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

static NodePtr allocateNode();
static NodePtr createNode(RegexInfoPtr,unsigned char*,NodePtr,NodePtr);
static NodePtr charClass(RegexInfoPtr);
static NodePtr group(RegexInfoPtr);
static void token(RegexInfoPtr);
static NodePtr regexAtom(RegexInfoPtr);
NodePtr regex(RegexInfoPtr);

/**
 * Create a node of regex parse tree.
 *     tokenType
 *     regexPosition(state)
 *     stateTransitionTable
 */

static
NodePtr allocateNode() {
    NodePtr n = (NodePtr)malloc(sizeof(node));
    n->cc = (CharClassPtr)malloc(sizeof(CharClass));
    n->cc->cond = (ConditionList)malloc(sizeof(Condition));
    return n;
}

static
NodePtr createNode(RegexInfoPtr ri,unsigned char *character, NodePtr left, NodePtr right) {
    NodePtr n = allocateNode();
    if (n == NULL) {
        mallocFailedMessage();
    }

    n->tokenType = ri->tokenType;
    n->left = left;
    n->right = right;
    n->nodeNumber = ri->nodeNumber;
    ri->nodeNumber++;

    if (ri->tokenType == 'a') {
        ri->tokenType = 0;
        n->cc->cond->w = getWord(ri->tokenValue);
        ri->ptr += n->cc->cond->w->length-1;
    } else {
        WordPtr w = (WordPtr)malloc(sizeof(Word));
        w->word = character;
        w->length = 1;
        n->cc->cond->w = w;
    }
    return n;
}

// <charClass> ::= '['<literal>'-'<literal>']'
static
NodePtr charClass(RegexInfoPtr ri) {
    NodePtr n = (NodePtr)malloc(sizeof(Node));
    if (n == NULL) {
        mallocFailedMessage();
    }
    while (ri->ptr[0] == '-') {
        ri->ptr++;
    }
    return n;
}

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

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

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

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

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

    return n;
}

// <regex> ::= <regexAtom>|<regexAtom>'*'|<regexAtom>'|'<regex>|<regexAtom><regex>
NodePtr regex(RegexInfoPtr ri) {
    NodePtr n = regexAtom(ri);
    while (ri->ptr[0]) {
        token(ri);
        if (ri->tokenType == '*') {
            unsigned char *syntax = (unsigned char*)malloc(sizeof(unsigned char));
            syntax[0] = '*';
            n = createNode(ri,syntax,n,0);
        } else if (ri->tokenType == '|') {
            NodePtr n1 = regex(ri);
            unsigned char *syntax = (unsigned char*)malloc(sizeof(unsigned char));
            syntax[0] = '|';
            n = createNode(ri,syntax,n,n1);
        } else if (ri->tokenType == ')') {
            return n;
        } else {
            NodePtr n1 = regex(ri);
            unsigned char *syntax = (unsigned char*)malloc(sizeof(unsigned char));
            syntax[0] = '+';
            n = createNode(ri,syntax,n,n1);
        }
    } return n;
}