/*
 * Copyright 2023 Oleg Borodin  <borodin@unix7.org>
 */

#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#include <rcache.h>
#include <cflexer.h>


#define CFLEXCONT_COMM    1
#define CFLEXCONT_END     2
#define CFLEXCONT_LWORD   3
#define CFLEXCONT_SEPAR   4
#define CFLEXCONT_SPACE   5
#define CFLEXCONT_UNDEF   6
#define CFLEXCONT_UNKNOW  7
#define CFLEXCONT_WORD    8
#define CFLEXCONT_NEWLN   9

#define CFLEXTYPE_CHAR    1
#define CFLEXTYPE_COMM    2
#define CFLEXTYPE_EOF     3
#define CFLEXTYPE_NEWLN   4
#define CFLEXTYPE_SCR     5
#define CFLEXTYPE_SEPAR   6
#define CFLEXTYPE_SPACE   7
#define CFLEXTYPE_UNDEF   8
#define CFLEXTYPE_WORDL   9

static int get_ltype(char letter) {
    switch (letter) {
        case EOF:
            return CFLEXTYPE_EOF;
        case ' ':
        case '\t':
            return CFLEXTYPE_SPACE;
        case '=':
            return CFLEXTYPE_SEPAR;
        case '\n':
            return CFLEXTYPE_NEWLN;
        case '#':
            return CFLEXTYPE_COMM;
        case '"':
            return CFLEXTYPE_WORDL;
        case '\\':
            return CFLEXTYPE_SCR;
        default:
            return CFLEXTYPE_CHAR;
    }
    return CFLEXTYPE_UNDEF;
}

void cflexer_init(cflexer_t * lexer, rcache_t * cache) {
    lexer->cache = cache;
    lexer->context = CFLEXCONT_UNDEF;
    lexer->tokpos = 0;
    lexer->letter = EOF;
    lexer->rewind = false;
    lexer->screen = false;
}

int cflexer_gettoken(cflexer_t * lexer, char* token) {

    while (true) {
        if (!lexer->rewind) {
            lexer->letter = rcache_getc(lexer->cache);
        }
        lexer->rewind = false;
        int type = get_ltype(lexer->letter);

        switch (lexer->context) {
            case CFLEXCONT_END:{
                lexer->context = CFLEXCONT_END;
                lexer->tokpos = 0;
                lexer->rewind = true;
                strcpy(token, "END");
                return CFLEXTOK_END;
            }
            case CFLEXCONT_UNDEF:{
                switch (type) {
                    case CFLEXTYPE_EOF:{
                        lexer->context = CFLEXCONT_END;
                        lexer->rewind = true;
                        break;
                    }
                    case CFLEXTYPE_CHAR:{
                        lexer->tokpos = 0;
                        token[lexer->tokpos++] = lexer->letter;
                        lexer->context = CFLEXCONT_WORD;
                        break;
                    }
                    case CFLEXTYPE_SEPAR:{
                        strcpy(token, "=");
                        lexer->context = CFLEXCONT_UNDEF;
                        return CFLEXTOK_SEPAR;
                    }
                    case CFLEXTYPE_NEWLN:{
                        lexer->tokpos = 0;
                        token[lexer->tokpos] = '\0';
                        strcpy(token, "NEWLN");
                        lexer->context = CFLEXCONT_UNDEF;
                        return CFLEXTOK_NEXT;
                    }
                    case CFLEXTYPE_SPACE:{
                        lexer->tokpos = 0;
                        token[lexer->tokpos] = '\0';
                        lexer->context = CFLEXCONT_SPACE;
                        break;
                    }
                    case CFLEXTYPE_COMM:{
                        lexer->tokpos = 0;
                        token[lexer->tokpos] = '\0';
                        lexer->context = CFLEXCONT_COMM;
                        break;
                    }
                    case CFLEXTYPE_WORDL:{
                        lexer->tokpos = 0;
                        token[lexer->tokpos] = '\0';
                        lexer->context = CFLEXCONT_LWORD;
                        break;
                    }
                    case CFLEXTYPE_SCR: {
                        lexer->tokpos = 0;
                        lexer->screen = true;
                        lexer->context = CFLEXCONT_WORD;
                        break;
                    }
                }
                break;
            }
            case CFLEXCONT_WORD:{
                switch (type) {
                    case CFLEXTYPE_SCR: {
                        if (lexer->screen == true) {
                            token[lexer->tokpos++] = lexer->letter;
                            lexer->screen = false;
                        } else {
                            lexer->screen = true;
                        }
                        continue;
                    }
                    case CFLEXTYPE_CHAR:
                        break;
                    case CFLEXTYPE_EOF:
                    default: {
                        if (lexer->screen == true) {
                            lexer->screen = false;
                            break;
                        }
                        token[lexer->tokpos++] = '\0';
                        lexer->context = CFLEXCONT_UNDEF;
                        lexer->rewind = true;
                        lexer->screen = false;
                        return CFLEXTOK_WORD;
                    }
                }
                lexer->screen = false;
                token[lexer->tokpos++] = lexer->letter;
                break;
            }
            case CFLEXCONT_LWORD:{
                switch (type) {
                    case CFLEXTYPE_SCR: {
                        if (lexer->screen == true) {
                            token[lexer->tokpos++] = lexer->letter;
                            lexer->screen = false;
                        } else {
                            lexer->screen = true;
                        }
                        continue;
                    }
                    case CFLEXTYPE_WORDL: {
                        if (lexer->screen == true) {
                            lexer->screen = false;
                            break;
                        }
                        token[lexer->tokpos++] = '\0';
                        lexer->context = CFLEXCONT_UNDEF;
                        lexer->screen = false;
                        return CFLEXTOK_WORD;
                    }
                    case CFLEXTYPE_EOF: {
                        token[lexer->tokpos++] = '\0';
                        lexer->context = CFLEXCONT_UNDEF;
                        lexer->rewind = true;
                        return CFLEXTOK_WORD;
                    }
                    default:{
                        break;
                    }
                }
                lexer->screen = false;
                token[lexer->tokpos++] = lexer->letter;
                break;
            }
            case CFLEXCONT_SPACE:{
                switch (type) {
                    case CFLEXTYPE_SPACE:
                        break;
                    case CFLEXTYPE_EOF:
                    default: {
                        lexer->rewind = true;
                        lexer->context = CFLEXCONT_UNDEF;
                        continue;
                        //lexer->context = CFLEXCONT_UNDEF;
                        //lexer->rewind = true;
                        //strcpy(token, "SPACE");
                        //return CFLEXTOK_SPACE;
                    }
                }
                break;
            }
            case CFLEXCONT_NEWLN:{
                switch (type) {
                    case CFLEXTYPE_NEWLN:
                        break;
                    case CFLEXTYPE_EOF:
                    default: {
                        lexer->rewind = true;
                        lexer->context = CFLEXCONT_UNDEF;
                        strcpy(token, "NEWSLN");
                        return CFLEXTOK_NEXT;
                    }
                }
                break;
            }
            case CFLEXCONT_COMM:{
                switch (type) {
                    case CFLEXTYPE_EOF:
                    case CFLEXTYPE_NEWLN:
                        lexer->context = CFLEXCONT_UNDEF;
                        lexer->rewind = true;
                        strcpy(token, "COMMENT");
                        return CFLEXTOK_COMM;
                    default: {
                        break;
                    }
                }
                break;
            }

        }
    }

    strcpy(token, "UNDEF");
    return CFLEXTOK_UNDEF;
}

void cflexer_destroy(cflexer_t * lexer) {
    (void)lexer;
}