Aug 4 - Update code to follow up - MT13b

migrations/versions/phase49_followup_requested_by.py

@@ -0,0 +1,97 @@
+"""phase49 — follow-up request attribution (customer-raised follow-ups)
+
+Ports single-tenant phase46 onto the multi-tenant chain. Adds to `inspections`:
+
+    follow_up_requested_by  INT NULL  FK → users(id) ON DELETE SET NULL
+    follow_up_requested_at  DATETIME NULL
+
+Customers can now request a follow-up re-inspection of a completed inspection at
+their own facilities (previously admin/director only), so `follow_up_required`
+alone is no longer enough — staff need to see WHO is waiting on the
+re-inspection, and a client request must be visibly distinct from an internal
+one. `flag_followup()` sets both columns; `clear_followup()` nulls them.
+
+No backfill: legacy rows keep NULL, which the UI renders as an unattributed
+follow-up exactly as it did before. FK is SET NULL so deleting a user never
+deletes inspection history.
+
+Revision id note
+----------------
+`alembic_version.version_num` is VARCHAR(32); the id below is 23 characters.
+The filename stays descriptive — Alembic keys on the `revision` string.
+
+Uses INFORMATION_SCHEMA checks — safe to re-run on every tenant DB. Additive
+only: nothing is renamed, retyped or dropped.
+"""
+
+revision      = 'phase49_followup_req_by'
+down_revision = 'phase48_sched_parent_insp'
+branch_labels = None
+depends_on    = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+_TABLE   = 'inspections'
+_FK_NAME = 'fk_inspections_follow_up_requested_by'
+
+
+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 _fk_exists(conn, table, name):
+    return conn.execute(sa.text(
+        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS "
+        "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = :t "
+        "AND CONSTRAINT_NAME = :n AND CONSTRAINT_TYPE = 'FOREIGN KEY'"
+    ), {"t": table, "n": name}).scalar() > 0
+
+
+def upgrade():
+    bind = op.get_bind()
+    if not _table_exists(bind, _TABLE):
+        return
+
+    if not _column_exists(bind, _TABLE, 'follow_up_requested_by'):
+        op.execute(sa.text(
+            f"ALTER TABLE {_TABLE} "
+            f"ADD COLUMN follow_up_requested_by INT NULL AFTER follow_up_note"
+        ))
+    if not _column_exists(bind, _TABLE, 'follow_up_requested_at'):
+        op.execute(sa.text(
+            f"ALTER TABLE {_TABLE} "
+            f"ADD COLUMN follow_up_requested_at DATETIME NULL "
+            f"AFTER follow_up_requested_by"
+        ))
+    if not _fk_exists(bind, _TABLE, _FK_NAME):
+        op.execute(sa.text(
+            f"ALTER TABLE {_TABLE} ADD CONSTRAINT {_FK_NAME} "
+            f"FOREIGN KEY (follow_up_requested_by) REFERENCES users(id) "
+            f"ON DELETE SET NULL"
+        ))
+
+
+def downgrade():
+    bind = op.get_bind()
+    if not _table_exists(bind, _TABLE):
+        return
+
+    # FK first — MySQL refuses to drop a column still referenced by one.
+    if _fk_exists(bind, _TABLE, _FK_NAME):
+        op.execute(sa.text(f"ALTER TABLE {_TABLE} DROP FOREIGN KEY {_FK_NAME}"))
+    for col in ('follow_up_requested_at', 'follow_up_requested_by'):
+        if _column_exists(bind, _TABLE, col):
+            op.execute(sa.text(f"ALTER TABLE {_TABLE} DROP COLUMN {col}"))