"""GEMS Pass 1: domain_id FK on extension_points/technical_debt, repo_id on contributions

Revision ID: e1f2a3b4c5d6
Revises: d3e4f5a6b7c8
Create Date: 2026-03-02 00:00:00.000000
"""
from typing import Sequence, Union

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

revision: str = "e1f2a3b4c5d6"
down_revision: Union[str, None] = "d3e4f5a6b7c8"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    # ── extension_points: add domain_id FK ────────────────────────────────────
    op.add_column(
        "extension_points",
        sa.Column("domain_id", postgresql.UUID(as_uuid=True), nullable=True),
    )
    op.create_foreign_key(
        "fk_ep_domain_id",
        "extension_points", "domains",
        ["domain_id"], ["id"],
        ondelete="RESTRICT",
    )

    # Backfill from slug string
    op.execute("""
        UPDATE extension_points ep
        SET domain_id = d.id
        FROM domains d
        WHERE d.slug = ep.domain
    """)

    # Safety check: abort if any rows remain unmatched
    op.execute("""
        DO $$
        BEGIN
            IF EXISTS (SELECT 1 FROM extension_points WHERE domain_id IS NULL) THEN
                RAISE EXCEPTION
                    'GEMS Pass 1: extension_points rows with unknown domain slug: %',
                    (SELECT string_agg(DISTINCT domain, ', ')
                     FROM extension_points WHERE domain_id IS NULL);
            END IF;
        END $$;
    """)

    op.alter_column("extension_points", "domain_id", nullable=False)
    op.drop_index("ix_extension_points_domain", table_name="extension_points")
    op.drop_column("extension_points", "domain")
    op.create_index("ix_extension_points_domain_id", "extension_points", ["domain_id"])

    # ── technical_debt: add domain_id FK ──────────────────────────────────────
    op.add_column(
        "technical_debt",
        sa.Column("domain_id", postgresql.UUID(as_uuid=True), nullable=True),
    )
    op.create_foreign_key(
        "fk_td_domain_id",
        "technical_debt", "domains",
        ["domain_id"], ["id"],
        ondelete="RESTRICT",
    )

    op.execute("""
        UPDATE technical_debt td
        SET domain_id = d.id
        FROM domains d
        WHERE d.slug = td.domain
    """)

    op.execute("""
        DO $$
        BEGIN
            IF EXISTS (SELECT 1 FROM technical_debt WHERE domain_id IS NULL) THEN
                RAISE EXCEPTION
                    'GEMS Pass 1: technical_debt rows with unknown domain slug: %',
                    (SELECT string_agg(DISTINCT domain, ', ')
                     FROM technical_debt WHERE domain_id IS NULL);
            END IF;
        END $$;
    """)

    op.alter_column("technical_debt", "domain_id", nullable=False)
    op.drop_index("ix_technical_debt_domain", table_name="technical_debt")
    op.drop_column("technical_debt", "domain")
    op.create_index("ix_technical_debt_domain_id", "technical_debt", ["domain_id"])

    # ── contributions: add nullable repo_id FK ────────────────────────────────
    op.add_column(
        "contributions",
        sa.Column(
            "repo_id",
            postgresql.UUID(as_uuid=True),
            sa.ForeignKey("managed_repos.id", ondelete="SET NULL"),
            nullable=True,
        ),
    )


def downgrade() -> None:
    # contributions: drop repo_id
    op.drop_column("contributions", "repo_id")

    # technical_debt: restore domain string
    op.add_column(
        "technical_debt",
        sa.Column("domain", sa.String(50), nullable=True),
    )
    op.execute("""
        UPDATE technical_debt td
        SET domain = d.slug
        FROM domains d
        WHERE d.id = td.domain_id
    """)
    op.alter_column("technical_debt", "domain", nullable=False)
    op.create_index("ix_technical_debt_domain", "technical_debt", ["domain"])
    op.drop_index("ix_technical_debt_domain_id", table_name="technical_debt")
    op.drop_constraint("fk_td_domain_id", "technical_debt", type_="foreignkey")
    op.drop_column("technical_debt", "domain_id")

    # extension_points: restore domain string
    op.add_column(
        "extension_points",
        sa.Column("domain", sa.String(50), nullable=True),
    )
    op.execute("""
        UPDATE extension_points ep
        SET domain = d.slug
        FROM domains d
        WHERE d.id = ep.domain_id
    """)
    op.alter_column("extension_points", "domain", nullable=False)
    op.create_index("ix_extension_points_domain", "extension_points", ["domain"])
    op.drop_index("ix_extension_points_domain_id", table_name="extension_points")
    op.drop_constraint("fk_ep_domain_id", "extension_points", type_="foreignkey")
    op.drop_column("extension_points", "domain_id")