"""phase25 — add GPS coordinates to inspections

Adds submit_latitude and submit_longitude columns to the inspections table.
Populated at web submission time via browser Geolocation API.
Null for all existing inspections and mobile submissions (handled separately).
"""

import sqlalchemy as sa
from alembic import op

revision      = 'phase25_inspection_gps'
down_revision = 'phase24_notify_defaults'
branch_labels = None
depends_on    = None


def upgrade():
    conn = op.get_bind()

    has_lat = conn.execute(sa.text(
        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS "
        "WHERE TABLE_SCHEMA = DATABASE() "
        "  AND TABLE_NAME = 'inspections' "
        "  AND COLUMN_NAME = 'submit_latitude'"
    )).scalar()

    if not has_lat:
        op.add_column('inspections',
            sa.Column('submit_latitude', sa.Numeric(10, 7), nullable=True))
        op.add_column('inspections',
            sa.Column('submit_longitude', sa.Numeric(10, 7), nullable=True))


def downgrade():
    op.drop_column('inspections', 'submit_longitude')
    op.drop_column('inspections', 'submit_latitude')