/*
* Copyright (c) 2024 Andrew Rowan Barlow. Licensed under the EUPL-1.2
* or later. You may obtain a copy of the licence at
* https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12. A copy
* of the EUPL-1.2 licence in English is given in LICENCE.txt which is
* found in the root directory of this repository.
*
* Author: Andrew Rowan Barlow <a.barlow.dev@gmail.com>
*/

// A 3 qubit circuit that implements Grovers algorithm. The oracle target the states |110> and
// |111>. This example will also print the circuit, and show the simulation in real time.
//
// This example will print a bin count of measured states from 500 repeated simulations, and the
// superposition itself.

use quantr::{Circuit, Gate, Measurement, Printer, QuantrError};

#[rustfmt::skip]
fn main() -> Result<(), QuantrError> {
    let mut circuit = Circuit::new(3)?;

    // Kick state into superposition of equal weights
    circuit.add_repeating_gate(Gate::H, &[0, 1, 2])?;

    // Oracle
    circuit.add_gate(Gate::CZ(1), 0)?;

    // Amplitude amplification
    circuit
        .add_repeating_gate(Gate::H, &[0, 1, 2])?
        .add_repeating_gate(Gate::X, &[0, 1, 2])?
        .add_gate(Gate::H, 2)?
        .add_gate(Gate::Toffoli(0, 1), 2)?
        .add_gate(Gate::H, 2)?
        .add_repeating_gate(Gate::X, &[0, 1, 2])?
        .add_repeating_gate(Gate::H, &[0, 1, 2])?;

    // Prints the circuit in UTF-8
    let mut printer = Printer::new(&circuit);
    printer.print_diagram();

    // Print the progress of the simulation
    circuit.set_print_progress(true);

    // Simulates the circuit
    let simulated_circuit = circuit.simulate();
    println!("");

    // Displays bin count of the resulting 500 repeat measurements of
    // superpositions. bin_count is a HashMap<ProductState, usize>.
    if let Measurement::Observable(bin_count) = simulated_circuit.measure_all(500) {
        println!("[Observable] Bin count of observed states.");
        for (state, count) in bin_count {
            println!("|{}> observed {} times", state, count);
        }
    } 

    // Returns the superpsoition that cannot be directly observed.
    if let Measurement::NonObservable(output_super_position) = simulated_circuit.get_state()
    {
        println!("\n[Non-Observable] The amplitudes of each state in the final superposition.");
        for (state, amplitude) in output_super_position.into_iter() {
            println!("|{}> : {}", state, amplitude);
        }
    }

    Ok(())
}