"""P0-03: Prediction 幂等指纹——移除旧唯一约束,改为 partial unique on input_hash

input_hash 非空时唯一(同指纹返回已有行,不 UPDATE/INSERT);
兼容旧数据 NULL input_hash(不强制回填)。

Revision ID: 0024_prediction_idempotent_fingerprint
Revises: 0023_standings_append_only
Create Date: 2026-09-22
"""

from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa

revision: str = '0024_prediction_idempotent_fingerprint'
down_revision: Union[str, None] = '0023_standings_append_only'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    # 移除旧唯一约束(match, provider, model, mode, run_type)
    op.drop_constraint(
        'uq_predictions_match_provider_model_mode_run_type',
        'predictions', type_unique=True,
    )
    # P0-03: partial unique on input_hash(非空时唯一)
    op.create_index(
        'ix_predictions_input_hash_unique', 'predictions', ['input_hash'], unique=True,
        postgresql_where=sa.text('input_hash IS NOT NULL'),
    )


def downgrade() -> None:
    op.drop_index('ix_predictions_input_hash_unique', table_name='predictions')
    op.create_unique_constraint(
        'uq_predictions_match_provider_model_mode_run_type',
        'predictions',
        ['match_id', 'provider', 'model', 'mode', 'run_type'],
    )