"""
Cirq Compiler for BioQL

This module provides compilation of BioQL IR to Cirq quantum circuits.
"""

import datetime
import random
from typing import Any, Dict, List, Optional, Union

from loguru import logger

from bioql.ir import (
    AlignmentOperation,
    BioQLProgram,
    BioQLResult,
    DockingOperation,
    QuantumBackend,
    QuantumOptimizationOperation,
)
from .base import BaseCompiler, CompilationError, QuantumCircuitInterface

# Try to import Cirq with graceful fallback
try:
    import cirq
    CIRQ_AVAILABLE = True
except ImportError:
    logger.warning("Cirq not available, using mock implementation")
    CIRQ_AVAILABLE = False
    cirq = None


class CirqCircuitWrapper(QuantumCircuitInterface):
    """Wrapper for Cirq Circuit to implement our interface."""

    def __init__(self, num_qubits: int):
        if not CIRQ_AVAILABLE:
            raise CompilationError("Cirq not available")

        self.num_qubits = num_qubits
        self.qubits = [cirq.LineQubit(i) for i in range(num_qubits)]
        self.circuit = cirq.Circuit()
        self.measurements_added = set()

    def add_hadamard(self, qubit: int) -> None:
        self.circuit.append(cirq.H(self.qubits[qubit]))

    def add_pauli_x(self, qubit: int) -> None:
        self.circuit.append(cirq.X(self.qubits[qubit]))

    def add_pauli_y(self, qubit: int) -> None:
        self.circuit.append(cirq.Y(self.qubits[qubit]))

    def add_pauli_z(self, qubit: int) -> None:
        self.circuit.append(cirq.Z(self.qubits[qubit]))

    def add_cnot(self, control: int, target: int) -> None:
        self.circuit.append(cirq.CNOT(self.qubits[control], self.qubits[target]))

    def add_rotation_x(self, qubit: int, angle: float) -> None:
        self.circuit.append(cirq.rx(angle)(self.qubits[qubit]))

    def add_rotation_y(self, qubit: int, angle: float) -> None:
        self.circuit.append(cirq.ry(angle)(self.qubits[qubit]))

    def add_rotation_z(self, qubit: int, angle: float) -> None:
        self.circuit.append(cirq.rz(angle)(self.qubits[qubit]))

    def add_measurement(self, qubit: int, classical_bit: int) -> None:
        if qubit not in self.measurements_added:
            self.circuit.append(cirq.measure(self.qubits[qubit], key=f'q{qubit}'))
            self.measurements_added.add(qubit)

    def get_depth(self) -> int:
        return len(self.circuit)

    def get_gate_count(self) -> int:
        return len(list(self.circuit.all_operations()))

    def to_qasm(self) -> str:
        """Convert Cirq circuit to OpenQASM (simplified)."""
        qasm_lines = [
            "OPENQASM 2.0;",
            'include "qelib1.inc";',
            f"qreg q[{self.num_qubits}];",
            f"creg c[{len(self.measurements_added)}];"
        ]

        gate_count = 0
        for moment in self.circuit:
            for operation in moment:
                if isinstance(operation.gate, cirq.H):
                    qubit_idx = self.qubits.index(operation.qubits[0])
                    qasm_lines.append(f"h q[{qubit_idx}];")
                elif isinstance(operation.gate, cirq.X):
                    qubit_idx = self.qubits.index(operation.qubits[0])
                    qasm_lines.append(f"x q[{qubit_idx}];")
                elif isinstance(operation.gate, cirq.Y):
                    qubit_idx = self.qubits.index(operation.qubits[0])
                    qasm_lines.append(f"y q[{qubit_idx}];")
                elif isinstance(operation.gate, cirq.Z):
                    qubit_idx = self.qubits.index(operation.qubits[0])
                    qasm_lines.append(f"z q[{qubit_idx}];")
                elif isinstance(operation.gate, cirq.CNOT):
                    control_idx = self.qubits.index(operation.qubits[0])
                    target_idx = self.qubits.index(operation.qubits[1])
                    qasm_lines.append(f"cx q[{control_idx}],q[{target_idx}];")
                # Add other gates as needed
                gate_count += 1

        # Add measurements
        for i, qubit in enumerate(self.measurements_added):
            qasm_lines.append(f"measure q[{qubit}] -> c[{i}];")

        return "\n".join(qasm_lines)

    def get_cirq_circuit(self) -> "cirq.Circuit":
        """Get the underlying Cirq circuit."""
        return self.circuit


class CirqCompiler(BaseCompiler):
    """Cirq-specific compiler for BioQL programs."""

    def __init__(self):
        super().__init__(QuantumBackend.CIRQ)
        if not CIRQ_AVAILABLE:
            logger.warning("Cirq not available, some features will be limited")

    def compile_program(self, program: BioQLProgram) -> Union[Any, Dict[str, Any]]:
        """
        Compile a BioQL program into a Cirq Circuit.

        Args:
            program: BioQL program to compile

        Returns:
            Compiled Cirq Circuit or mock representation

        Raises:
            CompilationError: If compilation fails
        """
        try:
            self.logger.info(f"Compiling program {program.name} for Cirq")

            # Estimate number of qubits needed
            num_qubits = self._estimate_qubits_needed(program)
            self.logger.debug(f"Using {num_qubits} qubits")

            if CIRQ_AVAILABLE:
                # Create Cirq circuit wrapper
                circuit_wrapper = CirqCircuitWrapper(num_qubits)
            else:
                # Use mock implementation
                from .base import MockQuantumCircuit
                circuit_wrapper = MockQuantumCircuit(num_qubits)

            # Compile each operation
            for i, operation in enumerate(program.operations):
                self.logger.debug(f"Compiling operation {i}: {operation.operation_type}")

                if isinstance(operation, DockingOperation):
                    self._compile_docking_operation(operation, circuit_wrapper)
                elif isinstance(operation, AlignmentOperation):
                    self._compile_alignment_operation(operation, circuit_wrapper)
                elif isinstance(operation, QuantumOptimizationOperation):
                    self._compile_optimization_operation(operation, circuit_wrapper)
                else:
                    raise CompilationError(f"Unsupported operation type: {type(operation)}")

            # Add measurements for all qubits
            for i in range(num_qubits):
                circuit_wrapper.add_measurement(i, i)

            if CIRQ_AVAILABLE and isinstance(circuit_wrapper, CirqCircuitWrapper):
                compiled_circuit = circuit_wrapper.get_cirq_circuit()
                self.logger.success(f"Compiled circuit: {len(compiled_circuit)} moments, {circuit_wrapper.get_gate_count()} gates")
                return compiled_circuit
            else:
                # Return mock representation
                return {
                    "type": "mock_cirq_circuit",
                    "num_qubits": num_qubits,
                    "gates": getattr(circuit_wrapper, 'gates', []),
                    "measurements": getattr(circuit_wrapper, 'measurements', [])
                }

        except Exception as e:
            self.logger.error(f"Compilation failed: {e}")
            raise CompilationError(f"Failed to compile program: {e}")

    def execute(self, compiled_program: Union[Any, Dict[str, Any]], shots: int = 1000, program_id: Optional[str] = None) -> BioQLResult:
        """
        Execute a compiled Cirq program.

        Args:
            compiled_program: Compiled program (Cirq Circuit or mock)
            shots: Number of shots

        Returns:
            Execution results
        """
        start_time = datetime.datetime.utcnow()

        try:
            if CIRQ_AVAILABLE and hasattr(compiled_program, 'all_operations'):
                # Execute on Cirq
                result = self._execute_cirq_circuit(compiled_program, shots)
            else:
                # Mock execution
                result = self._execute_mock_circuit(compiled_program, shots)

            execution_time = (datetime.datetime.utcnow() - start_time).total_seconds()

            from uuid import uuid4
            return BioQLResult(
                program_id=program_id or uuid4(),
                status="success",
                results=result,
                execution_time=execution_time,
                shots_executed=shots,
                backend_used=QuantumBackend.CIRQ,
                execution_timestamp=start_time.isoformat(),
                version_info={"cirq": "simulated" if not CIRQ_AVAILABLE else "real"}
            )

        except Exception as e:
            execution_time = (datetime.datetime.utcnow() - start_time).total_seconds()
            self.logger.error(f"Execution failed: {e}")

            from uuid import uuid4
            return BioQLResult(
                program_id=program_id or uuid4(),
                status="failed",
                error_message=str(e),
                error_type=type(e).__name__,
                execution_time=execution_time,
                backend_used=QuantumBackend.CIRQ,
                execution_timestamp=start_time.isoformat()
            )

    def _execute_cirq_circuit(self, circuit: Any, shots: int) -> Dict[str, Any]:
        """Execute a Cirq circuit."""
        # Use Cirq simulator
        simulator = cirq.Simulator()

        # Run the circuit
        result = simulator.run(circuit, repetitions=shots)

        # Process results
        counts = {}
        measurements = result.measurements

        # Convert measurement results to count dictionary
        if measurements:
            # Get all measurement keys
            keys = sorted(measurements.keys())
            for i in range(shots):
                bit_string = ''.join(str(measurements[key][i][0]) for key in keys)
                counts[bit_string] = counts.get(bit_string, 0) + 1

        return {
            "counts": counts,
            "circuit_depth": len(circuit),
            "gate_count": len(list(circuit.all_operations())),
            "shots_requested": shots,
            "shots_executed": shots
        }

    def _execute_mock_circuit(self, circuit_data: Dict[str, Any], shots: int) -> Dict[str, Any]:
        """Execute a mock circuit (for when Cirq is not available)."""
        num_qubits = circuit_data.get("num_qubits", 4)

        # Generate mock results
        counts = {}
        for _ in range(shots):
            # Generate random bit string
            bit_string = ''.join(str(random.randint(0, 1)) for _ in range(num_qubits))
            counts[bit_string] = counts.get(bit_string, 0) + 1

        return {
            "counts": counts,
            "circuit_depth": len(circuit_data.get("gates", [])),
            "gate_count": len(circuit_data.get("gates", [])),
            "shots_requested": shots,
            "shots_executed": shots,
            "note": "Mock execution (Cirq not available)"
        }

    def _compile_docking_operation(
        self,
        operation: DockingOperation,
        circuit: QuantumCircuitInterface
    ) -> None:
        """Compile a docking operation into quantum gates."""
        self.logger.debug("Compiling docking operation for Cirq")

        # Encode receptor molecule (qubits 0-3)
        self._create_molecular_encoding_circuit(
            circuit, operation.receptor.data, 0, 4
        )

        # Encode ligand molecule (qubits 4-7)
        self._create_molecular_encoding_circuit(
            circuit, operation.ligand.data, 4, 4
        )

        # Create entanglement for docking interaction
        self._create_entangling_layer(circuit, list(range(8)))

        # Add variational circuit for pose optimization
        # Cirq-style parameterized circuit
        parameters = [
            operation.energy_threshold / 10.0,
            operation.num_poses / 100.0,
            1.5708,  # π/2
            0.7854   # π/4
        ]
        self._create_variational_layer(circuit, list(range(8)), parameters)

        # Add some Cirq-specific optimization
        self._add_cirq_specific_gates(circuit, list(range(8)))

    def _compile_alignment_operation(
        self,
        operation: AlignmentOperation,
        circuit: QuantumCircuitInterface
    ) -> None:
        """Compile an alignment operation into quantum gates."""
        self.logger.debug("Compiling alignment operation for Cirq")

        # Encode sequences
        seq1_data = operation.sequences[0].data[:20]
        seq2_data = operation.sequences[1].data[:20]

        self._create_molecular_encoding_circuit(circuit, seq1_data, 0, 4)
        self._create_molecular_encoding_circuit(circuit, seq2_data, 4, 4)

        # Quantum alignment circuit with Cirq-specific optimizations
        for i in range(4):
            circuit.add_cnot(i, i + 4)

        # Add scoring based on alignment parameters
        match_angle = operation.match_score * 3.14159 / 10
        gap_angle = abs(operation.gap_penalty) * 3.14159 / 10

        for i in range(8):
            circuit.add_rotation_y(i, match_angle)
            circuit.add_rotation_z(i, gap_angle)

        self._add_cirq_specific_gates(circuit, list(range(8)))

    def _compile_optimization_operation(
        self,
        operation: QuantumOptimizationOperation,
        circuit: QuantumCircuitInterface
    ) -> None:
        """Compile an optimization operation into quantum gates."""
        self.logger.debug("Compiling optimization operation for Cirq")

        num_vars = len(operation.variables)
        qubits_per_var = max(1, 8 // max(1, num_vars))

        # Encode optimization variables
        for i, variable in enumerate(operation.variables):
            start_qubit = i * qubits_per_var
            end_qubit = min(start_qubit + qubits_per_var, 8)

            # Initialize superposition
            for q in range(start_qubit, end_qubit):
                circuit.add_hadamard(q)

            # Variable-specific encoding
            if hasattr(variable.value, '__float__'):
                angle = float(variable.value) * 3.14159 / 100
                for q in range(start_qubit, end_qubit):
                    circuit.add_rotation_y(q, angle)

        # QAOA-inspired circuit for Cirq
        self._create_qaoa_layer(circuit, list(range(8)))
        self._add_cirq_specific_gates(circuit, list(range(8)))

    def _add_cirq_specific_gates(self, circuit: QuantumCircuitInterface, qubits: List[int]) -> None:
        """Add Cirq-specific optimizations and gates."""
        # Add some phase gates for better optimization
        for i in range(0, len(qubits), 2):
            if i + 1 < len(qubits):
                # Controlled-Z gates (natural in Cirq)
                circuit.add_cnot(qubits[i], qubits[i + 1])
                circuit.add_pauli_z(qubits[i + 1])
                circuit.add_cnot(qubits[i], qubits[i + 1])

    def _create_qaoa_layer(self, circuit: QuantumCircuitInterface, qubits: List[int]) -> None:
        """Create a QAOA-style layer optimized for Cirq."""
        # Cost layer
        for i in range(0, len(qubits) - 1, 2):
            circuit.add_cnot(qubits[i], qubits[i + 1])
            circuit.add_rotation_z(qubits[i + 1], 3.14159 / 4)
            circuit.add_cnot(qubits[i], qubits[i + 1])

        # Mixer layer
        for qubit in qubits:
            circuit.add_rotation_x(qubit, 3.14159 / 3)


# Export main class
__all__ = ["CirqCompiler", "CirqCircuitWrapper"]