#include <stdio.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/mman.h>

#include <fcntl.h>

#include "dictre.h"

const static char indexext[] = ".index";

const static char dictext[] = ".dict";

int get_filesize(const char *fname)

{

    struct stat st;

    int res;

    res = stat(fname, &st);

    if (res == -1)

    {

        fprintf(stderr, "Problem stating the file %s\n", fname);

        perror("Error:");

        exit(-1);

    }

    return st.st_size;

}

void init_dictionary(struct Dict *d, const char *base)

{

    char *filename;

    filename = (char *) malloc(strlen(base) + 10);

    /* Prepare .index filename and open it*/

    strcpy(filename, base);

    strcat(filename, indexext);

    d->indexsize = get_filesize(filename);

    d->indexfd = open(filename, O_RDONLY);

    if (d->indexfd == -1)

    {

        fprintf(stderr, "Problem opening the file %s\n", filename);

        perror("Error:");

        exit(-1);

    }

    d->index = (unsigned char *) mmap(0, d->indexsize, PROT_READ, MAP_SHARED,

            d->indexfd, 0);

    /* Prepare .dict filename and open it*/

    strcpy(filename, base);

    strcat(filename, dictext);

    d->defs = fopen(filename, "r");

    if (d->defs == 0)

    {

        fprintf(stderr, "Problem opening the file %s\n", filename);

        perror("Error:");

        exit(-1);

    }

    d->trim_first_line = 0;

    d->trim_last_newlines = 0;

    free(filename);

}

void end_dictionary(struct Dict *d)

{

    munmap(d->index, d->indexsize);

    close(d->indexfd);

    fclose(d->defs);

}

static int trim_first_line(char *def, int len)

{

    int new_line_pos;

    int i,j;

    for(i=0; i < len; ++i)

    {

        /* prepare ltrimming when finding the first newline character */

        if (def[i] == '\n')

        {

            /* Remove spaces after the first newline */

            for(i+=1; def[i] == ' '; ++i);

            /* Break */

            memmove(def, def + i,

                    len - i - 1);

            def[len-i-1] = 0;

            return len-i-1+1/*\0*/;

        }

    }

    return len;

}

static int trim_last_newlines(char *def, int len)

{

    int new_line_pos;

    int i,j;

    if (len < 2)

        return len;

    for(i=len-2; i >= 0; --i)

    {

        if (def[i] != '\n' && def[i] != '\r')

        {

            def[i+1] = '\0';

            return i + 1;

        }

    }

    return len;

}

static void fill_def(struct Dict *d, int offset, int length, char * def)

{

    fseek(d->defs, offset, SEEK_SET);

    fread(def, 1, length, d->defs);

    def[length] = 0;

    if (d->trim_first_line)

    {

        length = trim_first_line(def, length + 1/*\0*/) - 1 /*\0*/;

    }

    if (d->trim_last_newlines)

    {

        length = trim_last_newlines(def, length+1) - 1; /* math as above*/

    }

}

static int pointer_at_end(struct Dict *d, const unsigned char *ptr)

{

    if (ptr >= (d->index + d->indexsize))

        return 1;

    return 0;

}

static const char * skip_until_newline(struct Dict *d, const char *from)

{

    if (pointer_at_end(d, from))

        return 0;

    while(*from != '\n' && *from != 0)

    {

        ++from;

        if(pointer_at_end(d, from))

            return 0;

    }

    return from;

}

static int compare(const unsigned char *word, const unsigned char *test)

{

    int i;

    /*printf("Comparing %s to %.20s\n", word, test);*/

    for(i=0; word[i] != 0 && test[i] != 0; ++i)

    {

        if (word[i] != test[i])

        {

            break;

        }

    }

    if (word[i] == 0 && test[i] == '\t')

        return 0;

    else if (word[i] == 0)

        return -1;

    else if (test[i] == '\t')

        return 1;

    else if (word[i] > test[i])

        return 1;

    else if (word[i] < test[i])

        return -1;

    /* It should never reach this. */

    return -1;

}

static const char * search_next(struct Dict *d, const char *word, const char *from)

{

    const char *ret;

    ret = skip_until_newline(d, from) + 1;

    if (ret == (char *) 1) /* pointer at end */

        return 0;

    if (compare(word, ret) == 0)

        return ret;

    return 0;

}

static const char * bin_search(struct Dict *d, const char *word)

{

    int step, pivot;

    const char *ret;

    const char *test;

    int comparision;

    int found_once = 0;

    pivot = d->indexsize / 2;

    step = d->indexsize / 2;

    do

    {

        test = d->index + pivot;

        test = skip_until_newline(d, test);

        if (test == 0)

            return 0;

        test += 1; /* skip exactly the new line */

        comparision = compare(word, test);

        if (comparision <= 0)

        {

            if (comparision == 0)

                found_once = 1;

            /* If == 0, we don't know that it's the FIRST

             * match possible in the dictionary.

             * We want all possible matches. */

            step = step / 2;

            pivot = pivot - step;

        } else if (comparision > 0)

        {

            step = step / 2;

            pivot = pivot + step;

        }

    } while(step > 0);

    if (!found_once)

        return 0;

    if (comparision == 0) /* last comparision */

    {

        ret = skip_until_newline(d, d->index + pivot) + 1;

    } else

    {

        ret = skip_until_newline(d, test) + 1;

    }

    return ret;

}

static int my_get_int(const char **pos)

{

    int i;

    const char *start;

    int val;

    start = *pos;

    for(i=0; start[i] != '\t' && start[i] != '\n'; ++i)

        ;

    val = str2int_len(start, i);

    *pos += i + 1;

    return val;

}

void find_def(struct Dict *d, const char *word, char * def)

{

    int offset, len;

    const char *found, *pos;

    int wordlen;

    def[0] = 0;

    /* we will get a pointer to the offset for the ints*/

    found = bin_search(d, word);

    if (found == 0)

        return;

    wordlen = strlen(word);

    do

    {

        found += wordlen+1;

        pos = found;

        offset = my_get_int(&pos); /* increments pos */

        len = my_get_int(&pos); /* increments pos */

        fill_def(d, offset, len, def);

        found = search_next(d, word, found);

        if (!found)

            break;

        strcat(def, ", ");

        def += strlen(def);

    } while(1);

}