"""rename tables so every module prefixes its own

Two tables were named after the concept they came from rather than the module
they belong to, which made the schema read as if the template tables were part
of the paper module:

    paper_template   -> template                 the 模板 module
    section_field    -> template_field_library   the 字段库, which the 模板 module
                                                 owns and every template draws on

The paper module (``paper``, ``paper_sentence``, ``paper_sentence_reference``)
and the join table (``template_field``) already followed the rule and are not
touched. After this revision the naming is:

    template                  template_field        template_field_library
    paper                     paper_sentence        paper_sentence_reference

A rename, not a copy: ``RENAME TABLE`` moves the rows and leaves the data in
place, and TiDB carries a referencing foreign key along with the renamed table
(verified against the running cluster before this migration was written), so
the constraints in ``template_field``, ``paper`` and ``paper_sentence`` now
point at ``template`` and ``template_field_library`` with no drop/recreate
step. Index names are left alone: they are per-table in MySQL and TiDB, and
``template_field`` — whose indexes embed its own name — is not renamed.

Revision ID: f27a1c6d9e04
Revises: c41d7b09e5af
Create Date: 2026-09-18

"""

from collections.abc import Sequence

from alembic import op

# revision identifiers, used by Alembic.
revision: str = "f27a1c6d9e04"
down_revision: str | None = "c41d7b09e5af"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    op.rename_table("paper_template", "template")
    op.rename_table("section_field", "template_field_library")


def downgrade() -> None:
    op.rename_table("template_field_library", "section_field")
    op.rename_table("template", "paper_template")