"""
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

from loguru import logger

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"]