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use super::*;

pub enum Operator
{
  Ascending,
  Descending,
}

/// Describe a single ordering condition using a label and an operator
pub struct Condition
{
  label: String,
  operator: Operator,
}

impl Condition
{
  pub fn from_label_operator(label: String, operator: Operator) -> Condition {
    Condition { label, operator }
  }
}

impl traits::Order for Condition
{
  /// Return the `ORDER BY` clause associated with the condition
  fn as_order_clause(&self) -> String {
    let label = &self.label;
    match &self.operator {
      Operator::Ascending   => format!("`{label}` ASC"),
      Operator::Descending  => format!("`{label}` DESC"),
    }
  }
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn it_display_correct_clause() -> Result<()> {
    use traits::Order;

    assert!(Condition::from_label_operator("key".to_string(), Operator::Ascending).as_order_clause().eq("`key` ASC"));
    assert!(Condition::from_label_operator("key".to_string(), Operator::Descending).as_order_clause().eq("`key` DESC"));

    Ok(())
  }
}