"""Add Phase Materials Table (Feature f19)

Erstellt die phase_materials Tabelle fuer die
Material-Verknuepfung an Unterrichtsphasen.

Revision ID: 004
Revises: 003
Create Date: 2026-01-15 17:00:00

"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa

# revision identifiers, used by Alembic.
revision: str = '004'
down_revision: Union[str, None] = '003'
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        'phase_materials',
        sa.Column('id', sa.String(36), primary_key=True),
        sa.Column('teacher_id', sa.String(100), nullable=False, index=True),
        sa.Column('title', sa.String(300), nullable=False),
        sa.Column(
            'material_type',
            sa.Enum('document', 'link', 'video', 'image', 'worksheet', 'presentation', 'other',
                    name='materialtypeenum'),
            default='document',
            nullable=False
        ),
        sa.Column('url', sa.String(2000), nullable=True),
        sa.Column('description', sa.Text(), default=''),
        sa.Column('phase', sa.String(50), nullable=True, index=True),
        sa.Column('subject', sa.String(100), default=''),
        sa.Column('grade_level', sa.String(50), default=''),
        sa.Column('tags', sa.JSON(), default=list),
        sa.Column('is_public', sa.Boolean(), default=False),
        sa.Column('usage_count', sa.Integer(), default=0),
        sa.Column('session_id', sa.String(36), sa.ForeignKey('lesson_sessions.id'), nullable=True, index=True),
        sa.Column('created_at', sa.DateTime(), server_default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime(), server_default=sa.func.now(), onupdate=sa.func.now()),
    )

    # Index fuer Phasen-Suche
    op.create_index(
        'ix_phase_materials_search',
        'phase_materials',
        ['teacher_id', 'phase', 'subject'],
    )

    # Index fuer oeffentliche Materialien
    op.create_index(
        'ix_phase_materials_public',
        'phase_materials',
        ['is_public', 'usage_count'],
        postgresql_where=sa.text('is_public = true')
    )


def downgrade() -> None:
    op.drop_index('ix_phase_materials_public', table_name='phase_materials')
    op.drop_index('ix_phase_materials_search', table_name='phase_materials')
    op.drop_table('phase_materials')
    op.execute("DROP TYPE IF EXISTS materialtypeenum")