"""Create chat_token_usage table

Revision ID: cba70ab35793
Revises: cd27562afa2e
Create Date: 2026-04-16 13:39:46.842540

"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision: str = 'cba70ab35793'
down_revision: Union[str, None] = 'cd27562afa2e'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


# (index_name, columns, unique, use_naming_convention)
# use_naming_convention=True wraps in batch_op.f(); False uses the raw string
# (matches the original auto-generated/hand-written split).
_INDEXES = [
    ('ix_chat_token_usage_chat_id', ['chat_id'], False, True),
    ('ix_chat_token_usage_document_id', ['document_id'], False, True),
    ('ix_chat_token_usage_id', ['id'], False, True),
    ('ix_chat_token_usage_model_name', ['model_name'], False, True),
    ('ix_chat_token_usage_model_time', ['model_name', 'timestamp'], False, False),
    ('ix_chat_token_usage_phase', ['phase'], False, True),
    ('ix_chat_token_usage_timestamp', ['timestamp'], False, True),
    ('ix_chat_token_usage_user_id', ['user_id'], False, True),
    ('ix_chat_token_usage_user_time', ['user_id', 'timestamp'], False, False),
]


def _index_names(bind, table_name: str) -> set[str]:
    inspector = sa.inspect(bind)
    return {idx["name"] for idx in inspector.get_indexes(table_name)}


def upgrade() -> None:
    bind = op.get_bind()
    inspector = sa.inspect(bind)

    if not inspector.has_table('chat_token_usage'):
        op.create_table('chat_token_usage',
        sa.Column('id', sa.Integer(), nullable=False),
        sa.Column('user_id', sa.Integer(), nullable=False),
        sa.Column('chat_id', sa.Integer(), nullable=True),
        sa.Column('document_id', sa.String(length=255), nullable=True),
        sa.Column('prompt_tokens', sa.BigInteger(), nullable=False),
        sa.Column('completion_tokens', sa.BigInteger(), nullable=False),
        sa.Column('total_tokens', sa.BigInteger(), nullable=False),
        sa.Column('model_name', sa.String(length=100), nullable=False),
        sa.Column('cost_usd', sa.DECIMAL(precision=12, scale=8), nullable=False),
        sa.Column('timestamp', sa.DateTime(timezone=True), server_default=sa.text('now()'), nullable=False),
        sa.Column('phase', sa.String(length=50), nullable=True),
        sa.ForeignKeyConstraint(['user_id'], ['users.id'], ondelete='CASCADE'),
        sa.PrimaryKeyConstraint('id')
        )

    existing = _index_names(bind, 'chat_token_usage')
    with op.batch_alter_table('chat_token_usage', schema=None) as batch_op:
        for name, cols, unique, use_f in _INDEXES:
            if name not in existing:
                ref = batch_op.f(name) if use_f else name
                batch_op.create_index(ref, cols, unique=unique)


def downgrade() -> None:
    bind = op.get_bind()
    inspector = sa.inspect(bind)

    if inspector.has_table('chat_token_usage'):
        existing = _index_names(bind, 'chat_token_usage')
        with op.batch_alter_table('chat_token_usage', schema=None) as batch_op:
            for name, _, _, use_f in reversed(_INDEXES):
                if name in existing:
                    ref = batch_op.f(name) if use_f else name
                    batch_op.drop_index(ref)

        op.drop_table('chat_token_usage')