"""手动迁移：建 site_nav_click（之前是 db.create_all() 建的，不在 alembic 里）。

现有 DB 已经有一张同名的表，迁移以空操作为主；对空 DB（首次部署 / 新容器）会建表。
"""
from alembic import op
import sqlalchemy as sa

revision = 'a47a5d2a3f1b'
down_revision = 'afa5cfb23a85'
branch_labels = None
depends_on = None


def upgrade():
    bind = op.get_bind()
    inspector = sa.inspect(bind)
    if 'site_nav_click' in inspector.get_table_names():
        # 已存在的 DB：表在，但 alembic 视角下没版本记录 → 跳过 DDL
        # 同时保证 anon_id 列存在（方案 C 升级路径）
        cols = {c['name'] for c in inspector.get_columns('site_nav_click')}
        with op.batch_alter_table('site_nav_click') as batch:
            if 'anon_id' not in cols:
                batch.add_column(sa.Column('anon_id', sa.String(length=36), nullable=True, comment='匿名访客ID'))
                batch.create_index('ix_site_nav_click_anon_id', ['anon_id'], unique=False)
        return

    op.create_table(
        'site_nav_click',
        sa.Column('id', sa.Integer(), autoincrement=True, nullable=False, comment='记录ID'),
        sa.Column('nav_id', sa.Integer(), nullable=False, comment='被点击的导航ID'),
        sa.Column('anon_id', sa.String(length=36), nullable=True, comment='匿名访客ID'),
        sa.Column('day', sa.String(length=10), nullable=True, comment='日期 YYYY-MM-DD'),
        sa.Column('ip', sa.String(length=64), nullable=True, comment='访客IP'),
        sa.Column('clicked_at', sa.DateTime(), nullable=True, comment='点击时间'),
        sa.PrimaryKeyConstraint('id'),
    )
    with op.batch_alter_table('site_nav_click') as batch:
        batch.create_index('ix_site_nav_click_nav_id', ['nav_id'], unique=False)
        batch.create_index('ix_site_nav_click_anon_id', ['anon_id'], unique=False)
        batch.create_index('ix_site_nav_click_day', ['day'], unique=False)
        batch.create_index('ix_site_nav_click_clicked_at', ['clicked_at'], unique=False)


def downgrade():
    op.drop_table('site_nav_click')