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// Copyright (C) 2019-2023 Aleo Systems Inc.
// This file is part of the snarkVM library.

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

mod command;
pub use command::*;

mod input;
use input::*;

mod bytes;
mod parse;

use crate::Instruction;
use console::{
    network::prelude::*,
    program::{Identifier, PlaintextType, Register, RegisterType},
};

use indexmap::IndexSet;

#[derive(Clone, PartialEq, Eq)]
pub struct Finalize<N: Network> {
    /// The name of the associated function.
    name: Identifier<N>,
    /// The input statements, added in order of the input registers.
    /// Input assignments are ensured to match the ordering of the input statements.
    inputs: IndexSet<Input<N>>,
    /// The commands, in order of execution.
    commands: Vec<Command<N>>,
}

impl<N: Network> Finalize<N> {
    /// Initializes a new finalize with the given name.
    pub fn new(name: Identifier<N>) -> Self {
        Self { name, inputs: IndexSet::new(), commands: Vec::new() }
    }

    /// Returns the name of the associated function.
    pub const fn name(&self) -> &Identifier<N> {
        &self.name
    }

    /// Returns the finalize inputs.
    pub const fn inputs(&self) -> &IndexSet<Input<N>> {
        &self.inputs
    }

    /// Returns the finalize input types.
    pub fn input_types(&self) -> Vec<PlaintextType<N>> {
        self.inputs.iter().map(|input| *input.plaintext_type()).collect()
    }

    /// Returns the finalize commands.
    pub fn commands(&self) -> &[Command<N>] {
        &self.commands
    }
}

impl<N: Network> Finalize<N> {
    /// Adds the input statement to finalize.
    ///
    /// # Errors
    /// This method will halt if a command was previously added.
    /// This method will halt if the maximum number of inputs has been reached.
    /// This method will halt if the input statement was previously added.
    #[inline]
    fn add_input(&mut self, input: Input<N>) -> Result<()> {
        // Ensure there are no commands in memory.
        ensure!(self.commands.is_empty(), "Cannot add inputs after commands have been added");

        // Ensure the maximum number of inputs has not been exceeded.
        ensure!(self.inputs.len() <= N::MAX_INPUTS, "Cannot add more than {} inputs", N::MAX_INPUTS);
        // Ensure the input statement was not previously added.
        ensure!(!self.inputs.contains(&input), "Cannot add duplicate input statement");

        // Ensure the input register is a locator.
        ensure!(matches!(input.register(), Register::Locator(..)), "Input register must be a locator");

        // Insert the input statement.
        self.inputs.insert(input);
        Ok(())
    }

    /// Adds the given command to finalize.
    ///
    /// # Errors
    /// This method will halt if the maximum number of commands has been reached.
    #[inline]
    pub fn add_command(&mut self, command: Command<N>) -> Result<()> {
        // Ensure the maximum number of commands has not been exceeded.
        ensure!(self.commands.len() < N::MAX_COMMANDS, "Cannot add more than {} commands", N::MAX_COMMANDS);

        // If the command is an instruction, `get` command, or `get.or_init` command, perform additional checks.
        match &command {
            Command::Instruction(instruction) => {
                match instruction {
                    // Ensure the instruction is not a `call`.
                    Instruction::Call(_) => bail!("Forbidden operation: Finalize cannot invoke a 'call'"),
                    // Ensure the instruction is not a `cast` to a record.
                    Instruction::Cast(cast) if !matches!(cast.register_type(), &RegisterType::Plaintext(_)) => {
                        bail!("Forbidden operation: Finalize cannot cast to a record")
                    }
                    _ => {}
                }
                // Ensure the destination register is a locator.
                for register in instruction.destinations() {
                    ensure!(matches!(register, Register::Locator(..)), "Destination register must be a locator");
                }
            }
            Command::Get(get) => {
                // Ensure the destination register is a locator.
                ensure!(matches!(get.destination(), Register::Locator(..)), "Destination register must be a locator");
            }
            Command::GetOrInit(get_or_init) => {
                // Ensure the destination register is a locator.
                ensure!(
                    matches!(get_or_init.destination(), Register::Locator(..)),
                    "Destination register must be a locator"
                );
            }
            Command::Set(_) => {}
        }

        // Insert the command.
        self.commands.push(command);
        Ok(())
    }
}

impl<N: Network> TypeName for Finalize<N> {
    /// Returns the type name as a string.
    #[inline]
    fn type_name() -> &'static str {
        "finalize"
    }
}