#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <errno.h>

#define OUT 0
#define ENTER 1
#define END_TAG 2
#define IMG_TAG 3
#define A_TAG 4
#define HREF_SRC_CONTENT 5

#define BUFFER_LENGTH 256
#define URL_LENGTH 1024

char my_get_char(){
    static char buff[BUFFER_LENGTH];
    static int i = 0;
    static int end = 0;
    if( i < end ){
        return buff[i++];
    }
    else {
        end = read( 0, buff, BUFFER_LENGTH );
        if( !end )
            exit(EXIT_SUCCESS);
        if( end == -1 ){
            printf("Echec de la lecture sur l'entrée standard %d !\n", errno);
            perror("");
            exit(EXIT_FAILURE);
        }
        i = 1;
        return buff[0];
    }
}

void parse()
{
    register int state = OUT;
    register int cur;
    char url[URL_LENGTH + 1];
    int i;
    while(1)
    {
        switch( state ){
            case OUT :
                while( my_get_char() != '<' );
                state = ENTER;
                break;
            
            case ENTER :
                cur = my_get_char();
                if( cur == '/' ){
                    state = END_TAG;
                    break;
                }
                if( cur == 'a' || cur == 'A' ){
                    if( isspace(cur = my_get_char()) ){
                        state = A_TAG;
                        break;
                    }
                }
                else if( cur == 'i' || cur == 'I' ){
                cur = my_get_char();
                if( cur == 'm' || cur == 'M' ){
                cur = my_get_char();
                if( cur == 'g' || cur == 'G' ){
                    if( isspace(cur = my_get_char()) ){
                        state = IMG_TAG;
                        break;
                    }
                }
                }
                }
                
                // ici je croise les doigts pour que le document
                // respecte la norme et ne mette pas de >
                // dans les attributs...
                while( cur != '>' )
                    cur = my_get_char();
                state = OUT;
                break;
            
            case END_TAG :
                while( my_get_char() != '>' );
                state = OUT;
                break;
            
            case A_TAG :
                while( 1 ){
                    
                    
                    if( isspace(cur) ){
                    cur = my_get_char();
                    if( cur == 'h' || cur == 'H' ){
                    cur = my_get_char();
                    if( cur == 'r' || cur == 'R' ){
                    cur = my_get_char();
                    if( cur == 'e' || cur == 'E' ){
                    cur = my_get_char();
                    if( cur == 'f' || cur == 'F' ){
                        if( (cur = my_get_char()) == '=' ){
                            state = HREF_SRC_CONTENT;
                            break;
                        }
                    }
                    }
                    }
                    }
                    }
                    
                    if( cur == '>' ){
                        state = OUT;
                        break;
                    }
                    
                    cur = my_get_char();
                }
                break;
            
            case IMG_TAG :
                while( 1 ){
                    
                    if( isspace(cur) ){
                    cur = my_get_char();
                    if( cur == 's' || cur == 'S' ){
                    cur = my_get_char();
                    if( cur == 'r' || cur == 'R' ){
                    cur = my_get_char();
                    if( cur == 'c' || cur == 'C' ){
                        if( (cur = my_get_char()) == '=' ){
                            state = HREF_SRC_CONTENT;
                            break;
                        }
                    }
                    }
                    }
                    }
                    
                    if( cur == '>' ){
                        state = OUT;
                        break;
                    }
                    
                    cur = my_get_char();
                }
                break;
                
            case HREF_SRC_CONTENT :
                
                i = 0;
                cur = my_get_char();
            
                while( isspace(cur) )
                    cur = my_get_char();
            
                if( cur == '"' ){
                    
                    while( 1 ){
                        
                        cur = my_get_char();                        
                        if( cur == '"' ){
                            url[i] = 0;
                            printf("%s\n", url);
                            state = OUT;
                            break;
                        }
                        
                        if( i < URL_LENGTH )
                            url[i++] = cur;
                        else {
                            url[i++] = 0;
                            printf("URL trop longue : %s\n", url);
                            state = OUT;
                            break;
                        }
                    }

                }
                else {
                    while( 1 ){
                                                
                        if( isspace(cur) || cur == '>' ){
                            url[i] = 0;
                            printf("%s\n", url);
                            state = OUT;
                            break;
                        }
                        
                        if( i < URL_LENGTH )
                            url[i++] = cur;
                        else {
                            url[i++] = 0;
                            printf("URL trop longue : %s\n", url);
                            state = OUT;
                            break;
                        }
                        
                        cur = my_get_char();
                    }
                }
                
        }
    }
    return;
}

int main()
{
    parse();
    return EXIT_SUCCESS;
}