Jul 17 - Fill the gaps between Single-tenant mode and Multi-tenant mode - MT4

migrations/versions/phase43_schedule_plan_fields.py

@@ -0,0 +1,120 @@
+"""phase43 — plan semantics for inspection_schedules
+
+Extends MT's `inspection_schedules` (phase34) with the single-tenant "plan"
+model (ST phase36_scheduled_inspections), rather than adding a second, competing
+scheduler table. Adds:
+
+  notes              TEXT      — free-text brief for the inspector
+  last_completed_at  DATETIME  — when the last occurrence was fulfilled
+  advance_notified   BOOL      — per-occurrence reminder de-dup flags, reset
+  due_notified       BOOL        when a recurring schedule rolls forward
+  overdue_notified   BOOL
+  mode               ENUM      — 'auto'  = cron materialises the Inspection
+                                 'plan'  = inspector clicks Start (ST behaviour)
+
+  inspections.inspection_schedule_id  — FK back to the originating schedule
+
+`next_run_at` (phase34) is reused as the due datetime — ST's `next_due_date` by
+another name. No duplicate column, no renames (rule 7).
+
+Existing rows keep working exactly as before: `mode` defaults to 'auto', which
+is the only behaviour that has ever existed in MT. Nothing flips to 'plan'
+unless someone chooses it in the form.
+
+INFORMATION_SCHEMA-guarded throughout — safe to re-run on every tenant DB.
+"""
+
+revision      = 'phase43_schedule_plan_fields'
+down_revision = 'phase42_area_qr_token'
+branch_labels = None
+depends_on    = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+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 _index_exists(conn, table, index):
+    return conn.execute(sa.text(
+        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS "
+        "WHERE TABLE_SCHEMA = DATABASE() "
+        "AND TABLE_NAME = :t AND INDEX_NAME = :i"
+    ), {"t": table, "i": index}).scalar() > 0
+
+
+_NEW_COLUMNS = (
+    ('notes',             'TEXT NULL'),
+    ('last_completed_at', 'DATETIME NULL'),
+    ('advance_notified',  'TINYINT(1) NOT NULL DEFAULT 0'),
+    ('due_notified',      'TINYINT(1) NOT NULL DEFAULT 0'),
+    ('overdue_notified',  'TINYINT(1) NOT NULL DEFAULT 0'),
+    ('mode',              "ENUM('auto','plan') NOT NULL DEFAULT 'auto'"),
+)
+
+
+def upgrade():
+    bind = op.get_bind()
+
+    for name, ddl in _NEW_COLUMNS:
+        if not _column_exists(bind, 'inspection_schedules', name):
+            op.execute(sa.text(
+                f"ALTER TABLE inspection_schedules ADD COLUMN {name} {ddl}"
+            ))
+
+    # Link a materialised/started Inspection back to its schedule.
+    if not _column_exists(bind, 'inspections', 'inspection_schedule_id'):
+        op.execute(sa.text(
+            "ALTER TABLE inspections ADD COLUMN inspection_schedule_id INT NULL"
+        ))
+    if not _index_exists(bind, 'inspections', 'ix_inspections_inspection_schedule_id'):
+        op.execute(sa.text(
+            "CREATE INDEX ix_inspections_inspection_schedule_id "
+            "ON inspections (inspection_schedule_id)"
+        ))
+    if not _fk_exists(bind, 'inspections', 'fk_inspections_inspection_schedule'):
+        # ON DELETE SET NULL: deleting a schedule must never delete completed
+        # inspection history.
+        op.execute(sa.text(
+            "ALTER TABLE inspections "
+            "ADD CONSTRAINT fk_inspections_inspection_schedule "
+            "FOREIGN KEY (inspection_schedule_id) "
+            "REFERENCES inspection_schedules (id) ON DELETE SET NULL"
+        ))
+
+
+def downgrade():
+    bind = op.get_bind()
+
+    if _fk_exists(bind, 'inspections', 'fk_inspections_inspection_schedule'):
+        op.execute(sa.text(
+            "ALTER TABLE inspections DROP FOREIGN KEY fk_inspections_inspection_schedule"
+        ))
+    if _index_exists(bind, 'inspections', 'ix_inspections_inspection_schedule_id'):
+        op.execute(sa.text(
+            "DROP INDEX ix_inspections_inspection_schedule_id ON inspections"
+        ))
+    if _column_exists(bind, 'inspections', 'inspection_schedule_id'):
+        op.execute(sa.text(
+            "ALTER TABLE inspections DROP COLUMN inspection_schedule_id"
+        ))
+
+    for name, _ddl in reversed(_NEW_COLUMNS):
+        if _column_exists(bind, 'inspection_schedules', name):
+            op.execute(sa.text(
+                f"ALTER TABLE inspection_schedules DROP COLUMN {name}"
+            ))