"""Figures on a question: many of them, labelled, and each a real image record.

Revision ID: f0a1b2c3d4e5
Revises: e9f0a1b2c3d4
"""
import sqlalchemy as sa
from alembic import op
from sqlalchemy import inspect

revision = "f0a1b2c3d4e5"
down_revision = "e9f0a1b2c3d4"
branch_labels = None
depends_on = None


def upgrade():
    # A question could carry exactly one stem image and one explanation image,
    # held as a bare path with no title, no legend and no way to refer to it
    # from the text. This makes a figure a row: it points at an image in the
    # bank, carries the label the prose calls it by, and there can be several.
    if "question_media" not in inspect(op.get_bind()).get_table_names():
        op.create_table(
            "question_media",
            sa.Column("id", sa.Integer, primary_key=True),
            sa.Column("question_id", sa.Integer,
                      sa.ForeignKey("questions.id", ondelete="CASCADE"), nullable=False, index=True),
            sa.Column("media_id", sa.Integer,
                      sa.ForeignKey("media_assets.id", ondelete="CASCADE"), nullable=False, index=True),
            # Where it belongs. A figure that illustrates the answer must not
            # appear beside the stem, which is the mistake this whole area had.
            sa.Column("role", sa.String(20), nullable=False, server_default="stem"),
            # What the prose calls it — "Figure 1" — so the text can say
            # "shown in Figure 1" and mean something.
            sa.Column("label", sa.String(80), nullable=True),
            sa.Column("caption", sa.Text, nullable=True),
            sa.Column("position", sa.Integer, server_default="0"),
            sa.UniqueConstraint("question_id", "media_id", "role", name="uq_question_media"),
        )


def downgrade():
    op.drop_table("question_media")