"""
Qiskit Compiler for BioQL

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

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

# Optional loguru import
try:
    from loguru import logger
except ImportError:
    import logging
    logger = logging.getLogger(__name__)

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

# Import Qiskit components (required for production)
from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister
from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager
from qiskit.circuit.library import RealAmplitudes, TwoLocal
from qiskit_aer import AerSimulator

QISKIT_AVAILABLE = True


class QiskitCircuitWrapper(QuantumCircuitInterface):
    """Wrapper for Qiskit QuantumCircuit to implement our interface."""

    def __init__(self, num_qubits: int):
        self.num_qubits = num_qubits
        self.qreg = QuantumRegister(num_qubits, 'q')
        self.creg = ClassicalRegister(num_qubits, 'c')
        self.circuit = QuantumCircuit(self.qreg, self.creg)

    def add_hadamard(self, qubit: int) -> None:
        self.circuit.h(qubit)

    def add_pauli_x(self, qubit: int) -> None:
        self.circuit.x(qubit)

    def add_pauli_y(self, qubit: int) -> None:
        self.circuit.y(qubit)

    def add_pauli_z(self, qubit: int) -> None:
        self.circuit.z(qubit)

    def add_cnot(self, control: int, target: int) -> None:
        self.circuit.cx(control, target)

    def add_rotation_x(self, qubit: int, angle: float) -> None:
        self.circuit.rx(angle, qubit)

    def add_rotation_y(self, qubit: int, angle: float) -> None:
        self.circuit.ry(angle, qubit)

    def add_rotation_z(self, qubit: int, angle: float) -> None:
        self.circuit.rz(angle, qubit)

    def add_measurement(self, qubit: int, classical_bit: int) -> None:
        self.circuit.measure(qubit, classical_bit)

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

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

    def to_qasm(self) -> str:
        return self.circuit.qasm()

    def get_qiskit_circuit(self) -> "QuantumCircuit":
        """Get the underlying Qiskit circuit."""
        return self.circuit


class QiskitCompiler(BaseCompiler):
    """Qiskit-specific compiler for BioQL programs."""

    def __init__(self):
        super().__init__(QuantumBackend.QISKIT)

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

        Args:
            program: BioQL program to compile

        Returns:
            Compiled Qiskit QuantumCircuit or mock representation

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

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

            # Create Qiskit circuit wrapper
            circuit_wrapper = QiskitCircuitWrapper(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)

            compiled_circuit = circuit_wrapper.get_qiskit_circuit()
            self.logger.success(f"Compiled circuit: {compiled_circuit.depth()} depth, {len(compiled_circuit.data)} gates")
            return compiled_circuit

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

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

        Args:
            compiled_program: Compiled QuantumCircuit
            shots: Number of shots

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

        try:
            # Execute on Qiskit
            result = self._execute_qiskit_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.QISKIT,
                execution_timestamp=start_time.isoformat(),
                version_info={"qiskit": "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.QISKIT,
                execution_timestamp=start_time.isoformat()
            )

    def _execute_qiskit_circuit(self, circuit: QuantumCircuit, shots: int) -> Dict[str, Any]:
        """Execute a Qiskit circuit."""
        # Use local simulator
        simulator = AerSimulator()

        # Transpile circuit for simulator
        pass_manager = generate_preset_pass_manager(1, simulator)
        transpiled_circuit = pass_manager.run(circuit)

        # Run the circuit
        job = simulator.run(transpiled_circuit, shots=shots)
        result = job.result()
        counts = result.get_counts()

        return {
            "counts": counts,
            "circuit_depth": transpiled_circuit.depth(),
            "gate_count": len(transpiled_circuit.data),
            "shots_requested": shots,
            "shots_executed": shots
        }


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

        # 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 between receptor and ligand
        self._create_entangling_layer(circuit, list(range(8)))

        # Add variational layer for pose optimization
        # Use energy threshold and number of poses as parameters
        parameters = [
            operation.energy_threshold / 10.0,  # Normalize to reasonable range
            operation.num_poses / 100.0,
            3.14159 / 4,  # Some default parameters
            3.14159 / 2
        ]
        self._create_variational_layer(circuit, list(range(8)), parameters)

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

        # Encode first sequence (qubits 0-3)
        seq1_data = operation.sequences[0].data[:20]  # Truncate for encoding
        self._create_molecular_encoding_circuit(circuit, seq1_data, 0, 4)

        # Encode second sequence (qubits 4-7)
        seq2_data = operation.sequences[1].data[:20]  # Truncate for encoding
        self._create_molecular_encoding_circuit(circuit, seq2_data, 4, 4)

        # Create quantum alignment circuit
        # This is a simplified version - real quantum sequence alignment
        # would be much more complex
        for i in range(4):
            circuit.add_cnot(i, i + 4)  # Compare corresponding positions

        # Add penalty-based optimization
        penalty_angle = abs(operation.gap_penalty) * 3.14159 / 10
        for i in range(8):
            circuit.add_rotation_z(i, penalty_angle)

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

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

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

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

            # Add variable-specific rotation
            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)

        # Create QAOA-like structure
        # Cost layer
        for i in range(0, 8, 2):
            if i + 1 < 8:
                circuit.add_cnot(i, i + 1)
                circuit.add_rotation_z(i + 1, 3.14159 / 4)
                circuit.add_cnot(i, i + 1)

        # Mixer layer
        for i in range(8):
            circuit.add_rotation_x(i, 3.14159 / 2)


# Export main class
__all__ = ["QiskitCompiler", "QiskitCircuitWrapper"]