#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdbool.h>

#ifndef STACK_H
#include "stack.h"
#endif
#ifndef OPTABLE_H
#include "optable.h"
#endif

bool isnumber(char *text) {
    for(int j = strlen(text); j > 0; j--) {
        if(text[j] < '0' && text[j] > '9') {
            return false;
        }
    }
    return true;
}

bool notdelim(char c) {
    return c != ' ' && c != '\n' && c != '\t' && c != '\0';
}

typedef struct {
    optable* ot;
    stack* s;
} forthmachine;

forthmachine* forthmachine_new() {
    forthmachine* fm = malloc(sizeof(forthmachine));
    fm->ot = optable_new();
    fm->s = stack_new();
    return fm;
}

void eval(forthmachine* fm, int len, char* line);

void op_exec(wordop* op, forthmachine* fm, char *word, int len, char* line, int* i) {
    switch (op->optype) {
        case script:
            eval(fm, op->scriptlen, op->script);
            break;
        case builtin:
            op->op(fm->s);
            break;
        case directive:
            op->directive(fm->s, len, line, i, fm->ot);
            break;
        case compiled:
            for (int j = 0; j < op->oplistlen; j++) {
                if (op->oplist[j].isliteral) {
                    stack_push(fm->s, op->oplist[j].literal);
                } else {
                    op_exec(op->oplist[j].wordop, fm, word, len, line, i);
                }
            }
    }
}

void exec(forthmachine* fm, char *word, int len, char* line, int* i) {
    wordop* op = optable_getop(fm->ot, word);
    if (op) {
        op_exec(op, fm, word, len, line, i);
    } else if (isnumber(word)) {
        stack_push(fm->s, atoi(word));
    }
}

void eval(forthmachine* fm, int len, char* line) {
    char word[WORD_LEN_LIMIT];
    int wordi = 0;
    for (int i = 0; i < len; i++) {
        if (notdelim(line[i]) && wordi < WORD_LEN_LIMIT - 1) {
            word[wordi++] = line[i];
        } else { // end of word
            if (wordi > 0) { // don't exec an empty string
                word[wordi] = '\0';
                exec(fm, word, len, line, &i);
            }
            // start new word
            wordi = 0;
        }
        // end of input string
        if (line[i] == '\0') {
            return;
        }
    }
}

int initialised = false;
forthmachine* fm;
int lastline = 0;

char* buffer_eval(int len, char* line) {
    if (!initialised) {
        fm = forthmachine_new();
        initialised = true;
        outputline = 0;
        outputbuffer = malloc(sizeof(char) * 1024);
    }
    strcpy(outputbuffer, "");
    eval(fm, len, line);
    if (outputline) {
        outputline = 0;
        return outputbuffer;
    } else {
        return "";
    }
}

void stdin_eval() {
    forthmachine* fm = forthmachine_new();
    char *line = NULL;
    size_t len = 0;
    ssize_t read;
    while ((read = getline(&line, &len, stdin)) != -1) {
        eval(fm, len, line);
    }
}

#ifndef __EMSCRIPTEN__

int main(int argc, char** argv) {
    if (argc>1) printf("%s", buffer_eval(strlen(argv[1])+1, argv[1]));
    else stdin_eval();
}

#else

#include <emscripten/emscripten.h>
#define EXTERN

EXTERN EMSCRIPTEN_KEEPALIVE char* extern_eval(char* line) {
    return buffer_eval(strlen(line)+1, line);
}
#endif