"""phase36 — scheduled_inspections + inspections.scheduled_inspection_id

Planned/recurring inspection assignments (facility + template + inspector +
due date). Completed inspections link back via inspections.scheduled_inspection_id.

Uses INFORMATION_SCHEMA existence checks — safe to re-run.
"""

revision      = 'phase36_scheduled_insp'
down_revision = 'phase35_issue_handler'
branch_labels = None
depends_on    = None

from alembic import op
import sqlalchemy as sa


def _table_exists(conn, table):
    return conn.execute(sa.text(
        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES "
        "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = :t"
    ), {"t": table}).scalar() > 0


def _column_exists(conn, table, column):
    return conn.execute(sa.text(
        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS "
        "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = :t AND COLUMN_NAME = :c"
    ), {"t": table, "c": column}).scalar() > 0


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

    if not _table_exists(bind, 'scheduled_inspections'):
        op.create_table(
            'scheduled_inspections',
            sa.Column('id', sa.Integer, primary_key=True),
            sa.Column('facility_id', sa.Integer,
                      sa.ForeignKey('facilities.id', ondelete='CASCADE'), nullable=False),
            sa.Column('template_id', sa.Integer,
                      sa.ForeignKey('inspection_templates.id', ondelete='CASCADE'), nullable=False),
            sa.Column('inspector_id', sa.Integer,
                      sa.ForeignKey('users.id', ondelete='SET NULL'), nullable=True),
            sa.Column('frequency', sa.Enum('once', 'daily', 'weekly', 'monthly'),
                      nullable=False, server_default='once'),
            sa.Column('next_due_date', sa.Date, nullable=False),
            sa.Column('active', sa.Boolean, nullable=False, server_default='1'),
            sa.Column('notes', sa.Text, nullable=True),
            sa.Column('created_by', sa.Integer,
                      sa.ForeignKey('users.id', ondelete='SET NULL'), nullable=True),
            sa.Column('created_at', sa.DateTime, nullable=False),
            sa.Column('last_completed_at', sa.DateTime, nullable=True),
            sa.Column('advance_notified', sa.Boolean, nullable=False, server_default='0'),
            sa.Column('due_notified', sa.Boolean, nullable=False, server_default='0'),
            sa.Column('overdue_notified', sa.Boolean, nullable=False, server_default='0'),
        )
        op.create_index('ix_sched_insp_facility', 'scheduled_inspections', ['facility_id'])
        op.create_index('ix_sched_insp_inspector', 'scheduled_inspections', ['inspector_id'])
        op.create_index('ix_sched_insp_due', 'scheduled_inspections', ['next_due_date'])

    if not _column_exists(bind, 'inspections', 'scheduled_inspection_id'):
        op.execute(sa.text(
            "ALTER TABLE inspections ADD COLUMN scheduled_inspection_id INT NULL"
        ))
        op.execute(sa.text(
            "ALTER TABLE inspections ADD CONSTRAINT fk_inspection_scheduled "
            "FOREIGN KEY (scheduled_inspection_id) REFERENCES scheduled_inspections(id) "
            "ON DELETE SET NULL"
        ))


def downgrade():
    bind = op.get_bind()
    if _column_exists(bind, 'inspections', 'scheduled_inspection_id'):
        op.execute(sa.text("ALTER TABLE inspections DROP FOREIGN KEY fk_inspection_scheduled"))
        op.execute(sa.text("ALTER TABLE inspections DROP COLUMN scheduled_inspection_id"))
    if _table_exists(bind, 'scheduled_inspections'):
        op.drop_table('scheduled_inspections')