        raise OpError(f"No root named {root_name!r} in this group", status=404)
    if not root.removable:
        raise OpError(f"Root {root_name!r} is not marked as removable", status=400)
    if root.ejected:
        return {"status": "already_ejected", "name": root_name,
                "group_id": group_id, "roots": roots.describe()}

    # The indexer stops its watchdog and freezes the entries; it holds the same
    # RootSet object, but the flags are set here too so a context whose indexer
    # was replaced by a retarget cannot be left disagreeing with the roster.
    indexer = state.get("indexers", {}).get(group_id)
    if indexer:
        indexer.eject_root(root_name)
    root.ejected = True
    root.available = False

    await _roster(state).set_root_ejected(
        group_id, root_name, True, set_by=state.get("node_user_id", ""))

    log.info("Root ejected: %s from group %s", root_name, group_id[:8])
    return {"status": "ejected", "name": root_name, "group_id": group_id,
            "roots": roots.describe()}


async def plug_root(state: dict, group_id: str, root_name: str) -> dict:
    """Re-enable an ejected root after the device is plugged back in."""
    config = _config(state)
    cfg = next((g for g in config.groups if g.id == group_id), None)
    if cfg is None:
        raise OpError("Group not configured on this node", status=404)

    from meshbay_common.paths import fold
    target = fold(root_name)
    ctx = _group_ctx(state, group_id)
    roots: RootSet | None = ctx.get("roots")
    if not roots:
        raise OpError("Group has no roots", status=503)

    root = None
    for r in roots:
        if fold(r.name) == target:
            root = r
            break
    if root is None:
        raise OpError(f"No root named {root_name!r} in this group", status=404)
    if not root.ejected:
        return {"status": "already_plugged", "name": root_name,
                "group_id": group_id, "roots": roots.describe()}
    if not await off_disk(roots, root.is_live):
        raise OpError(
            f"Directory not found: {root.path}. Is the device connected?",
            status=409)

    # Persisted before the rescan, which can take minutes on a large library:
    # a crash halfway through must leave the root plugged, not ejected with
    # entries half rebuilt.
    await _roster(state).set_root_ejected(
        group_id, root_name, False, set_by=state.get("node_user_id", ""))

    indexer = state.get("indexers", {}).get(group_id)
    if indexer:
        await indexer.plug_root(root_name)
    root.ejected = False
    root.available = await off_disk(roots, root.is_live)

    log.info("Root plugged: %s in group %s", root_name, group_id[:8])
    return {"status": "plugged", "name": root_name, "group_id": group_id,
            "roots": roots.describe()}