use proc_macro::TokenStream;

use proc_macro2::{Delimiter, Group, TokenStream as TokenStream2, TokenTree};

mod expand;

use expand::{expand_expr, expand_expr_vec};

/// Parses an Essence expression into its corresponding Conjure AST at compile time.

///

/// ## Input

/// The input can be one of the following:

/// - The raw Essence tokens (`essence_expr!(2 + 2)`)

/// - A string literal (`essence_expr!("2 + 2")`)

///

/// The macro may reference variables in the current scope (called "metavars")

/// using the syntax `&<name>`. For example:

/// ```rust

/// use conjure_cp_essence_macros::essence_expr;

/// let x = 42;

/// let expr = essence_expr!(2 + &x);

/// ```

///

///

/// ## Expansion

/// If the input is valid Essence, expands to a valid AST constructor

///

/// ## Note

/// Some characters (e.g. `\`) are valid Essence tokens, but not Rust tokens.

/// If you encounter an error similar to:

///

/// > rustc: unknown start of token: \

///

/// The workaround is to wrap the Essence code in a string literal (e.g. `r"a /\ b"`).

///

/// ## Example

///

/// ```rust

/// use conjure_cp::ast::{Atom, Expression, Moo, Metadata};

/// use conjure_cp::matrix_expr;

/// use conjure_cp_essence_macros::essence_expr;

/// let x = 42;

/// let expr = essence_expr!(2 + &x);

/// assert_eq!(

///     expr,

///     Expression::Sum(Metadata::new(), Moo::new(matrix_expr![

///         Expression::Atomic(Metadata::new(), 2.into()),

///         Expression::Atomic(Metadata::new(), 42.into())

///     ]))

/// );

/// ```

#[proc_macro]

    }

/// Parses a sequence of Essence expressions into a vector of Conjure AST instances

///

/// ## Example

/// ```rust

/// use conjure_cp::ast::{Atom, Expression, Moo, Metadata};

/// use conjure_cp::matrix_expr;

/// use conjure_cp_essence_macros::essence_vec;

///

/// let exprs = essence_vec!(2 + 2, false = true);

/// println!("{:?}", exprs);

/// assert_eq!(exprs.len(), 2);

/// assert_eq!(

///     exprs[0],

///     Expression::Sum(Metadata::new(), Moo::new(matrix_expr![

///         Expression::Atomic(Metadata::new(), 2.into()),

///         Expression::Atomic(Metadata::new(), 2.into())

///     ]))

/// );

/// assert_eq!(

///    exprs[1],

///     Expression::Eq(Metadata::new(),

///         Moo::new(Expression::Atomic(Metadata::new(), false.into())),

///         Moo::new(Expression::Atomic(Metadata::new(), true.into()))

///     )

/// );

/// ```

#[proc_macro]

    }