#include <stdlib.h>
#include <string.h>
#include "events.h"

void events_init_handler(EventHandler *handler) {
    handler->vars = 0;
}

int events_bind_variable(EventHandler *handler, int *var, char *name) {
    if(handler->vars < MAX_VARIABLES){
        handler->variables[handler->vars] = var;
        handler->var_names[handler->vars++] = name;
    }else{
        return 1;
    }
    return 0;
}

char op_chars[OP_AMOUNT+1] = " =+-/*%";

int _op_null(int a, int b) {
    return 0;
}

int _op_set(int a, int b) {
    return b;
}

int _op_add(int a, int b) {
    return a+b;
}

int _op_sub(int a, int b) {
    return a-b;
}

int _op_div(int a, int b) {
    if(b == 0) return 0;
    return a/b;
}

int _op_mul(int a, int b) {
    return a*b;
}

int _op_mod(int a, int b) {
    if(b == 0) return 0;
    return a%b;
}

int (*_operations[OP_AMOUNT])(int, int) = {
    _op_null,
    _op_set,
    _op_add,
    _op_sub,
    _op_div,
    _op_mul,
    _op_mod
};

#define MIN(a, b) a < b ? a : b

char _message_buffer[MESSAGE_BUFFER_SZ];
char *events_parse_string(EventHandler *handler, char *message) {
    size_t message_pos = 0;
    char in_token = 0;
    char var_name[TOKEN_MAX_SZ];
    size_t name_pos = 0;
    Operation var_op = OP_NULL;
    char num[TOKEN_MAX_SZ];
    size_t num_pos = 0;
    Token tok_type = T_NULL;
    char c;
    size_t i, n;
    int *var;
    for(i=0;i<strlen(message);i++){
        c = message[i];
        if(c == '`'){
            in_token = !in_token;
            if(!in_token){
                if(tok_type == T_VAR_EDIT){
                    /* Do the calculation */
                    var_name[MIN(name_pos, TOKEN_MAX_SZ)] = '\0';
                    num[MIN(num_pos, TOKEN_MAX_SZ)] = '\0';
                    for(n=0;n<handler->vars;n++){
                        if(!strcmp(var_name, handler->var_names[n])){
                            var = handler->variables[n];
                            if(var_op){
                                *var = _operations[var_op](*var, atoi(num));
                            }
                            break;
                        }
                    }
                }
                /* Reset everything */
                tok_type = T_NULL;
                name_pos = 0;
                var_op = OP_NULL;
                num_pos = 0;
            }
        }else if(!in_token){
            if(message_pos < TOKEN_MAX_SZ) _message_buffer[message_pos++] = c;
        }
        if(in_token && c != ' '){
            if(tok_type == T_VAR_EDIT){
                if(var_op != OP_NULL){
                    if(num_pos < TOKEN_MAX_SZ) num[num_pos++] = c;
                }
                if(strchr(op_chars, c)){
                    var_op = (Operation)(strchr(op_chars, c)-op_chars);
                }
                if(var_op == OP_NULL){
                    if(name_pos < TOKEN_MAX_SZ) var_name[name_pos++] = c;
                }
            }
            if(c == '$'){
                tok_type = T_VAR_EDIT;
            }
        }
    }
    _message_buffer[MIN(message_pos, MESSAGE_BUFFER_SZ)] = '\0';
    return _message_buffer;
}