pub fn parse_essence_file_native(

    path: &str,

    context: Arc<RwLock<Context<'static>>>,

) -> Result<Model, Box<ParseErrorCollection>> {

    let source_code = fs::read_to_string(path)

        .unwrap_or_else(|_| panic!("Failed to read the source code file {path}"));

    let mut errors = vec![];

    let model = parse_essence_with_context(&source_code, context, &mut errors);

    match model {

        Ok(m) => {

            if !errors.is_empty() {

                return Err(Box::new(ParseErrorCollection::multiple(

                    errors,

                    Some(source_code),

                    Some(path.to_string()),

                )));

            }

            Ok(m)

        }

}

pub fn parse_essence_with_context(

    src: &str,

    context: Arc<RwLock<Context<'static>>>,

    errors: &mut Vec<RecoverableParseError>,

) -> Result<Model, FatalParseError> {

    let (tree, source_code) = match get_tree(src) {

        Some(tree) => tree,

        None => {

            return Err(FatalParseError::TreeSitterError(

            ));

    };

    if tree.root_node().has_error() {

        detect_syntactic_errors(src, &tree, errors);

        return Ok(Model::new(context));

    }

    let mut model = Model::new(context);

    let root_node = tree.root_node();

    let symbols_ptr = model.symbols_ptr_unchecked().clone();

    for statement in named_children(&root_node) {

        match statement.kind() {

            "single_line_comment" => {}

            "language_declaration" => {}

            "find_statement" => {

                let var_hashmap = parse_find_statement(

                    statement,

                    &source_code,

                    Some(symbols_ptr.clone()),

                    errors,

                )?;

                for (name, domain) in var_hashmap {

                    model

                        .symbols_mut()

                        .insert(DeclarationPtr::new_find(name, domain));

                }

            }

            "bool_expr" | "atom" | "comparison_expr" => {

                model.add_constraint(parse_expression(

                    statement,

                    &source_code,

                    &statement,

                    Some(symbols_ptr.clone()),

                    errors,

                )?);

            "language_label" => {}

            "letting_statement" => {

                let letting_vars = parse_letting_statement(

                    statement,

                    &source_code,

                    Some(symbols_ptr.clone()),

                    errors,

                )?;

                model.symbols_mut().extend(letting_vars);

            }

            "dominance_relation" => {

                let inner = statement

                    .child_by_field_name("expression")

                    .expect("Expected a sub-expression inside `dominanceRelation`");

                let expr = parse_expression(

                    inner,

                    &source_code,

                    &statement,

                    Some(symbols_ptr.clone()),

                    errors,

                )?;

                let dominance = Expression::DominanceRelation(Metadata::new(), Moo::new(expr));

                if model.dominance.is_some() {

                    errors.push(RecoverableParseError::new(

                        "Duplicate dominance relation".to_string(),

                        None,

                    ));

                    continue;

                model.dominance = Some(dominance);

            }

                let raw_expr = &source_code[statement.start_byte()..statement.end_byte()];

                errors.push(RecoverableParseError::new(

                    format!("'{raw_expr}' is not a valid expression"),

                    Some(statement.range()),

                ));

            }

            _ => {

                let kind = statement.kind();

                errors.push(RecoverableParseError::new(

                    format!("Unrecognized top level statement kind: {kind}"),

                ));

            }

        }

        keyword_as_identifier(root_node, &source_code, errors);

    }

    Ok(model)

}

    "forall", "exists", "such", "that", "letting", "find", "minimise", "maximise", "subject", "to",

fn keyword_as_identifier(

    root: tree_sitter::Node,

    src: &str,

    errors: &mut Vec<RecoverableParseError>,

) {

    let mut stack = vec![root];

    while let Some(node) = stack.pop() {

        if (node.kind() == "variable" || node.kind() == "identifier" || node.kind() == "parameter")

            && let Ok(text) = node.utf8_text(src.as_bytes())

            let ident = text.trim();

            if KEYWORDS.contains(&ident) {

                let start_point = node.start_position();

                let end_point = node.end_position();

                errors.push(RecoverableParseError::new(

                    format!("Keyword '{ident}' used as identifier"),

                    Some(tree_sitter::Range {

                        start_byte: node.start_byte(),

                        end_byte: node.end_byte(),

                        start_point,

                        end_point,

                    }),

                ));

            }

        }

        for i in 0..node.child_count() {

            if let Some(child) = u32::try_from(i).ok().and_then(|i| node.child(i)) {

                stack.push(child);

            }

        }

}

pub fn parse_essence(src: &str) -> Result<Model, Box<ParseErrorCollection>> {

    let context = Arc::new(RwLock::new(Context::default()));

    let mut errors = vec![];

    match parse_essence_with_context(src, context, &mut errors) {

        Ok(model) => {

            if !errors.is_empty() {

                Err(Box::new(ParseErrorCollection::multiple(

                    errors,

                    None,

                )))

            } else {

                Ok(model)

            }

        }

        Err(fatal) => Err(Box::new(ParseErrorCollection::fatal(fatal))),

    }

}

mod test {

    #[allow(unused_imports)]

    use crate::parse_essence;

    #[allow(unused_imports)]

    use conjure_cp_core::ast::{Atom, Expression, Metadata, Moo, Name};

    #[allow(unused_imports)]

    use std::ops::Deref;

    #[test]

    pub fn test_parse_xyz() {

        let src = "

        find x, y, z : int(1..4)

        such that x + y + z = 4

        such that x >= y

        ";

        let model = parse_essence(src).unwrap();

        let st = model.symbols();

        let x = st.lookup(&Name::user("x")).unwrap();

        let y = st.lookup(&Name::user("y")).unwrap();

        let z = st.lookup(&Name::user("z")).unwrap();

        assert_eq!(x.domain(), Some(domain_int!(1..4)));

        assert_eq!(y.domain(), Some(domain_int!(1..4)));

        assert_eq!(z.domain(), Some(domain_int!(1..4)));

        let constraints = model.constraints();

        assert_eq!(constraints.len(), 2);

        let c1 = constraints[0].clone();

        let x_e = Expression::Atomic(Metadata::new(), Atom::new_ref(x));

        let y_e = Expression::Atomic(Metadata::new(), Atom::new_ref(y));

        let z_e = Expression::Atomic(Metadata::new(), Atom::new_ref(z));

        assert_eq!(

            Expression::Eq(

                Metadata::new(),

                Moo::new(Expression::Sum(

                    Metadata::new(),

                    Moo::new(matrix_expr!(

                        Expression::Sum(

                            Metadata::new(),

                            Moo::new(matrix_expr!(x_e.clone(), y_e.clone()))

                        ),

                        z_e

                    ))

                )),

                Moo::new(Expression::Atomic(Metadata::new(), 4.into()))

            )

        let c2 = constraints[1].clone();

        assert_eq!(

            c2,

            Expression::Geq(Metadata::new(), Moo::new(x_e), Moo::new(y_e))

        );

    }

    #[test]

    pub fn test_parse_letting_index() {

        let src = "

        letting a be [ [ 1,2,3 ; int(1,2,4) ], [ 1,3,2 ; int(1,2,4) ], [ 3,2,1 ; int(1,2,4) ] ; int(-2..0) ]

        find b: int(1..5)

        such that

        b < a[-2,2],

        allDiff(a[-2,..])

        ";

        let model = parse_essence(src).unwrap();

        let st = model.symbols();

        let a_decl = st.lookup(&Name::user("a")).unwrap();

        let a = a_decl.as_value_letting().unwrap().deref().clone();

        assert_eq!(

            a,

            matrix_expr!(

                matrix_expr!(1.into(), 2.into(), 3.into() ; domain_int!(1, 2, 4)),

                matrix_expr!(1.into(), 3.into(), 2.into() ; domain_int!(1, 2, 4)),

                matrix_expr!(3.into(), 2.into(), 1.into() ; domain_int!(1, 2, 4));

                domain_int!(-2..0)

            )

        )

    }