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// Copyright (C) 2019-2020 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/>.

//! Allocates an array as a main function input parameter in a compiled Leo program.

use crate::{
    errors::FunctionError,
    inner_array_type,
    parse_index,
    program::{new_scope, ConstrainedProgram},
    value::ConstrainedValue,
    GroupType,
};

use leo_ast::{ArrayDimensions, InputValue, Span, Type};

use crate::errors::ExpressionError;
use snarkos_models::{
    curves::{Field, PrimeField},
    gadgets::r1cs::ConstraintSystem,
};

impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedProgram<F, G> {
    pub fn allocate_array<CS: ConstraintSystem<F>>(
        &mut self,
        cs: &mut CS,
        name: &str,
        array_type: Type,
        mut array_dimensions: ArrayDimensions,
        input_value: Option<InputValue>,
        span: &Span,
    ) -> Result<ConstrainedValue<F, G>, FunctionError> {
        let expected_length = match array_dimensions.remove_first() {
            Some(number) => {
                // Parse the array dimension into a `usize`.
                parse_index(&number, &span)?
            }
            None => {
                return Err(FunctionError::ExpressionError(ExpressionError::unexpected_array(
                    array_type.to_string(),
                    span.to_owned(),
                )));
            }
        };

        // Get the expected type for each array element.
        let inner_array_type = inner_array_type(array_type, array_dimensions);

        // Build the array value using the expected types.
        let mut array_value = vec![];

        match input_value {
            Some(InputValue::Array(arr)) => {
                // Allocate each value in the current row
                for (i, value) in arr.into_iter().enumerate() {
                    let value_name = new_scope(&name, &i.to_string());

                    array_value.push(self.allocate_main_function_input(
                        cs,
                        inner_array_type.clone(),
                        &value_name,
                        Some(value),
                        span,
                    )?)
                }
            }
            None => {
                // Allocate all row values as none
                for i in 0..expected_length {
                    let value_name = new_scope(&name, &i.to_string());

                    array_value.push(self.allocate_main_function_input(
                        cs,
                        inner_array_type.clone(),
                        &value_name,
                        None,
                        span,
                    )?);
                }
            }
            _ => {
                return Err(FunctionError::invalid_array(
                    input_value.unwrap().to_string(),
                    span.to_owned(),
                ));
            }
        }

        Ok(ConstrainedValue::Array(array_value))
    }
}