bsql-macros 0.20.0

#![forbid(unsafe_code)]

//! Proc macros for bsql.
//!
//! This crate is an implementation detail. Use [`bsql`] instead.

extern crate proc_macro;

mod codegen;
#[cfg(feature = "sqlite")]
mod codegen_sqlite;
mod connection;
mod dynamic;
mod offline;
mod parse;
mod pg_enum;
mod sort_enum;
mod sql_norm;
mod stmt_name;
mod suggest;
pub(crate) mod types;
#[cfg(feature = "sqlite")]
mod types_sqlite;
mod validate;
#[cfg(feature = "sqlite")]
mod validate_sqlite;

use proc_macro::TokenStream;

/// Validate a SQL query against PostgreSQL at compile time and generate
/// typed Rust code for executing it.
///
/// # Syntax
///
/// ```text
/// bsql::query! {
///     SELECT column1, column2
///     FROM table
///     WHERE column1 = $param_name: RustType
/// }
/// ```
///
/// Parameters are declared inline as `$name: Type`. The macro replaces them
/// with positional `$1`, `$2`, ... and verifies type compatibility against
/// the database schema.
///
/// # Execution methods
///
/// The macro returns an executor with these methods:
/// - `.fetch_one(executor)` — returns exactly one row (errors on 0 or 2+)
/// - `.fetch_all(executor)` — returns all rows as `Vec<T>`
/// - `.fetch_optional(executor)` — returns `Option<T>` (errors on 2+)
/// - `.execute(executor)` — returns affected row count (`u64`)
///
/// # Compile-time guarantees
///
/// - Table and column names are verified against the live database
/// - Parameter types are checked against PostgreSQL's expected types
/// - Nullable columns are automatically mapped to `Option<T>`
/// - Invalid SQL produces a compile error, not a runtime error
#[proc_macro]
pub fn query(input: TokenStream) -> TokenStream {
    let input2: proc_macro2::TokenStream = input.into();
    match query_impl(input2) {
        Ok(output) => output.into(),
        Err(err) => err.to_compile_error().into(),
    }
}

fn query_impl(input: proc_macro2::TokenStream) -> Result<proc_macro2::TokenStream, syn::Error> {
    // Extract the SQL string from the input.
    // Accepts either a string literal: query!("SELECT ...")
    // or raw tokens: query! { SELECT ... } converted to string.
    let sql = extract_sql(input)?;

    // 1. Parse: extract params, query kind, normalize SQL, optional clauses, sort placeholder
    let parsed = parse::parse_query(&sql)
        .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?;

    // Detect backend from database URL (if not offline)
    #[cfg(feature = "sqlite")]
    {
        let backend = connection::detect_backend()
            .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?;
        if backend == Some(connection::Backend::Sqlite) {
            return query_impl_sqlite(parsed);
        }
    }

    // PostgreSQL path (default)
    query_impl_postgres(parsed)
}

/// PostgreSQL query implementation (the original path).
fn query_impl_postgres(parsed: parse::ParsedQuery) -> Result<proc_macro2::TokenStream, syn::Error> {
    // 2. Sort query path — $[sort: EnumType] present
    if parsed.sort_placeholder.is_some() {
        return query_impl_sort(parsed);
    }

    if parsed.optional_clauses.is_empty() {
        // Static query path — no optional clauses
        let validation = if offline::is_offline() {
            // OFFLINE: read cached validation result
            offline::lookup_cached_validation(&parsed)
                .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
        } else {
            // ONLINE: validate against PostgreSQL via PREPARE with suggestions
            let result = connection::with_connection(|conn| {
                validate::validate_query_with_suggestions(&parsed, conn)
            })?;

            // Write to offline cache for future use
            offline::write_cache(&parsed, &result);

            result
        };

        // Check parameter type compatibility
        validate::check_param_types(&parsed, &validation)
            .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?;

        // Generate Rust code
        Ok(codegen::generate_query_code(&parsed, &validation))
    } else {
        // Dynamic query path — has optional clauses.
        //
        // Validation: O(N+1) PREPAREs — base query + one per clause.
        // Codegen: O(N) runtime SQL builder (no 2^N match arms).
        let validation = if offline::is_offline() {
            // OFFLINE: read cached validation result for the base query.
            //
            // The cache stores the base query's param_pg_oids (not optional
            // clause params). Param type checking is skipped here because:
            //  1. The online build already validated all clauses' param types.
            //  2. The cached columns are identical (SELECT list never changes).
            //  3. Codegen only needs the column info, not per-clause param OIDs.
            offline::lookup_cached_validation(&parsed)
                .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
        } else {
            // ONLINE: full 2^N validation — every combination checked.
            // "If it compiles, the SQL is correct" — no exceptions.
            let result = connection::with_connection(|conn| {
                let variants = dynamic::expand_variants(&parsed)?;
                validate::validate_variants(&variants, &parsed, conn)
            })?;

            // Write to offline cache for future use
            offline::write_cache(&parsed, &result);

            result
        };

        // Generate dynamic Rust code with runtime SQL dispatcher
        Ok(codegen::generate_dynamic_query_code(&parsed, &validation))
    }
}

/// SQLite query implementation.
///
/// Validates against a live SQLite database at compile time, then generates
/// code that executes via `bsql_core::SqlitePool`.
#[cfg(feature = "sqlite")]
fn query_impl_sqlite(parsed: parse::ParsedQuery) -> Result<proc_macro2::TokenStream, syn::Error> {
    // Sort queries: $[sort: EnumType] present
    if parsed.sort_placeholder.is_some() {
        return query_impl_sqlite_sort(parsed);
    }

    if parsed.optional_clauses.is_empty() {
        // Static query path — no optional clauses
        let validation = if offline::is_offline() {
            offline::lookup_cached_validation(&parsed)
                .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
        } else {
            let result = connection::with_sqlite_connection(|conn| {
                validate_sqlite::validate_query_sqlite(&parsed, conn)
            })?;

            // Write to offline cache for future use
            offline::write_cache(&parsed, &result);

            result
        };

        // SQLite doesn't type parameters at prepare time, so we skip
        // the PG-style param type check. Parameter types are verified
        // at runtime by the SqliteEncode trait.

        Ok(codegen_sqlite::generate_sqlite_query_code(
            &parsed,
            &validation,
        ))
    } else {
        // Dynamic query path — has optional clauses.
        // Validation: O(N+1) — base + each clause individually.
        // Codegen: O(N) runtime SQL builder.
        let validation = if offline::is_offline() {
            offline::lookup_cached_validation(&parsed)
                .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
        } else {
            // Full 2^N validation — every combination checked.
            let result = connection::with_sqlite_connection(|conn| {
                let variants = dynamic::expand_variants(&parsed)?;
                validate_sqlite::validate_variants_sqlite(&variants, &parsed, conn)
            })?;

            offline::write_cache(&parsed, &result);

            result
        };

        Ok(codegen_sqlite::generate_dynamic_sqlite_query_code(
            &parsed,
            &validation,
        ))
    }
}

/// SQLite sort query implementation.
#[cfg(feature = "sqlite")]
fn query_impl_sqlite_sort(
    parsed: parse::ParsedQuery,
) -> Result<proc_macro2::TokenStream, syn::Error> {
    let sort_placeholder = parsed.sort_placeholder.as_ref().unwrap();
    let sort_enum_name = &sort_placeholder.enum_name;

    // Replace {SORT} with "1" to validate the query shape
    let dummy_sql = parsed.positional_sql.replace("{SORT}", "1");

    let dummy_parsed = parse::ParsedQuery {
        normalized_sql: parsed.normalized_sql.replace("{sort}", "1"),
        positional_sql: dummy_sql,
        params: parsed.params.clone(),
        kind: parsed.kind,
        statement_name: parsed.statement_name.clone(),
        optional_clauses: parsed.optional_clauses.clone(),
        sort_placeholder: None,
    };

    let validation = if offline::is_offline() {
        offline::lookup_cached_validation(&parsed)
            .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
    } else {
        let result = connection::with_sqlite_connection(|conn| {
            validate_sqlite::validate_query_sqlite(&dummy_parsed, conn)
        })?;

        offline::write_cache(&parsed, &result);
        result
    };

    Ok(codegen_sqlite::generate_sort_sqlite_query_code(
        &parsed,
        &validation,
        sort_enum_name,
    ))
}

/// Handle sort queries — queries with `$[sort: EnumType]`.
///
/// The sort enum is NOT resolved at macro expansion time (we don't have access
/// to the enum definition from within the proc macro). Instead, we generate code
/// that takes the sort enum as a parameter and uses `match` to select the SQL.
///
/// Validation: we validate each sort variant's expanded SQL at compile time
/// by reading sort variant info. However, since the sort enum is defined via
/// `#[bsql::sort]` in user code, we cannot read its variants from within
/// the `query!` macro. Instead, the generated code uses the enum's `sql()`
/// method at runtime. Validation of individual sort fragments happens when
/// the user compiles — the sort enum's SQL fragments are checked by the user
/// running their tests or by a separate validation step.
///
/// For now: generate code that takes a `sort` parameter with a `sql() -> &str`
/// method, and splices the SQL at runtime via string replacement + pre-hashed
/// dispatch.
fn query_impl_sort(parsed: parse::ParsedQuery) -> Result<proc_macro2::TokenStream, syn::Error> {
    let sort_placeholder = parsed.sort_placeholder.as_ref().unwrap();
    let sort_enum_name = &sort_placeholder.enum_name;

    // We can't validate sort variants at proc-macro time because we don't have
    // the enum definition. Instead, generate code that does runtime SQL dispatch.
    // The `{SORT}` in positional_sql will be a sentinel that codegen handles.

    // For validation, we need at least the base query structure. Use a dummy
    // ORDER BY to validate the query shape (columns, params) — replace {SORT}
    // with "1" (which is always valid in ORDER BY).
    let dummy_sql = parsed.positional_sql.replace("{SORT}", "1");

    // Create a temporary ParsedQuery with the dummy SQL for validation
    let dummy_parsed = parse::ParsedQuery {
        normalized_sql: parsed.normalized_sql.replace("{sort}", "1"),
        positional_sql: dummy_sql,
        params: parsed.params.clone(),
        kind: parsed.kind,
        statement_name: parsed.statement_name.clone(),
        optional_clauses: parsed.optional_clauses.clone(),
        sort_placeholder: None,
    };

    let validation = if offline::is_offline() {
        offline::lookup_cached_validation(&parsed)
            .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?
    } else {
        let result = connection::with_connection(|conn| {
            validate::validate_query_with_suggestions(&dummy_parsed, conn)
        })?;

        offline::write_cache(&parsed, &result);
        result
    };

    validate::check_param_types(&parsed, &validation)
        .map_err(|msg| syn::Error::new(proc_macro2::Span::call_site(), msg))?;

    // Generate sort-aware code
    Ok(codegen::generate_sort_query_code(
        &parsed,
        &validation,
        sort_enum_name,
    ))
}

/// Extract the SQL text from the macro input.
///
/// Accepts a string literal: `query!("SELECT ...")`
fn extract_sql(input: proc_macro2::TokenStream) -> Result<String, syn::Error> {
    let lit: syn::LitStr = syn::parse2(input)?;
    Ok(lit.value())
}

/// Derive PostgreSQL enum <-> Rust enum mapping with `FromSql` and `ToSql`.
///
/// # Usage
///
/// ```rust,ignore
/// #[bsql::pg_enum]
/// pub enum TicketStatus {
///     #[sql("new")]
///     New,
///     #[sql("in_progress")]
///     InProgress,
///     #[sql("resolved")]
///     Resolved,
///     #[sql("closed")]
///     Closed,
/// }
/// ```
///
/// Each variant must have a `#[sql("label")]` attribute mapping it to the
/// exact PostgreSQL enum label. The macro generates:
/// - `FromSql` — deserializes from PostgreSQL text representation
/// - `ToSql` — serializes to PostgreSQL text representation
/// - `Display` — formats as the SQL label
/// - Derives: `Debug, Clone, Copy, PartialEq, Eq, Hash`
///
/// If PostgreSQL sends a variant not present in the Rust enum, `FromSql`
/// returns an error describing the schema mismatch.
#[proc_macro_attribute]
pub fn pg_enum(attr: TokenStream, item: TokenStream) -> TokenStream {
    let attr2: proc_macro2::TokenStream = attr.into();
    let item2: proc_macro2::TokenStream = item.into();
    match pg_enum::expand_pg_enum(attr2, item2) {
        Ok(output) => output.into(),
        Err(err) => err.to_compile_error().into(),
    }
}

/// Define a sort enum for compile-time verified dynamic `ORDER BY` clauses.
///
/// # Usage
///
/// ```rust,ignore
/// #[bsql::sort]
/// pub enum TicketSort {
///     #[sql("t.updated_at DESC, t.id DESC")]
///     UpdatedAt,
///     #[sql("t.deadline ASC NULLS LAST, t.id ASC")]
///     Deadline,
///     #[sql("t.id DESC")]
///     Id,
/// }
/// ```
///
/// Use with the `$[sort: EnumType]` placeholder in `bsql::query!`:
///
/// ```rust,ignore
/// let tickets = bsql::query!(
///     "SELECT id, title FROM tickets ORDER BY $[sort: TicketSort] LIMIT $limit: i64"
/// ).fetch_all(&pool)?;
/// ```
///
/// Each variant must have a `#[sql("...")]` attribute mapping it to the
/// SQL `ORDER BY` fragment. The macro generates:
/// - The enum with `Debug, Clone, Copy, PartialEq, Eq, Hash`
/// - A `sql(&self) -> &'static str` method returning the SQL fragment
/// - `Display` — formats as the SQL fragment
///
/// Unlike `#[bsql::pg_enum]`, sort enums are NOT parameterized values.
/// The SQL fragment is spliced directly into the query string.
#[proc_macro_attribute]
pub fn sort(attr: TokenStream, item: TokenStream) -> TokenStream {
    let attr2: proc_macro2::TokenStream = attr.into();
    let item2: proc_macro2::TokenStream = item.into();
    match sort_enum::expand_sort_enum(attr2, item2) {
        Ok(output) => output.into(),
        Err(err) => err.to_compile_error().into(),
    }
}