magic = (b"\x00\x00\x00\x00\x00\x00\x00\x00" +
         b"\x00\x00\x00\x00\xc2\xea\x81\x60" +
         b"\xb3\x14\x11\xcf\xbd\x92\x08\x00" +
         b"\x09\xc7\x31\x8c\x18\x1f\x10\x11")

align_1_checker_value = b'3'
align_1_offset = 32
align_1_length = 1
align_1_value = 4
u64_byte_checker_value = b'3'
align_2_offset = 35
align_2_length = 1
align_2_value = 4
endianness_offset = 37
endianness_length = 1
platform_offset = 39
platform_length = 1
encoding_offset = 70
encoding_length = 1
dataset_offset = 92
dataset_length = 64
file_type_offset = 156
file_type_length = 8
date_created_offset = 164
date_created_length = 8
date_modified_offset = 172
date_modified_length = 8
header_size_offset = 196
header_size_length = 4
page_size_offset = 200
page_size_length = 4
page_count_offset = 204
page_count_length = 4
sas_release_offset = 216
sas_release_length = 8
sas_server_type_offset = 224
sas_server_type_length = 16
os_version_number_offset = 240
os_version_number_length = 16
os_maker_offset = 256
os_maker_length = 16
os_name_offset = 272
os_name_length = 16
page_bit_offset_x86 = 16
page_bit_offset_x64 = 32
subheader_pointer_length_x86 = 12
subheader_pointer_length_x64 = 24
page_type_offset = 0
page_type_length = 2
block_count_offset = 2
block_count_length = 2
subheader_count_offset = 4
subheader_count_length = 2
page_meta_type = 0
page_data_type = 256
page_amd_type = 1024
page_metc_type = 16384
page_comp_type = -28672
page_mix_types = [512, 640]
subheader_pointers_offset = 8
truncated_subheader_id = 1
compressed_subheader_id = 4
compressed_subheader_type = 1
text_block_size_length = 2
row_length_offset_multiplier = 5
row_count_offset_multiplier = 6
col_count_p1_multiplier = 9
col_count_p2_multiplier = 10
row_count_on_mix_page_offset_multiplier = 15
column_name_pointer_length = 8
column_name_text_subheader_offset = 0
column_name_text_subheader_length = 2
column_name_offset_offset = 2
column_name_offset_length = 2
column_name_length_offset = 4
column_name_length_length = 2
column_data_offset_offset = 8
column_data_length_offset = 8
column_data_length_length = 4
column_type_offset = 14
column_type_length = 1
column_format_text_subheader_index_offset = 22
column_format_text_subheader_index_length = 2
column_format_offset_offset = 24
column_format_offset_length = 2
column_format_length_offset = 26
column_format_length_length = 2
column_label_text_subheader_index_offset = 28
column_label_text_subheader_index_length = 2
column_label_offset_offset = 30
column_label_offset_length = 2
column_label_length_offset = 32
column_label_length_length = 2
rle_compression = b'SASYZCRL'
rdc_compression = b'SASYZCR2'

compression_literals = [rle_compression, rdc_compression]

# Incomplete list of encodings, using SAS nomenclature:
# http://support.sas.com/documentation/cdl/en/nlsref/61893/HTML/default/viewer.htm#a002607278.htm
encoding_names = {29: "latin1", 20: "utf-8", 33: "cyrillic", 60: "wlatin2",
                  61: "wcyrillic", 62: "wlatin1", 90: "ebcdic870"}


class SASIndex(object):
    row_size_index = 0
    column_size_index = 1
    subheader_counts_index = 2
    column_text_index = 3
    column_name_index = 4
    column_attributes_index = 5
    format_and_label_index = 6
    column_list_index = 7
    data_subheader_index = 8


subheader_signature_to_index = {
    b"\xF7\xF7\xF7\xF7": SASIndex.row_size_index,
    b"\x00\x00\x00\x00\xF7\xF7\xF7\xF7": SASIndex.row_size_index,
    b"\xF7\xF7\xF7\xF7\x00\x00\x00\x00": SASIndex.row_size_index,
    b"\xF7\xF7\xF7\xF7\xFF\xFF\xFB\xFE": SASIndex.row_size_index,
    b"\xF6\xF6\xF6\xF6": SASIndex.column_size_index,
    b"\x00\x00\x00\x00\xF6\xF6\xF6\xF6": SASIndex.column_size_index,
    b"\xF6\xF6\xF6\xF6\x00\x00\x00\x00": SASIndex.column_size_index,
    b"\xF6\xF6\xF6\xF6\xFF\xFF\xFB\xFE": SASIndex.column_size_index,
    b"\x00\xFC\xFF\xFF": SASIndex.subheader_counts_index,
    b"\xFF\xFF\xFC\x00": SASIndex.subheader_counts_index,
    b"\x00\xFC\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.subheader_counts_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFC\x00": SASIndex.subheader_counts_index,
    b"\xFD\xFF\xFF\xFF": SASIndex.column_text_index,
    b"\xFF\xFF\xFF\xFD": SASIndex.column_text_index,
    b"\xFD\xFF\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.column_text_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFD": SASIndex.column_text_index,
    b"\xFF\xFF\xFF\xFF": SASIndex.column_name_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.column_name_index,
    b"\xFC\xFF\xFF\xFF": SASIndex.column_attributes_index,
    b"\xFF\xFF\xFF\xFC": SASIndex.column_attributes_index,
    b"\xFC\xFF\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.column_attributes_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFC": SASIndex.column_attributes_index,
    b"\xFE\xFB\xFF\xFF": SASIndex.format_and_label_index,
    b"\xFF\xFF\xFB\xFE": SASIndex.format_and_label_index,
    b"\xFE\xFB\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.format_and_label_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFB\xFE": SASIndex.format_and_label_index,
    b"\xFE\xFF\xFF\xFF": SASIndex.column_list_index,
    b"\xFF\xFF\xFF\xFE": SASIndex.column_list_index,
    b"\xFE\xFF\xFF\xFF\xFF\xFF\xFF\xFF": SASIndex.column_list_index,
    b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFE": SASIndex.column_list_index}


# List of frequently used SAS date and datetime formats
# http://support.sas.com/documentation/cdl/en/etsug/60372/HTML/default/viewer.htm#etsug_intervals_sect009.htm
# https://github.com/epam/parso/blob/master/src/main/java/com/epam/parso/impl/SasFileConstants.java
sas_date_formats = ("DATE", "DAY", "DDMMYY", "DOWNAME", "JULDAY", "JULIAN",
                    "MMDDYY", "MMYY", "MMYYC", "MMYYD", "MMYYP", "MMYYS",
                    "MMYYN", "MONNAME", "MONTH", "MONYY", "QTR", "QTRR",
                    "NENGO", "WEEKDATE", "WEEKDATX", "WEEKDAY", "WEEKV",
                    "WORDDATE", "WORDDATX", "YEAR", "YYMM", "YYMMC", "YYMMD",
                    "YYMMP", "YYMMS", "YYMMN", "YYMON", "YYMMDD", "YYQ",
                    "YYQC", "YYQD", "YYQP", "YYQS", "YYQN", "YYQR", "YYQRC",
                    "YYQRD", "YYQRP", "YYQRS", "YYQRN",
                    "YYMMDDP", "YYMMDDC", "E8601DA", "YYMMDDN", "MMDDYYC",
                    "MMDDYYS", "MMDDYYD", "YYMMDDS", "B8601DA", "DDMMYYN",
                    "YYMMDDD", "DDMMYYB", "DDMMYYP", "MMDDYYP", "YYMMDDB",
                    "MMDDYYN", "DDMMYYC", "DDMMYYD", "DDMMYYS",
                    "MINGUO")

sas_datetime_formats = ("DATETIME", "DTWKDATX",
                        "B8601DN", "B8601DT", "B8601DX", "B8601DZ", "B8601LX",
                        "E8601DN", "E8601DT", "E8601DX", "E8601DZ", "E8601LX",
                        "DATEAMPM", "DTDATE", "DTMONYY", "DTMONYY", "DTWKDATX",
                        "DTYEAR", "TOD", "MDYAMPM")