"""Validation for the ``platform_toolsets`` config section."""

import ast
from typing import Callable, List, Optional

from hermes_cli.platforms import PLATFORMS
from hermes_cli.toolset_scope import toolset_allowed_for_platform

_NO_TOOLS = "the agent will have no tools on this platform. Run `hermes tools` to reconfigure."


def parse_platform_toolsets_value(value: object) -> Optional[List[str]]:
    """The toolset list a saved ``platform_toolsets.<platform>`` value encodes, or None.

    Older ``hermes config set`` builds stored a bare ``[...]`` argument as a plain string, so an
    explicit selection like ``'["browser", "terminal"]'`` parses as str, not list (#115866).
    Every reader and writer of the section goes through this one parser so the runtime,
    ``hermes doctor`` and ``hermes plugins enable`` agree on what the user configured. Any other
    shape (null, scalar, unparseable string) is None: the caller decides how to report it.
    """
    if isinstance(value, list):
        return value
    if isinstance(value, str) and value.strip().startswith("["):
        try:
            parsed = ast.literal_eval(value.strip())
        except (ValueError, SyntaxError):
            return None
        if isinstance(parsed, list):
            return [str(item) for item in parsed]
    return None


def _platform_default_toolset(platform: object) -> str:
    info = PLATFORMS.get(platform)
    return info.default_toolset if info is not None else f"hermes-{platform}"


def _platform_default_is_valid(
    platform: object, default_toolset: str, is_valid_toolset: Callable[[str], bool],
    is_allowed_for_platform: Callable[[str, str], bool]) -> bool:
    if is_valid_toolset(default_toolset) and is_allowed_for_platform(default_toolset, str(platform)):
        return True
    # Dynamic plugin platforms are resolved by toolsets.resolve_toolset() even though their synthesized
    # hermes-<platform> name is not in TOOLSETS.
    try:
        from gateway.platform_registry import platform_registry

        return platform_registry.is_registered(platform)
    except Exception:
        return False


def saved_toolset_resolver(config: dict) -> Callable[[str], bool]:
    """``is_valid_toolset`` for a saved ``platform_toolsets`` list, mirroring what
    ``tools_config._get_platform_tools`` lets through: registered toolsets, any configured MCP server
    (a disabled one is inactive, not a typo), ``hermes-<platform>`` plugin-platform bundles and the
    ``no_mcp`` sentinel. The manifest scan and the plugin lookup (which may run plugin discovery)
    happen only for a name the cheaper checks cannot place."""
    from functools import cache

    from toolsets import validate_toolset

    mcp_servers = config.get("mcp_servers")
    known = {str(name) for name in mcp_servers} if isinstance(mcp_servers, dict) else set()
    known.add("no_mcp")

    @cache
    def platform_bundles() -> frozenset:
        from hermes_cli.config import _platform_plugin_manifests

        return frozenset(f"hermes-{name}" for name, _manifest in _platform_plugin_manifests())

    @cache
    def plugin_names() -> frozenset:
        from hermes_cli.plugins import get_plugin_toolset_keys_nowait, get_portable_mcp_server_names_nowait

        return frozenset(get_plugin_toolset_keys_nowait() | get_portable_mcp_server_names_nowait())

    return lambda name: (validate_toolset(name) or name in known
                         or name in platform_bundles() or name in plugin_names())


def validate_platform_toolsets(
    platform_toolsets: object, is_valid_toolset: Callable[[str], bool],
    is_allowed_for_platform: Callable[[str, str], bool] = toolset_allowed_for_platform,
) -> List[str]:
    """Return human-readable warnings for a ``platform_toolsets`` mapping.
    Reports: a toolset name ``is_valid_toolset`` rejects (suggesting ``hermes-<platform>`` when that
    would have been valid); a non-empty mapping resolving to zero valid toolsets (agent would start with
    no tools); a platform with no valid toolsets, checked per-platform because the global net is
    suppressed once any platform is valid; and non-list platform values, which fall back to the platform
    default. ``is_valid_toolset`` is injected so this does no registry imports or I/O."""
    warnings: List[str] = []
    if not isinstance(platform_toolsets, dict) or not platform_toolsets:
        return warnings

    valid_count = 0
    for platform, raw in platform_toolsets.items():
        default = _platform_default_toolset(platform)
        default_valid = _platform_default_is_valid(platform, default, is_valid_toolset, is_allowed_for_platform)
        platform_valid_count = 0
        toolsets = parse_platform_toolsets_value(raw)
        if toolsets is None:
            if default_valid:
                valid_count += 1
                platform_valid_count += 1
            fallback_detail = f"falling back to '{default}'" if default_valid else f"falling back to unknown default '{default}'"
            if raw is None:
                value_detail = "a null toolset value"
            elif isinstance(raw, str):
                value_detail = f"invalid toolset value '{raw}'"
            else:
                value_detail = f"invalid {type(raw).__name__} toolset value"
            warnings.append(
                f"platform '{platform}' has {value_detail} — "
                f"{fallback_detail}. Run `hermes tools` to configure explicitly.")
            if platform_valid_count == 0:
                warnings.append(f"platform '{platform}' has no valid toolsets configured — {_NO_TOOLS}")
            continue

        for name in toolsets:
            if not isinstance(name, str) or not name:
                continue
            if not is_valid_toolset(name):
                hint = f" — did you mean '{default}'?" if default_valid else ""
                warnings.append(f"platform '{platform}' references unknown toolset '{name}'{hint}")
            elif is_allowed_for_platform(name, str(platform)):
                valid_count += 1
                platform_valid_count += 1
            else:
                warnings.append(
                    f"platform '{platform}' references toolset '{name}' which is not available on this platform"
                )

        if platform_valid_count == 0:
            reason = "is configured with an empty toolset list" if not toolsets else "has no valid toolsets configured"
            warnings.append(f"platform '{platform}' {reason} — {_NO_TOOLS}")

    if valid_count == 0:
        warnings.append(
            "platform_toolsets resolves to zero valid toolsets — the agent will "
            "have no tools. Run `hermes tools` to reconfigure.")
    return warnings