/*
 * <literal> ::= [a-z][A-Z][0-9]
 * <charClass> ::= '['<literal>'-'<literal>']'
 * <group> ::= '('<regex>')'
 * <regexAtom> ::= <literal>|<charClass>|<group>
 * <regex> ::= <regexAtom>|<regexAtom>'*'|<regexAtom>'|'<regex>|<regexAtom><regex>
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "regexParser.h"

unsigned char *ptr;
unsigned char tokenType;
int tokenValue;
NodePtr regexHeadNode;

NodePtr charClass();
NodePtr group();
NodePtr regex();
NodePtr createNode(unsigned char,NodePtr,NodePtr);
void token();
NodePtr regexAtom();


bool isLiteral(char c) {
    if (*ptr > 0x7f) return true;
    else if (*ptr == '(') return false;
    else if (*ptr == '[') return false;
    else if (*ptr == '|') return false;
    else if (*ptr == '*') return false;
    return true;
}

/**
 * Create a node of regex parse tree.
 *     tokenType
 *     regexPosition(state)
 *     stateTransitionTable
 */
NodePtr createNode(unsigned char character, NodePtr left, NodePtr right) {
    NodePtr n = (NodePtr)malloc(sizeof(Node));
    n->self = n;
    n->Value.character = character;
    n->left = left;
    n->right = right;
    return n;
}

// <charClass> ::= '['<literal>'-'<literal>']'
NodePtr charClass() {
    NodePtr n = (NodePtr)malloc(sizeof(Node));
    unsigned char startChar = *ptr;
    while (*ptr == '-') {
        ptr++;
    }
    unsigned char endChar = *ptr;
    unsigned char *charTable = (unsigned char*)malloc(sizeof(char)*256);

    return n;
}

// <literal> ::= [a-z][A-Z][0-9]
NodePtr literal() {
    NodePtr n = createNode(*ptr,0,0);
    ptr++;
    return n;
}

// <group> ::= '('<regex>')'
NodePtr group() {
    return regex();
}



void token() {
    while (*ptr != '\0') {
        if (*ptr == '('){
            ptr++;
            tokenType = '(';
            tokenValue = 0;
            if (ptr[1] == ')') {
                ptr++;
            }
            return;
        } else if (*ptr == ')') {
            ptr++;
            tokenType = ')';
            tokenValue = *ptr;
            return;
        } else if (*ptr == '[') {
            ptr++;
            tokenType = '[';
            tokenValue = *ptr;
            if (ptr[1] == ']') {
                ptr++;
            }
            return;
        } else if (*ptr == '|'){
            ptr++;
            tokenType = '|';
            tokenValue = 0;
            return;
        } else if (*ptr == '*'){
            ptr++;
            tokenType = '*';
            tokenValue = 0;
            return;
        } else if (*ptr == '\\'){
            // need more proccesing 
            /*
                \277
                \0xa5
                \[
                \\
                \utf-8 etc...
            */
        } else {
            tokenType = 'a';
            tokenValue = *ptr;
            return;
        }
    }

    tokenType = 0;
    tokenValue = 0;
    return;
}

// <regexAtom> ::= <literal>|<charClass>|<group>
NodePtr regexAtom() {

    token();
    NodePtr n = NULL;
    if (tokenType == 'a') n = literal();
    else if (tokenType == '[') n = charClass();
    else if (tokenType == '(') n = group();

    return n;
}

// <regex> ::= <regexAtom>|<regexAtom>'*'|<regexAtom>'|'<regex>|<regexAtom><regex>
NodePtr regex() {
    NodePtr n = regexAtom();
    while (*ptr) {
        token();
        if (tokenType == '*') {
            n = createNode('*',n,0);
        } else if (tokenType == '|') {
            NodePtr n1 = regex();
            n = createNode('|',n,n1);
        } else if (tokenType == ')') {
            return n;
        } else {
            NodePtr n1 = regex();
            n = createNode('+',n,n1);
        }
    } return n;
}

void descendTree(NodePtr n) {
    static int d = 0;
    if (n->right != NULL) {
        d++;
        descendTree(n->right);
        d--;
    }
    printf("%*c%c\n",d*4, ' ',n->Value.character);
    if (n->left != NULL) {
        d++;
        descendTree(n->left);
        d--;
    }
}

void printTree(NodePtr n) {
    puts("---Print Node----");
    descendTree(n);
    puts("-----------------");
}


int main(int argc, char **argv)
{
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i],"-regex") == 0) {
            ptr = (unsigned char*)argv[i+1]; i++;
        }
    }

    printf("regex : %s\n",ptr);
    NodePtr n = regex();
    printTree(n);
    return 0;
}