#!/usr/bin/env python3
from itertools import chain

from osaca import utils
from osaca.parser import AttrDict, ParserAArch64, ParserX86ATT

from .hw_model import MachineModel


class INSTR_FLAGS:
    """
    Flags used for unknown or special instructions
    """

    LD = 'is_load_instruction'
    TP_UNKWN = 'tp_unknown'
    LT_UNKWN = 'lt_unknown'
    NOT_BOUND = 'not_bound'
    HIDDEN_LD = 'hidden_load'
    HAS_LD = 'performs_load'
    HAS_ST = 'performs_store'


class ISASemantics(object):
    GAS_SUFFIXES = 'bswlqt'

    def __init__(self, isa, path_to_yaml=None):
        self._isa = isa.lower()
        path = path_to_yaml or utils.find_datafile('isa/' + self._isa + '.yml')
        self._isa_model = MachineModel(path_to_yaml=path)
        if self._isa == 'x86':
            self._parser = ParserX86ATT()
        elif self._isa == 'aarch64':
            self._parser = ParserAArch64()

    def process(self, instruction_forms):
        """Process a list of instruction forms."""
        for i in instruction_forms:
            self.assign_src_dst(i)

    # get ;parser result and assign operands to
    # - source
    # - destination
    # - source/destination
    def assign_src_dst(self, instruction_form):
        """Update instruction form dictionary with source, destination and flag information."""
        # if the instruction form doesn't have operands or is None, there's nothing to do
        if instruction_form['operands'] is None or instruction_form['instruction'] is None:
            instruction_form['semantic_operands'] = AttrDict(
                {'source': [], 'destination': [], 'src_dst': []}
            )
            return
        # check if instruction form is in ISA yaml, otherwise apply standard operand assignment
        # (one dest, others source)
        isa_data = self._isa_model.get_instruction(
            instruction_form['instruction'], instruction_form['operands']
        )
        if (
            isa_data is None
            and self._isa == 'x86'
            and instruction_form['instruction'][-1] in self.GAS_SUFFIXES
        ):
            # Check for instruction without GAS suffix
            isa_data = self._isa_model.get_instruction(
                instruction_form['instruction'][:-1], instruction_form['operands']
            )
        operands = instruction_form['operands']
        op_dict = {}
        assign_default = False
        if isa_data:
            # load src/dst structure from isa_data
            op_dict = self._apply_found_ISA_data(isa_data, operands)
        else:
            # Couldn't found instruction form in ISA DB
            assign_default = True
            # check for equivalent register-operands DB entry if LD/ST
            if any(['memory' in op for op in operands]):
                operands_reg = self.substitute_mem_address(instruction_form['operands'])
                isa_data_reg = self._isa_model.get_instruction(
                    instruction_form['instruction'], operands_reg
                )
                if (
                    isa_data_reg is None
                    and self._isa == 'x86'
                    and instruction_form['instruction'][-1] in self.GAS_SUFFIXES
                ):
                    # Check for instruction without GAS suffix
                    isa_data_reg = self._isa_model.get_instruction(
                        instruction_form['instruction'][:-1], operands_reg
                    )
                if isa_data_reg:
                    assign_default = False
                    op_dict = self._apply_found_ISA_data(isa_data_reg, operands)
        if assign_default:
            # no irregular operand structure, apply default
            op_dict['source'] = self._get_regular_source_operands(instruction_form)
            op_dict['destination'] = self._get_regular_destination_operands(instruction_form)
            op_dict['src_dst'] = []
        # post-process pre- and post-indexing for aarch64 memory operands
        if self._isa == 'aarch64':
            for operand in [op for op in op_dict['source'] if 'memory' in op]:
                if ('post_indexed' in operand['memory'] and operand['memory']['post_indexed']) or (
                    'pre_indexed' in operand['memory'] and operand['memory']['pre_indexed']
                ):
                    op_dict['src_dst'].append(AttrDict.convert_dict(
                        {'register': operand['memory']['base']}))
            for operand in [op for op in op_dict['destination'] if 'memory' in op]:
                if ('post_indexed' in operand['memory'] and operand['memory']['post_indexed']) or (
                    'pre_indexed' in operand['memory'] and operand['memory']['pre_indexed']
                ):
                    op_dict['src_dst'].append(AttrDict.convert_dict(
                        {'register': operand['memory']['base']}))
        # store operand list in dict and reassign operand key/value pair
        instruction_form['semantic_operands'] = AttrDict.convert_dict(op_dict)
        # assign LD/ST flags
        instruction_form['flags'] = (
            instruction_form['flags'] if 'flags' in instruction_form else []
        )
        if self._has_load(instruction_form):
            instruction_form['flags'] += [INSTR_FLAGS.HAS_LD]
        if self._has_store(instruction_form):
            instruction_form['flags'] += [INSTR_FLAGS.HAS_ST]

    def _apply_found_ISA_data(self, isa_data, operands):
        """
        Create operand dictionary containing src/dst operands out of the ISA data entry and
        the oeprands of an instruction form

        :param dict isa_data: ISA DB entry
        :param list operands: operands of the instruction form
        :returns: `dict` -- operands dictionary with src/dst assignment
        """
        op_dict = {}
        op_dict['source'] = []
        op_dict['destination'] = []
        op_dict['src_dst'] = []
        for i, op in enumerate(isa_data['operands']):
            if op['source'] and op['destination']:
                op_dict['src_dst'].append(operands[i])
                continue
            if op['source']:
                op_dict['source'].append(operands[i])
                continue
            if op['destination']:
                op_dict['destination'].append(operands[i])
                continue
        # check for hidden operands like flags or registers
        if 'hidden_operands' in isa_data:
            # add operand(s) to semantic_operands of instruction form
            for op in isa_data['hidden_operands']:
                dict_key = (
                    'src_dst'
                    if op['source'] and op['destination']
                    else 'source'
                    if op['source']
                    else 'destination'
                )
                hidden_op = {op['class']: {}}
                key_filter = ['class', 'source', 'destination']
                for key in [k for k in op.keys() if k not in key_filter]:
                    hidden_op[op['class']][key] = op[key]
                hidden_op = AttrDict.convert_dict(hidden_op)
                op_dict[dict_key].append(hidden_op)
        return op_dict

    def _has_load(self, instruction_form):
        """Check if instruction form performs a LOAD"""
        for operand in chain(
            instruction_form['semantic_operands']['source'],
            instruction_form['semantic_operands']['src_dst'],
        ):
            if 'memory' in operand:
                return True
        return False

    def _has_store(self, instruction_form):
        """Check if instruction form perfroms a STORE"""
        for operand in chain(
            instruction_form['semantic_operands']['destination'],
            instruction_form['semantic_operands']['src_dst'],
        ):
            if 'memory' in operand:
                return True
        return False

    def _get_regular_source_operands(self, instruction_form):
        """Get source operand of given instruction form assuming regular src/dst behavior."""
        # if there is only one operand, assume it is a source operand
        if len(instruction_form['operands']) == 1:
            return [instruction_form['operands'][0]]
        if self._isa == 'x86':
            # return all but last operand
            return [op for op in instruction_form['operands'][0:-1]]
        elif self._isa == 'aarch64':
            return [op for op in instruction_form['operands'][1:]]
        else:
            raise ValueError("Unsupported ISA {}.".format(self._isa))

    def _get_regular_destination_operands(self, instruction_form):
        """Get destination operand of given instruction form assuming regular src/dst behavior."""
        # if there is only one operand, assume no destination
        if len(instruction_form['operands']) == 1:
            return []
        if self._isa == 'x86':
            # return last operand
            return instruction_form['operands'][-1:]
        if self._isa == 'aarch64':
            # return first operand
            return instruction_form['operands'][:1]
        else:
            raise ValueError("Unsupported ISA {}.".format(self._isa))

    def substitute_mem_address(self, operands):
        """Create memory wildcard for all memory operands"""
        return [self._create_reg_wildcard() if 'memory' in op else op for op in operands]

    def _create_reg_wildcard(self):
        """Wildcard constructor"""
        return {'*': '*'}