//! What a database call can fail with.
//!
//! Two distinct failures, kept separate rather than flattened: the statement
//! itself (rusqlite) and getting a connection to run it on (r2d2). A pool
//! timeout says the app is saturated, which is a different thing to diagnose
//! than a constraint violation.

/// Why a repository call failed.
#[derive(Debug, thiserror::Error)]
pub enum DbError {
    #[error("database error: {0}")]
    Sqlite(#[from] rusqlite::Error),

    #[error("could not check out a database connection: {0}")]
    Pool(#[from] r2d2::Error),
}

impl DbError {
    /// Whether this is rusqlite's "no rows returned" for a single-row query.
    ///
    /// Repository methods that can legitimately find nothing return `Option`
    /// instead, so this is for the callers that go around them.
    #[must_use]
    pub fn is_not_found(&self) -> bool {
        matches!(self, Self::Sqlite(rusqlite::Error::QueryReturnedNoRows))
    }
}

/// Why a database could not be opened.
///
/// r2d2's error type is opaque and cannot carry a rusqlite failure, so opening
/// the anchor connection and building the pool around it stay separate.
#[derive(Debug, thiserror::Error)]
pub enum OpenError {
    #[error("could not open the database: {0}")]
    Sqlite(#[from] rusqlite::Error),

    #[error("could not build the connection pool: {0}")]
    Pool(#[from] r2d2::Error),
}