// file: kb-store/src/postgres/query/health_queries.rs
// version: 1

//! PostgreSQL health and diagnostic SQL queries.

pub(in crate::postgres) async fn run_health_check(pool: &sqlx::PgPool) -> kb_core::Result<()> {
    let query_result = sqlx::query_scalar::<sqlx::Postgres, i32>("SELECT 1").fetch_one(pool).await;
    return match query_result {
        std::result::Result::Ok(_value) => std::result::Result::Ok(()),
        std::result::Result::Err(error) => std::result::Result::Err(kb_core::Error::db(format!(
            "postgres healthcheck failed: {error}"
        ))),
    };
}

pub(in crate::postgres) async fn load_current_schema(
    pool: &sqlx::PgPool,
) -> kb_core::Result<std::string::String> {
    let query_result =
        sqlx::query_scalar::<sqlx::Postgres, std::string::String>("SELECT current_schema()")
            .fetch_one(pool)
            .await;
    return match query_result {
        std::result::Result::Ok(schema) => std::result::Result::Ok(schema),
        std::result::Result::Err(error) => std::result::Result::Err(kb_core::Error::db(format!(
            "postgres current schema query failed: {error}"
        ))),
    };
}

pub(in crate::postgres) async fn load_server_version(
    pool: &sqlx::PgPool,
) -> kb_core::Result<std::string::String> {
    let query_result =
        sqlx::query_scalar::<sqlx::Postgres, std::string::String>("SELECT version()")
            .fetch_one(pool)
            .await;
    return match query_result {
        std::result::Result::Ok(version) => std::result::Result::Ok(version),
        std::result::Result::Err(error) => std::result::Result::Err(kb_core::Error::db(format!(
            "postgres version query failed: {error}"
        ))),
    };
}

pub(in crate::postgres) async fn load_migration_table_name(
    pool: &sqlx::PgPool,
) -> kb_core::Result<std::option::Option<std::string::String>> {
    let query_result =
        sqlx::query_scalar::<sqlx::Postgres, std::option::Option<std::string::String>>(
            "SELECT to_regclass('_sqlx_migrations')::text",
        )
        .fetch_one(pool)
        .await;
    return match query_result {
        std::result::Result::Ok(table_name) => std::result::Result::Ok(table_name),
        std::result::Result::Err(error) => std::result::Result::Err(kb_core::Error::db(format!(
            "postgres migration table query failed: {error}"
        ))),
    };
}

pub(in crate::postgres) async fn load_latest_migration_version(
    pool: &sqlx::PgPool,
) -> kb_core::Result<std::option::Option<std::string::String>> {
    let query_result = sqlx::query_scalar::<sqlx::Postgres, std::option::Option<std::string::String>>(
        "SELECT version::text FROM _sqlx_migrations WHERE success = true ORDER BY version DESC LIMIT 1",
    )
    .fetch_optional(pool)
    .await;
    return match query_result {
        std::result::Result::Ok(version) => std::result::Result::Ok(version.flatten()),
        std::result::Result::Err(error) => std::result::Result::Err(kb_core::Error::db(format!(
            "postgres latest migration query failed: {error}"
        ))),
    };
}