"""Widen system_settings value from VARCHAR(500) to TEXT

Revision ID: 004_widen_system_setting_value
Revises: 003_render_comments
Create Date: 2026-04-17

Rationale
---------
SystemSetting.value was VARCHAR(500), which is sufficient for short config
values but overflows when the email_ingested_message_ids key accumulates
multiple Outlook Message-IDs.  A single Outlook Message-ID can be ~100 chars,
so even a modest backlog of 6–7 messages exceeds the 500-byte limit, causing:

    pymysql.err.DataError: (1406, "Data too long for column 'value' at row 1")

TEXT (up to 65,535 bytes) is the correct type for any value store that can
hold accumulated lists or free-form strings of unbounded length.  This mirrors
the same fix applied to ticket_history in migration 001.

Apply
-----
    flask db upgrade

Rollback
--------
    flask db downgrade
"""

from alembic import op
import sqlalchemy as sa

revision = '004_widen_system_setting_value'
down_revision = '003_render_comments'
branch_labels = None
depends_on = None


def upgrade():
    with op.batch_alter_table('system_settings', schema=None) as batch_op:
        batch_op.alter_column(
            'value',
            existing_type=sa.String(length=500),
            type_=sa.Text(),
            existing_nullable=False,
        )


def downgrade():
    with op.batch_alter_table('system_settings', schema=None) as batch_op:
        batch_op.alter_column(
            'value',
            existing_type=sa.Text(),
            type_=sa.String(length=500),
            existing_nullable=False,
        )