"""
DiracHash - A simple quantum-resistant hash function.

This module provides a pure Python implementation of DiracHash
without any dependencies on Numba or complex libraries.
"""

import hashlib
import struct
import os
import binascii

class DiracHash:
    """
    DiracHash implements quantum-resistant hash functions in pure Python.
    
    This version is simplified and focuses on reliability rather than
    maximum performance.
    """
    
    # Constants for the hash function
    PRIME1 = 0x9E3779B1
    PRIME2 = 0x85EBCA77
    PRIME3 = 0xC2B2AE3D
    PRIME4 = 0x27D4EB2F
    
    # Supported algorithms
    ALGORITHMS = ['standard', 'improved', 'grover', 'shor']
    
    @staticmethod
    def _mix(a, b, c):
        """Basic mixing function for the hash"""
        a = (a - c) & 0xFFFFFFFF
        a ^= DiracHash._rotate_right(b, 13)
        b = (b - c) & 0xFFFFFFFF
        b ^= DiracHash._rotate_left(a, 8)
        c = (c - a) & 0xFFFFFFFF
        c ^= DiracHash._rotate_right(b, 13)
        a = (a - b) & 0xFFFFFFFF
        a ^= DiracHash._rotate_right(c, 12)
        b = (b - c) & 0xFFFFFFFF
        b ^= DiracHash._rotate_left(a, 16)
        c = (c - a) & 0xFFFFFFFF
        c ^= DiracHash._rotate_right(b, 5)
        a = (a - b) & 0xFFFFFFFF
        a ^= DiracHash._rotate_right(c, 3)
        b = (b - c) & 0xFFFFFFFF
        b ^= DiracHash._rotate_left(a, 10)
        c = (c - a) & 0xFFFFFFFF
        c ^= DiracHash._rotate_right(b, 15)
        return a, b, c
    
    @staticmethod
    def _rotate_left(x, n):
        """Rotate left operation"""
        return ((x << n) | (x >> (32 - n))) & 0xFFFFFFFF
    
    @staticmethod
    def _rotate_right(x, n):
        """Rotate right operation"""
        return ((x >> n) | (x << (32 - n))) & 0xFFFFFFFF
    
    @staticmethod
    def _improved_mix(a, b, c, d):
        """Improved mixing function with 4 state variables"""
        a = (a + b) & 0xFFFFFFFF
        d = DiracHash._rotate_right(d ^ a, 16)
        c = (c + d) & 0xFFFFFFFF
        b = DiracHash._rotate_right(b ^ c, 12)
        a = (a + b) & 0xFFFFFFFF
        d = DiracHash._rotate_right(d ^ a, 8)
        c = (c + d) & 0xFFFFFFFF
        b = DiracHash._rotate_right(b ^ c, 7)
        return a, b, c, d
    
    @staticmethod
    def _merkle_damgard_finalize(hash_blocks, length, digest_size):
        """Finalize a hash using a Merkle-Damgård construction"""
        # Add the length as the final block
        hash_blocks.append(length & 0xFFFFFFFF)
        hash_blocks.append((length >> 32) & 0xFFFFFFFF)
        
        # Initialize state
        state = [
            DiracHash.PRIME1,
            DiracHash.PRIME2,
            DiracHash.PRIME3,
            DiracHash.PRIME4
        ]
        
        # Process all blocks
        for i in range(0, len(hash_blocks), 4):
            a, b, c, d = state
            chunk = hash_blocks[i:i+4]
            # Pad with zeros if needed
            chunk.extend([0] * (4 - len(chunk)))
            
            a ^= chunk[0]
            b ^= chunk[1]
            c ^= chunk[2]
            d ^= chunk[3]
            
            a, b, c, d = DiracHash._improved_mix(a, b, c, d)
            a, b, c, d = DiracHash._improved_mix(a, b, c, d)
            
            state[0] = (state[0] ^ a) & 0xFFFFFFFF
            state[1] = (state[1] ^ b) & 0xFFFFFFFF
            state[2] = (state[2] ^ c) & 0xFFFFFFFF
            state[3] = (state[3] ^ d) & 0xFFFFFFFF
        
        # Convert state to bytes
        result = bytearray()
        for s in state:
            result.extend(struct.pack("<I", s))
        
        # If we need more bytes, use a counter mode construction
        if digest_size > len(result):
            original_result = bytes(result)
            counter = 1
            while len(result) < digest_size:
                # Hash the original result with a counter
                counter_bytes = struct.pack("<I", counter)
                additional = hashlib.sha256(original_result + counter_bytes).digest()
                result.extend(additional)
                counter += 1
                
        # Truncate or return the exact size needed
        return bytes(result[:digest_size])
    
    @classmethod
    def standard_hash(cls, data, digest_size=32):
        """Standard DiracHash algorithm"""
        # Convert to bytes if it's a string
        if isinstance(data, str):
            data = data.encode('utf-8')
            
        # Process the data in 4-byte blocks
        blocks = []
        for i in range(0, len(data), 4):
            chunk = data[i:min(i+4, len(data))]
            # Pad with zeros if needed
            if len(chunk) < 4:
                chunk = chunk + b'\x00' * (4 - len(chunk))
            blocks.append(struct.unpack("<I", chunk)[0])
            
        # Finalize
        return cls._merkle_damgard_finalize(blocks, len(data), digest_size)
    
    @classmethod
    def improved_hash(cls, data, digest_size=32):
        """Improved DiracHash with better diffusion"""
        # Convert to bytes if it's a string
        if isinstance(data, str):
            data = data.encode('utf-8')
            
        # Add a salt derived from the data length for extra entropy
        salt = (len(data) * cls.PRIME1) & 0xFFFFFFFF
        salted_data = struct.pack("<I", salt) + data
        
        # Use standard hash but with the salted data
        return cls.standard_hash(salted_data, digest_size)
    
    @classmethod
    def grover_hash(cls, data, digest_size=32):
        """Grover-resistant variant with additional rounds"""
        # Convert to bytes if it's a string
        if isinstance(data, str):
            data = data.encode('utf-8')
            
        # First, get a preliminary hash
        prelim_hash = cls.improved_hash(data, digest_size)
        
        # Then hash it again with a different salt derived from the original data
        salt = hashlib.sha256(data).digest()[:4]
        return cls.improved_hash(salt + prelim_hash, digest_size)
    
    @classmethod
    def shor_hash(cls, data, digest_size=32):
        """
        Shor-resistant variant that uses a hybrid approach
        combining multiple hash functions.
        """
        # Convert to bytes if it's a string
        if isinstance(data, str):
            data = data.encode('utf-8')
            
        # Use a combination of hashing methods
        hash1 = cls.improved_hash(data, digest_size)
        hash2 = hashlib.sha256(data).digest()[:digest_size]
        
        # XOR the results
        result = bytearray(digest_size)
        for i in range(digest_size):
            result[i] = hash1[i] ^ hash2[i]
            
        return bytes(result)
    
    @classmethod
    def hash(cls, data, algorithm='standard', digest_size=32):
        """
        Compute a hash using the specified algorithm.
        
        Args:
            data: The input data (bytes or string)
            algorithm: The hash algorithm to use
            digest_size: The desired size of the output digest
            
        Returns:
            bytes: The computed hash
        """
        algorithm = algorithm.lower()
        
        if algorithm == 'standard':
            return cls.standard_hash(data, digest_size)
        elif algorithm == 'improved':
            return cls.improved_hash(data, digest_size)
        elif algorithm == 'grover':
            return cls.grover_hash(data, digest_size)
        elif algorithm == 'shor':
            return cls.shor_hash(data, digest_size)
        else:
            raise ValueError(f"Unknown algorithm: {algorithm}. " +
                             f"Supported algorithms: {cls.ALGORITHMS}")
    
    @classmethod
    def get_supported_algorithms(cls):
        """Return a list of supported algorithms"""
        return cls.ALGORITHMS 