"""
Process raw qstr file and output qstr data with length, hash and data bytes.

This script works with Python 2.7, 3.3 and 3.4.

For documentation about the format of compressed translated strings, see
supervisor/shared/translate.h
"""

from __future__ import print_function

import re
import sys

import collections
import gettext
import os.path

py = os.path.dirname(sys.argv[0])
top = os.path.dirname(py)

sys.path.append(os.path.join(top, "tools/huffman"))

import huffman

# Python 2/3 compatibility:
#   - iterating through bytes is different
#   - codepoint2name lives in a different module
import platform
if platform.python_version_tuple()[0] == '2':
    bytes_cons = lambda val, enc=None: bytearray(val)
    from htmlentitydefs import codepoint2name
elif platform.python_version_tuple()[0] == '3':
    bytes_cons = bytes
    from html.entities import codepoint2name
# end compatibility code

codepoint2name[ord('-')] = 'hyphen';

# add some custom names to map characters that aren't in HTML
codepoint2name[ord(' ')] = 'space'
codepoint2name[ord('\'')] = 'squot'
codepoint2name[ord(',')] = 'comma'
codepoint2name[ord('.')] = 'dot'
codepoint2name[ord(':')] = 'colon'
codepoint2name[ord(';')] = 'semicolon'
codepoint2name[ord('/')] = 'slash'
codepoint2name[ord('%')] = 'percent'
codepoint2name[ord('#')] = 'hash'
codepoint2name[ord('(')] = 'paren_open'
codepoint2name[ord(')')] = 'paren_close'
codepoint2name[ord('[')] = 'bracket_open'
codepoint2name[ord(']')] = 'bracket_close'
codepoint2name[ord('{')] = 'brace_open'
codepoint2name[ord('}')] = 'brace_close'
codepoint2name[ord('*')] = 'star'
codepoint2name[ord('!')] = 'bang'
codepoint2name[ord('\\')] = 'backslash'
codepoint2name[ord('+')] = 'plus'
codepoint2name[ord('$')] = 'dollar'
codepoint2name[ord('=')] = 'equals'
codepoint2name[ord('?')] = 'question'
codepoint2name[ord('@')] = 'at_sign'
codepoint2name[ord('^')] = 'caret'
codepoint2name[ord('|')] = 'pipe'
codepoint2name[ord('~')] = 'tilde'

C_ESCAPES = {
    "\a": "\\a",
    "\b": "\\b",
    "\f": "\\f",
    "\n": "\\n",
    "\r": "\\r",
    "\t": "\\t",
    "\v": "\\v",
    "\'": "\\'",
    "\"": "\\\""
}

# this must match the equivalent function in qstr.c
def compute_hash(qstr, bytes_hash):
    hash = 5381
    for b in qstr:
        hash = (hash * 33) ^ b
    # Make sure that valid hash is never zero, zero means "hash not computed"
    return (hash & ((1 << (8 * bytes_hash)) - 1)) or 1

def translate(translation_file, i18ns):
    with open(translation_file, "rb") as f:
        table = gettext.GNUTranslations(f)

        translations = []
        for original in i18ns:
            unescaped = original
            for s in C_ESCAPES:
                unescaped = unescaped.replace(C_ESCAPES[s], s)
            translation = table.gettext(unescaped)
            # Add in carriage returns to work in terminals
            translation = translation.replace("\n", "\r\n")
            translations.append((original, translation))
        return translations

def frequent_ngrams(corpus, sz, n):
    return collections.Counter(corpus[i:i+sz] for i in range(len(corpus)-sz)).most_common(n)

def encode_ngrams(translation, ngrams):
    if len(ngrams) > 32:
        start = 0xe000
    else:
        start = 0x80
    for i, g in enumerate(ngrams):
        translation = translation.replace(g, chr(start + i))
    return translation

def decode_ngrams(compressed, ngrams):
    if len(ngrams) > 32:
        start, end = 0xe000, 0xf8ff
    else:
        start, end = 0x80, 0x9f
    return "".join(ngrams[ord(c) - start] if (start <= ord(c) <= end) else c for c in compressed)

def compute_huffman_coding(translations, qstrs, compression_filename):
    all_strings = [x[1] for x in translations]
    all_strings_concat = "".join(all_strings)
    ngrams = [i[0] for i in frequent_ngrams(all_strings_concat, 2, 32)]
    all_strings_concat = encode_ngrams(all_strings_concat, ngrams)
    counts = collections.Counter(all_strings_concat)
    cb = huffman.codebook(counts.items())
    values = []
    length_count = {}
    renumbered = 0
    last_l = None
    canonical = {}
    for ch, code in sorted(cb.items(), key=lambda x: (len(x[1]), x[0])):
        values.append(ch)
        l = len(code)
        if l not in length_count:
            length_count[l] = 0
        length_count[l] += 1
        if last_l:
            renumbered <<= (l - last_l)
        canonical[ch] = '{0:0{width}b}'.format(renumbered, width=l)
        s = C_ESCAPES.get(ch, ch)
        print("//", ord(ch), s, counts[ch], canonical[ch], renumbered)
        renumbered += 1
        last_l = l
    lengths = bytearray()
    print("// length count", length_count)
    print("// bigrams", ngrams)
    for i in range(1, max(length_count) + 2):
        lengths.append(length_count.get(i, 0))
    print("// values", values, "lengths", len(lengths), lengths)
    ngramdata = [ord(ni) for i in ngrams for ni in i]
    print("// estimated total memory size", len(lengths) + 2*len(values) + 2 * len(ngramdata) + sum((len(cb[u]) + 7)//8 for u in all_strings_concat))
    print("//", values, lengths)
    values_type = "uint16_t" if max(ord(u) for u in values) > 255 else "uint8_t"
    max_translation_encoded_length = max(len(translation.encode("utf-8")) for original,translation in translations)
    with open(compression_filename, "w") as f:
        f.write("const uint8_t lengths[] = {{ {} }};\n".format(", ".join(map(str, lengths))))
        f.write("const {} values[] = {{ {} }};\n".format(values_type, ", ".join(str(ord(u)) for u in values)))
        f.write("#define compress_max_length_bits ({})\n".format(max_translation_encoded_length.bit_length()))
        f.write("const {} bigrams[] = {{ {} }};\n".format(values_type, ", ".join(str(u) for u in ngramdata)))
        if len(ngrams) > 32:
            bigram_start = 0xe000
        else:
            bigram_start = 0x80
        bigram_end = bigram_start + len(ngrams) - 1 # End is inclusive
        f.write("#define bigram_start {}\n".format(bigram_start))
        f.write("#define bigram_end {}\n".format(bigram_end))
    return values, lengths, ngrams

def decompress(encoding_table, encoded, encoded_length_bits):
    values, lengths, ngrams = encoding_table
    dec = []
    this_byte = 0
    this_bit = 7
    b = encoded[this_byte]
    bits = 0
    for i in range(encoded_length_bits):
        bits <<= 1
        if 0x80 & b:
            bits |= 1

        b <<= 1
        if this_bit == 0:
            this_bit = 7
            this_byte += 1
            if this_byte < len(encoded):
                b = encoded[this_byte]
        else:
            this_bit -= 1
    length = bits

    i = 0
    while i < length:
        bits = 0
        bit_length = 0
        max_code = lengths[0]
        searched_length = lengths[0]
        while True:
            bits <<= 1
            if 0x80 & b:
                bits |= 1

            b <<= 1
            bit_length += 1
            if this_bit == 0:
                this_bit = 7
                this_byte += 1
                if this_byte < len(encoded):
                    b = encoded[this_byte]
            else:
                this_bit -= 1
            if max_code > 0 and bits < max_code:
                #print('{0:0{width}b}'.format(bits, width=bit_length))
                break
            max_code = (max_code << 1) + lengths[bit_length]
            searched_length += lengths[bit_length]

        v = values[searched_length + bits - max_code]
        v = decode_ngrams(v, ngrams)
        i += len(v.encode('utf-8'))
        dec.append(v)
    return ''.join(dec)

def compress(encoding_table, decompressed, encoded_length_bits, len_translation_encoded):
    if not isinstance(decompressed, str):
        raise TypeError()
    values, lengths, ngrams = encoding_table
    decompressed = encode_ngrams(decompressed, ngrams)
    enc = bytearray(len(decompressed) * 3)
    #print(decompressed)
    #print(lengths)
    current_bit = 7
    current_byte = 0

    code = len_translation_encoded
    bits = encoded_length_bits+1
    for i in range(bits - 1, 0, -1):
        if len_translation_encoded & (1 << (i - 1)):
            enc[current_byte] |= 1 << current_bit
        if current_bit == 0:
            current_bit = 7
            #print("packed {0:0{width}b}".format(enc[current_byte], width=8))
            current_byte += 1
        else:
            current_bit -= 1

    for c in decompressed:
        #print()
        #print("char", c, values.index(c))
        start = 0
        end = lengths[0]
        bits = 1
        compressed = None
        code = 0
        while compressed is None:
            s = start
            e = end
            #print("{0:0{width}b}".format(code, width=bits))
            # Binary search!
            while e > s:
                midpoint = (s + e) // 2
                #print(s, e, midpoint)
                if values[midpoint] == c:
                    compressed = code + (midpoint - start)
                    #print("found {0:0{width}b}".format(compressed, width=bits))
                    break
                elif c < values[midpoint]:
                    e = midpoint
                else:
                    s = midpoint + 1
            code += end - start
            code <<= 1
            start = end
            end += lengths[bits]
            bits += 1
            #print("next bit", bits)

        for i in range(bits - 1, 0, -1):
            if compressed & (1 << (i - 1)):
                enc[current_byte] |= 1 << current_bit
            if current_bit == 0:
                current_bit = 7
                #print("packed {0:0{width}b}".format(enc[current_byte], width=8))
                current_byte += 1
            else:
                current_bit -= 1
    if current_bit != 7:
        current_byte += 1
    return enc[:current_byte]

def qstr_escape(qst):
    def esc_char(m):
        c = ord(m.group(0))
        try:
            name = codepoint2name[c]
        except KeyError:
            name = '0x%02x' % c
        return "_" + name + '_'
    return re.sub(r'[^A-Za-z0-9_]', esc_char, qst)

def parse_input_headers(infiles):
    # read the qstrs in from the input files
    qcfgs = {}
    qstrs = {}
    i18ns = set()
    for infile in infiles:
        with open(infile, 'rt') as f:
            for line in f:
                line = line.strip()

                # is this a config line?
                match = re.match(r'^QCFG\((.+), (.+)\)', line)
                if match:
                    value = match.group(2)
                    if value[0] == '(' and value[-1] == ')':
                        # strip parenthesis from config value
                        value = value[1:-1]
                    qcfgs[match.group(1)] = value
                    continue


                match = re.match(r'^TRANSLATE\("(.*)"\)$', line)
                if match:
                    i18ns.add(match.group(1))
                    continue

                # is this a QSTR line?
                match = re.match(r'^Q\((.*)\)$', line)
                if not match:
                    continue

                # get the qstr value
                qstr = match.group(1)

                # special case to specify control characters
                if qstr == '\\n':
                    qstr = '\n'

                # work out the corresponding qstr name
                ident = qstr_escape(qstr)

                # don't add duplicates
                if ident in qstrs:
                    continue

                # add the qstr to the list, with order number to retain original order in file
                order = len(qstrs)
                # but put special method names like __add__ at the top of list, so
                # that their id's fit into a byte
                if ident == "":
                    # Sort empty qstr above all still
                    order = -200000
                elif ident == "__dir__":
                    # Put __dir__ after empty qstr for builtin dir() to work
                    order = -190000
                elif ident.startswith("__"):
                    order -= 100000
                qstrs[ident] = (order, ident, qstr)

    if not qcfgs and qstrs:
        sys.stderr.write("ERROR: Empty preprocessor output - check for errors above\n")
        sys.exit(1)

    return qcfgs, qstrs, i18ns

def make_bytes(cfg_bytes_len, cfg_bytes_hash, qstr):
    qbytes = bytes_cons(qstr, 'utf8')
    qlen = len(qbytes)
    qhash = compute_hash(qbytes, cfg_bytes_hash)
    if all(32 <= ord(c) <= 126 and c != '\\' and c != '"' for c in qstr):
        # qstr is all printable ASCII so render it as-is (for easier debugging)
        qdata = qstr
    else:
        # qstr contains non-printable codes so render entire thing as hex pairs
        qdata = ''.join(('\\x%02x' % b) for b in qbytes)
    if qlen >= (1 << (8 * cfg_bytes_len)):
        print('qstr is too long:', qstr)
        assert False
    qlen_str = ('\\x%02x' * cfg_bytes_len) % tuple(((qlen >> (8 * i)) & 0xff) for i in range(cfg_bytes_len))
    qhash_str = ('\\x%02x' * cfg_bytes_hash) % tuple(((qhash >> (8 * i)) & 0xff) for i in range(cfg_bytes_hash))
    return '(const byte*)"%s%s" "%s"' % (qhash_str, qlen_str, qdata)

def print_qstr_data(encoding_table, qcfgs, qstrs, i18ns):
    # get config variables
    cfg_bytes_len = int(qcfgs['BYTES_IN_LEN'])
    cfg_bytes_hash = int(qcfgs['BYTES_IN_HASH'])

    # print out the starter of the generated C header file
    print('// This file was automatically generated by makeqstrdata.py')
    print('')

    # add NULL qstr with no hash or data
    print('QDEF(MP_QSTR_NULL, (const byte*)"%s%s" "")' % ('\\x00' * cfg_bytes_hash, '\\x00' * cfg_bytes_len))

    total_qstr_size = 0
    total_qstr_compressed_size = 0
    # go through each qstr and print it out
    for order, ident, qstr in sorted(qstrs.values(), key=lambda x: x[0]):
        qbytes = make_bytes(cfg_bytes_len, cfg_bytes_hash, qstr)
        print('QDEF(MP_QSTR_%s, %s)' % (ident, qbytes))
        total_qstr_size += len(qstr)

    total_text_size = 0
    total_text_compressed_size = 0
    max_translation_encoded_length = max(len(translation.encode("utf-8")) for original, translation in i18ns)
    encoded_length_bits = max_translation_encoded_length.bit_length()
    for original, translation in i18ns:
        translation_encoded = translation.encode("utf-8")
        compressed = compress(encoding_table, translation, encoded_length_bits, len(translation_encoded))
        total_text_compressed_size += len(compressed)
        decompressed = decompress(encoding_table, compressed, encoded_length_bits)
        assert decompressed == translation
        for c in C_ESCAPES:
            decompressed = decompressed.replace(c, C_ESCAPES[c])
        print("TRANSLATION(\"{}\", {}) // {}".format(original, ", ".join(["{:d}".format(x) for x in compressed]), decompressed))
        total_text_size += len(translation.encode("utf-8"))

    print()
    print("// {} bytes worth of qstr".format(total_qstr_size))
    print("// {} bytes worth of translations".format(total_text_size))
    print("// {} bytes worth of translations compressed".format(total_text_compressed_size))
    print("// {} bytes saved".format(total_text_size - total_text_compressed_size))

def print_qstr_enums(qstrs):
    # print out the starter of the generated C header file
    print('// This file was automatically generated by makeqstrdata.py')
    print('')

    # add NULL qstr with no hash or data
    print('QENUM(MP_QSTR_NULL)')

    # go through each qstr and print it out
    for order, ident, qstr in sorted(qstrs.values(), key=lambda x: x[0]):
        print('QENUM(MP_QSTR_%s)' % (ident,))

if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser(description='Process QSTR definitions into headers for compilation')
    parser.add_argument('infiles', metavar='N', type=str, nargs='+',
                        help='an integer for the accumulator')
    parser.add_argument('--translation', default=None, type=str,
                        help='translations for i18n() items')
    parser.add_argument('--compression_filename', default=None, type=str,
                        help='header for compression info')

    args = parser.parse_args()

    qcfgs, qstrs, i18ns = parse_input_headers(args.infiles)
    if args.translation:
        i18ns = sorted(i18ns)
        translations = translate(args.translation, i18ns)
        encoding_table = compute_huffman_coding(translations, qstrs, args.compression_filename)
        print_qstr_data(encoding_table, qcfgs, qstrs, translations)
    else:
        print_qstr_enums(qstrs)