/**
 * @file util.c
 */

#include "internal.h"
#define _XOPEN_SOURCE 700
#include <wchar.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

/**
 * Portable strdup.
 *
 * @param string C "string" to copy.
 * @return Copy of the given C "string".
 */
char* _bmStrdup(const char *string)
{
    size_t len = strlen(string);
    if (len == 0)
        return NULL;

    void *copy = calloc(1, len + 1);
    if (copy == NULL)
        return NULL;

    return (char *)memcpy(copy, string, len);
}

/**
 * Shrink bmItem** list pointer.
 *
 * Useful helper function for filter functions.
 *
 * @param list Pointer to pointer to list of bmItem pointers.
 * @param osize Current size of the list.
 * @param nsize New size the list will be shrinked to.
 * @return Pointer to list of bmItem pointers.
 */
bmItem** _bmShrinkItemList(bmItem ***list, size_t osize, size_t nsize)
{
    if (nsize >= osize)
        return *list;

    void *tmp = malloc(sizeof(bmItem*) * nsize);
    if (!tmp)
        return *list;

    memcpy(tmp, *list, sizeof(bmItem*) * nsize);
    free(*list);
    *list = tmp;
    return *list;
}

/**
 * Determite columns needed to display UTF8 string.
 *
 * @param string C "string" to determite.
 * @return Number of columns, or -1 on failure.
 */
int _bmUtf8StringScreenWidth(const char *string)
{
    if (!string)
        return 0;

    int num_char = mbstowcs(NULL, string, 0) + 1;
    wchar_t *wstring = malloc((num_char + 1) * sizeof (wstring[0]));

    if (mbstowcs(wstring, string, num_char) == (size_t)(-1)) {
        free(wstring);
        return strlen(string);
    }

    int length = wcswidth(wstring, num_char);
    free(wstring);
    return length;
}

/**
 * Figure out how many bytes to shift to next UTF8 rune.
 *
 * @param string C "string" which contains the runes.
 * @param start Offset where to figure out next rune. (cursor)
 * @return Number of bytes to next UTF8 rune.
 */
size_t _bmUtf8RuneNext(const char *string, size_t start)
{
    assert(string != NULL);

    size_t len = strlen(string), i = start;
    if (len == 0 || len <= i || !*string)
        return 0;

    while (++i < len && (string[i] & 0xc0) == 0x80);
    return i - start;
}

/**
 * Figure out how many bytes to shift to previous UTF8 rune.
 *
 * @param string C "string" which contains the runes.
 * @param start Offset where to figure out previous rune. (cursor)
 * @return Number of bytes to previous UTF8 rune.
 */
size_t _bmUtf8RunePrev(const char *string, size_t start)
{
    assert(string != NULL);

    size_t len = strlen(string), i = start;
    if (i == 0 || len < start || !*string)
        return 0;

    while (--i > 0 && (string[i] & 0xc0) == 0x80);
    return start - i;
}

/**
 * Figure out how many columns are needed to display UTF8 rune.
 *
 * @param rune Buffer which contains the rune.
 * @param u8len Byte length of the rune.
 * @return Number of columns, or -1 on failure.
 */
size_t _bmUtf8RuneWidth(const char *rune, unsigned int u8len)
{
    assert(rune != NULL);
    char mb[5] = { 0, 0, 0, 0, 0 };
    memcpy(mb, rune, (u8len > 4 ? 4 : u8len));
    return _bmUtf8StringScreenWidth(mb);
}

/**
 * Remove previous UTF8 rune from buffer.
 *
 * @param string Null terminated C "string".
 * @param start Start offset where to delete from. (cursor)
 * @param runeWidth Reference to size_t, return number of columns for removed rune, or -1 on failure.
 * @return Number of bytes removed from buffer.
 */
size_t _bmUtf8RuneRemove(char *string, size_t start, size_t *runeWidth)
{
    assert(string != NULL);

    if (runeWidth)
        *runeWidth = 0;

    size_t len = strlen(string), oldStart = start;
    if (len == 0 || len < start || !*string)
        return 0;

    start -= _bmUtf8RunePrev(string, start);

    if (runeWidth)
        *runeWidth = _bmUtf8RuneWidth(string + start, oldStart - start);

    memmove(string + start, string + oldStart, len - oldStart);
    string[len - (oldStart - start)] = 0;
    return (oldStart - start);
}

/**
 * Insert UTF8 rune to buffer.
 *
 * @param string Null terminated C "string".
 * @param bufSize Size of the buffer.
 * @param start Start offset where to insert to. (cursor)
 * @param rune Buffer to insert to string.
 * @param u8len Byte length of the rune.
 * @param runeWidth Reference to size_t, return number of columns for inserted rune, or -1 on failure.
 * @return Number of bytes inserted to buffer.
 */
size_t _bmUtf8RuneInsert(char *string, size_t bufSize, size_t start, const char *rune, unsigned int u8len, size_t *runeWidth)
{
    assert(string != NULL);

    if (runeWidth)
        *runeWidth = 0;

    size_t len = strlen(string);
    if (len + u8len >= bufSize)
        return 0;

    if (u8len == 1 && iscntrl(*rune))
        return 0;

    char *str = string + start;
    memmove(str + u8len, str, len - start);
    memcpy(str, rune, u8len);

    if (runeWidth)
        *runeWidth = _bmUtf8RuneWidth(rune, u8len);
    return u8len;
}

/**
 * Insert unicode character to UTF8 buffer.
 *
 * @param string Null terminated C "string".
 * @param bufSize Size of the buffer.
 * @param start Start offset where to insert to. (cursor)
 * @param unicode Unicode character to insert.
 * @param runeWidth Reference to size_t, return number of columns for inserted rune, or -1 on failure.
 * @return Number of bytes inserted to buffer.
 */
size_t _bmUnicodeInsert(char *string, size_t bufSize, size_t start, unsigned int unicode, size_t *runeWidth)
{
    assert(string != NULL);

    char u8len = ((unicode < 0x80) ? 1 : ((unicode < 0x800) ? 2 : ((unicode < 0x10000) ? 3 : 4)));
    char mb[5] = { 0, 0, 0, 0 };

    if (u8len == 1) {
        mb[0] = unicode;
    } else {
        size_t i, j;
        for (i = j = u8len; j > 1; --j) mb[j - 1] = 0x80 | (0x3F & (unicode >> ((i - j) * 6)));
        mb[0] = (~0) << (8 - i);
        mb[0] |= (unicode >> (i * 6 - 6));
    }

    return _bmUtf8RuneInsert(string, bufSize, start, mb, u8len, runeWidth);
}

/* vim: set ts=8 sw=4 tw=0 :*/