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#include "columns.h"
#include "data_struct.h"
#include <string.h>
#include <stddef.h>
/* column indexes used for alignment */
enum column_type {
col_links = 1,
col_owner = 2,
col_group = 3,
col_size = 4
};
/*
* find pointer to beginning of column in line.
* pad_spaces -- column index
*/
static char *find_start_column_pos(char *line, enum column_type pad_spaces)
{
size_t found_whitespace = 0;
while(found_whitespace != pad_spaces) {
if(*line == ' ') {
++found_whitespace;
/* skip consecutive spaces */
while(*line == ' ')
++line;
} else
++line;
}
return line;
}
/* Find pointer to the end of current column */
static char *find_end_column_pos(char *line)
{
while(*line && *line != ' ')
++line;
return line;
}
/*
* Count number of symbols in column.
* Special case: when dealing with major and minor numbers (contains ',').
*/
static size_t compute_symbols(const char *line, enum column_type pad_spaces)
{
size_t symbols_counter = 0;
while(*line && *line != ' ') {
++symbols_counter;
/* extra space for alignment after comma */
if(*line == ',' && pad_spaces == col_size) {
++symbols_counter;
++line;
}
++line;
}
return symbols_counter;
}
/* scan all items and find maximum column width */
static size_t find_max_column(struct file_item *list,
enum column_type pad_spaces)
{
size_t max_columns = 0;
size_t current_columns = 0;
char *pos = NULL;
while(list) {
pos = find_start_column_pos(list->info_line, pad_spaces);
current_columns = compute_symbols(pos, pad_spaces);
if(current_columns > max_columns)
max_columns = current_columns;
list = list->next;
}
return max_columns;
}
/* check if column must be left aligned */
static int is_left_alignment(enum column_type pad_spaces)
{
return pad_spaces == col_owner || pad_spaces == col_group;
}
/* calculate remaining string length including null symbol */
static size_t get_remaining_line_length(const char *line)
{
size_t symbols_counter = 0;
while(*line) {
++symbols_counter;
++line;
}
/* null-terminated */
++symbols_counter;
return symbols_counter;
}
/* fill alignment gap with spaces */
static void pad_with_spaces(char *pos, int alignment) {
for (; alignment > 0; --alignment, ++pos)
*pos = ' ';
}
/* shift contents to the right and pad with spaces */
static void shift_and_pad(char *insert_pos, size_t alignment,
char *start_buffer_pos)
{
size_t remaining_symbols = get_remaining_line_length(insert_pos);
size_t offset = (size_t)(insert_pos - start_buffer_pos);
if (offset + remaining_symbols + alignment <= buffer_size) {
memmove(insert_pos + alignment, insert_pos, remaining_symbols);
pad_with_spaces(insert_pos, alignment);
}
}
/* insert spaces after column (left alignment) */
static void left_align(char *column_pos, size_t alignment,
char *start_buffer_pos)
{
char *end_column_pos = find_end_column_pos(column_pos);
shift_and_pad(end_column_pos, alignment, start_buffer_pos);
}
/* insert spaces before column (right alignment) */
static void right_align(char *column_pos, size_t alignment,
char *start_buffer_pos)
{
shift_and_pad(column_pos, alignment, start_buffer_pos);
}
/* align single column*/
static void align_column(struct file_item *list, enum column_type pad_spaces)
{
char *column_pos = NULL;
size_t max_columns = find_max_column(list, pad_spaces);
size_t current_columns = 0;
size_t different = 0;
if(max_columns == 1)
return;
while(list) {
column_pos = find_start_column_pos(list->info_line, pad_spaces);
current_columns = compute_symbols(column_pos, pad_spaces);
different = max_columns - current_columns;
if(different > 0) {
if(is_left_alignment(pad_spaces))
left_align(column_pos, different, list->info_line);
else
right_align(column_pos, different, list->info_line);
}
list = list->next;
}
}
/*
* Align all columns (links, owner, group, size).
* Must be called after building info_line
*/
void align_columns(struct file_item *list)
{
align_column(list, col_links);
align_column(list, col_owner);
align_column(list, col_group);
align_column(list, col_size);
}
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