# Copyright (c) 2026 Krzysztof Rudnicki. MIT licence.
"""The !pomoc command: every command the bot has, and what each one does.

Nothing in the chat used to say the commands existed. The README's table was
the only list, it was stale within two releases, and nobody in a Signal group
reads a README anyway -- so the list is built from the registry itself. A
command cannot be registered without a description (``CommandRegistry.register``
requires one), and any command this module's ``GROUPS`` does not mention is
printed anyway, under no heading. Between those two, a new command cannot
quietly fail to appear here.

The trigger printed is ``Command.primary``, the first *raw* alias, because
``Command.triggers`` holds folded skeletons in an unordered set: "!papież"
survives there only as "!papiez", and the styled Unicode aliases would come
out as the zalgo they are.
"""

from __future__ import annotations

from typing import TYPE_CHECKING, Final

from signal_bot.animals import load_aliases
from signal_bot.pack_command import NAME_PREFIX

if TYPE_CHECKING:
    from collections.abc import Sequence

    from signal_bot.decorators import Decorator
    from signal_bot.registry import Command, CommandContext, CommandRegistry

COMMAND_NAME: Final = "help"
DESCRIPTION: Final = "ta lista"

HEADING: Final = "Komendy"

# Which commands sit under which heading, in the order they are printed.
# Anything missing from here still gets printed, in a block of its own -- see
# the module docstring.
GROUPS: Final[tuple[tuple[str, tuple[str, ...]], ...]] = (
    ("Obrazki", ("cat", "dog", "gecko")),
    ("Papież", ("pope",)),
    (
        "Statystyki",
        (
            "stats_today",
            "stats_yesterday",
            "stats_week",
            "stats_month",
            "stats_year",
            "stats_records",
            "stats_crown",
            "stats_weekdays",
            "stats_me",
        ),
    ),
)

# Only the canonical spelling is listed above, but half the group types the
# English one. Without this line "!cat" looks broken to somebody holding a
# list that says "!kot".
SPELLINGS: Final = "Każda komenda ma też inne pisownie, np. !cat, !stats, !week."

# The private album, when a group has one. Its heading is here and its
# commands are not: they come from a file this repository never sees, so
# GROUPS could not name them even if it wanted to -- and naming an optional
# command there would make !pomoc fail in every group that has no pack.
PACK_HEADING: Final = "Zdjęcia"
PACK_HINT: Final = "Kilka naraz ({first} {second}) = zdjęcie, na którym są wszyscy."


def _line(command: Command) -> str:
    """One command as !pomoc prints it."""
    return f"{command.primary} — {command.description}"


def _pack_block(commands: Sequence[Command]) -> str:
    """The album's own block, or "" for a group that has no album.

    Built from whatever is registered rather than from a table, because the
    entries are private data: this file cannot know how many there are or
    what they are called, and must not need to.
    """
    entries = [c for c in commands if c.name.startswith(NAME_PREFIX)]
    if not entries:
        return ""
    lines = [PACK_HEADING, *(_line(command) for command in entries)]
    if len(entries) > 1:
        lines.append(PACK_HINT.format(first=entries[0].primary, second=entries[1].primary))
    return "\n".join(lines)


def render_help(commands: Sequence[Command], group_id: str) -> str:
    """Render the command list for one group, grouped, in registration order.

    Per group, because a command can be scoped to one: the private album
    exists in its own groups and nowhere else, and a help text that listed it
    everywhere would announce it to every group the bot is in.
    """
    visible = [command for command in commands if command.allowed_in(group_id)]
    by_name = {command.name: command for command in visible}
    # Indexed, not .get(): a name in GROUPS that no command answers to is a
    # typo in this file, and it should fail loudly the first time the command
    # is used rather than silently drop a line.
    grouped = {name for _, names in GROUPS for name in names}
    blocks = [HEADING]
    for title, names in GROUPS:
        blocks.append("\n".join([title, *(_line(by_name[name]) for name in names)]))
    pack = _pack_block(visible)
    if pack:
        blocks.append(pack)
    blocks.append(
        "\n".join(
            _line(c)
            for c in visible
            if c.name not in grouped and not c.name.startswith(NAME_PREFIX)
        )
    )
    blocks.append(SPELLINGS)
    return "\n\n".join(blocks)


def register_help_command(
    registry: CommandRegistry,
    *,
    decorate: Decorator | None = None,
    aliases: dict[str, list[str]] | None = None,
) -> None:
    """Register !pomoc, which reads the registry it is registered on.

    The registry is read when the command *runs*, not when it is registered,
    so this may be wired up in any order and still list everything.
    """
    table = load_aliases() if aliases is None else aliases

    async def handler(ctx: CommandContext) -> None:
        await ctx.reply(render_help(registry.commands, ctx.group_id))

    wrapped = decorate(handler) if decorate is not None else handler
    registry.register(COMMAND_NAME, table[COMMAND_NAME], wrapped, DESCRIPTION)