# cython: profile=True
# cython: embedsignature=True
"""Common classes and utilities across languages.

Provides the main implementation for the spacy tokenizer. Specific languages
subclass the Language class, over-writing the tokenization rules as necessary.
Special-case tokenization rules are read from data/<lang>/tokenization .
"""
from __future__ import unicode_literals

from libc.stdlib cimport calloc, free

import json
import random
from os import path

from .util import read_lang_data
from spacy.tokens import Tokens
from spacy.lexeme cimport LexemeC, lexeme_init
from murmurhash.mrmr cimport hash64

from spacy._hashing cimport PointerHash
from spacy import orth
from spacy import util


cdef enum Flags:
    Flag_IsAlpha
    Flag_IsAscii
    Flag_IsDigit
    Flag_IsLower
    Flag_IsPunct
    Flag_IsSpace
    Flag_IsTitle
    Flag_IsUpper

    Flag_CanAdj
    Flag_CanAdp
    Flag_CanAdv
    Flag_CanConj
    Flag_CanDet
    Flag_CanNoun
    Flag_CanNum
    Flag_CanPdt
    Flag_CanPos
    Flag_CanPron
    Flag_CanPrt
    Flag_CanPunct
    Flag_CanVerb

    Flag_OftLower
    Flag_OftTitle
    Flag_OftUpper
    Flag_N


cdef enum Views:
    View_CanonForm
    View_WordShape
    View_NonSparse
    View_Asciied
    View_N



# Assign the flag and view functions by enum value.
# This is verbose, but it ensures we don't get nasty order sensitivities.
STRING_VIEW_FUNCS = [None] * View_N
STRING_VIEW_FUNCS[View_CanonForm] = orth.canon_case
STRING_VIEW_FUNCS[View_WordShape] = orth.word_shape
STRING_VIEW_FUNCS[View_NonSparse] = orth.non_sparse
STRING_VIEW_FUNCS[View_Asciied] = orth.asciied

FLAG_FUNCS = [None] * Flag_N
FLAG_FUNCS[Flag_IsAlpha] = orth.is_alpha
FLAG_FUNCS[Flag_IsAscii] = orth.is_ascii
FLAG_FUNCS[Flag_IsDigit] = orth.is_digit
FLAG_FUNCS[Flag_IsLower] = orth.is_lower
FLAG_FUNCS[Flag_IsPunct] = orth.is_punct
FLAG_FUNCS[Flag_IsSpace] = orth.is_space
FLAG_FUNCS[Flag_IsTitle] = orth.is_title
FLAG_FUNCS[Flag_IsUpper] = orth.is_upper

FLAG_FUNCS[Flag_CanAdj] = orth.can_tag('ADJ')
FLAG_FUNCS[Flag_CanAdp] = orth.can_tag('ADP')
FLAG_FUNCS[Flag_CanAdv] = orth.can_tag('ADV')
FLAG_FUNCS[Flag_CanConj] = orth.can_tag('CONJ')
FLAG_FUNCS[Flag_CanDet] = orth.can_tag('DET')
FLAG_FUNCS[Flag_CanNoun] = orth.can_tag('NOUN')
FLAG_FUNCS[Flag_CanNum] = orth.can_tag('NUM')
FLAG_FUNCS[Flag_CanPdt] = orth.can_tag('PDT')
FLAG_FUNCS[Flag_CanPos] = orth.can_tag('POS')
FLAG_FUNCS[Flag_CanPron] = orth.can_tag('PRON')
FLAG_FUNCS[Flag_CanPrt] = orth.can_tag('PRT')
FLAG_FUNCS[Flag_CanPunct] = orth.can_tag('PUNCT')
FLAG_FUNCS[Flag_CanVerb] = orth.can_tag('VERB')

FLAG_FUNCS[Flag_OftLower] = orth.oft_case('lower', 0.7)
FLAG_FUNCS[Flag_OftTitle] = orth.oft_case('title', 0.7)
FLAG_FUNCS[Flag_OftUpper] = orth.oft_case('upper', 0.7)




cdef class Language:
    """Base class for language-specific tokenizers.

    Most subclasses will override the _split or _split_one methods, which take
    a string of non-whitespace characters and output a list of strings.  This
    function is called by _tokenize, which sits behind a cache and turns the
    list of strings into Lexeme objects via the Lexicon. Most languages will not
    need to override _tokenize or tokenize.

    The language is supplied a list of boolean functions, used to compute flag
    features. These are passed to the language's Lexicon object.

    The language's name is used to look up default data-files, found in data/<name.
    """
    fl_is_alpha = Flag_IsAlpha
    fl_is_digit = Flag_IsDigit
    v_shape = View_WordShape

    def __cinit__(self, name, user_string_features, user_flag_features):
        self.name = name
        self.cache = PointerHash(2 ** 25)
        self.specials = PointerHash(2 ** 16)
        lang_data = util.read_lang_data(name)
        rules, words, probs, clusters, case_stats, tag_stats = lang_data
        self.lexicon = Lexicon(words, probs, clusters, case_stats, tag_stats,
                               STRING_VIEW_FUNCS + user_string_features,
                               FLAG_FUNCS + user_flag_features)
        self._load_special_tokenization(rules)

    def __dealloc__(self):
        pass

    property nr_types:
        def __get__(self):
            """Return the number of lexical types in the vocabulary"""
            return self.lexicon.size

    cpdef Lexeme lookup(self, unicode string):
        """Retrieve (or create, if not found) a Lexeme for a string, and return it.
    
        Args:
            string (unicode): The string to be looked up. Must be unicode, not bytes.

        Returns:
            lexeme (Lexeme): A reference to a lexical type.
        """
        return self.lexicon.lookup(string)

    cpdef Tokens tokenize(self, unicode string):
        """Tokenize a string.

        The tokenization rules are defined in two places:

        * The data/<lang>/tokenization table, which handles special cases like contractions;
        * The appropriate :py:meth:`find_split` function, which is used to split
          off punctuation etc.

        Args:
            string (unicode): The string to be tokenized. 

        Returns:
            tokens (Tokens): A Tokens object, giving access to a sequence of LexIDs.
        """
        cdef size_t length = len(string)
        cdef Tokens tokens = Tokens(length)
        if length == 0:
            return tokens

        cdef size_t start = 0
        cdef size_t i = 0
        cdef Py_UNICODE* chars = string
        cdef Py_UNICODE c
        cdef String span
        for i in range(length):
            c = chars[i]
            if Py_UNICODE_ISSPACE(c) == 1:
                if start < i:
                    string_from_slice(&span, chars, start, i)
                    self._tokenize(tokens, &span)
                start = i + 1
        i += 1
        if start < i:
            string_from_slice(&span, chars, start, i)
            self._tokenize(tokens, &span)
        return tokens

    cdef int _tokenize(self, Tokens tokens, String* string):
        cdef LexemeC** lexemes = <LexemeC**>self.cache.get(string.key)
        cdef size_t i
        if lexemes != NULL:
            i = 0
            while lexemes[i] != NULL:
                tokens.push_back(lexemes[i])
                i += 1
            return 0
        cdef uint64_t key = string.key 
        cdef size_t first_token = tokens.length
        cdef int split
        cdef int remaining = string.n
        cdef String prefix
        while remaining >= 1:
            split = self._split_one(string.chars, string.n)
            remaining -= split
            string_slice_prefix(string, &prefix, split)
            lexemes = <LexemeC**>self.specials.get(prefix.key)
            if lexemes != NULL:
                i = 0
                while lexemes[i] != NULL:
                    tokens.push_back(lexemes[i])
                    i += 1
            else:
                tokens.push_back(<LexemeC*>self.lexicon.get(&prefix))
        lexemes = <LexemeC**>calloc(tokens.length - first_token, sizeof(LexemeC*))
        cdef size_t j
        for i, j in enumerate(range(first_token, tokens.length)):
            lexemes[i] = tokens.lexemes[j]
        self.cache.set(key, lexemes)

    cdef int _split_one(self, Py_UNICODE* characters, size_t length):
        return length

    def _load_special_tokenization(self, token_rules):
        '''Load special-case tokenization rules.

        Loads special-case tokenization rules into the Language.cache cache,
        read from data/<lang>/tokenization . The special cases are loaded before
        any language data is tokenized, giving these priority.  For instance,
        the English tokenization rules map "ain't" to ["are", "not"].

        Args:
            token_rules (list): A list of (chunk, tokens) pairs, where chunk is
                a string and tokens is a list of strings.
        '''
        cdef LexemeC** lexemes
        cdef uint64_t hashed
        cdef String string
        for uni_string, substrings in token_rules:
            lexemes = <LexemeC**>calloc(len(substrings) + 1, sizeof(LexemeC*))
            for i, substring in enumerate(substrings):
                string_from_unicode(&string, substring)
                lexemes[i] = <LexemeC*>self.lexicon.get(&string)
            lexemes[i + 1] = NULL
            string_from_unicode(&string, uni_string)
            self.specials.set(string.key, lexemes)
            self.cache.set(string.key, lexemes)


cdef class Lexicon:
    def __cinit__(self, words, probs, clusters, case_stats, tag_stats,
                  string_features, flag_features):
        self._flag_features = flag_features
        self._string_features = string_features
        self._dict = PointerHash(2 ** 20)
        self.size = 0
        cdef String string
        for uni_string in words:
            prob = probs.get(uni_string, 0.0)
            cluster = clusters.get(uni_string, 0.0)
            cases = case_stats.get(uni_string, {})
            tags = tag_stats.get(uni_string, {})
            views = [string_view(uni_string, prob, cluster, cases, tags)
                     for string_view in self._string_features]
            flags = set()
            for i, flag_feature in enumerate(self._flag_features):
                if flag_feature(uni_string, prob, cluster, cases, tags):
                    flags.add(i)
            lexeme = lexeme_init(uni_string, prob, cluster, views, flags)
            string_from_unicode(&string, uni_string)
            self._dict.set(string.key, lexeme)
            self.size += 1

    cdef LexemeC* get(self, String* string):
        cdef LexemeC* lexeme
        lexeme = <LexemeC*>self._dict.get(string.key)
        if lexeme != NULL:
            return lexeme
        
        cdef unicode uni_string = string.chars[:string.n]
        views = [string_view(uni_string, 0.0, 0, {}, {})
                 for string_view in self._string_features]
        flags = set()
        for i, flag_feature in enumerate(self._flag_features):
            if flag_feature(uni_string, 0.0, {}, {}):
                flags.add(i)
 
        lexeme = lexeme_init(uni_string, 0, 0, views, flags)
        self._dict.set(string.key, lexeme)
        self.size += 1
        return lexeme

    cpdef Lexeme lookup(self, unicode uni_string):
        """Retrieve (or create, if not found) a Lexeme for a string, and return it.
    
        Args
            string (unicode):  The string to be looked up. Must be unicode, not bytes.

        Returns:
            lexeme (Lexeme): A reference to a lexical type.
        """
        cdef String string
        string_from_unicode(&string, uni_string)
        cdef LexemeC* lexeme = self.get(&string)
        return Lexeme(<size_t>lexeme)


_unicodes = set()
cdef void string_from_unicode(String* s, unicode uni):
    global _unicodes
    _unicodes.add(uni)
    cdef Py_UNICODE* c_uni = <Py_UNICODE*>uni
    string_from_slice(s, c_uni, 0, len(uni))


cdef inline void string_from_slice(String* s, Py_UNICODE* chars, size_t start, size_t end) nogil:
    s.chars = &chars[start]
    s.n = end - start
    s.key = hash64(s.chars, s.n * sizeof(Py_UNICODE), 0)


cdef inline void string_slice_prefix(String* s, String* prefix, size_t n) nogil:
    string_from_slice(prefix, s.chars, 0, n)
    s.chars += n
    s.n -= n
    s.key = hash64(s.chars, s.n * sizeof(Py_UNICODE), 0)