/*
 * Copyright (c) 2004 Teodor Sigaev <teodor@sigaev.ru>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *        notice, this list of conditions and the following disclaimer in the
 *        documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of any co-contributors
 *        may be used to endorse or promote products derived from this software
 *        without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CONTRIBUTORS ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

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

static void pushoutstr(FILE *out, char *buf, int len);

static void
usage() {
        printf("Clear text from lib.ru for Pocket PC, Version 0.2.\n");
        printf("Copyright (c) 2004 Teodor Sigaev <teodor@sigaev.ru>\n");
        printf("       All rights reserved.\n");
        printf("Usage:\n   clrlibru [-i INPUTFILE] [-o OUTPUT] [-l NUMSPACE]\n");
        exit(0);
}

static char* RemoveTag[]={
	"select",
	"head",
	"div",
	"a",
	"form",
	"script",
	"style",
	"title",
	NULL
};

static int
is_rtag(char *tag, int len) {
	char **ptr=RemoveTag;

	tag[len]='\0';
	while( *ptr ) {
		if ( strcmp(tag, *ptr) == 0 ) 
			return 1;
		ptr++;
	} 
	return 0;
}

typedef struct {
	char 	*quote;
	char	*str;
	int	len;
} Quote;

static Quote quoteChange[] = {
	{"quot", "\"", -1},
	{"laquo", "\"", -1},
	{"raquo", "\"", -1},
	{"quot", "\"", -1},
	{"lt", "<", -1},
	{"gt", ">", -1},
	{"nbsp", " ", -1},
	{"mdash", "-", -1},
	{"amp", "&", -1},
	{"shy", "", -1},
	{NULL, NULL, -1}
}; 

static int
pushoutquot(FILE *out, char *buf, int buflen) {
	Quote	*ptr = quoteChange;

	buf[buflen]='\0';
	while( ptr->quote ) {
		if ( strcmp( ptr->quote, buf ) == 0 ) {
			if ( ptr->len < 0 ) 
				ptr->len = strlen( ptr->str );
			pushoutstr( out, ptr->str, ptr->len );
			return 1;
		}
		ptr++;
	}
	return 0;
}


static char *optarg = NULL;
static int current=1;

int
mgetopt(int argn, char* argv[], char *option) {
	char key;

	if ( current >= argn ) return -1;

	key = *(argv[current]+1);
	if ( *(argv[current]) == '-' || *(argv[current]) == '/' ) {
		char *ptr = strchr( option, key );
		if ( ptr == NULL ) {
			printf( "Unknown option: %s\n", argv[current]);
			exit(1);
		}
		current++;
		if ( *(ptr+1) == ':' ) {
			if (current < argn) {
				optarg=argv[current];
				current++;
			} else {
				printf("No value for -%c\n" ,key);
				exit(1);
			}
		} else
			optarg=NULL;
	} else {
		printf("Unknown option: %s\n", argv[current]);
		exit(1);
	}
	return (int)key;
}

#define INTXT		0
#define INTAG		1
#define FINDEND		2
#define INDROPTAG	3
#define INDROPINTAG	4
#define INHEADTAG	5
#define INDROPINCLSTAG	6
#define WAITAFTERRED	7
#define COMMENTBEGIN1	8	
#define COMMENTBEGIN2	9	
#define COMMENTIN	10	
#define COMMENTEND1	11	
#define COMMENTEND2	12	
#define	INQUOTE		13

#define	BUFFERLENGTH	8192
#define REDSTRING	"  "

typedef enum TypeOut {
	Char,
	NewLine,
	Tag,
	Paragraph,
	None
} TypeOut;

 
static void
pushout( FILE *out, TypeOut type, int value ) {
	static TypeOut PrevType=None;
	static int  prevvalue=0;
	static int newlinecount=0;

	if ( type == Char ) {
		if ( !(( PrevType==Tag || PrevType==None || PrevType==NewLine ) && ( value == ' ' || value == '\t' )) ) { 
			newlinecount=0;
			fputc(value ,out);
		}
		prevvalue = value;
	} else if ( type == NewLine ) {
		if ( newlinecount < 2 ) 
			fputc('\n', out);
		newlinecount++;
	} else if ( type != PrevType ) {
		switch(type) {
			case Tag:
				if ( !(PrevType==None || PrevType==NewLine || ( PrevType==Char && ( prevvalue == ' ' || prevvalue == '\t' || prevvalue == '\n'  ) )) ) { 
					newlinecount=0;
					fputc(' ', out);
				}
				break;
			case Paragraph:
				pushout(out, NewLine, 0);
				fwrite(REDSTRING, sizeof(char), strlen(REDSTRING), out); 
				newlinecount=0;
				break;
			default:
				printf("Unknown type: %d", type);
				exit(1);
		}
	}
	PrevType = type;
}

static void
pushoutstr(FILE *out, char *buf, int len) {
	char *ptr=buf;
	while( ptr-buf<len ) {
		pushout(out, Char, (int)(*ptr));
		ptr++;
	} 
}

int 
main(int argn, char *argv[]) {
	int ch;
	FILE	*in=stdin, *out=stdout;
	int state=INTXT;
	char	buf[BUFFERLENGTH];
	int lenbuf=0,closelen=0;
        int spacelen=4;

	while((ch = mgetopt(argn, argv, "l:i:o:h?"))!=-1) {
		switch (ch) {
			case 'i':
				if ( (in=fopen(optarg, "r"))==NULL) {
					printf("Can't open file %s\n", optarg);
					exit(1);
				}
				break;
			case 'o':
				if ( (out=fopen(optarg, "w"))==NULL) {
					printf("Can't open file %s\n",optarg);
					exit(1);
				}
				break;
			case 'l':
				spacelen = atoi(optarg);
				if ( spacelen < 0 || spacelen >= BUFFERLENGTH ) {
					printf("-l should be >= 0 and < %d\n", BUFFERLENGTH);
					exit(1);
				}
				break;
			case 'h':
			case '?':
			default:
				usage();
		}
	}
	
	while( (ch=getc(in)) != EOF ) {
		if ( ch == '\r' )
			continue;

		if ( state==INTXT ) {
			if ( ch == '<' ) {
				state=INHEADTAG;
				lenbuf=0;
			} else if ( ch == '\n' ) {
				state=FINDEND;
				lenbuf=1;
			} else if ( ch=='&' ) {
				*buf='&';
				lenbuf=1;	
				state=INQUOTE;
			} else { 
				pushout(out, Char, ch);
			}
		} else if ( state==INHEADTAG ) {
			if ( isalpha(ch) ) {
				if ( lenbuf < BUFFERLENGTH-1 ) { 
					buf[ lenbuf ] = tolower(ch);
					lenbuf++;
				}
			} else if ( ch == '!' ) {
				state = COMMENTBEGIN1;
			} else if ( ch == '>' ) {
				if ( is_rtag(buf,lenbuf) ) {
					state = INDROPTAG;
					closelen=0;
				} else {
					state=INTXT;
					if ( lenbuf==0 )
						pushoutstr(out, "<>", 2);
					else
						pushout(out, Tag, 0);
				}
			} else if ( lenbuf == 0 && ch != '/' ) {
				pushout(out, Char, '<');
				pushout(out, Char, ch);
				state=INTXT;
			} else { 
				if ( is_rtag(buf,lenbuf) ) {
					state = INDROPTAG;
					closelen=0;
				} else {
					state=INTAG;
				}
			}
		} else if ( state==INTAG ) {
			if ( ch == '>' ) {
				state=INTXT;
				pushout(out, Tag, 0);
			}
		} else if ( state == INDROPTAG ) {
			if ( ch == '<' ) {
				state=INDROPINTAG;
				closelen=0;
			}
		} else if ( state == INDROPINTAG ) {
			if ( ch == '/' )
				state=INDROPINCLSTAG;
			else
				state=INDROPTAG;
		} else if ( state == INDROPINCLSTAG ) {
			if ( isalpha(ch) ) {
				if ( closelen < lenbuf && tolower(ch) == buf[closelen] ) {
					closelen++;
					if ( closelen==lenbuf )
						state=INTAG;
				} else 
					state=INDROPTAG;
			} else
				state=INDROPTAG;
		} else if ( state==FINDEND ) {
			if ( ch == ' ' || ch == '\t' ) {
				lenbuf++;
				if ( lenbuf > spacelen ) {
					pushout( out, Paragraph, 0 );
					state=WAITAFTERRED;
				}
			} else if ( ch=='\n' ) {
				pushout( out, NewLine, 0 );
				pushout( out, NewLine, 0 );
				lenbuf++;
			} else {
				state=INTXT;
				pushout(out, Char, ' ');
				ungetc(ch,in);
			}
		} else if ( state==WAITAFTERRED ) {
			if ( !isspace(ch) ) {
				ungetc(ch,in);
				state=INTXT;
			}
		} else if ( state==COMMENTBEGIN1 ) {
			if ( ch == '-' ) {
				state = COMMENTBEGIN2;
			} else {
				pushoutstr(out, "<!", 2);
				ungetc(ch,in);
				state=INTXT;
			}
		} else if ( state==COMMENTBEGIN2 ) {
			if ( ch == '-' ) {
				state = COMMENTIN;
			} else {
				pushoutstr(out, "<!-", 2);
				ungetc(ch,in);
				state=INTXT;
			}
		} else if ( state==COMMENTIN ) {
			if ( ch == '-' ) 
				state = COMMENTEND1;
		} else if ( state==COMMENTEND1 ) {
			state = ( ch == '-' ) ? COMMENTEND2 : COMMENTIN;
		} else if ( state==COMMENTEND2 ) {
			if ( ch == '>' )
				state = INTXT;
			else if ( ch != '-' )
				state = COMMENTIN;
		} else if ( state==INQUOTE ) {
			if ( isalpha( ch ) && lenbuf < BUFFERLENGTH-2 ) {
				buf[ lenbuf ] = ch;
				lenbuf++;
			} else if ( ch == ';' && lenbuf>1 && pushoutquot( out, buf+1, lenbuf-1 ) ) {
				state = INTXT;
			} else {
				pushoutstr(out, buf, lenbuf);
				state = INTXT;
				ungetc(ch,in);
			}
		} else {
			printf("Unknown state: %d\n", state);
			exit(1);
		}
	}
			
	if ( in!=stdin )
		fclose(in);
	if ( out!=stdout )
		fclose(out);

	return 0;	
}