pub fn model_from_json(str: &str, context: Arc<RwLock<Context<'static>>>) -> Result<Model> {

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

    let v: JsonValue = serde_json::from_str(str)?;

    let statements = v["mStatements"]

        .as_array()

        .ok_or(error!("mStatements is not an array"))?;

    for statement in statements {

        let entry = statement

            .as_object()

            .ok_or(error!("mStatements contains a non-object"))?

            .iter()

            .next()

            .ok_or(error!("mStatements contains an empty object"))?;

        match entry.0.as_str() {

            "Declaration" => {

                let decl = entry

                    .1

                    .as_object()

                    .ok_or(error!("Declaration is not an object".to_owned()))?;

                let mut valid_decl: bool = false;

                let submodel = m.as_submodel_mut();

                for (kind, value) in decl {

                    match kind.as_str() {

                        "FindOrGiven" => {

                            parse_variable(value, &mut submodel.symbols_mut())?;

                            valid_decl = true;

                            break;

                        "Letting" => {

                            parse_letting(value, &mut submodel.symbols_mut())?;

                            valid_decl = true;

                            break;

                if !valid_decl {

                }

            "SuchThat" => {

                let constraints_arr = match entry.1.as_array() {

                    Some(x) => x,

                let constraints: Vec<Expression> = constraints_arr

                    .iter()

                    .map(|x| parse_expression(x).unwrap())

                    .collect();

                m.as_submodel_mut().add_constraints(constraints);

                // println!("Nb constraints {}", m.constraints.len());

            }

    Ok(m)

}

fn parse_variable(v: &JsonValue, symtab: &mut SymbolTable) -> Result<()> {

    let arr = v.as_array().ok_or(error!("FindOrGiven is not an array"))?;

    let name = arr[1]

        .as_object()

        .ok_or(error!("FindOrGiven[1] is not an object"))?["Name"]

        .as_str()

        .ok_or(error!("FindOrGiven[1].Name is not a string"))?;

    let name = Name::UserName(name.to_owned());

    let domain = arr[2]

        .as_object()

        .ok_or(error!("FindOrGiven[2] is not an object"))?

        .iter()

        .next()

        .ok_or(error!("FindOrGiven[2] is an empty object"))?;

    let domain = parse_domain(domain.0, domain.1)?;

    symtab

        .insert(Rc::new(Declaration::new_var(name.clone(), domain)))

        .ok_or(Error::Parse(format!(

            "Could not add {name} to symbol table as it already exists"

        )))

}

fn parse_letting(v: &JsonValue, symtab: &mut SymbolTable) -> Result<()> {

    let arr = v.as_array().ok_or(error!("Letting is not an array"))?;

    let name = arr[0]

        .as_object()

        .ok_or(error!("Letting[0] is not an object"))?["Name"]

        .as_str()

        .ok_or(error!("Letting[0].Name is not a string"))?;

    let name = Name::UserName(name.to_owned());

    if let Some(value) = parse_expression(&arr[1]) {

        symtab

            .insert(Rc::new(Declaration::new_value_letting(name.clone(), value)))

            .ok_or(Error::Parse(format!(

                "Could not add {name} to symbol table as it already exists"

            )))

        let domain = &arr[1]

            .as_object()

            .ok_or(error!("Letting[1] is not an object".to_owned()))?["Domain"]

            .as_object()

            .ok_or(error!("Letting[1].Domain is not an object"))?

            .iter()

            .next()

            .ok_or(error!("Letting[1].Domain is an empty object"))?;

        let domain = parse_domain(domain.0, domain.1)?;

        symtab

            .insert(Rc::new(Declaration::new_domain_letting(

                name.clone(),

                domain,

            )))

            .ok_or(Error::Parse(format!(

                "Could not add {name} to symbol table as it already exists"

            )))

}

fn parse_domain(domain_name: &str, domain_value: &JsonValue) -> Result<Domain> {

    match domain_name {

        "DomainInt" => Ok(parse_int_domain(domain_value)?),

        "DomainBool" => Ok(Domain::BoolDomain),

        "DomainReference" => Ok(Domain::DomainReference(Name::UserName(

            domain_value

                .as_array()

                .ok_or(error!("DomainReference is not an array"))?[0]

                .as_object()

                .ok_or(error!("DomainReference[0] is not an object"))?["Name"]

                .as_str()

                .ok_or(error!("DomainReference[0].Name is not a string"))?

                .into(),

        "DomainSet" => {

        "DomainMatrix" => {

            let domain_value = domain_value

                .as_array()

                .ok_or(error!("Domain matrix is not an array"))?;

            let indexed_by_domain = domain_value[0].clone();

            let (index_domain_name, index_domain_value) = indexed_by_domain

                .as_object()

                .ok_or(error!("DomainMatrix[0] is not an object"))?

                .iter()

                .next()

                .ok_or(error!(""))?;

            let (value_domain_name, value_domain_value) = domain_value[1]

                .as_object()

                .ok_or(error!(""))?

                .iter()

                .next()

                .ok_or(error!(""))?;

            let mut index_domains: Vec<Domain> = vec![];

            index_domains.push(parse_domain(index_domain_name, index_domain_value)?);

            let mut value_domain = parse_domain(value_domain_name, value_domain_value)?;

            while let Domain::DomainMatrix(new_value_domain, mut indices) = value_domain {

                index_domains.append(&mut indices);

                value_domain = *new_value_domain.clone()

            Ok(Domain::DomainMatrix(Box::new(value_domain), index_domains))

}

fn parse_int_domain(v: &JsonValue) -> Result<Domain> {

    let mut ranges = Vec::new();

    let arr = v

        .as_array()

        .ok_or(error!("DomainInt is not an array".to_owned()))?[1]

        .as_array()

        .ok_or(error!("DomainInt[1] is not an array".to_owned()))?;

    for range in arr {

        let range = range

            .as_object()

            .ok_or(error!("DomainInt[1] contains a non-object"))?

            .iter()

            .next()

            .ok_or(error!("DomainInt[1] contains an empty object"))?;

        match range.0.as_str() {

            "RangeBounded" => {

                let arr = range

                    .1

                    .as_array()

                    .ok_or(error!("RangeBounded is not an array".to_owned()))?;

                let mut nums = Vec::new();

                for item in arr.iter() {

                    let num = parse_domain_value_int(item)

                        .ok_or(error!("Could not parse int domain constant"))?;

                    nums.push(num);

                ranges.push(Range::Bounded(nums[0], nums[1]));

            "RangeSingle" => {

                let num = parse_domain_value_int(range.1)

                    .ok_or(error!("Could not parse int domain constant"))?;

                ranges.push(Range::Single(num));

    Ok(Domain::IntDomain(ranges))

}

fn parse_domain_value_int(obj: &JsonValue) -> Option<i32> {

    parser_trace!("trying to parse domain value: {}", obj);

    fn try_parse_positive_int(obj: &JsonValue) -> Option<i32> {

        parser_trace!(".. trying as a positive domain value: {}", obj);

        let leaf_node = obj

            .pointer("/Constant/ConstantInt/1")

            .or_else(|| obj.pointer("/ConstantInt/1"))?;

        match leaf_node.as_i64()?.try_into() {

            Ok(x) => {

                parser_trace!(".. success!");

                Some(x)

    }

    fn try_parse_negative_int(obj: &JsonValue) -> Option<i32> {

        // Negative number: Op/MkOpNegate/Constant/ConstantInt/1

        // Unwrap negation operator, giving us a Constant/ConstantInt/1

        //

        // This is just a positive constant, so try to parse it as such

        parser_trace!(".. trying as a negative domain value: {}", obj);

        let inner_constant_node = obj.pointer("/Op/MkOpNegate")?;

        let inner_num = try_parse_positive_int(inner_constant_node)?;

        parser_trace!(".. success!");

        Some(-inner_num)

    }

    try_parse_positive_int(obj).or_else(|| try_parse_negative_int(obj))

}

fn parse_expression(obj: &JsonValue) -> Option<Expression> {

    let binary_operators: HashMap<&str, BinOp> = [

        (

            "MkOpEq",

            Box::new(Expression::Eq) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpNeq",

            Box::new(Expression::Neq) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpGeq",

            Box::new(Expression::Geq) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpLeq",

            Box::new(Expression::Leq) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpGt",

            Box::new(Expression::Gt) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpLt",

            Box::new(Expression::Lt) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpGt",

            Box::new(Expression::Gt) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpLt",

            Box::new(Expression::Lt) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpDiv",

            Box::new(Expression::UnsafeDiv) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpMod",

            Box::new(Expression::UnsafeMod) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpMinus",

            Box::new(Expression::Minus) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpImply",

            Box::new(Expression::Imply) as Box<dyn Fn(_, _, _) -> _>,

        ),

        (

            "MkOpPow",

            Box::new(Expression::UnsafePow) as Box<dyn Fn(_, _, _) -> _>,

        ),

    ]

    .into_iter()

    .collect();

    let unary_operators: HashMap<&str, UnaryOp> = [

        (

            "MkOpNot",

            Box::new(Expression::Not) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpNegate",

            Box::new(Expression::Neg) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpTwoBars",

            Box::new(Expression::Abs) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpAnd",

            Box::new(Expression::And) as Box<dyn Fn(_, _) -> _>,

        ),

        ("MkOpOr", Box::new(Expression::Or) as Box<dyn Fn(_, _) -> _>),

        (

            "MkOpMin",

            Box::new(Expression::Min) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpMax",

            Box::new(Expression::Max) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpAllDiff",

            Box::new(Expression::AllDiff) as Box<dyn Fn(_, _) -> _>,

        ),

    ]

    .into_iter()

    .collect();

    let vec_operators: HashMap<&str, VecOp> = [

        (

            "MkOpSum",

            Box::new(Expression::Sum) as Box<dyn Fn(_, _) -> _>,

        ),

        (

            "MkOpProduct",

            Box::new(Expression::Product) as Box<dyn Fn(_, _) -> _>,

        ),

    ]

    .into_iter()

    .collect();

    let mut binary_operator_names = binary_operators.iter().map(|x| x.0);

    let mut unary_operator_names = unary_operators.iter().map(|x| x.0);

    let mut vec_operator_names = vec_operators.iter().map(|x| x.0);

    match obj {

        Value::Object(op) if op.contains_key("Op") => match &op["Op"] {

            Value::Object(bin_op) if binary_operator_names.any(|key| bin_op.contains_key(*key)) => {

                Some(parse_bin_op(bin_op, binary_operators).unwrap())

            Value::Object(un_op) if unary_operator_names.any(|key| un_op.contains_key(*key)) => {

                Some(parse_unary_op(un_op, unary_operators).unwrap())

            Value::Object(vec_op) if vec_operator_names.any(|key| vec_op.contains_key(*key)) => {

                Some(parse_vec_op(vec_op, vec_operators).unwrap())

            Value::Object(op)

                if op.contains_key("MkOpIndexing") || op.contains_key("MkOpSlicing") =>

            {

                parse_indexing_slicing_op(op)

        Value::Object(refe) if refe.contains_key("Reference") => {

            let name = refe["Reference"].as_array()?[0].as_object()?["Name"].as_str()?;

            Some(Expression::Atomic(

                Metadata::new(),

                Atom::Reference(Name::UserName(name.to_string())),

            ))

        Value::Object(abslit) if abslit.contains_key("AbstractLiteral") => {

            Some(parse_abstract_matrix_as_expr(obj).unwrap())

        Value::Object(constant) if constant.contains_key("Constant") => Some(

            parse_constant(constant)

                .or_else(|| parse_abstract_matrix_as_expr(obj))

                .unwrap(),

        ),

        Value::Object(constant) if constant.contains_key("ConstantAbstract") => {

            Some(parse_abstract_matrix_as_expr(obj).unwrap())

        Value::Object(constant) if constant.contains_key("ConstantInt") => {

            Some(parse_constant(constant).unwrap())

        Value::Object(constant) if constant.contains_key("ConstantBool") => {

        _ => None,

}

fn parse_bin_op(

    bin_op: &serde_json::Map<String, Value>,

    binary_operators: HashMap<&str, BinOp>,

) -> Option<Expression> {

    let (key, value) = bin_op.into_iter().next()?;

    let constructor = binary_operators.get(key.as_str())?;

    match &value {

        Value::Array(bin_op_args) if bin_op_args.len() == 2 => {

            let arg1 = parse_expression(&bin_op_args[0])?;

            let arg2 = parse_expression(&bin_op_args[1])?;

            Some(constructor(Metadata::new(), Box::new(arg1), Box::new(arg2)))

}

fn parse_indexing_slicing_op(op: &serde_json::Map<String, Value>) -> Option<Expression> {

    let (key, value) = op.into_iter().next()?;

    let mut indices: Vec<Option<Expression>> = vec![];

    // true if this has no slicing, false otherwise.

    let mut all_known = true;

    match key.as_str() {

        "MkOpIndexing" => {

            match &value {

                Value::Array(op_args) if op_args.len() == 2 => {

                    target = parse_expression(&op_args[0]).expect("expected an expression");

                    indices.push(Some(

                        parse_expression(&op_args[1]).expect("expected an expression"),

                    ));

                }

        "MkOpSlicing" => {

            all_known = false;

            match &value {

                Value::Array(op_args) if op_args.len() == 3 => {

                    target = parse_expression(&op_args[0]).expect("expected an expression");

                    indices.push(None);

                }

        match &mut target {

            Expression::UnsafeIndex(_, new_target, new_indices) => {

                indices.extend(new_indices.iter().cloned().map(Some));

                target = *new_target.clone();

            }

            Expression::UnsafeSlice(_, new_target, new_indices) => {

                all_known = false;

                indices.append(new_indices);

                target = *new_target.clone();

            }

                break;

            }

        }

    }

    indices.reverse();

    if all_known {

        Some(Expression::UnsafeIndex(

            Metadata::new(),

            Box::new(target),

            indices.into_iter().map(|x| x.unwrap()).collect(),

        ))

        Some(Expression::UnsafeSlice(

            Metadata::new(),

            Box::new(target),

            indices,

        ))

}

fn parse_unary_op(

    un_op: &serde_json::Map<String, Value>,

    unary_operators: HashMap<&str, UnaryOp>,

) -> Option<Expression> {

    let (key, value) = un_op.into_iter().next()?;

    let constructor = unary_operators.get(key.as_str())?;

    let arg = parse_expression(value)?;

    Some(constructor(Metadata::new(), Box::new(arg)))

}

fn parse_vec_op(

    vec_op: &serde_json::Map<String, Value>,

    vec_operators: HashMap<&str, VecOp>,

) -> Option<Expression> {

    let (key, value) = vec_op.into_iter().next()?;

    let constructor = vec_operators.get(key.as_str())?;

    let mut args_parsed: Option<Vec<Option<Expression>>> = None;

    if let Some(abs_lit_matrix) = value.pointer("/AbstractLiteral/AbsLitMatrix/1") {

        parser_trace!("... containing a matrix of literals");

        args_parsed = abs_lit_matrix.as_array().map(|x| {

            x.iter()

                .map(parse_expression)

                .collect::<Vec<Option<Expression>>>()

        });

    }

    let args_parsed = args_parsed?;

    let number_of_args = args_parsed.len();

    let valid_args: Vec<Expression> = args_parsed.into_iter().flatten().collect();

    if number_of_args != valid_args.len() {

        Some(constructor(Metadata::new(), valid_args))

}

fn parse_abstract_matrix_as_expr(value: &serde_json::Value) -> Option<Expression> {

    parser_trace!("trying to parse an abstract literal matrix");

    let (values, domain_name, domain_value) =

        if let Some(abs_lit_matrix) = value.pointer("/AbstractLiteral/AbsLitMatrix") {

            parser_trace!(".. found JSON pointer /AbstractLiteral/AbstractLitMatrix");

            let (domain_name, domain_value) =

                abs_lit_matrix.pointer("/0")?.as_object()?.iter().next()?;

            let values = abs_lit_matrix.pointer("/1")?;

            Some((values, domain_name, domain_value))

        else if let Some(const_abs_lit_matrix) =

            value.pointer("/Constant/ConstantAbstract/AbsLitMatrix")

            parser_trace!(".. found JSON pointer /Constant/ConstantAbstract/AbsLitMatrix");

            let (domain_name, domain_value) = const_abs_lit_matrix

                .pointer("/0")?

                .as_object()?

                .iter()

                .next()?;

            let values = const_abs_lit_matrix.pointer("/1")?;

            Some((values, domain_name, domain_value))

        } else if let Some(const_abs_lit_matrix) = value.pointer("/ConstantAbstract/AbsLitMatrix") {

            parser_trace!(".. found JSON pointer /ConstantAbstract/AbsLitMatrix");

            let (domain_name, domain_value) = const_abs_lit_matrix

                .pointer("/0")?

                .as_object()?

                .iter()

                .next()?;

            let values = const_abs_lit_matrix.pointer("/1")?;

            Some((values, domain_name, domain_value))

    parser_trace!(".. found in domain and values in JSON:");

    parser_trace!(".. .. index domain name {domain_name}");

    parser_trace!(".. .. values {value}");

    let args_parsed = values.as_array().map(|x| {

        x.iter()

            .map(parse_expression)

            .map(|x| x.expect("invalid subexpression"))

            .collect::<Vec<Expression>>()

    })?;

    if !args_parsed.is_empty() {

        parser_trace!(

        parser_trace!(".. successfully parsed empty values ",);

    match parse_domain(domain_name, domain_value) {

        Ok(domain) => {

            parser_trace!("... sucessfully parsed domain as {domain}");

            Some(into_matrix_expr![args_parsed;domain])

}

fn parse_constant(constant: &serde_json::Map<String, Value>) -> Option<Expression> {

    match &constant.get("Constant") {

        Some(Value::Object(int)) if int.contains_key("ConstantInt") => {

            let int_32: i32 = match int["ConstantInt"].as_array()?[1].as_i64()?.try_into() {

                Ok(x) => x,

            Some(Expression::Atomic(

                Metadata::new(),

                Atom::Literal(Literal::Int(int_32)),

            ))

        Some(Value::Object(b)) if b.contains_key("ConstantBool") => {

            let b: bool = b["ConstantBool"].as_bool()?;

            Some(Expression::Atomic(

                Metadata::new(),

                Atom::Literal(Literal::Bool(b)),

            ))

        Some(Value::Object(int)) if int.contains_key("ConstantAbstract") => {

            if let Some(Value::Object(obj)) = int.get("ConstantAbstract") {

                if let Some(arr) = obj.get("AbsLitSet") {

                    let mut expressions: Vec<Expression> = Vec::new();

                    for expr in arr.as_array()?.iter().filter_map(parse_expression) {

                        if let Expression::Atomic(_, Atom::Literal(literal)) = expr {

                            expressions

                                .push(Expression::Atomic(Metadata::new(), Atom::Literal(literal)))

                    return Some(Expression::AbstractLiteral(

                        Metadata::new(),

                        AbstractLiteral::Set(expressions),

                    ));

                }

            None

            let int_expr = constant["ConstantInt"]

                .as_array()

                .and_then(|x| x[1].as_i64())

                .and_then(|x| x.try_into().ok())

                .map(|x| Expression::Atomic(Metadata::new(), Atom::Literal(Literal::Int(x))));

            if let e @ Some(_) = int_expr {

                return e;

}