cqlib-core 0.1.0-beta.5

// This code is part of Cqlib.
//
// (C) Copyright China Telecom Quantum Group 2026
//
// This code is licensed under the Apache License, Version 2.0. You may
// obtain a copy of this license in the LICENSE.txt file in the root directory
// of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
//
// Any modifications or derivative works of this code must retain this
// copyright notice, and modified files need to carry a notice indicating
// that they have been altered from the originals.

use crate::circuit::gate::circuit_gate::FrozenCircuit;
use crate::circuit::gate::{StandardGate, UnitaryGate};
use crate::circuit::parameter::Parameter;
use crate::circuit::symbolic_matrix::standard_gate_symbolic_matrix;
use crate::circuit::{Circuit, ClassicalExpr, ClassicalType, Instruction, Qubit};
use crate::ir::qasm2::dump::{QasmDumpError, dump, dumps, to_path, to_string};
use crate::ir::qasm2::load::loads;
use std::fs;
use std::path::PathBuf;
use std::sync::Arc;
use std::time::{SystemTime, UNIX_EPOCH};

fn unique_temp_path(test_name: &str) -> PathBuf {
    let nonce = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_nanos();
    std::env::temp_dir().join(format!(
        "cqlib_qasm2_dump_{}_{}_{}.qasm",
        std::process::id(),
        test_name,
        nonce
    ))
}

/// Assert that QASM output contains all expected lines in order
fn assert_qasm_contains_ordered(qasm: &str, expected_lines: &[&str]) {
    let mut search_start = 0;
    for (i, &line) in expected_lines.iter().enumerate() {
        let pos = qasm[search_start..].find(line);
        assert!(
            pos.is_some(),
            "QASM output missing expected line #{}:\n'{}'\n\nActual QASM:\n{}",
            i + 1,
            line,
            qasm
        );
        search_start += pos.unwrap() + line.len();
    }
}

/// Verify that generated QASM can be parsed back and has correct structure
fn verify_qasm_roundtrip(qasm: &str, expected_qubits: usize) {
    let parsed = loads(qasm);
    assert!(
        parsed.is_ok(),
        "Generated QASM should be valid and parseable. Error: {:?}\nQASM:\n{}",
        parsed.err(),
        qasm
    );
    let circuit = parsed.unwrap();
    assert_eq!(
        circuit.num_qubits(),
        expected_qubits,
        "Parsed circuit should have {} qubits",
        expected_qubits
    );
}

/// Simple contains check (for backwards compatibility)
fn assert_qasm_contains(qasm: &str, expected_lines: &[&str]) {
    for &line in expected_lines {
        assert!(
            qasm.contains(line),
            "QASM output missing expected line:\n'{}'\n\nActual QASM:\n{}",
            line,
            qasm
        );
    }
}

#[test]
fn test_dump_standard_gates() {
    let mut circuit = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);

    circuit.h(q0).unwrap();
    circuit.cx(q0, q1).unwrap();
    circuit.x(q1).unwrap();
    circuit.y(q2).unwrap();
    circuit.z(q0).unwrap();
    circuit.ccx(q0, q1, q2).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Strict: Verify complete structure
    let expected = &[
        concat!(
            "// This file is auto-generated by Cqlib v",
            env!("CARGO_PKG_VERSION"),
            "."
        ),
        "OPENQASM 2.0;",
        "include \"qelib1.inc\";",
        "qreg q[3];",
        "h q[0];",
        "cx q[0],q[1];",
        "x q[1];",
        "y q[2];",
        "z q[0];",
        "ccx q[0],q[1],q[2];",
    ];
    assert_qasm_contains_ordered(&qasm, expected);

    // Verify no creg declarations (no conditional ops)
    assert!(
        !qasm.contains("creg"),
        "Should not have creg without conditional ops"
    );

    // Verify roundtrip
    verify_qasm_roundtrip(&qasm, 3);
}

#[test]
fn test_to_string_alias_matches_dumps() {
    let mut circuit = Circuit::new(1);
    circuit.h(Qubit::new(0)).unwrap();

    assert_eq!(to_string(&circuit).unwrap(), dumps(&circuit).unwrap());
}

#[test]
fn test_to_path_alias_writes_file() {
    let mut circuit = Circuit::new(1);
    circuit.h(Qubit::new(0)).unwrap();
    let path = unique_temp_path("to_path");

    to_path(&circuit, path.as_path()).unwrap();

    assert_eq!(fs::read_to_string(&path).unwrap(), dumps(&circuit).unwrap());
    fs::remove_file(path).unwrap();
}

#[test]
fn test_dump_parametric_gates() {
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);

    // Fixed parameter
    circuit.rx(q0, std::f64::consts::PI / 2.0).unwrap();
    // Symbolic parameter
    let theta = Parameter::try_from("theta").unwrap();
    circuit.ry(q0, theta.clone()).unwrap();
    // Expression
    let phi = theta + 0.5;
    circuit.rz(q0, phi).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify all parametric gates are present with correct syntax
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "rx(1.5707963267948966) q[0];",
            "ry(theta) q[0];",
            "rz(0.5 + theta) q[0];",
        ],
    );

    // Note: Skip roundtrip verification because symbolic parameters (theta)
    // cannot be parsed back without being defined in the QASM
    // verify_qasm_roundtrip(&qasm, 1);
}

#[test]
fn test_dump_complex_parameters() {
    // Test complex parameter expressions
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    let theta = Parameter::try_from("theta").unwrap();
    let phi = Parameter::try_from("phi").unwrap();

    // Parameter with pi
    circuit.rx(q0, theta.clone() * Parameter::pi()).unwrap();
    // Division
    circuit.ry(q0, phi.clone() / 2.0).unwrap();
    // Complex expression
    circuit.rz(q1, (theta + phi) * 0.5).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify expressions are properly formatted
    // Note: Actual output format uses π symbol and reorders some expressions
    assert!(
        qasm.contains("rx(theta*pi)"),
        "Should contain 'rx(theta*pi)', got: {}",
        qasm
    );
    assert!(
        qasm.contains("ry(phi/2)"),
        "Should contain 'ry(phi/2)', got: {}",
        qasm
    );
    assert!(
        qasm.contains("rz(0.5*(phi + theta))"),
        "Should contain complex expression, got: {}",
        qasm
    );

    // Note: Skip roundtrip verification because symbolic parameters (theta, phi)
    // cannot be parsed back without being defined in the QASM, and π symbol is not valid
    // verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_directives_no_condition() {
    // Test directives without conditional operations
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    circuit.reset(q0).unwrap();
    circuit.barrier(vec![q0, q1]).unwrap();
    circuit.measure(q0).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Strict verification
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "reset q[0];",
            "barrier q[0],q[1];",
            "measure q[0] -> v0[0];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_custom_gate() {
    // Define a sub-circuit
    let mut sub_circ = Circuit::new(2);
    let sq0 = Qubit::new(0);
    let sq1 = Qubit::new(1);
    sub_circ.h(sq0).unwrap();
    sub_circ.cx(sq0, sq1).unwrap();

    // Create a gate from it
    let gate = sub_circ.to_gate("bell").unwrap();

    // Use it in main circuit
    let mut main_circ = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    // Append requires manual building of the instruction call,
    // but `Circuit::append` handles the wrapping.
    main_circ.append(gate, vec![q0, q1], vec![], None).unwrap();

    let qasm = dumps(&main_circ).expect("Dump failed");

    // Check Definition
    let expected_def = &["gate bell q0,q1 {", "h q0;", "cx q0,q1;", "}"];
    assert_qasm_contains(&qasm, expected_def);

    // Check Usage
    assert_qasm_contains(&qasm, &["bell q[0],q[1];"]);
}

#[test]
fn test_dump_rejects_measurement_in_gate_definition() {
    let mut inner = Circuit::new(1);
    inner.measure(Qubit::new(0)).unwrap();
    let gate = inner.to_gate("measuring_gate").unwrap();

    let mut circuit = Circuit::new(1);
    circuit
        .append(gate, [Qubit::new(0)], std::iter::empty(), None)
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::MeasureInGateNotAllowed)
    ));
}

#[test]
fn test_dump_rejects_reset_in_circuit_gate_definition() {
    let mut inner = Circuit::new(1);
    inner.reset(Qubit::new(0)).unwrap();
    let gate = inner.to_gate("resetting_gate").unwrap();

    let mut circuit = Circuit::new(1);
    circuit
        .append(gate, [Qubit::new(0)], std::iter::empty(), None)
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::ResetInGateNotAllowed)
    ));
}

#[test]
fn test_dump_rejects_reset_in_unitary_gate_definition() {
    let mut inner = Circuit::new(1);
    inner.reset(Qubit::new(0)).unwrap();
    let gate = UnitaryGate::new("ResettingUnitary", 1, 0)
        .with_circuit(Arc::new(FrozenCircuit::new(inner)))
        .unwrap();

    let mut circuit = Circuit::new(1);
    circuit.unitary(gate, vec![Qubit::new(0)]).unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::ResetInGateNotAllowed)
    ));
}

#[test]
fn test_dump_parameterized_custom_gate() {
    // Sub-circuit with parameter
    let mut sub_circ = Circuit::new(1);
    let sq0 = Qubit::new(0);
    let lambda = Parameter::try_from("lambda").unwrap();
    sub_circ.rx(sq0, lambda).unwrap();

    let gate = sub_circ.to_gate("my_rot").unwrap();

    let mut main_circ = Circuit::new(1);
    let q0 = Qubit::new(0);

    // Use with fixed value
    main_circ
        .append(gate.clone(), vec![q0], vec![1.23.into()], None)
        .unwrap();

    // Use with symbolic value
    let gamma = Parameter::try_from("gamma").unwrap();
    main_circ
        .append(gate, vec![q0], vec![gamma.into()], None)
        .unwrap();

    let qasm = dumps(&main_circ).expect("Dump failed");

    // Definition should use the parameter name from the sub-circuit
    let expected_def = &["gate my_rot(lambda) q0 {", "rx(lambda) q0;", "}"];
    assert_qasm_contains(&qasm, expected_def);

    // Usages
    let expected_usage = &["my_rot(1.23) q[0];", "my_rot(gamma) q[0];"];
    assert_qasm_contains(&qasm, expected_usage);
}

#[test]
fn test_global_phase() {
    let circuit = Circuit::new(1);

    let qasm = dumps(&circuit).expect("Dump failed");
    assert!(!qasm.contains("// Global Phase: 0"));
}

#[test]
fn test_dump_mc_gate() {
    let mut circuit = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);

    // Multi-controlled X with 2 controls -> ccx
    circuit
        .multi_control(StandardGate::X, vec![q0, q1], vec![q2], vec![])
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    assert_qasm_contains(&qasm, &["ccx q[0],q[1],q[2];"]);
}

#[test]
fn test_dump_gate_collision_same_interface() {
    // Define Gate A: H gate
    let mut c1 = Circuit::new(1);
    c1.h(Qubit::new(0)).unwrap();
    let g1 = c1.to_gate("my_gate").unwrap();

    // Define Gate B: X gate (same name "my_gate")
    let mut c2 = Circuit::new(1);
    c2.x(Qubit::new(0)).unwrap();
    let g2 = c2.to_gate("my_gate").unwrap();

    let mut main = Circuit::new(1);
    let q0 = Qubit::new(0);

    main.append(g1, vec![q0], vec![], None).unwrap();
    main.append(g2, vec![q0], vec![], None).unwrap();

    assert!(matches!(
        dumps(&main),
        Err(QasmDumpError::ConflictingGateDefinition { name, .. }) if name == "my_gate"
    ));
}

#[test]
fn test_dump_nested_custom_gates() {
    // 1. Define Leaf Gate: rz(p) q
    let mut leaf = Circuit::new(1);
    let p = Parameter::try_from("p").unwrap();
    leaf.rz(Qubit::new(0), p).unwrap();
    let gate_leaf = leaf.to_gate("gate_leaf").unwrap();

    // 2. Define Middle Gate: calls gate_leaf(m * 2.0)
    let mut mid = Circuit::new(1);
    let m = Parameter::try_from("m").unwrap();
    let param_expr: Parameter = m.clone() * 2.0;
    mid.append(
        gate_leaf,
        vec![Qubit::new(0)],
        vec![param_expr.into()],
        None,
    )
    .unwrap();
    let gate_mid = mid.to_gate("gate_mid").unwrap();

    // 3. Main Circuit: calls gate_mid(theta)
    let mut main = Circuit::new(1);
    let theta = Parameter::try_from("theta").unwrap();
    main.append(gate_mid, vec![Qubit::new(0)], vec![theta.into()], None)
        .unwrap();

    let qasm = dumps(&main).expect("Dump failed");

    // Expected Output Analysis:
    // 1. gate gate_leaf(p) q0 { rz(p) q0; }
    // 2. gate gate_mid(m) q0 { gate_leaf(m * 2) q0; }  <-- Note: 2.0 might be '2' or '2.0' depending on formatting
    // 3. gate_mid(theta) q[0];

    assert_qasm_contains(
        &qasm,
        &[
            "gate gate_leaf(p) q0 {",
            "rz(p) q0;",
            "}",
            "gate gate_mid(m) q0 {",
            "gate_leaf(2*m) q0;", // Simplified check, might need regex if float formatting varies
            "}",
            "gate_mid(theta) q[0];",
        ],
    );
}

#[test]
fn test_dump_unitary_gate_with_circuit() {
    // 1. Create an inner circuit for the UnitaryGate
    let mut inner_circuit = Circuit::new(2);
    inner_circuit.h(Qubit::new(0)).unwrap();
    inner_circuit.cx(Qubit::new(0), Qubit::new(1)).unwrap();

    // 2. Create a UnitaryGate with the inner circuit
    let frozen_circuit = FrozenCircuit::new(inner_circuit);
    let u_gate = UnitaryGate::new("MyBell", 2, 0)
        .with_circuit(Arc::new(frozen_circuit))
        .unwrap();

    // 3. Use the UnitaryGate in a main circuit
    let mut main_circuit = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    // Add some standard gates
    main_circuit.x(q0).unwrap();

    // Add the UnitaryGate
    main_circuit.unitary(u_gate, vec![q0, q1]).unwrap();

    // Add more gates after
    main_circuit.z(q1).unwrap();

    // 4. Dump and verify
    let qasm = dumps(&main_circuit).expect("Dump failed");
    println!("{}", qasm);

    // The UnitaryGate should be output as a gate definition and then called
    // Check gate definition
    assert_qasm_contains(&qasm, &["gate MyBell q0,q1 {", "h q0;", "cx q0,q1;", "}"]);

    // Check gate call
    assert_qasm_contains(&qasm, &["x q[0];", "MyBell q[0],q[1];", "z q[1];"]);
}

#[test]
fn test_dump_parameterized_unitary_gate_with_circuit() {
    let mut inner = Circuit::new(1);
    inner.rx(Qubit::new(0), Parameter::symbol("theta")).unwrap();
    let gate = UnitaryGate::new("param_unitary", 1, 1)
        .with_circuit(Arc::new(FrozenCircuit::new(inner)))
        .unwrap();

    let mut circuit = Circuit::new(1);
    circuit
        .unitary_with_params(gate, vec![Qubit::new(0)], [1.25.into()])
        .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains(
        &qasm,
        &[
            "gate param_unitary(theta) q0 {",
            "rx(theta) q0;",
            "param_unitary(1.25) q[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 1);
}

#[test]
fn test_dump_parameterized_symbolic_unitary_as_opaque() {
    let gate = UnitaryGate::new("symbolic_opaque", 1, 1)
        .with_symbolic_matrix(
            ["angle"],
            standard_gate_symbolic_matrix(StandardGate::RX, &[Parameter::symbol("angle")]).unwrap(),
        )
        .unwrap();

    let mut circuit = Circuit::new(1);
    circuit
        .unitary_with_params(gate, vec![Qubit::new(0)], [0.5.into()])
        .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains(
        &qasm,
        &[
            "opaque symbolic_opaque(angle) q0;",
            "symbolic_opaque(0.5) q[0];",
        ],
    );
}

#[test]
fn test_dump_parameterized_opaque_unitary_generates_parameter_names() {
    let gate = UnitaryGate::new("opaque_params", 1, 2);
    let mut circuit = Circuit::new(1);
    circuit
        .unitary_with_params(
            gate,
            vec![Qubit::new(0)],
            [Parameter::from(0.25).into(), Parameter::from(0.75).into()],
        )
        .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains(
        &qasm,
        &[
            "opaque opaque_params(p0,p1) q0;",
            "opaque_params(0.25,0.75) q[0];",
        ],
    );
}

#[test]
fn test_dump_parameterized_unitary_call_inside_circuit_gate() {
    let mut leaf_body = Circuit::new(1);
    leaf_body
        .rx(Qubit::new(0), Parameter::symbol("alpha"))
        .unwrap();
    let leaf = UnitaryGate::new("param_leaf", 1, 1)
        .with_circuit(Arc::new(FrozenCircuit::new(leaf_body)))
        .unwrap();

    let mut wrapper_body = Circuit::new(1);
    wrapper_body
        .unitary_with_params(
            leaf,
            vec![Qubit::new(0)],
            [Parameter::symbol("theta").into()],
        )
        .unwrap();
    let wrapper = wrapper_body.to_gate("unitary_wrapper").unwrap();

    let mut circuit = Circuit::new(1);
    circuit
        .append(wrapper, [Qubit::new(0)], [0.3.into()], None)
        .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains(
        &qasm,
        &[
            "gate unitary_wrapper(theta) q0 {",
            "param_leaf(theta) q0;",
            "gate param_leaf(alpha) q0 {",
            "unitary_wrapper(0.3) q[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 1);
}

#[test]
fn test_dump_parameterized_unitary_call_inside_condition() {
    let mut inner = Circuit::new(1);
    inner.rx(Qubit::new(0), Parameter::symbol("theta")).unwrap();
    let gate = UnitaryGate::new("conditional_unitary", 1, 1)
        .with_circuit(Arc::new(FrozenCircuit::new(inner)))
        .unwrap();
    let mut circuit = Circuit::new(2);
    let measured = circuit.measure(Qubit::new(0)).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_(condition, move |body| {
            body.unitary_with_params(gate, vec![Qubit::new(1)], [0.75.into()])?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains(
        &qasm,
        &[
            "gate conditional_unitary(theta) q0 {",
            "if (v0 == 1) conditional_unitary(0.75) q[1];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_unitary_gate_with_circuit_nested() {
    // Test that UnitaryGate properly handles nested CircuitGate inside it
    // 1. Create a CircuitGate definition
    let mut sub_circ = Circuit::new(1);
    sub_circ.h(Qubit::new(0)).unwrap();
    sub_circ.s(Qubit::new(0)).unwrap();
    let gate_def = sub_circ.to_gate("hs_gate").unwrap();

    // 2. Create an inner circuit that uses the CircuitGate
    let mut inner_circuit = Circuit::new(2);
    inner_circuit
        .append(gate_def.clone(), vec![Qubit::new(0)], vec![], None)
        .unwrap();
    inner_circuit.cx(Qubit::new(0), Qubit::new(1)).unwrap();
    inner_circuit
        .append(gate_def, vec![Qubit::new(1)], vec![], None)
        .unwrap();

    // 3. Create a UnitaryGate with this inner circuit
    let frozen_circuit = FrozenCircuit::new(inner_circuit);
    let u_gate = UnitaryGate::new("CustomOp", 2, 0)
        .with_circuit(Arc::new(frozen_circuit))
        .unwrap();

    // 4. Use in main circuit
    let mut main_circuit = Circuit::new(2);
    main_circuit
        .unitary(u_gate, vec![Qubit::new(0), Qubit::new(1)])
        .unwrap();

    // 5. Dump and verify
    let qasm = dumps(&main_circuit).expect("Dump failed");

    // Should contain the CircuitGate definition
    assert_qasm_contains(&qasm, &["gate hs_gate q0 {", "h q0;", "s q0;", "}"]);

    // Should contain the UnitaryGate definition that calls the CircuitGate
    assert_qasm_contains(
        &qasm,
        &[
            "gate CustomOp q0,q1 {",
            "hs_gate q0;",
            "cx q0,q1;",
            "hs_gate q1;",
            "}",
        ],
    );

    // Should call the UnitaryGate
    assert_qasm_contains(&qasm, &["CustomOp q[0],q[1];"]);
}

#[test]
fn test_dump_unitary_gate_without_circuit() {
    // Test that UnitaryGate without circuit (only matrix) outputs opaque declaration
    use ndarray::Array2;
    use num_complex::Complex64;

    // Create a UnitaryGate with only matrix (no circuit)
    let mat = Array2::eye(2).mapv(|x| Complex64::new(x, 0.0));
    let u_gate = UnitaryGate::new("MatrixOnly", 1, 0)
        .with_matrix(mat)
        .unwrap();

    let mut circuit = Circuit::new(1);
    circuit.unitary(u_gate, vec![Qubit::new(0)]).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    println!("{}", qasm);
    // Should output opaque declaration and gate call
    assert_qasm_contains(&qasm, &["opaque MatrixOnly q0;", "MatrixOnly q[0];"]);
}

#[test]
fn test_dump_extended_gates() {
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let theta = 1.0;

    circuit.crx(q0, q1, theta).unwrap();
    circuit.cry(q0, q1, theta).unwrap();
    circuit.rzz(q0, q1, theta).unwrap();
    circuit.rxx(q0, q1, theta).unwrap();
    circuit.ryy(q0, q1, theta).unwrap();
    circuit.rzx(q0, q1, theta).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Check Definitions (in order)
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "gate crx(theta) a,b { h b;rz(theta/2) b; cx a,b; rz(-theta/2) b; cx a,b; h b;}",
            "gate cry(theta) a,b { ry(theta/2) b; cx a,b; ry(-theta/2) b; cx a,b; }",
            "gate rzz(theta) a,b { cx a,b; rz(theta) b; cx a,b; }",
            "gate rxx(theta) a,b { h a; h b; cx a,b; rz(theta) b; cx a,b; h a; h b; }",
            "gate ryy(theta) a,b { rx(pi/2) a; rx(pi/2) b; cx a,b; rz(theta) b; cx a,b; rx(-pi/2) a; rx(-pi/2) b; }",
            "gate rzx(theta) a,b { h b; cx a,b; rz(theta) b; cx a,b; h b; }",
        ],
    );

    // Check Usages in order
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "crx(1) q[0],q[1];",
            "cry(1) q[0],q[1];",
            "rzz(1) q[0],q[1];",
            "rxx(1) q[0],q[1];",
            "ryy(1) q[0],q[1];",
            "rzx(1) q[0],q[1];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_if_statement_simple() {
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_(condition, |body| {
            body.x(q1)?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump should succeed");
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "h q[0];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) x q[1];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_conditional_measurement() {
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let target = circuit.var(ClassicalType::Bit);

    let measured = circuit.measure(q0).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_(condition, |body| {
            body.measure_into(q1, target)?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump should succeed");
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg c0[1];",
            "creg v0[1];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) measure q[1] -> c0[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_conditional_barrier_is_rejected() {
    let mut circuit = Circuit::new(2);
    let measured = circuit.measure(Qubit::new(0)).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_(condition, |body| {
            body.barrier(vec![Qubit::new(1)])?;
            Ok(())
        })
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalControl(_))
    ));
}

#[test]
fn test_dump_measure_into_bitvec_and_multibit_condition() {
    let mut circuit = Circuit::new(3);
    let register = circuit.var(ClassicalType::bit_vec(3).unwrap());
    circuit
        .measure_bits_into([Qubit::new(0), Qubit::new(1), Qubit::new(2)], register)
        .unwrap();
    let condition = ClassicalExpr::eq(
        ClassicalExpr::bit_vec_to_uint(register.expr()).unwrap(),
        ClassicalExpr::uint_literal(3, 5).unwrap(),
    )
    .unwrap();
    circuit
        .if_(condition, |body| {
            body.x(Qubit::new(0))?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump should succeed");
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg c0[3];",
            "measure q[0] -> c0[0];",
            "measure q[1] -> c0[1];",
            "measure q[2] -> c0[2];",
            "if (c0 == 5) x q[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 3);
}

#[test]
fn test_dynamic_qasm_load_dump_roundtrip() {
    let circuit = loads(
        r#"
        OPENQASM 2.0;
        qreg q[3];
        creg c[3];
        measure q -> c;
        if (c == 5) x q[0];
        "#,
    )
    .unwrap();

    let qasm = dumps(&circuit).unwrap();
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg c0[3];",
            "measure q[0] -> c0[0];",
            "measure q[1] -> c0[1];",
            "measure q[2] -> c0[2];",
            "if (c0 == 5) x q[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 3);
}

#[test]
fn test_dynamic_qasm_roundtrip_does_not_grow_unused_cregs() {
    let circuit = loads(
        r#"
        OPENQASM 2.0;
        include "qelib1.inc";
        qreg q[2];
        creg c[2];
        h q[0];
        measure q[0] -> c[0];
        if (c == 1) x q[1];
        "#,
    )
    .unwrap();

    let first_dump = dumps(&circuit).unwrap();
    let restored = loads(&first_dump).unwrap();
    let second_dump = dumps(&restored).unwrap();
    let restored_again = loads(&second_dump).unwrap();
    let third_dump = dumps(&restored_again).unwrap();

    assert_eq!(second_dump, first_dump);
    assert_eq!(third_dump, second_dump);
    assert_qasm_contains_ordered(
        &first_dump,
        &[
            "creg c0[2];",
            "h q[0];",
            "measure q[0] -> c0[0];",
            "if (c0 == 1) x q[1];",
        ],
    );
    assert!(!first_dump.contains("creg v0[1];"), "got:\n{first_dump}");
}

#[test]
fn test_dump_if_else_is_rejected() {
    let mut circuit = Circuit::new(2);
    let measured = circuit.measure(Qubit::new(0)).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_else(
            condition,
            |body| {
                body.x(Qubit::new(1))?;
                Ok(())
            },
            |body| {
                body.z(Qubit::new(1))?;
                Ok(())
            },
        )
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalControl(_))
    ));
}

#[test]
fn test_dump_while_loop_error() {
    let mut circuit = Circuit::new(1);
    circuit
        .while_(ClassicalExpr::bool_literal(true), |body| {
            body.h(Qubit::new(0))?;
            Ok(())
        })
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalControl(_))
    ));
}

#[test]
fn test_dump_general_store_is_rejected() {
    let mut circuit = Circuit::new(1);
    let register = circuit.var(ClassicalType::bit_vec(2).unwrap());
    circuit
        .store(register, ClassicalExpr::bit_vec_literal(2, 1).unwrap())
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalData(_))
    ));
}

#[test]
fn test_dump_rejects_reusing_fused_measurement_value() {
    let mut circuit = Circuit::new(1);
    let register = circuit.var(ClassicalType::bit_vec(1).unwrap());
    let measured = circuit
        .measure_bits_into([Qubit::new(0)], register)
        .unwrap();
    let condition = ClassicalExpr::eq(
        ClassicalExpr::bit_vec_to_uint(measured.expr()).unwrap(),
        ClassicalExpr::uint_literal(1, 1).unwrap(),
    )
    .unwrap();
    circuit.if_(condition, |_| Ok(())).unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalData(_))
    ));
}

#[test]
fn test_dump_empty_circuit() {
    let circuit = Circuit::new(2);

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify minimal valid QASM
    assert_qasm_contains_ordered(
        &qasm,
        &["OPENQASM 2.0;", "include \"qelib1.inc\";", "qreg q[2];"],
    );

    // Verify no gates or operations
    assert!(!qasm.contains("h q["), "Empty circuit should have no gates");
    assert!(!qasm.contains("creg"), "Empty circuit should have no creg");

    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_multiple_conditional_qubits() {
    let mut circuit = Circuit::new(4);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);
    let q3 = Qubit::new(3);

    circuit.h(q0).unwrap();
    circuit.h(q1).unwrap();
    let measured0 = circuit.measure(q0).unwrap();
    let measured1 = circuit.measure(q1).unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured0.expr()).unwrap(),
            |body| {
                body.x(q2)?;
                Ok(())
            },
        )
        .unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured1.expr()).unwrap(),
            |body| {
                body.z(q3)?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify both single-bit registers are declared
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "creg v1[1];",
            "h q[0];",
            "h q[1];",
            "measure q[0] -> v0[0];",
            "measure q[1] -> v1[0];",
            "if (v0 == 1) x q[2];",
            "if (v1 == 1) z q[3];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 4);
}

#[test]
fn test_dump_if_body_with_mcgate() {
    let mut circuit = Circuit::new(4);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);
    let q3 = Qubit::new(3);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured.expr()).unwrap(),
            |body| {
                body.append(
                    Instruction::McGate(Box::new(crate::circuit::gate::MCGate::new(
                        2,
                        StandardGate::X,
                    ))),
                    [q1, q2, q3],
                    std::iter::empty(),
                    None,
                )?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify if-body contains ccx
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "h q[0];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) ccx q[1],q[2],q[3];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 4);
}

#[test]
fn test_dump_if_body_with_parameterized_mcgate() {
    let mut circuit = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured.expr()).unwrap(),
            |body| {
                body.append(
                    Instruction::McGate(Box::new(crate::circuit::gate::MCGate::new(
                        1,
                        StandardGate::RX,
                    ))),
                    [q1, q2],
                    [crate::circuit::ParameterValue::from(0.5)],
                    None,
                )?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify if-body contains crx with parameter
    // Note: Using fixed parameter value 0.5 instead of symbolic theta
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "h q[0];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) crx(0.5) q[1],q[2];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 3);
}

#[test]
fn test_dump_if_body_with_custom_gate() {
    let mut sub_circ = Circuit::new(2);
    sub_circ.h(Qubit::new(0)).unwrap();
    sub_circ.cx(Qubit::new(0), Qubit::new(1)).unwrap();

    let mut circuit = Circuit::new(4);
    let q0 = Qubit::new(0);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    let custom_gate = sub_circ.to_gate("my_bell").unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured.expr()).unwrap(),
            |body| {
                body.append(
                    custom_gate,
                    [Qubit::new(1), Qubit::new(2)],
                    std::iter::empty(),
                    None,
                )?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Gate discovery must recurse into structured control-flow bodies.
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "gate my_bell q0,q1 {",
            "h q[0];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) my_bell q[1],q[2];",
        ],
    );
}

#[test]
fn test_dump_nested_control_flow_error() {
    let mut circuit = Circuit::new(2);
    let outer = circuit.measure(Qubit::new(0)).unwrap();
    let inner = circuit.measure(Qubit::new(1)).unwrap();
    circuit
        .if_(ClassicalExpr::bit_to_bool(outer.expr()).unwrap(), |body| {
            body.if_(ClassicalExpr::bit_to_bool(inner.expr())?, |inner_body| {
                inner_body.z(Qubit::new(1))?;
                Ok(())
            })?;
            Ok(())
        })
        .unwrap();

    assert!(matches!(
        dumps(&circuit),
        Err(QasmDumpError::UnsupportedClassicalControl(_))
    ));
}

#[test]
fn test_dump_empty_if_body() {
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    circuit
        .if_(ClassicalExpr::bit_to_bool(measured.expr()).unwrap(), |_| {
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    assert_qasm_contains_ordered(&qasm, &["creg v0[1];", "h q[0];", "measure q[0] -> v0[0];"]);
    assert!(
        !qasm.contains("if ("),
        "Empty body should not generate if statement"
    );
    verify_qasm_roundtrip(&qasm, 1);
}

#[test]
fn test_dump_multi_operation_if_body() {
    let mut circuit = Circuit::new(4);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);
    let q3 = Qubit::new(3);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured.expr()).unwrap(),
            |body| {
                body.x(q1)?;
                body.y(q2)?;
                body.z(q3)?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // All three operations should be guarded by if
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "creg v0[1];",
            "h q[0];",
            "measure q[0] -> v0[0];",
            "if (v0 == 1) x q[1];",
            "if (v0 == 1) y q[2];",
            "if (v0 == 1) z q[3];",
        ],
    );

    verify_qasm_roundtrip(&qasm, 4);
}

#[test]
fn test_dump_unsupported_mcgate_error() {
    let mut circuit = Circuit::new(4);
    circuit
        .append(
            Instruction::McGate(Box::new(crate::circuit::gate::MCGate::new(
                3,
                StandardGate::X,
            ))),
            [Qubit::new(0), Qubit::new(1), Qubit::new(2), Qubit::new(3)],
            std::iter::empty(),
            None,
        )
        .unwrap();

    let result = dumps(&circuit);
    assert!(result.is_err(), "Unsupported McGate should fail");

    match result.err().unwrap() {
        QasmDumpError::FormatError(msg) => {
            assert!(
                msg.contains("Unsupported"),
                "Error should mention unsupported: {}",
                msg
            );
        }
        other => panic!("Expected FormatError, got {:?}", other),
    }
}

#[test]
fn test_dump_delay_gate() {
    // Test delay gate output using ParameterValue
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);

    // Use circuit.delay() method with ParameterValue
    use crate::circuit::circuit_param::ParameterValue;
    circuit.delay(q0, ParameterValue::Fixed(100.0)).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify delay gate declaration and usage
    // Note: ParameterValue::Fixed wraps value in parentheses
    assert_qasm_contains_ordered(&qasm, &["opaque delay(t) q;", "delay((100)) q[0];"]);
}

#[test]
fn test_dump_gate_collision_different_interface() {
    // Test gate collision when interfaces differ
    let mut c1 = Circuit::new(1);
    c1.h(Qubit::new(0)).unwrap();
    let g1 = c1.to_gate("collision_gate").unwrap();

    // Different number of qubits
    let mut c2 = Circuit::new(2);
    c2.cx(Qubit::new(0), Qubit::new(1)).unwrap();
    let g2 = c2.to_gate("collision_gate").unwrap();

    let mut main = Circuit::new(2);
    main.append(g1, vec![Qubit::new(0)], vec![], None).unwrap();
    main.append(g2, vec![Qubit::new(0), Qubit::new(1)], vec![], None)
        .unwrap();

    assert!(matches!(
        dumps(&main),
        Err(QasmDumpError::ConflictingGateDefinition {
            name,
            existing_qubits: 1,
            existing_params: 0,
            conflicting_qubits: 2,
            conflicting_params: 0,
        }) if name == "collision_gate"
    ));
}

#[test]
fn test_dump_all_standard_gates() {
    // Test that all standard gates can be dumped
    let mut circuit = Circuit::new(3);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);
    let q2 = Qubit::new(2);

    // Single qubit gates
    circuit.i(q0).unwrap();
    circuit.x(q0).unwrap();
    circuit.y(q0).unwrap();
    circuit.z(q0).unwrap();
    circuit.h(q0).unwrap();
    circuit.s(q0).unwrap();
    circuit.sdg(q0).unwrap();
    circuit.t(q0).unwrap();
    circuit.tdg(q0).unwrap();
    circuit.rx(q0, 0.1).unwrap();
    circuit.ry(q0, 0.2).unwrap();
    circuit.rz(q0, 0.3).unwrap();

    // Two qubit gates
    circuit.cx(q0, q1).unwrap();
    circuit.cy(q0, q1).unwrap();
    circuit.cz(q0, q1).unwrap();
    circuit.swap(q0, q1).unwrap();

    // Three qubit gates
    circuit.ccx(q0, q1, q2).unwrap();

    // U gates
    circuit.u(q0, 0.1, 0.2, 0.3).unwrap();
    circuit.crz(q0, q1, 0.4).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify all gates are present
    let expected_gates = [
        "id q[0];",
        "x q[0];",
        "y q[0];",
        "z q[0];",
        "h q[0];",
        "s q[0];",
        "sdg q[0];",
        "t q[0];",
        "tdg q[0];",
        "rx(0.1) q[0];",
        "ry(0.2) q[0];",
        "rz(0.3) q[0];",
        "cx q[0],q[1];",
        "cy q[0],q[1];",
        "cz q[0],q[1];",
        "swap q[0],q[1];",
        "ccx q[0],q[1],q[2];",
        "u3(0.1,0.2,0.3) q[0];",
        "crz(0.4) q[0],q[1];",
    ];

    for gate in &expected_gates {
        assert!(
            qasm.contains(gate),
            "QASM should contain '{}',\ngot:\n{}",
            gate,
            qasm
        );
    }

    verify_qasm_roundtrip(&qasm, 3);
}

#[test]
fn test_dump_qelib1_cu1_without_redefinition_roundtrips() {
    let circuit = loads(
        r#"
        OPENQASM 2.0;
        include "qelib1.inc";
        qreg q[2];
        cu1(pi/2) q[0],q[1];
        "#,
    )
    .unwrap();

    let qasm = dumps(&circuit).unwrap();

    assert!(!qasm.contains("gate cu1"), "got:\n{qasm}");
    assert!(
        qasm.contains("cu1(1.5707963267948966) q[0],q[1];"),
        "got:\n{qasm}"
    );
    loads(&qasm).expect("dumped qelib1 cu1 call should reload");
}

#[test]
fn test_dump_fsim_gate_roundtrips_as_cqlib_extension() {
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    circuit.fsim(q0, q1, 0.1, 0.2).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    assert!(qasm.contains("fsim"), "QASM should contain fsim gate");
    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_xy_and_rxy_as_u3_decompositions() {
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);
    circuit.xy(q0, 0.5).unwrap();
    circuit.rxy(q0, 0.3, 0.4).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    assert_qasm_contains_ordered(
        &qasm,
        &[
            "// xy(0.5) q[0]",
            "u3(pi,0.5 - pi/2,-0.5 + pi/2) q[0];",
            "// rxy(0.3,0.4) q[0]",
            "u3(0.3,0.4 - pi/2,-0.4 + pi/2) q[0];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 1);
}

#[test]
fn test_dump_conditional_rxy_as_u3_decomposition() {
    let mut circuit = Circuit::new(2);
    let measured = circuit.measure(Qubit::new(0)).unwrap();
    let condition = ClassicalExpr::bit_to_bool(measured.expr()).unwrap();
    circuit
        .if_(condition, |body| {
            body.rxy(Qubit::new(1), 0.3, 0.4)?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "measure q[0] -> v0[0];",
            "if (v0 == 1) u3(0.3,0.4 - pi/2,-0.4 + pi/2) q[1];",
        ],
    );
    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_x2p_x2m_y2p_y2m() {
    // Test X2P, X2M, Y2P, Y2M gates (decomposed to rx/ry)
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);

    circuit.x2p(q0).unwrap();
    circuit.x2m(q0).unwrap();
    circuit.y2p(q0).unwrap();
    circuit.y2m(q0).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify decomposed gates
    // Note: Comments don't have trailing semicolons in output
    assert_qasm_contains_ordered(
        &qasm,
        &[
            "// x2p q[0]",
            "rx(pi/2) q[0]",
            "// x2m q[0]",
            "rx(-pi/2) q[0]",
            "// y2p q[0]",
            "ry(pi/2) q[0]",
            "// y2m q[0]",
            "ry(-pi/2) q[0]",
        ],
    );
}

#[test]
fn test_dump_phase_gate_outputs_u1() {
    let mut circuit = Circuit::new(1);
    let q0 = Qubit::new(0);

    circuit.phase(q0, 0.5).unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Phase gate outputs as u1 in OpenQASM 2.0
    assert!(
        qasm.contains("u1(0.5)"),
        "Phase gate should output as u1: {}",
        qasm
    );
}

#[test]
fn test_dump_gphase_outputs_lossy_comment() {
    let mut circuit = Circuit::new(1);
    circuit
        .append(
            Instruction::Standard(StandardGate::GPhase),
            Vec::<Qubit>::new(),
            vec![0.5.into()],
            None,
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    assert!(qasm.contains("// gphase(0.5)"), "got:\n{qasm}");

    let parsed = loads(&qasm).expect("Generated QASM should still parse");
    assert_eq!(parsed.global_phase().evaluate(&None).unwrap(), 0.0);
}

#[test]
fn test_dump_global_phase_outputs_lossy_comment() {
    let mut circuit = Circuit::new(1);
    circuit.set_global_phase(Parameter::from(0.25));

    let qasm = dumps(&circuit).expect("Dump failed");
    assert!(qasm.contains("// Global Phase: 0.25"), "got:\n{qasm}");

    let parsed = loads(&qasm).expect("Generated QASM should still parse");
    assert_eq!(parsed.global_phase().evaluate(&None).unwrap(), 0.0);
}

#[test]
fn test_dump_file_io_error_preserves_source() {
    let circuit = Circuit::new(0);
    let path = std::env::temp_dir()
        .join("cqlib_qasm2_missing_parent_for_io_source")
        .join("out.qasm");
    let error = dump(&circuit, path).unwrap_err();

    assert!(matches!(error, QasmDumpError::IoError(_)));
    assert!(std::error::Error::source(&error).is_some());
}

#[test]
fn test_dump_condition_value_zero() {
    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();
    let condition =
        ClassicalExpr::try_not(ClassicalExpr::bit_to_bool(measured.expr()).unwrap()).unwrap();
    circuit
        .if_(condition, |body| {
            body.x(q1)?;
            Ok(())
        })
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");

    // Verify condition value 0
    assert!(
        qasm.contains("if (v0 == 0)"),
        "Should have condition with value 0: {}",
        qasm
    );

    verify_qasm_roundtrip(&qasm, 2);
}

#[test]
fn test_dump_qasm_ordering() {
    // Test that QASM output follows correct ordering:
    // 1. Header
    // 2. QReg/CReg declarations
    // 3. Gate definitions
    // 4. Main circuit operations

    let mut sub_circ = Circuit::new(1);
    sub_circ.h(Qubit::new(0)).unwrap();
    let custom_gate = sub_circ.to_gate("my_h").unwrap();

    let mut circuit = Circuit::new(2);
    let q0 = Qubit::new(0);
    let q1 = Qubit::new(1);

    circuit.h(q0).unwrap();
    let measured = circuit.measure(q0).unwrap();

    // Use custom gate
    circuit.append(custom_gate, vec![q1], vec![], None).unwrap();

    circuit
        .if_(
            ClassicalExpr::bit_to_bool(measured.expr()).unwrap(),
            |body| {
                body.x(q1)?;
                Ok(())
            },
        )
        .unwrap();

    let qasm = dumps(&circuit).expect("Dump failed");
    let lines: Vec<_> = qasm
        .lines()
        .map(|l| l.trim())
        .filter(|l| !l.is_empty())
        .collect();

    // Find positions of key elements
    let header_pos = lines.iter().position(|l| l.contains("OPENQASM")).unwrap();
    let qreg_pos = lines.iter().position(|l| l.starts_with("qreg")).unwrap();
    let creg_pos = lines.iter().position(|l| l.starts_with("creg")).unwrap();
    let gate_def_pos = lines.iter().position(|l| l.starts_with("gate ")).unwrap();
    let h_pos = lines.iter().position(|l| *l == "h q[0];").unwrap();
    let measure_pos = lines.iter().position(|l| l.contains("measure")).unwrap();
    let if_pos = lines.iter().position(|l| l.contains("if (")).unwrap();

    // Verify ordering
    assert!(header_pos < qreg_pos, "Header before qreg");
    assert!(qreg_pos < creg_pos, "Qreg before creg");
    assert!(creg_pos < gate_def_pos, "Creg before gate definitions");
    assert!(gate_def_pos < h_pos, "Gate definitions before operations");
    assert!(h_pos < measure_pos, "H before measure");
    assert!(measure_pos < if_pos, "Measure before if");
}

#[test]
fn parameter_errors_propagate_from_gate_export_with_context() {
    use crate::circuit::{CircuitParam, ParameterValue};
    use std::collections::HashMap;

    let mut circuit = Circuit::new(1);
    let qubit = Qubit::new(0);
    let qubit_map = HashMap::from([(qubit, "q[0]".to_string())]);
    // RX uses general formatting; RXY uses the QASM2 special expansion path.
    for (gate, params) in [
        (StandardGate::RX, vec![ParameterValue::Fixed(0.5)]),
        (
            StandardGate::RXY,
            vec![ParameterValue::Fixed(0.5), ParameterValue::Fixed(0.25)],
        ),
    ] {
        circuit
            .append(Instruction::Standard(gate), [qubit], params, None)
            .unwrap();
        let valid = circuit.operations().last().unwrap();
        let param_index = valid.params.len() - 1;
        for param in [
            CircuitParam::Index(99),
            CircuitParam::Fixed(f64::NAN),
            CircuitParam::Fixed(f64::INFINITY),
            CircuitParam::Fixed(f64::NEG_INFINITY),
        ] {
            let mut operation = valid.clone();
            operation.params[param_index] = param;
            let mut output = String::new();
            let error = super::dump_standard_gate(
                &gate,
                &operation,
                &circuit,
                &mut output,
                &qubit_map,
                &HashMap::new(),
            )
            .unwrap_err();
            assert!(
                matches!(error, QasmDumpError::FormatError(ref message)
                if message.contains(&format!("parameter {param_index}"))
                    && message.contains(&format!("{gate:?}"))),
                "{error}"
            );
            let error = super::operation_to_qasm(&operation, &circuit, &qubit_map, &HashMap::new())
                .unwrap_err();
            assert!(matches!(error, QasmDumpError::FormatError(_)));
        }
    }
}

#[test]
fn export_preserves_indexed_constants_and_symbol_substitution() {
    use crate::circuit::ParameterValue;
    use std::collections::HashMap;

    let mut circuit = Circuit::new(1);
    circuit
        .rx(Qubit::new(0), ParameterValue::Param(Parameter::pi()))
        .unwrap();
    circuit
        .rx(
            Qubit::new(0),
            ParameterValue::Param(Parameter::symbol("theta")),
        )
        .unwrap();
    let qasm = dumps(&circuit).unwrap();
    assert!(qasm.contains("rx(pi)"), "{qasm}");
    let replacements = HashMap::from([("theta".to_string(), Parameter::symbol("angle0"))]);
    assert_eq!(
        super::format_params(&circuit.operations()[1], &circuit, &replacements).unwrap(),
        "(angle0)"
    );
}