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// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the Leo library.

// The Leo library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The Leo library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the Leo library. If not, see <https://www.gnu.org/licenses/>.

//! Enforces an iteration statement in a compiled Leo program.

use crate::{
    program::ConstrainedProgram,
    value::ConstrainedValue,
    GroupType,
    IndicatorAndConstrainedValue,
    Integer,
    StatementResult,
};
use leo_asg::IterationStatement;

use snarkvm_models::{
    curves::{Field, PrimeField},
    gadgets::{
        r1cs::ConstraintSystem,
        utilities::{boolean::Boolean, uint::UInt32},
    },
};

impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
    #[allow(clippy::too_many_arguments)]
    pub fn enforce_iteration_statement<CS: ConstraintSystem<F>>(
        &mut self,
        cs: &mut CS,
        indicator: &Boolean,
        statement: &IterationStatement,
    ) -> StatementResult<Vec<IndicatorAndConstrainedValue<F, G>>> {
        let mut results = vec![];

        let span = statement.span.clone().unwrap_or_default();

        let from = self.enforce_index(cs, &statement.start, &span)?;
        let to = self.enforce_index(cs, &statement.stop, &span)?;

        for i in from..to {
            // Store index in current function scope.
            // For loop scope is not implemented.
            let variable = statement.variable.borrow();

            // todo: replace definition with var typed
            self.store(
                variable.id,
                ConstrainedValue::Integer(Integer::U32(UInt32::constant(i as u32))),
            );

            // Evaluate statements and possibly return early
            let result = self.enforce_statement(
                &mut cs.ns(|| format!("for loop iteration {} {}:{}", i, &span.line, &span.start)),
                indicator,
                &statement.body,
            )?;

            results.extend(result);
        }

        Ok(results)
    }
}