colcat/colcat.c

#include "colours/colours.h"
#include <getopt.h>
#include <stdbool.h>

#define READ_BUFFER_SIZE 200

/*
 * Basic Settings
 */
int rainbow_len = 80;   // how many characters long is one full rainbow (360deg)
int col_change;         // how many degrees between colours in the rainbow
int col_dist;           // how many characters per colour in output

struct colour* colours; // the rainbow 
int num_colours;        // the length of the rainbow

/* Print the nth colour of the <rainbow_len> rainbow */
void print_next_colour(int current) {
    if (current % col_dist == 0) {
        struct colour c = colours[(current % num_colours) / col_dist];
        c = get_rgb(c);
        printf("\x1b[38;2;%d;%d;%dm", c.r, c.g, c.b);
    }
}

int display(FILE *file) {
    char c = fgetc(file);

    int counter = 0;
    while (c != EOF) {
        if (c == '\n') {
            counter = 0;
        }
        print_next_colour(counter);
        printf("%c", c);

        counter++;
        c = fgetc(file);
    }
    return 0;
}

int open_and_cat(char *file_name) {
    FILE *file = fopen(file_name, "r");

    if (!file) {
        return 1;
    }

    return display(file);
}

int generate_rainbow() {
    if (rainbow_len < 360) {
        num_colours = rainbow_len;
        col_change = 360 / num_colours;
        if (col_change == 0) {
            col_change = 1;
        }
    } else {
        num_colours = 360;
        col_change = 1;
    }

    col_dist = rainbow_len / num_colours;
    colours = calloc(num_colours, sizeof(struct colour));
    struct colour c;
    c.h = 0;
    c.s = 1;
    c.v = 1;
    c.sp = CS_HSV;
    for (int i = 0; i < num_colours; i++) {
        c.h = (int)(c.h + col_change) % 360;
        colours[i] = c;
    }

    return 0;
}

int main(int argc, char** argv) {
    int opt;
    int optcount = 0;
    while ((opt = getopt(argc, argv, "l:")) != -1) {
        optcount++;
        if (opt == 'l') {
            optcount++;
            rainbow_len = atoi(optarg);
        } else {
            printf("Usage: colcat -l [rainbow length]");
        }
    }

    generate_rainbow();

    if (argc > optcount + 1) {
        for (int i = 1; i < argc; i++) {
            int err = open_and_cat(argv[i]);
            if (err) {
                perror("Unable to open file");
                exit(err);
            }
        }
    } else {
        display(stdin);
    }
}