#include "../command.h"

static void help(void) {
    printf("Usage: dd [if=FILE] [of=FILE] [bs=N] [count=N]\n\n");
    printf("Copy a file with converting and formatting\n\n");
    printf("\tif=FILE\t\tRead from FILE instead of stdin\n");
    printf("\tof=FILE\t\tWrite to FILE instead of stdout\n");
    printf("\tbs=N\t\tRead and write N bytes at a time\n");
    printf("\tcount=N\t\tCopy only N input blocks\n");
}

COMMAND(dd) {

    FILE* in_file = stdin;
    FILE* out_file = stdout;
    int bs = 1024;
    int count = -1;

    parse_help(argc, argv, help);

    for (int i = 0; i < argc; i++) {
        if (prefix("if=", argv[i])) {
            char* path = argv[i] + 3;
            in_file = get_file(path, "rb");
        } else if (prefix("of=", argv[i])) {
            char* path = argv[i] + 3;
            out_file = get_file(path, "wb");
        } else if (prefix("bs=", argv[i])) {
            char* str = argv[i] + 3;
            bs = get_number(str);
            if (bs < 1) {
                error("block size must be greater than 0");
            }
        } else if (prefix("count=", argv[i])) {
            char* str = argv[i] + 6;
            count = get_number(str);
            if (count < 1) {
                error("count must be greather than 0");
            }
        } else {
            error("unkown option %s", argv[i]);
        }
    }
 
    char* buffer = malloc(bs);
    size_t read;
    while ((read = fread(buffer, 1, bs, in_file)) != 0) {
        fwrite(buffer, 1, read, out_file);
        if (--count, count == 0) break;
    }

    free(buffer);
    fclose(in_file);
    fclose(out_file);

    return EXIT_SUCCESS;
}