"""Add band_storage table for provider-agnostic, encrypted storage configs.

Each band can have one active storage provider (Nextcloud, Google Drive, etc.).
Credentials are Fernet-encrypted at the application layer — never stored in plaintext.
A partial unique index enforces at most one active config per band at the DB level.

Revision ID: 0007_band_storage
Revises: 0006_waveform_peaks_in_db
Create Date: 2026-04-10
"""

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import UUID

revision = "0007_band_storage"
down_revision = "0006_waveform_peaks_in_db"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "band_storage",
        sa.Column("id", UUID(as_uuid=True), primary_key=True),
        sa.Column(
            "band_id",
            UUID(as_uuid=True),
            sa.ForeignKey("bands.id", ondelete="CASCADE"),
            nullable=False,
        ),
        sa.Column("provider", sa.String(20), nullable=False),
        sa.Column("label", sa.String(255), nullable=True),
        sa.Column("is_active", sa.Boolean, nullable=False, server_default="false"),
        sa.Column("root_path", sa.Text, nullable=True),
        # Fernet-encrypted JSON — never plaintext
        sa.Column("credentials", sa.Text, nullable=False),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
    )

    # Index for fast per-band lookups
    op.create_index("ix_band_storage_band_id", "band_storage", ["band_id"])

    # Partial unique index: at most one active storage per band
    op.execute(
        """
        CREATE UNIQUE INDEX uq_band_active_storage
        ON band_storage (band_id)
        WHERE is_active = true
        """
    )


def downgrade() -> None:
    op.execute("DROP INDEX IF EXISTS uq_band_active_storage")
    op.drop_index("ix_band_storage_band_id", table_name="band_storage")
    op.drop_table("band_storage")