es-entity-macros 0.12.7

use darling::ToTokens;
use proc_macro2::TokenStream;
use quote::{TokenStreamExt, quote};

use super::options::*;

/// Postgres reports the bare table name in errors, so a schema-qualified
/// events table from the repo options is reduced to its last path component
/// before being compared.
fn bare_table_name(events_table_name: &str) -> &str {
    events_table_name
        .rsplit('.')
        .next()
        .expect("rsplit yields at least one element")
}

/// The `extract_concurrent_modification` helper, which turns a unique
/// violation into the caller's `ConcurrentModification` variant.
///
/// It is emitted separately from `persist_events` because the combined write
/// statements classify their own errors, yet the follow-up forgettable
/// payload inserts (which are plain statements) still need it.
pub fn extract_concurrent_modification_fn() -> TokenStream {
    let mut tokens = TokenStream::new();
    tokens.append_all(quote! {
        fn extract_concurrent_modification<T, __EsErr: From<sqlx::Error>>(
            res: Result<T, sqlx::Error>,
            concurrent_modification: __EsErr,
        ) -> Result<T, __EsErr> {
            match res {
                Ok(v) => Ok(v),
                Err(sqlx::Error::Database(ref db_err)) if db_err.is_unique_violation() => {
                    Err(concurrent_modification)
                }
                Err(e) => Err(__EsErr::from(e)),
            }
        }
    });
    tokens
}

/// The `map_err` closure for a combined write statement whose error type has
/// no `ConstraintViolation` variant (e.g. the generated `{Entity}ForgetError`).
/// Only the events-table unique violation is distinguished; everything else
/// stays `Sqlx`.
pub fn concurrent_modification_classifier(
    error: &syn::Ident,
    events_table_name: &str,
) -> TokenStream {
    let events_table = bare_table_name(events_table_name);
    quote! {
        |e| match &e {
            sqlx::Error::Database(db_err)
                if db_err.is_unique_violation()
                    && db_err.table() == Some(#events_table) =>
            {
                #error::ConcurrentModification
            }
            _ => #error::Sqlx(e),
        }
    }
}

/// The match arm shared by both combined-write classifiers: a classified
/// violation reported against any table other than the events table is the
/// index table's, and maps straight from the constraint Postgres named.
///
/// The events table name may be schema-qualified in the repo options;
/// Postgres reports the bare table name in errors, so only the last path
/// component is compared.
fn index_violation_arm(error: &syn::Ident, events_table: &str) -> TokenStream {
    quote! {
        sqlx::Error::Database(db_err)
            if db_err.table() != Some(#events_table)
                && es_entity::is_classified_constraint_violation(db_err.as_ref()) =>
        {
            #error::ConstraintViolation {
                column: Self::map_constraint_column(db_err.constraint()),
                value: es_entity::extract_constraint_value(db_err.as_ref()),
                inner: e,
            }
        }
    }
}

/// The classifier helpers for the combined index+events write statements,
/// emitted once per repo so the call sites are a bare `map_err` function
/// reference instead of a match rendered into every write path.
pub struct ErrorClassifier<'a> {
    create_error: syn::Ident,
    modify_error: syn::Ident,
    events_table_name: &'a str,
    table_name: &'a str,
    /// `classify_write_error` is emitted only where a write path actually
    /// calls it — an uncalled private helper is dead code, and consumers build
    /// with `-D warnings`. `classify_create_error` needs no such gate:
    /// `create` and `create_all` always issue the combined statement.
    needs_write_classifier: bool,
}

impl<'a> From<&'a RepositoryOptions> for ErrorClassifier<'a> {
    fn from(opts: &'a RepositoryOptions) -> Self {
        Self {
            create_error: opts.create_error(),
            modify_error: opts.modify_error(),
            events_table_name: opts.events_table_name(),
            table_name: opts.table_name(),
            needs_write_classifier: opts.columns.updates_needed() || opts.delete.is_soft(),
        }
    }
}

impl ToTokens for ErrorClassifier<'_> {
    fn to_tokens(&self, tokens: &mut TokenStream) {
        tokens.append_all(create_error_classifier_fn(
            &self.create_error,
            self.events_table_name,
            self.table_name,
        ));
        if self.needs_write_classifier {
            tokens.append_all(write_error_classifier_fn(
                &self.modify_error,
                self.events_table_name,
            ));
        }
    }
}

/// Classifier for the create paths' combined index+events write statement
/// (`create` / `create_all`).
///
/// A brand-new entity's events always start at sequence 1, so a unique
/// violation on the events-table `(id, sequence)` primary key can only mean
/// the id already exists — a pre-existing row, a concurrent create, or an
/// intra-batch duplicate in `create_all`. That is semantically a duplicate
/// id, not a concurrent modification.
///
/// Postgres executes the data-modifying CTE (index insert) and the main
/// statement (events insert) interleaved with no guaranteed ordering, so for
/// a duplicate id either table's constraint may fire first depending on the
/// chosen plan. Both are therefore classified identically as the id column's
/// `ConstraintViolation`:
///
/// - unique violation on the events table → `ConstraintViolation` with the
///   column resolved via the index table's pkey constraint name and the value
///   being the id half of the `(id, sequence)` key
/// - classified violation elsewhere (the index table) → `ConstraintViolation`
///   mapped from the reported constraint
/// - anything else → `Sqlx`
fn create_error_classifier_fn(
    error: &syn::Ident,
    events_table_name: &str,
    table_name: &str,
) -> TokenStream {
    let events_table = bare_table_name(events_table_name);
    // Must match the id column's constraint name in `ErrorTypes::new`, which
    // formats it from the un-shortened table name.
    let index_pkey = format!("{table_name}_pkey");
    let index_arm = index_violation_arm(error, events_table);
    quote! {
        #[inline(always)]
        fn classify_create_error(e: sqlx::Error) -> #error {
            match &e {
                sqlx::Error::Database(db_err)
                    if db_err.is_unique_violation()
                        && db_err.table() == Some(#events_table) =>
                {
                    #error::ConstraintViolation {
                        column: Self::map_constraint_column(Some(#index_pkey)),
                        value: es_entity::extract_events_pkey_id_value(db_err.as_ref()),
                        inner: e,
                    }
                }
                #index_arm
                _ => #error::Sqlx(e),
            }
        }
    }
}

/// Classifier for a combined index+events write statement on the
/// update/delete paths.
///
/// A single statement can fail from either table, so classification switches
/// on `DatabaseError::table()` instead of on which statement failed:
///
/// - unique violation on the events table → `ConcurrentModification`
/// - classified violation elsewhere (the index table) → `ConstraintViolation`
/// - anything else (including events-table FK violations) → `Sqlx`
///
/// Unlike the create paths, the entity here already has persisted events, so
/// an events-table `(id, sequence)` conflict genuinely means another writer
/// claimed the next sequence first.
fn write_error_classifier_fn(error: &syn::Ident, events_table_name: &str) -> TokenStream {
    let events_table = bare_table_name(events_table_name);
    let index_arm = index_violation_arm(error, events_table);
    quote! {
        #[inline(always)]
        fn classify_write_error(e: sqlx::Error) -> #error {
            match &e {
                sqlx::Error::Database(db_err)
                    if db_err.is_unique_violation()
                        && db_err.table() == Some(#events_table) =>
                {
                    #error::ConcurrentModification
                }
                #index_arm
                _ => #error::Sqlx(e),
            }
        }
    }
}