"""Add optimistic document review decisions and immutable review audit.

Revision ID: 0004_document_review
Revises: 0003_document_ingestion
Create Date: 2026-07-13
"""

from collections.abc import Sequence

from alembic import op

revision: str = "0004_document_review"
down_revision: str | None = "0003_document_ingestion"
branch_labels: str | Sequence[str] | None = None
depends_on: str | Sequence[str] | None = None


def upgrade() -> None:
    op.execute(
        """
        ALTER TABLE rag.document_versions
          ADD COLUMN review_revision integer NOT NULL DEFAULT 0,
          ADD CONSTRAINT document_versions_review_revision_valid
            CHECK (review_revision >= 0);
        """
    )
    op.execute(
        """
        CREATE TABLE rag.document_review_events (
          id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
          document_id uuid NOT NULL,
          document_version_id uuid NOT NULL,
          actor_subject text NOT NULL,
          decision text NOT NULL,
          reason_code text NOT NULL,
          previous_revision integer NOT NULL,
          resulting_revision integer NOT NULL,
          outbound_manifest_sha256 char(64),
          embedding_profile_hash char(64),
          trace_id uuid NOT NULL,
          created_at timestamptz NOT NULL DEFAULT now(),
          CONSTRAINT document_review_events_document_fk
            FOREIGN KEY (document_id, document_version_id)
            REFERENCES rag.document_versions (document_id, id)
            ON DELETE CASCADE,
          CONSTRAINT document_review_events_actor_nonempty
            CHECK (btrim(actor_subject) <> '' AND length(actor_subject) <= 200),
          CONSTRAINT document_review_events_decision_valid
            CHECK (decision IN ('APPROVE', 'REJECT')),
          CONSTRAINT document_review_events_reason_valid
            CHECK (reason_code IN (
              'SYNTHETIC_REVIEW_APPROVED',
              'RIGHTS_NOT_VERIFIED',
              'CONTENT_QUALITY_REJECTED',
              'CLOUD_PROCESSING_REJECTED'
            )),
          CONSTRAINT document_review_events_revision_valid
            CHECK (
              previous_revision >= 0
              AND resulting_revision = previous_revision + 1
            ),
          CONSTRAINT document_review_events_hashes_valid
            CHECK (
              (
                decision = 'APPROVE'
                AND outbound_manifest_sha256 ~ '^[0-9a-f]{64}$'
                AND embedding_profile_hash ~ '^[0-9a-f]{64}$'
              )
              OR (
                decision = 'REJECT'
                AND embedding_profile_hash IS NULL
              )
            ),
          CONSTRAINT document_review_events_version_revision_key
            UNIQUE (document_version_id, resulting_revision)
        );
        """
    )
    op.execute(
        """
        CREATE INDEX document_review_events_document_timeline
          ON rag.document_review_events (document_id, created_at, id);
        """
    )
    op.execute(
        """
        CREATE FUNCTION rag.reject_document_review_event_mutation()
        RETURNS trigger
        LANGUAGE plpgsql
        SECURITY INVOKER
        SET search_path = pg_catalog, rag
        AS $function$
        BEGIN
          RAISE EXCEPTION 'document review events are append-only'
            USING ERRCODE = '23514';
        END
        $function$;
        """
    )
    op.execute(
        """
        CREATE TRIGGER document_review_events_append_only
        BEFORE UPDATE OR DELETE
        ON rag.document_review_events
        FOR EACH ROW
        EXECUTE FUNCTION rag.reject_document_review_event_mutation();
        """
    )


def downgrade() -> None:
    op.execute(
        "DROP TRIGGER IF EXISTS document_review_events_append_only ON rag.document_review_events;"
    )
    op.execute("DROP FUNCTION IF EXISTS rag.reject_document_review_event_mutation();")
    op.execute("DROP TABLE IF EXISTS rag.document_review_events;")
    op.execute(
        """
        ALTER TABLE rag.document_versions
          DROP CONSTRAINT IF EXISTS document_versions_review_revision_valid,
          DROP COLUMN IF EXISTS review_revision;
        """
    )