/*
    This is part of pyahocorasick Python module.

    AutomatonSearchIter implementation

    Author    : Wojciech Muła, wojciech_mula@poczta.onet.pl
    WWW       : http://0x80.pl
    License   : BSD-3-Clause (see LICENSE)
*/

#include "AutomatonSearchIter.h"
#include <wctype.h>

static PyTypeObject automaton_search_iter_type;


#ifdef VARIABLE_LEN_CHARCODES
static int
automaton_search_iter_substring_index(struct Input* input, int position) {

    TRIE_LETTER_TYPE letter;

    int index = 0;
    int i;

    for (i=0; i < position; i++) {

        letter = input->word[index];
        if (UNLIKELY(Py_UNICODE_IS_SURROGATE(letter))) {
            if (UNLIKELY(!Py_UNICODE_IS_HIGH_SURROGATE(letter))) {
                PyErr_Format(PyExc_ValueError,
                    "Malformed UCS-2 string: expected a high surrogate at %d, got %04x",
                    index, letter);
                return -1;
            }

            index += 1;

            if (index >= input->wordlen) {
                PyErr_Format(PyExc_ValueError,
                    "Malformed UCS-2 string: unexpected end of string");
                return -1;
            }

            letter = input->word[index];
            if (UNLIKELY(!Py_UNICODE_IS_LOW_SURROGATE(letter))) {
                PyErr_Format(PyExc_ValueError,
                    "Malformed UCS-2 string: expected a low surrogate at %d, got %04x",
                    index, letter);
                return -1;
            }

            index += 1;

        } else {
            index += 1;
        }
    }

    return index;
}
#endif // VARIABLE_LEN_CHARCODES


static PyObject*
automaton_search_iter_new(
    Automaton* automaton,
    PyObject* object,
    int start,
    int end,
    bool ignore_white_space
) {
    AutomatonSearchIter* iter;
#ifdef VARIABLE_LEN_CHARCODES
    int tmp;
#endif

    iter = (AutomatonSearchIter*)F(PyObject_New)(AutomatonSearchIter, &automaton_search_iter_type);
    if (iter == NULL)
        return NULL;


    iter->automaton = automaton;
    iter->version   = automaton->version;

    iter->state = automaton->root;
    iter->output= NULL;
    iter->shift = 0;
    iter->ignore_white_space = ignore_white_space;

    init_input(&iter->input);

    Py_INCREF(iter->automaton);

    if (!prepare_input((PyObject*)automaton, object, &iter->input)) {
        goto error;
    }

#ifdef VARIABLE_LEN_CHARCODES
    if (automaton->key_type == KEY_STRING) {
        tmp = automaton_search_iter_substring_index(&iter->input, start);
        if (tmp >= 0) {
            iter->index    = tmp - 1;
            iter->position = start - 1;
        } else {
            goto error;
        }

        tmp = automaton_search_iter_substring_index(&iter->input, end);
        if (tmp >= 0) {
            iter->end = end;
        } else {
            goto error;
        }

        iter->expected  = pyaho_UCS2_Any;
    } else {
        iter->index = start - 1;
        iter->end   = end;
    }
#else
    // -1 because the first instruction in next() increments index
    iter->index = start - 1;
    iter->end   = end;
#endif
    return (PyObject*)iter;

error:
    Py_DECREF(iter);
    return NULL;
}

#define iter ((AutomatonSearchIter*)self)

static void
automaton_search_iter_del(PyObject* self) {
    Py_DECREF(iter->automaton);
    destroy_input(&iter->input);
    PyObject_Del(self);
}


static PyObject*
automaton_search_iter_iter(PyObject* self) {
    Py_INCREF(self);
    return self;
}


enum {
    OutputValue,
    OutputNone,
    OutputError
};


static int
automaton_build_output(PyObject* self, PyObject** result) {
    TrieNode* node;
    Py_ssize_t idx = 0;

    while (iter->output && !iter->output->eow) {
        iter->output = iter->output->fail;
    }

    if (iter->output) {
        node = iter->output;
        iter->output = iter->output->fail;

#ifdef VARIABLE_LEN_CHARCODES
        idx = iter->shift;
        if (iter->automaton->key_type == KEY_STRING) {
            idx += iter->position;
        } else {
            idx += iter->index;
        }
#else
        idx = iter->index + iter->shift;
#endif
        switch (iter->automaton->store) {
            case STORE_LENGTH:
            case STORE_INTS:
                *result = F(Py_BuildValue)("ii", idx, node->output.integer);
                return OutputValue;

            case STORE_ANY:
                *result = F(Py_BuildValue)("iO", idx, node->output.object);
                return OutputValue;

            default:
                PyErr_SetString(PyExc_ValueError, "inconsistent internal state!");
                return OutputError;
        }
    }

    return OutputNone;
}



#ifdef VARIABLE_LEN_CHARCODES
static bool
automaton_search_iter_advance_index(PyObject* self) {

    TRIE_LETTER_TYPE letter;

    iter->index += 1;
    if (iter->automaton->key_type == KEY_SEQUENCE) {
        return true;
    }

    letter = iter->input.word[iter->index];
    if (iter->expected == pyaho_UCS2_Any) {
        if (UNLIKELY(Py_UNICODE_IS_SURROGATE(letter))) {
            if (LIKELY(Py_UNICODE_IS_HIGH_SURROGATE(letter))) {
                iter->expected = pyaho_UCS2_LowSurrogate;
            } else {
                PyErr_Format(PyExc_ValueError,
                    "Malformed UCS-2 string: expected a high surrogate at %d, got %04x",
                    iter->index, letter);
                return false;
            }
        } else {
            iter->position += 1;
        }
    } else {
        assert(iter->expected == pyaho_UCS2_LowSurrogate);
        if (LIKELY(Py_UNICODE_IS_LOW_SURROGATE(letter))) {
            iter->expected  = pyaho_UCS2_Any;
            iter->position += 1;
        } else {
            PyErr_Format(PyExc_ValueError,
                "Malformed UCS-2 string: expected a low surrogate at %d, got %04x",
                iter->index, letter);
            return false;
        }
    }

    return true;
}
#endif

static PyObject*
automaton_search_iter_next(PyObject* self) {
    PyObject* output;

    if (iter->version != iter->automaton->version) {
        PyErr_SetString(PyExc_ValueError, "underlaying automaton has changed, iterator is not valid anymore");
        return NULL;
    }

return_output:
    switch (automaton_build_output(self, &output)) {
        case OutputValue:
            return output;

        case OutputNone:
            break;

        case OutputError:
            return NULL;
    }

#ifdef VARIABLE_LEN_CHARCODES
    if (!automaton_search_iter_advance_index(self)) {
        return NULL;
    }
#else
    iter->index += 1;
    if (iter->ignore_white_space) {
        while ((iter->index < iter->end) and iswspace(iter->input.word[iter->index])) {
            iter->index += 1;
        }
    }
#endif
    while (iter->index < iter->end) {
        // process single char
        iter->state = ahocorasick_next(
                        iter->state,
                        iter->automaton->root,
                        iter->input.word[iter->index]
                        );

        ASSERT(iter->state);

        iter->output = iter->state;
        goto return_output;

#ifdef VARIABLE_LEN_CHARCODES
        if (!automaton_search_iter_advance_index(self)) {
            return NULL;
        }
#else
        iter->index += 1;
#endif

    } // while

    return NULL;    // StopIteration
}


static PyObject*
automaton_search_iter_set(PyObject* self, PyObject* args) {
    PyObject* object;
    PyObject* flag;
    Py_ssize_t position;
    bool reset;
    struct Input new_input;

    // first argument - required string or buffer
    object = F(PyTuple_GetItem)(args, 0);
    if (object) {
        init_input(&new_input);
        if (!prepare_input((PyObject*)iter->automaton, object, &new_input)) {
            return NULL;
        }
    }
    else
        return NULL;

    // second argument - optional bool
    flag = F(PyTuple_GetItem)(args, 1);
    if (flag) {
        switch (PyObject_IsTrue(flag)) {
            case 0:
                reset = false;
                break;
            case 1:
                reset = true;
                break;
            default:
                return NULL;
        }
    }
    else {
        PyErr_Clear();
        reset = false;
    }

    destroy_input(&iter->input);
    assign_input(&iter->input, &new_input);

    if (!reset) {
        position = iter->index;
#ifdef VARIABLE_LEN_CHARCODES
        if (iter->automaton->key_type == KEY_STRING) {
            position = iter->position;
        }
#endif
        iter->shift += (position >= 0) ? position : 0;
    }

    iter->index     = -1;
    iter->end       = new_input.wordlen;

    if (reset) {
        iter->state  = iter->automaton->root;
        iter->shift  = 0;
        iter->output = NULL;
#ifdef VARIABLE_LEN_CHARCODES
        iter->position = -1;
        iter->expected = pyaho_UCS2_Any;
#endif
    }

    Py_RETURN_NONE;
}


#undef iter

#define method(name, kind) {#name, automaton_search_iter_##name, kind, automaton_search_iter_##name##_doc}

static
PyMethodDef automaton_search_iter_methods[] = {
    method(set, METH_VARARGS),

    {NULL, NULL, 0, NULL}
};
#undef method


static PyTypeObject automaton_search_iter_type = {
    PY_OBJECT_HEAD_INIT
    "ahocorasick.AutomatonSearchIter",          /* tp_name */
    sizeof(AutomatonSearchIter),                /* tp_size */
    0,                                          /* tp_itemsize? */
    (destructor)automaton_search_iter_del,      /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                          /* tp_reserved */
    0,                                          /* tp_repr */
    0,                                          /* tp_as_number */
    0,                                          /* tp_as_sequence */
    0,                                          /* tp_as_mapping */
    0,                                          /* tp_hash */
    0,                                          /* tp_call */
    0,                                          /* tp_str */
    PyObject_GenericGetAttr,                    /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT,                         /* tp_flags */
    automaton_search_iter_doc,                  /* tp_doc */
    0,                                          /* tp_traverse */
    0,                                          /* tp_clear */
    0,                                          /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    automaton_search_iter_iter,                 /* tp_iter */
    automaton_search_iter_next,                 /* tp_iternext */
    automaton_search_iter_methods,              /* tp_methods */
    0,                                          /* tp_members */
    0,                                          /* tp_getset */
    0,                                          /* tp_base */
    0,                                          /* tp_dict */
    0,                                          /* tp_descr_get */
    0,                                          /* tp_descr_set */
    0,                                          /* tp_dictoffset */
    0,                                          /* tp_init */
    0,                                          /* tp_alloc */
    0,                                          /* tp_new */
};