#ifdef COSMOPOLITAN
#include "cosmopolitan.h"
#else
#include <getopt.h>
#include <stdbool.h>
#endif

#include "c-colours/colours.h"

#define READ_BUFFER_SIZE 200

/*
 * Basic Settings
 */
int rainbow_len = 90;   // how many characters long is one full rainbow (360deg)
int col_change = -1;         // how many degrees between colours in the rainbow
int col_dist = -1;           // how many characters per colour in output
int frequency = -1;          // how many degrees to rotate start_hue point on new line

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

// start_hue and end_hue hue values
int start_hue = -1;
int end_hue = -1;
bool reverse = false;

char help_text[] = "\nUsage: colcat [args] [--] [FILES] \n"
                     "\n"
                     "Concatenate files (or standard input) and print on the standard\n"
                     "output, with a rainbow colour. The colour range and repeat\n"
                     "distance can be specified.\n\n"
                     "Args:\n\n"
                     "      -h           Print help text and exit\n"
                     "      -w <int>     Width, in chars, of the rainbow sequence\n"
                     "      -r <int>     The amount the hue is rotated on new lines\n"
                     "      -s <int>     The hue to start the rainbow at\n"
                     "      -e <int>     The hue to end the rainbow at\n"
                     "\n";


/* Print the nth colour of the <rainbow_len> chars long rainbow */
void print_next_colour(int current) {

    if (current % (num_colours) == 0 && current > 0) {
        reverse = !reverse;
    }

    int index = 0;
    if (!reverse) {
        index = (current % num_colours) / col_dist;
    } else {
        index = num_colours -1- (current % num_colours) / col_dist;
    }

    if (current % col_dist == 0) {
        struct colour c = colours[index];
        printf("\x1b[38;2;%d;%d;%dm", c.r, c.g, c.b);
    }
}

/* Checks if a car is a possible ANSI escape code end_hueing */
bool end_hue_ansi_code(char c) {
    char codes[] = "HfABCDsuJKmhlP";
    for (int i = 0; i < strlen(codes); i++) {
        if (c == codes[i]) {
            return true;
        }
    }
    return false;
}

/* Print a file with rainbow */
int display(FILE *file) {
    char c = fgetc(file);

    int start = 0;
    int end;
    int counter = 0;
    if (frequency) 
        end = (num_colours / frequency);
    else {
        end = 0;
        counter = num_colours; // so that print starts at reverse=true
    }
    bool in_escape = false;
    bool in_utf8_mbchar = false;
    bool vert_reverse = false;
    while (c != EOF) {


        if (c == '\n') {
            if (frequency && end) {
                if (counter % (end) == 0) {
                    vert_reverse = !vert_reverse;
                }
                counter = start += (vert_reverse ? -1 : 1) * frequency;
                if (counter < 0) {
                    counter = -counter;
                }
            } else {
                counter = num_colours;
            }
            reverse = false;
        }

        if ((c & 0b11000000) == 0b10000000) {
            in_utf8_mbchar = true;
        } else {
            in_utf8_mbchar = false;
        }

        if (c == '\033') {
            in_escape = true;
        } else if (end_hue_ansi_code(c) && in_escape) {
            in_escape = false;
            putc(c, stdout);
            c = fgetc(file);
            counter++;
            continue;
        }
        
        if (!in_escape && !in_utf8_mbchar) {
            print_next_colour(counter);
        }

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

/* Attempt to open a file and display, or return 1 on error */
int open_and_cat(char *file_name) {
    FILE *file = fopen(file_name, "r");

    if (!file) {
        return 1;
    }

    return display(file);
}

/* - Generate an array containing all the colours to use for the 
 * rainbow by rotating HSV(0, 100, 100) through hue 0 to 360, using
 * intervals fitting to how many characters are in the interval. 
 * - They are stored as RGB.
 * - sets all the relevant global variables for printing the 
 * rainbow out again
 */
int generate_rainbow() {

    if (start_hue == -1) {
        start_hue = 0;
    }
    if (end_hue == -1) {
        end_hue = 360;
    }

    if (end_hue < start_hue) {
        exit(1);
    }

    int arclen = end_hue - start_hue;

    if (rainbow_len < arclen) {
        num_colours = rainbow_len;
        col_change = arclen / num_colours;
        if (col_change == 0) {
            col_change = 1;
        }
    } else {
        num_colours = arclen;
        col_change = 1;
    }

    col_dist = (rainbow_len) / (num_colours);
    colours = calloc(num_colours, sizeof(struct colour));
    struct colour c;
    c.h = start_hue;
    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) % arclen;
        colours[i] = get_rgb(c);
    }

    c.h = end_hue;
    colours[num_colours - 1] = get_rgb(c);

    return 0;
}

/* Parses args, sets globals, and chooses whether to read files or stdin */
int main(int argc, char** argv) {
    int opt;
    int optcount = 0;
    while ((opt = getopt(argc, argv, "hw:r:s:e:")) != -1) {
        optcount++;
        if (opt == 'w') {
            optcount++;
            rainbow_len = atoi(optarg);
        } else if (opt == 'r') {
            optcount++;
            frequency = atoi(optarg);
        } else if (opt == 's') {
            optcount++;
            start_hue = atoi(optarg);
        } else if (opt == 'e') {
            optcount++;
            end_hue = atoi(optarg);
        } else if (opt == 'h') {
            printf("%s", help_text);
            exit(0);
        } else {
            printf("%s", help_text);
            exit(1);
        }
    }

    generate_rainbow();

    if (frequency == -1) {
        frequency = col_change;
    }

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