"""add project create idempotency indexes

Revision ID: add_project_create_idempotency_indexes
Revises: add_work_item_draft_confirmation_fields
Create Date: 2026-03-24
"""

from __future__ import annotations

from alembic import op
import sqlalchemy as sa


revision = "add_project_create_idempotency_indexes"
down_revision = "add_work_item_draft_confirmation_fields"
branch_labels = None
depends_on = None


def _table_exists(bind, table_name: str) -> bool:
    return sa.inspect(bind).has_table(table_name)


def _duplicate_active_titles(bind) -> list[tuple[int, str, int]]:
    rows = bind.execute(
        sa.text(
            """
            SELECT
                tenant_id,
                lower(coalesce(nullif(title, ''), nullif(name, ''))) AS normalized_title,
                count(*) AS duplicate_count
            FROM projects
            WHERE status <> 'inactive'
              AND coalesce(nullif(title, ''), nullif(name, '')) IS NOT NULL
            GROUP BY tenant_id, lower(coalesce(nullif(title, ''), nullif(name, '')))
            HAVING count(*) > 1
            ORDER BY duplicate_count DESC, tenant_id ASC
            LIMIT 10
            """
        )
    ).fetchall()
    return [
        (int(row[0]), str(row[1] or ""), int(row[2]))
        for row in rows
    ]


def upgrade() -> None:
    bind = op.get_bind()
    if not _table_exists(bind, "projects"):
        return

    duplicates = _duplicate_active_titles(bind)
    if duplicates:
        sample = ", ".join(
            f"tenant={tenant_id}, title={title}, count={count}"
            for tenant_id, title, count in duplicates[:3]
        )
        raise RuntimeError(
            "cannot create uq_projects_tenant_active_title_ci because duplicate active project titles exist: "
            + sample
        )

    op.execute(
        sa.text(
            """
            CREATE UNIQUE INDEX IF NOT EXISTS uq_projects_tenant_active_title_ci
            ON projects (
                tenant_id,
                lower(coalesce(nullif(title, ''), nullif(name, '')))
            )
            WHERE status <> 'inactive'
              AND coalesce(nullif(title, ''), nullif(name, '')) IS NOT NULL
            """
        )
    )


def downgrade() -> None:
    bind = op.get_bind()
    if not _table_exists(bind, "projects"):
        return
    op.execute(sa.text("DROP INDEX IF EXISTS uq_projects_tenant_active_title_ci"))