#-------------------------------------------------------------------------------
# elftools: dwarf/descriptions.py
#
# Textual descriptions of the various values and enums of DWARF
#
# Eli Bendersky (eliben@gmail.com)
# This code is in the public domain
#-------------------------------------------------------------------------------
from collections import defaultdict

from .constants import *
from .dwarf_expr import ExprDumper
from .die import DIE
from ..common.utils import preserve_stream_pos


def describe_attr_value(attr, die, section_offset):
    """ Given an attribute attr, return the textual representation of its
        value, suitable for tools like readelf.
        
        To cover all cases, this function needs some extra arguments:

        die: the DIE this attribute was extracted from
        section_offset: offset in the stream of the section the DIE belongs to
    """
    descr_func = _ATTR_DESCRIPTION_MAP[attr.form]
    val_description = descr_func(attr, die, section_offset)
    
    # For some attributes we can display further information
    extra_info_func = _EXTRA_INFO_DESCRIPTION_MAP[attr.name]
    extra_info = extra_info_func(attr, die, section_offset)
    return str(val_description) + '\t' + extra_info    


#-------------------------------------------------------------------------------

def _describe_attr_ref(attr, die, section_offset):
    return '<0x%x>' % (attr.value + die.cu.cu_offset)

def _describe_attr_value_passthrough(attr, die, section_offset):
    return attr.value

def _describe_attr_hex(attr, die, section_offset):
    return '0x%x' % (attr.value)

def _describe_attr_hex_addr(attr, die, section_offset):
    return '<0x%x>' % (attr.value)

def _describe_attr_split_64bit(attr, die, section_offset):
    low_word = attr.value & 0xFFFFFFFF
    high_word = (attr.value >> 32) & 0xFFFFFFFF
    return '0x%x 0x%x' % (low_word, high_word)

def _describe_attr_strp(attr, die, section_offset):
    return '(indirect string, offset: 0x%x): %s' % (attr.raw_value, attr.value)

def _describe_attr_debool(attr, die, section_offset):
    """ To be consistent with readelf, generate 1 for True flags, 0 for False
        flags.
    """
    return '1' if attr.value else '0'

def _describe_attr_block(attr, die, section_offset):
    s = '%s byte block: ' % len(attr.value)
    s += ' '.join('%x' % item for item in attr.value)
    return s
    

_ATTR_DESCRIPTION_MAP = defaultdict(
    lambda: _describe_attr_value_passthrough, # default_factory
    
    DW_FORM_ref1=_describe_attr_ref,
    DW_FORM_ref2=_describe_attr_ref,
    DW_FORM_ref4=_describe_attr_ref,
    DW_FORM_ref8=_describe_attr_split_64bit,
    DW_FORM_ref_udata=_describe_attr_ref,        
    DW_FORM_ref_addr=_describe_attr_hex_addr,
    DW_FORM_data4=_describe_attr_hex,
    DW_FORM_data8=_describe_attr_split_64bit,
    DW_FORM_addr=_describe_attr_hex,
    DW_FORM_sec_offset=_describe_attr_hex,
    DW_FORM_flag=_describe_attr_debool,
    DW_FORM_data1=_describe_attr_value_passthrough,
    DW_FORM_data2=_describe_attr_value_passthrough,
    DW_FORM_sdata=_describe_attr_value_passthrough,
    DW_FORM_udata=_describe_attr_value_passthrough,
    DW_FORM_string=_describe_attr_value_passthrough,
    DW_FORM_strp=_describe_attr_strp,
    DW_FORM_block1=_describe_attr_block,
    DW_FORM_block2=_describe_attr_block,
    DW_FORM_block4=_describe_attr_block,
    DW_FORM_block=_describe_attr_block,
)


_DESCR_DW_INL = {
    DW_INL_not_inlined: '(not inlined)',
    DW_INL_inlined: '(inlined)',
    DW_INL_declared_not_inlined: '(declared as inline but ignored)',
    DW_INL_declared_inlined: '(declared as inline and inlined)',
}

_DESCR_DW_LANG = {
    DW_LANG_C89: '(ANSI C)',
    DW_LANG_C: '(non-ANSI C)',
    DW_LANG_Ada83: '(Ada)',
    DW_LANG_C_plus_plus: '(C++)',
    DW_LANG_Cobol74: '(Cobol 74)',
    DW_LANG_Cobol85: '(Cobol 85)',
    DW_LANG_Fortran77: '(FORTRAN 77)',
    DW_LANG_Fortran90: '(Fortran 90)',
    DW_LANG_Pascal83: '(ANSI Pascal)',
    DW_LANG_Modula2: '(Modula 2)',
    DW_LANG_Java: '(Java)',
    DW_LANG_C99: '(ANSI C99)',
    DW_LANG_Ada95: '(ADA 95)',
    DW_LANG_Fortran95: '(Fortran 95)',
    DW_LANG_PLI: '(PLI)',
    DW_LANG_ObjC: '(Objective C)',
    DW_LANG_ObjC_plus_plus: '(Objective C++)',
    DW_LANG_UPC: '(Unified Parallel C)',
    DW_LANG_D: '(D)',
    DW_LANG_Python: '(Python)',
    DW_LANG_Mips_Assembler: '(MIPS assembler)',
    DW_LANG_Upc: '(nified Parallel C)',
    DW_LANG_HP_Bliss: '(HP Bliss)',
    DW_LANG_HP_Basic91: '(HP Basic 91)',
    DW_LANG_HP_Pascal91: '(HP Pascal 91)',
    DW_LANG_HP_IMacro: '(HP IMacro)',
    DW_LANG_HP_Assembler: '(HP assembler)',
}

_DESCR_DW_ATE = {
    DW_ATE_void: '(void)',
    DW_ATE_address: '(machine address)',
    DW_ATE_boolean: '(boolean)',
    DW_ATE_complex_float: '(complex float)',
    DW_ATE_float: '(float)',
    DW_ATE_signed: '(signed)',
    DW_ATE_signed_char: '(signed char)',
    DW_ATE_unsigned: '(unsigned)',
    DW_ATE_unsigned_char: '(unsigned char)',
    DW_ATE_imaginary_float: '(imaginary float)',
    DW_ATE_decimal_float: '(decimal float)',
    DW_ATE_packed_decimal: '(packed_decimal)',
    DW_ATE_numeric_string: '(numeric_string)',
    DW_ATE_edited: '(edited)',
    DW_ATE_signed_fixed: '(signed_fixed)',
    DW_ATE_unsigned_fixed: '(unsigned_fixed)',
    DW_ATE_HP_float80: '(HP_float80)',
    DW_ATE_HP_complex_float80: '(HP_complex_float80)',
    DW_ATE_HP_float128: '(HP_float128)',
    DW_ATE_HP_complex_float128: '(HP_complex_float128)',
    DW_ATE_HP_floathpintel: '(HP_floathpintel)',
    DW_ATE_HP_imaginary_float80: '(HP_imaginary_float80)',
    DW_ATE_HP_imaginary_float128: '(HP_imaginary_float128)',
}

_DESCR_DW_ACCESS = {
    DW_ACCESS_public: '(public)',
    DW_ACCESS_protected: '(protected)',
    DW_ACCESS_private: '(private)',
}

_DESCR_DW_VIS = {
    DW_VIS_local: '(local)',
    DW_VIS_exported: '(exported)',
    DW_VIS_qualified: '(qualified)',
}

_DESCR_DW_VIRTUALITY = {
    DW_VIRTUALITY_none: '(none)',
    DW_VIRTUALITY_virtual: '(virtual)',
    DW_VIRTUALITY_pure_virtual: '(pure virtual)',
}

_DESCR_DW_ID_CASE = {
    DW_ID_case_sensitive: '(case_sensitive)',
    DW_ID_up_case: '(up_case)',
    DW_ID_down_case: '(down_case)',
    DW_ID_case_insensitive: '(case_insensitive)',
}

_DESCR_DW_CC = {
    DW_CC_normal: '(normal)',
    DW_CC_program: '(program)',
    DW_CC_nocall: '(nocall)',
}

_DESCR_DW_ORD = {
    DW_ORD_row_major: '(row major)',
    DW_ORD_col_major: '(column major)',
}


def _make_extra_mapper(mapping, default, default_interpolate_value=False):
    """ Create a mapping function from attribute parameters to an extra
        value that should be displayed.
    """
    def mapper(attr, die, section_offset):
        if default_interpolate_value:
            d = default % attr.value
        else:
            d = default
        return mapping.get(attr.value, d)
    return mapper


def _make_extra_string(s=''):
    """ Create an extra function that just returns a constant string.
    """
    def extra(attr, die, section_offset):
        return s
    return extra


_DWARF_EXPR_DUMPER_CACHE = {}

def _location_list_extra(attr, die, section_offset):
    # According to section 2.6 of the DWARF spec v3, class loclistptr means
    # a location list, and class block means a location expression.
    #
    if attr.form in ('DW_FORM_data4', 'DW_FORM_data8'):
        return '(location list)'
    else:
        # Since this function can be called a lot, initializing a fresh new
        # LocationExpressionDumper per call is expensive. So a rudimentary
        # caching scheme is in place to create only one such dumper per
        # processed CU.
        cache_key = id(die.cu.structs)
        if cache_key not in _DWARF_EXPR_DUMPER_CACHE:
            _DWARF_EXPR_DUMPER_CACHE[cache_key] = \
                ExprDumper(die.cu.structs)
        dwarf_expr_dumper = _DWARF_EXPR_DUMPER_CACHE[cache_key]
        dwarf_expr_dumper.clear()
        dwarf_expr_dumper.process_expr(attr.value)
        return '(' + dwarf_expr_dumper.get_str() + ')'


def _import_extra(attr, die, section_offset):
    # For DW_AT_import the value points to a DIE (that can be either in the
    # current DIE's CU or in another CU, depending on the FORM). The extra
    # information for it is the abbreviation number in this DIE and its tag.
    if attr.form == 'DW_FORM_ref_addr':
        # Absolute offset value
        ref_die_offset = section_offset + attr.value
    else:
        # Relative offset to the current DIE's CU
        ref_die_offset = attr.value + die.cu.cu_offset

    # Now find the CU this DIE belongs to (since we have to find its abbrev
    # table). This is done by linearly scanning through all CUs, looking for
    # one spanning an address space containing the referred DIE's offset.
    for cu in die.dwarfinfo.iter_CUs():
        if cu['unit_length'] + cu.cu_offset > ref_die_offset >= cu.cu_offset:
            # Once we have the CU, we can actually parse this DIE from the
            # stream.
            with preserve_stream_pos(die.stream):
                ref_die = DIE(cu, die.stream, ref_die_offset)
            #print '&&& ref_die', ref_die
            return '[Abbrev Number: %s (%s)]' % (
                ref_die.abbrev_code, ref_die.tag)

    return '[unknown]'


_EXTRA_INFO_DESCRIPTION_MAP = defaultdict(
    lambda: _make_extra_string(''), # default_factory
    
    DW_AT_inline=_make_extra_mapper(
        _DESCR_DW_INL, '(Unknown inline attribute value: %x',
        default_interpolate_value=True),
    DW_AT_language=_make_extra_mapper(
        _DESCR_DW_LANG, '(Unknown: %x)', default_interpolate_value=True),
    DW_AT_encoding=_make_extra_mapper(_DESCR_DW_ATE, '(unknown type)'),
    DW_AT_accessibility=_make_extra_mapper(
        _DESCR_DW_ACCESS, '(unknown accessibility)'),
    DW_AT_visibility=_make_extra_mapper(
        _DESCR_DW_VIS, '(unknown visibility)'),
    DW_AT_virtuality=_make_extra_mapper(
        _DESCR_DW_VIRTUALITY, '(unknown virtuality)'),
    DW_AT_identifier_case=_make_extra_mapper(
        _DESCR_DW_ID_CASE, '(unknown case)'),
    DW_AT_calling_convention=_make_extra_mapper(
        _DESCR_DW_CC, '(unknown convention)'),
    DW_AT_ordering=_make_extra_mapper(
        _DESCR_DW_ORD, '(undefined)'),
    DW_AT_frame_base=_location_list_extra,
    DW_AT_location=_location_list_extra,
    DW_AT_string_length=_location_list_extra,
    DW_AT_return_addr=_location_list_extra,
    DW_AT_data_member_location=_location_list_extra,
    DW_AT_vtable_elem_location=_location_list_extra,
    DW_AT_segment=_location_list_extra,
    DW_AT_static_link=_location_list_extra,
    DW_AT_use_location=_location_list_extra,
    DW_AT_allocated=_location_list_extra,
    DW_AT_associated=_location_list_extra,
    DW_AT_data_location=_location_list_extra,
    DW_AT_stride=_location_list_extra,
    DW_AT_import=_import_extra,
)