r/r_diff.c at 6b64e96abecf388785046f41626628648bf957f9

 // retoor <retoor@molodetz.nl>
 #include "r_diff.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
 #define COLOR_RED     "\x1b[31m"
 #define COLOR_GREEN   "\x1b[32m"
 #define COLOR_CYAN    "\x1b[36m"
 #define COLOR_RESET   "\x1b[0m"
 #define COLOR_DIM     "\x1b[2m"
 #define COLOR_BG_RED  "\x1b[41;37m"
 #define COLOR_BG_GREEN "\x1b[42;30m"
 typedef struct {
     char **lines;
     size_t count;
 } line_set_t;
 static line_set_t split_lines(const char *str) {
     line_set_t set = {NULL, 0};
     if (!str || !*str) return set;
     char *copy = strdup(str);
     char *p = copy;
     char *line_start = copy;
     while (*p) {
         if (*p == '\n') {
             *p = '\0';
             set.lines = realloc(set.lines, sizeof(char *) * (set.count + 1));
             set.lines[set.count++] = strdup(line_start);
             line_start = p + 1;
         }
         p++;
     }
     // Handle last line if no trailing newline
     if (*line_start) {
         set.lines = realloc(set.lines, sizeof(char *) * (set.count + 1));
         set.lines[set.count++] = strdup(line_start);
     }
     free(copy);
     return set;
 }
 static void free_line_set(line_set_t set) {
     for (size_t i = 0; i < set.count; i++) free(set.lines[i]);
     free(set.lines);
 }
 static void print_truncated(const char *str, int width, const char *color) {
     if (width <= 0) return;
     int len = (int)strlen(str);
     if (color) printf("%s", color);
     if (len > width && width > 3) {
         char *temp = strndup(str, (size_t)width - 3);
         printf("%s...", temp);
         free(temp);
     } else {
         printf("%-*.*s", width, width, str);
     }
     if (color) printf("%s", COLOR_RESET);
 }
 void r_diff_print(const char *path, const char *old_content, const char *new_content) {
     line_set_t old_set = split_lines(old_content);
     line_set_t new_set = split_lines(new_content);
     struct winsize w;
     ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
     int term_width = w.ws_col > 0 ? w.ws_col : 120;
     if (term_width < 40) term_width = 40; // Minimum usable width
     int col_width = (term_width - 15) / 2;
     if (col_width < 5) col_width = 5;
     printf("\n%s %s CHANGES: %s %s\n", COLOR_CYAN, COLOR_DIM, path, COLOR_RESET);
     printf("%4s %-*s | %4s %-*s\n", "LINE", col_width, " OLD", "LINE", col_width, " NEW");
     printf("%.*s\n", term_width, "--------------------------------------------------------------------------------------------------------------------------------------------");
     size_t o = 0, n = 0;
     while (o < old_set.count || n < new_set.count) {
         bool match = false;
         if (o < old_set.count && n < new_set.count) {
             if (strcmp(old_set.lines[o], new_set.lines[n]) == 0) {
                 printf("%4zu   ", o + 1);
                 print_truncated(old_set.lines[o], col_width - 2, NULL);
                 printf(" | %4zu   ", n + 1);
                 print_truncated(new_set.lines[n], col_width - 2, NULL);
                 printf("\n");
                 o++; n++;
                 match = true;
             }
         }
         if (!match) {
             bool found_o_later = false;
             if (o < old_set.count) {
                 for (size_t i = n + 1; i < new_set.count && i < n + 5; i++) {
                     if (strcmp(old_set.lines[o], new_set.lines[i]) == 0) {
                         found_o_later = true;
                         break;
                     }
                 }
             }
             if (found_o_later) {
                 // Line added on NEW side
                 printf("%4s   ", "");
                 print_truncated("", col_width - 2, NULL);
                 printf(" | %4zu %s+%s ", n + 1, COLOR_GREEN, COLOR_RESET);
                 print_truncated(new_set.lines[n], col_width - 2, COLOR_GREEN);
                 printf("\n");
                 n++;
             } else if (o < old_set.count) {
                 // Line removed on OLD side
                 printf("%4zu %s-%s ", o + 1, COLOR_RED, COLOR_RESET);
                 print_truncated(old_set.lines[o], col_width - 2, COLOR_RED);
                 printf(" | %4s   ", "");
                 print_truncated("", col_width - 2, NULL);
                 printf("\n");
                 o++;
             } else if (n < new_set.count) {
                 // Line added on NEW side
                 printf("%4s   ", "");
                 print_truncated("", col_width - 2, NULL);
                 printf(" | %4zu %s+%s ", n + 1, COLOR_GREEN, COLOR_RESET);
                 print_truncated(new_set.lines[n], col_width - 2, COLOR_GREEN);
                 printf("\n");
                 n++;
             }
         }
         fflush(stdout);
         usleep(30000); // 30ms delay for streaming effect
     }
     printf("\n");
     fflush(stdout);
     free_line_set(old_set);
     free_line_set(new_set);
 }