fn minion_rs_callback(solutions: HashMap<minion_ast::VarName, minion_ast::Constant>) -> bool {

    *(ANY_SOLUTIONS.lock().unwrap()) = true;

    let callback = USER_CALLBACK

        .get_or_init(|| Mutex::new(Box::new(|x| true)))

        .lock()

        .unwrap();

    let mut conjure_solutions: HashMap<conjure_ast::Name, conjure_ast::Literal> = HashMap::new();

    for (minion_name, minion_const) in solutions.into_iter() {

        let conjure_const = match minion_const {

            minion_ast::Constant::Integer(x) => conjure_ast::Literal::Int(x),

        let machine_name_re = Regex::new(r"__conjure_machine_name_([0-9]+)").unwrap();

        let conjure_name = if let Some(caps) = machine_name_re.captures(&minion_name) {

            conjure_ast::Name::MachineName(caps[1].parse::<i32>().unwrap())

            conjure_ast::Name::UserName(minion_name)

        conjure_solutions.insert(conjure_name, conjure_const);

    let continue_search = (**callback)(conjure_solutions);

    if !continue_search {

    }

    continue_search

}

    pub fn new() -> Minion {

        Minion {

            __non_constructable: private::Internal,

            model: None,

        }

    }

    fn solve(

        &mut self,

        callback: SolverCallback,

        _: private::Internal,

    ) -> Result<SolveSuccess, SolverError> {

        // our minion callback is global state, so single threading the adaptor as a whole is

        // probably a good move...

        #[allow(clippy::unwrap_used)]

        let mut minion_lock = MINION_LOCK.lock().unwrap();

        #[allow(clippy::unwrap_used)]

        let mut user_callback = USER_CALLBACK

            .get_or_init(|| Mutex::new(Box::new(|x| true)))

            .lock()

            .unwrap();

        *user_callback = callback;

        drop(user_callback); // release mutex. REQUIRED so that run_minion can use the

                             // user callback and not deadlock.

        run_minion(

            self.model.clone().expect("STATE MACHINE ERR"),

            minion_rs_callback,

        )

        .map_err(|err| match err {

        })?;

        let mut status = Complete(HasSolutions);

        if *(USER_TERMINATED.lock()).unwrap() {

        } else if *(ANY_SOLUTIONS.lock()).unwrap() {

            status = Complete(NoSolutions);

        }

        Ok(SolveSuccess {

            stats: get_solver_stats(),

            status,

        })

    }

    fn load_model(&mut self, model: ConjureModel, _: private::Internal) -> Result<(), SolverError> {

        let mut minion_model = MinionModel::new();

        parse_vars(&model, &mut minion_model)?;

        parse_exprs(&model, &mut minion_model)?;

        self.model = Some(minion_model);

        Ok(())

    }

    fn get_family(&self) -> SolverFamily {

        SolverFamily::Minion

    }

    fn get_name(&self) -> Option<String> {

        Some("Minion".to_owned())

    }

fn parse_vars(

    conjure_model: &ConjureModel,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    for (name, variable) in conjure_model.variables.iter() {

        parse_var(name, variable, minion_model)?;

    Ok(())

}

fn parse_var(

    name: &conjure_ast::Name,

    var: &conjure_ast::DecisionVariable,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    match &var.domain {

        conjure_ast::Domain::IntDomain(ranges) => _parse_intdomain_var(name, ranges, minion_model),

        conjure_ast::Domain::BoolDomain => _parse_booldomain_var(name, minion_model),

}

fn _parse_intdomain_var(

    name: &conjure_ast::Name,

    ranges: &[conjure_ast::Range<i32>],

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    let str_name = _name_to_string(name.to_owned());

    if ranges.len() != 1 {

    }

    let range = ranges.first().ok_or(ModelInvalid(format!(

        "variable {:?} has no range",

        str_name

    )))?;

    let (low, high) = match range {

        conjure_ast::Range::Bounded(x, y) => Ok((x.to_owned(), y.to_owned())),

        conjure_ast::Range::Single(x) => Ok((x.to_owned(), x.to_owned())),

    _try_add_var(

        str_name.to_owned(),

        minion_ast::VarDomain::Bound(low, high),

        minion_model,

    )

}

fn _parse_booldomain_var(

    name: &conjure_ast::Name,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    let str_name = _name_to_string(name.to_owned());

    _try_add_var(

        str_name.to_owned(),

        minion_ast::VarDomain::Bool,

        minion_model,

    )

}

fn _try_add_var(

    name: minion_ast::VarName,

    domain: minion_ast::VarDomain,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    minion_model

        .named_variables

        .add_var(name.clone(), domain)

        .ok_or(ModelInvalid(format!(

            "variable {:?} is defined twice",

            name

        )))

}

fn parse_exprs(

    conjure_model: &ConjureModel,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    for expr in conjure_model.get_constraints_vec().iter() {

        use crate::metadata::Metadata;

        use conjure_ast::Expression as Expr;

        use conjure_ast::Factor;

        use conjure_ast::Literal::*;

        match expr {

                minion_model.constraints.push(minion_ast::Constraint::False);

                return Ok(());

                minion_model.constraints.push(minion_ast::Constraint::True);

                return Ok(());

                parse_expr(expr.to_owned(), minion_model)?;

    Ok(())

}

fn parse_expr(

    expr: conjure_ast::Expression,

    minion_model: &mut MinionModel,

) -> Result<(), SolverError> {

    minion_model.constraints.push(read_expr(expr)?);

    Ok(())

}

fn read_expr(expr: conjure_ast::Expression) -> Result<minion_ast::Constraint, SolverError> {

    match expr {

        conjure_ast::Expression::SumLeq(_metadata, lhs, rhs) => Ok(minion_ast::Constraint::SumLeq(

            read_vars(lhs)?,

            read_var(*rhs)?,

        conjure_ast::Expression::SumGeq(_metadata, lhs, rhs) => Ok(minion_ast::Constraint::SumGeq(

            read_vars(lhs)?,

            read_var(*rhs)?,

        conjure_ast::Expression::Ineq(_metadata, a, b, c) => Ok(minion_ast::Constraint::Ineq(

            read_var(*a)?,

            read_var(*b)?,

            minion_ast::Constant::Integer(read_const(*c)?),

        conjure_ast::Expression::Neq(_metadata, a, b) => {

            Ok(minion_ast::Constraint::DisEq(read_var(*a)?, read_var(*b)?))

        conjure_ast::Expression::DivEq(_metadata, a, b, c) => {

            Ok(minion_ast::Constraint::DivUndefZero(

                (read_var(a.into())?, read_var(b.into())?),

                read_var(c.into())?,

        conjure_ast::Expression::Or(_metadata, exprs) => Ok(minion_ast::Constraint::WatchedOr(

            exprs

                .iter()

                .map(|x| read_expr(x.to_owned()))

                .collect::<Result<Vec<minion_ast::Constraint>, SolverError>>()?,

        conjure_ast::Expression::Eq(_metadata, a, b) => {

            Ok(minion_ast::Constraint::Eq(read_var(*a)?, read_var(*b)?))

        conjure_ast::Expression::WatchedLiteral(_metadata, name, k) => {

            Ok(minion_ast::Constraint::WLiteral(

                minion_ast::Var::NameRef(_name_to_string(name)),

                minion_ast::Constant::Integer(read_const_1(k)?),

}

fn read_vars(exprs: Vec<conjure_ast::Expression>) -> Result<Vec<minion_ast::Var>, SolverError> {

    let mut minion_vars: Vec<minion_ast::Var> = vec![];

    for expr in exprs {

        let minion_var = read_var(expr)?;

        minion_vars.push(minion_var);

    Ok(minion_vars)

}

fn read_var(e: conjure_ast::Expression) -> Result<minion_ast::Var, SolverError> {

    // a minion var is either a reference or a "var as const"

    match _read_ref(e.clone()) {

        Ok(name) => Ok(minion_ast::Var::NameRef(name)),

        Err(_) => match read_const(e) {

            Ok(n) => Ok(minion_ast::Var::ConstantAsVar(n)),

}

fn _read_ref(e: conjure_ast::Expression) -> Result<String, SolverError> {

    let name = match e {

        conjure_ast::Expression::FactorE(_metadata, conjure_ast::Factor::Reference(n)) => Ok(n),

        x => Err(ModelInvalid(format!(

            "expected a reference, but got `{0:?}`",

            x

        ))),

    }?;

    let str_name = _name_to_string(name);

    Ok(str_name)

}

fn read_const(e: conjure_ast::Expression) -> Result<i32, SolverError> {

    match e {

        conjure_ast::Expression::FactorE(_, conjure_ast::Factor::Literal(x)) => {

            Ok(read_const_1(x)?)

}

fn read_const_1(k: conjure_ast::Literal) -> Result<i32, SolverError> {

    match k {

        conjure_ast::Literal::Int(n) => Ok(n),

        conjure_ast::Literal::Bool(true) => Ok(1),

        conjure_ast::Literal::Bool(false) => Ok(0),

}

fn _name_to_string(name: conjure_ast::Name) -> String {

    match name {

        conjure_ast::Name::UserName(x) => x,

        conjure_ast::Name::MachineName(x) => format!("__conjure_machine_name_{}", x),

}

fn get_solver_stats() -> SolverStats {

    SolverStats {

        nodes: get_from_table("Nodes".into()).map(|x| x.parse::<u64>().unwrap()),

        ..Default::default()

    }

}