#include "util.h"
#include <ctype.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

char *remove_whitespaces(const char *str) {
    char tmp[strlen(str)];
    size_t i = 0;
    size_t j = 0;
    while (str[i] != '\0') {
        if (isspace(str[i])) {
            i += 1;
            continue;
        }
        tmp[j] = str[i];
        i += 1;
        j += 1;
    }

    char *ret = malloc(j * sizeof(char));
    strncpy(ret, tmp, j);
    ret[j] = '\0';

    return ret;
}

char *resolve_env_vars(const char *str) {
    size_t len = strlen(str);
    char *ret = malloc(MAX_PATH_LENGTH * sizeof(char));
    size_t ret_offset = 0;
    bool in_env_var = false;
    char env_var[MAX_PATH_LENGTH];
    memset(env_var, 0, sizeof(env_var));
    size_t env_var_offset = 0;

    for (size_t i = 0; i < len; ++i) {
        if (str[i] == '~') {
            char *home = getenv("HOME");
            strcat(ret, home);
            ret_offset += strlen(home);
            continue;
        }
        
        if (str[i] == '$') {
            in_env_var = true;
            continue;
        }

        // end of current env var
        if (in_env_var && !(isalpha(str[i]) || isdigit(str[i]) || str[i] == '_')) {
            in_env_var = false;

            char *env = getenv(env_var);
            strcat(ret, env);
            ret_offset += strlen(env);
            memset(env_var, 0, sizeof(env_var));
            env_var_offset = 0;
        }

        if (in_env_var) {
            env_var[env_var_offset] = str[i];
            env_var_offset += 1;
            continue;
        }

        ret[ret_offset] = str[i];
        ret_offset += 1;
    }
    ret[ret_offset] = '\0';

    return ret;
}

char *process_str(const char *str) {
    char *whitespaceless = remove_whitespaces(str);
    char *ret = resolve_env_vars(whitespaceless);
    free(whitespaceless);
    return ret;
}