#include <string>
#include "contexthandler.h"

ContextMatch ContextHandler::getContext (
    char *s,
    int len,
    char *origin,
    int context )
{
    char *t, *u;
    int maxrange = context * 20;

    int range = context + 1, i = 0;
    for ( t = s; t != origin; --t )
        if ( *t == ' ' || *t == '\t' || *t == '\r' || *t == '\n' )
            if ( ++i == range )
            {
                ++t;
                break;
            }

    i = 0;
    for ( u = s + len; *u; ++u )
        if ( *u == ' ' || *u == '\t' || *u == '\r' || *u == '\n' )
            if ( ++i == range )
                break;

    ContextMatch match;

    // prevent excessive context
    if ( ( s - t ) < maxrange )
        match.prelog.assign ( t, s - t );
    else
        match.prelog = "...";
    match.match.assign ( s, len );
    if ( ( u - s ) < maxrange )
        match.postlog.assign ( s + len, u - ( s + len ) );
    else
        match.postlog = "...";

    return match;
}