"""Remove product variant system — products are unique, no variant concept.

Revision ID: 027
Revises: 026
Create Date: 2026-03-03
"""
from alembic import op
import sqlalchemy as sa

revision = "027"
down_revision = "026"
branch_labels = None
depends_on = None

NIL_UUID = "00000000-0000-0000-0000-000000000000"


def upgrade() -> None:
    # Drop variant-aware unique indexes on order_lines
    op.execute("DROP INDEX IF EXISTS uq_order_lines_tracking")
    op.execute("DROP INDEX IF EXISTS uq_order_lines_render")

    # Drop variant_id column from order_lines
    op.execute("ALTER TABLE order_lines DROP COLUMN IF EXISTS variant_id")

    # Deduplicate tracking-only lines (output_type_id IS NULL) — keep the newest row per
    # (order_id, product_id) pair so the unique index can be created cleanly.
    op.execute("""
        DELETE FROM order_lines
        WHERE output_type_id IS NULL
          AND id NOT IN (
              SELECT DISTINCT ON (order_id, product_id) id
              FROM order_lines
              WHERE output_type_id IS NULL
              ORDER BY order_id, product_id, created_at DESC
          )
    """)

    # Deduplicate render lines — keep the newest row per (order_id, product_id, output_type_id).
    op.execute("""
        DELETE FROM order_lines
        WHERE output_type_id IS NOT NULL
          AND id NOT IN (
              SELECT DISTINCT ON (order_id, product_id, output_type_id) id
              FROM order_lines
              WHERE output_type_id IS NOT NULL
              ORDER BY order_id, product_id, output_type_id, created_at DESC
          )
    """)

    # Recreate simpler unique indexes without variant_id
    op.execute(
        "CREATE UNIQUE INDEX uq_order_lines_tracking "
        "ON order_lines (order_id, product_id) "
        "WHERE output_type_id IS NULL"
    )
    op.execute(
        "CREATE UNIQUE INDEX uq_order_lines_render "
        "ON order_lines (order_id, product_id, output_type_id) "
        "WHERE output_type_id IS NOT NULL"
    )

    # Drop product_variants table (CASCADE removes its indexes automatically)
    op.execute("DROP TABLE IF EXISTS product_variants CASCADE")


def downgrade() -> None:
    # Recreate product_variants table
    op.execute("""
        CREATE TABLE product_variants (
            id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
            product_id UUID NOT NULL REFERENCES products(id) ON DELETE CASCADE,
            name VARCHAR(500) NOT NULL,
            gewuenschte_bildnummer VARCHAR(500),
            components JSONB NOT NULL DEFAULT '[]',
            is_default BOOLEAN NOT NULL DEFAULT false,
            source_excel VARCHAR(1000),
            created_at TIMESTAMP NOT NULL DEFAULT NOW(),
            updated_at TIMESTAMP NOT NULL DEFAULT NOW()
        )
    """)
    op.execute(
        "CREATE UNIQUE INDEX uq_product_variants_product_name "
        "ON product_variants (product_id, lower(name))"
    )
    op.execute("CREATE INDEX ON product_variants (product_id)")

    # Add back variant_id to order_lines
    op.execute(
        "ALTER TABLE order_lines ADD COLUMN variant_id UUID "
        "REFERENCES product_variants(id) ON DELETE SET NULL"
    )

    # Drop simple indexes and restore variant-aware indexes
    op.execute("DROP INDEX IF EXISTS uq_order_lines_tracking")
    op.execute("DROP INDEX IF EXISTS uq_order_lines_render")

    op.execute(
        "CREATE UNIQUE INDEX uq_order_lines_tracking "
        f"ON order_lines (order_id, product_id, COALESCE(variant_id, '{NIL_UUID}'::uuid)) "
        "WHERE output_type_id IS NULL"
    )
    op.execute(
        "CREATE UNIQUE INDEX uq_order_lines_render "
        "ON order_lines (order_id, product_id, output_type_id, "
        f"COALESCE(variant_id, '{NIL_UUID}'::uuid)) "
        "WHERE output_type_id IS NOT NULL"
    )