from __future__ import annotations

import typing

from .. import operator, entities, errors


@operator.operator_class(name='del', help='删除当前会话的历史记录', usage='!del <序号>\n!del all')
class DelOperator(operator.CommandOperator):
    async def execute(self, context: entities.ExecuteContext) -> typing.AsyncGenerator[entities.CommandReturn, None]:
        if context.session.conversations:
            delete_index = 0
            if len(context.crt_params) > 0:
                try:
                    delete_index = int(context.crt_params[0])
                except Exception:
                    yield entities.CommandReturn(error=errors.CommandOperationError('索引必须是整数'))
                    return

            if delete_index < 0 or delete_index >= len(context.session.conversations):
                yield entities.CommandReturn(error=errors.CommandOperationError('索引超出范围'))
                return

            # 倒序
            to_delete_index = len(context.session.conversations) - 1 - delete_index

            if context.session.conversations[to_delete_index] == context.session.using_conversation:
                context.session.using_conversation = None

            del context.session.conversations[to_delete_index]

            yield entities.CommandReturn(text=f'已删除对话: {delete_index}')
        else:
            yield entities.CommandReturn(error=errors.CommandOperationError('当前没有对话'))


@operator.operator_class(name='all', help='删除此会话的所有历史记录', parent_class=DelOperator)
class DelAllOperator(operator.CommandOperator):
    async def execute(self, context: entities.ExecuteContext) -> typing.AsyncGenerator[entities.CommandReturn, None]:
        context.session.conversations = []
        context.session.using_conversation = None

        yield entities.CommandReturn(text='已删除所有对话')