Yale University Library Map Application Algorithm 
// one web file is used, default.aspx
// in .Net this has a "code behind" file where the bulk of things happen.
// There's a lot of localized logic in that file. But in a nutshell the page
// makes a call to the cLocation class shown below like this:
private cLocation cl;
private string _location = "";
private string _callNumber = "";
private string _mapfloor = "";
private string _mapsection = "";
private string _mapid = "";
private string _bibID = "";
private int _manualMode = 0;

protected void Page_Load(object sender, EventArgs e)
{
    StringBuilder sb = new StringBuilder();
    cl = new cLocation(_location, _callNumber, _mapsection);
    Response.ContentType = "text/html";
    sb.AppendLine("<img src=\"img/" + cl.getImg() + "\">");
    sb.AppendLine(boxBuilder());
}

private string boxBuilder()
{
    List<cCoordinates> coords = cl.getCoordinates();
    StringBuilder sb = new StringBuilder();
    if (coords.Count > 0)
    {
        for (int i = 0; i < coords.Count; i++)
        {
            sb.AppendLine("<div class=\"mapOn\" style=\"position: absolute; top: "
                + coords[i].Top.ToString() + "px; left: " + coords[i].Left.ToString() + "px; width: "
                + coords[i].Width.ToString() + "px; height: " + coords[i].Height.ToString() + "px;\">&nbsp;</div>");
        }
    }
    return sb.ToString();
}
// the following is the cLocation class called from the default.aspx.cs page
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Web;
using System.Text.RegularExpressions;

public class cLocation
{
    // this stores the location sent from the catalog
    private string _location;
    // this stores the call number sent from the catalog
    public string _callnumber;
    // a failsafe URL is provided if we are unable to locate a map to show you, the URL is usually to a page about the location
    public string[] _locationError = { "", "" };
    // the call numbers are split into an array by white space
    public string[] _callSplit;
    // MapID is an abbreviated location code used as part of the .GIF name of the map displayed on the web page
    public string MapID = "";
    // a flag that checks if the book is oversized
    public bool isOversized = false;
    // a flag that checks if the book is a folio
    public bool folio = false;
    // We work with two classifications, Yale and LC, the default is LC. The code will try and prove it is Yale instead of the other way around
    public string Classification = "LC";
    // prefix is the first letters of a call number
    public string Prefix = "";
    // this refers to the call number range which goes from 0 to 9999
    public int Range = 0;
    // Both MapSection and _mapSection are numbers that represents a section of a map. 
    // This is a one to many relationship to coordinates. So a map section may contain several
    // coordinates to form an L shaped box on the map
    // there are failover mechanisms and checks that require the same value be set twice to see if they match. If there is no match then
    // the one more likely to match is used. 
    public string MapSection = "";
    public string _mapSection = "";
    // this is the floor of the map, the MapID + mapFloor + ".gif" is how the map is called in the <img> tags on the web page
    public string MapFloor = "";
    // this list contains all the possible matches found in the database
    public List<cCode> ccodes;
    // this is the SQL connection info used
    private const string dbReader = "user id=[sql username];"
        + "password=[sql user pwd];"
        + "server=[sql server];"
        + "Trusted_Connection=false;"
        + "database=[sql database];"
        + "connection timeout=10;";

    public cLocation(string LOCATION, string CALLNUMBER, string MAPSECTION)
    {
        if (MAPSECTION.Length > 0)
        {
            // for debugging, it is possible to force a map to appear by manipulating the URL
            _mapSection = MAPSECTION;
            MapSection = _mapSection;
            // we skip a lot of steps if we know exactly what we want
            bypass();
            loadCodes();
            setURL();
        }
        else
        {
            _location = LOCATION;
            _callnumber = CALLNUMBER;
            _callSplit = _callnumber.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            if (_callnumber.Length > 0)
            {
                if (_callSplit[0].ToLower() == "folio")
                {
                    string[] temp = new string[_callSplit.Length - 1];
                    for (int i = 1; i < _callSplit.Length; i++)
                        temp[i - 1] = _callSplit[i];
                    _callSplit = new string[temp.Length];
                    for (int i = 0; i < temp.Length; i++)
                        _callSplit[i] = temp[i];
                }
                if (_callSplit[0].ToLower() == "judaica")
                {
                    Classification = "judaica";
                    string[] temp = new string[_callSplit.Length - 1];
                    for (int i = 1; i < _callSplit.Length; i++)
                        temp[i - 1] = _callSplit[i];
                    _callSplit = new string[temp.Length];
                    for (int i = 0; i < temp.Length; i++)
                        _callSplit[i] = temp[i];
                }
                if (_callSplit[0].ToLower() == "near")
                {
                    Classification = "near";
                    string[] temp = new string[_callSplit.Length - 2];
                    for (int i = 2; i < _callSplit.Length; i++)
                        temp[i - 2] = _callSplit[i];
                    _callSplit = new string[temp.Length];
                    for (int i = 0; i < temp.Length; i++)
                        _callSplit[i] = temp[i];
                }
            }

            ccodes = new List<cCode>();
            // a procedural stack, this is the order in which the operations must fire
            // we decided at the start that the classification was LC
            // so setClassification() gives the Yale class a chance to override the default
            // any number of other classifications would work in the method
            setClassification();
            // oversized materials are stored separately, so we do a quick check
            checkOversize();

            getMapID();
            loadCodes();
            setRange();
            setPrefix();
            // this happens late because some exceptions must be considered for classification
            // for LC the word "folio" appears but for Yale Classification there are other rules
            checkFolio();
            setURL();
            // there are a number of temporary location codes that use "in process" so we have to direct
            // users to a general info page
            if (_callnumber.Trim().ToLower().IndexOf("in process") >= 0)
            {
                HttpContext.Current.Response.Redirect(_locationError[1]);
            }
        }
    }
    // public methods
    public string getImg()
    {
        // this sets the GIF to call.
        return MapID.ToLower()
            .Replace("smljud", "sml")
            .Replace("smlnear", "sml")
            .Replace("smlengin", "sml") 
            + "_" + MapFloor + ".gif";
    }

    public List<cCoordinates> getCoordinates()
    {
        // requires mapSection to query [stackMap_coordinates]
        List<cCoordinates> rex = new List<cCoordinates>();
        string mySQL = "/*stackmap get coord*/ select csstop,cssleft,csswidth,cssheight " 
            + " from stackmap_coordinates where mapsection = @ms ";
        using (SqlConnection conn = new SqlConnection(dbReader))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(mySQL, conn))
            {
                SqlParameter p = new SqlParameter();
                p.ParameterName = "ms";
                p.Value = MapSection;
                cmd.Parameters.Add(p);

                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        rex.Add(new cCoordinates(
                            reader.GetInt32(0), 
                            reader.GetInt32(1),
                            reader.GetInt32(2),
                            reader.GetInt32(3)));
                    }
                }
            }
            conn.Close();
            conn.Dispose();
        }

        return rex;
    }

    // private methods
    private void setClassification()
    {
        try
        {
            // the Judaica and Near East collections are flagged by location code, we don't use call numbers
            if (Classification != "judaica" && Classification != "near")
            {
                if (_callSplit.Length == 2)
                {
                    // if the call number splits into only 2 segments, it is most likely LC
                    // so we do a simple check, if it starts with two ucase letters, it is LC
                    string exp = "[A-Z]{2}";
                    string temp = _callSplit[0];
                    if (Regex.IsMatch(temp.Replace("+", ""), exp))
                    {
                        Classification = "LC";
                    }
                    else
                    {
                        Classification = "YALE";
                    }
                }
                else
                {
                    // Yale class is an upper case letter, followed by a lower case, followed by any amount of numbers
                    string exp = "[A-Z]{1}[a-z]{1}\\d*";
                    string temp = _callSplit[0];
                    if (Regex.IsMatch(temp.Replace("+", ""), exp))
                    {
                        Classification = "YALE";
                    }
                }
            }
        }
        catch { }
    }
    private void checkOversize()
    {
        // there are only two things that appear in an oversize call number "+" and "oversize"
        // we set the call number to lowercase because "Oversize" appears in all sorts of mized cases
        if (_callnumber.ToLower().IndexOf("oversize") >= 0 || _callnumber.IndexOf("+") >= 0)
            isOversized = true;
    }
    private void getMapID()
    {
        // from the Voyager database we pull all the location codes into 
        // a table to match them to library locations used in this application
        // this query finds the abbreviated code based on the locations in Voyager, 
        // we refresh the data periodically from Voyager but in general
        // these values do not change often
        string mySQL = "/*stackmap get map id*/select top 1 mapID, defaultclassification " 
            + " from stackmap_locationCode where display_name = @dn ";
        string locOverride = "";
        using (SqlConnection conn = new SqlConnection(dbReader))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(mySQL, conn))
            {
                SqlParameter p = new SqlParameter();
                p.ParameterName = "dn";
                p.Value = _location;
                cmd.Parameters.Add(p);

                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        MapID = reader[0].ToString();
                        locOverride = reader[1].ToString();
                    }
                }
            }
            conn.Close();
            conn.Dispose();
        }
        // it is possible that even after the call number is parsed, it will be wrong and the database knows the exceptions
        // so we let it override the classification here. An example is part of a call number range being in a special 
        // place in the stacks.
        if (locOverride.Trim().Length > 0)
        {
            Classification = locOverride;
        }
        // for these three exceptions we know exactly where the materials are. 
        // it's not ideal, this should be handled as an exception but is so rare that
        // adding a few lines to the code is simpler
        if (MapID.ToLower() == "smljud")
        {
            // the Judaica section in SML is all in one place, covering half the floor
            MapSection = "115";
            MapFloor = "6";
        }
        else if (MapID.ToLower() == "smlnear")
        {
            // the Near East section in SML is all in one place, covering half the floor
            MapSection = "120";
            MapFloor = "6";
        }
        else if (MapID.ToLower() == "smlengin")
        {
            // this is a temp move as the engineering library is moving
            // map section 149 is always temp storage
            // so after engineering moves, a different SML location will be put into the MapID
            MapSection = "149";
            MapFloor = "1";
        }
    }
    private void bypass()
    {
        // this method loads a map by the map section in the database, ignoring any location or call numbers sent in the URL
        // it will highlight the area requested making it possible to link directly to an area in the stacks
        // the purpose is sort of like a kiosk mode or if a web page wants to lead you to a section in the stacks
        // it is possible to do the same by sending a fake call number in the URL which would be better in case the stacks
        // shift. But this method also comes in real handy for debugging the highlighted coordinates on a map.
        string tclass = "";
        string mySQL = "select top 1 calltype,oversized,mapid,mapfloor from stackmap where mapsection = @mapsec";
        using (SqlConnection conn = new SqlConnection(dbReader))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(mySQL, conn))
            {
                SqlParameter p = new SqlParameter();
                p.ParameterName = "mapsec";
                p.Value = _mapSection;
                cmd.Parameters.Add(p);

                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        tclass = reader[0].ToString();
                        isOversized = reader[1].ToString() == "1" ? true : false;
                        MapID = reader[2].ToString();
                        MapFloor = reader[3].ToString();
                    }
                }
            }
            conn.Close();
            conn.Dispose();
        }
        if (tclass.ToLower() == "yale")
        {
            Classification = "YALE";
        }
        else if (tclass.ToLower() == "lc")
        {
            Classification = "LC";
        }
        else
        {
            Classification = tclass.ToLower();
        }
    }
    private void setURL()
    {
        // the URLs that are queried here are for library location specific web pages 
        // like the Divinity Library or external shelving facility
        // these web pages generally provide information about the location,
        // hours and links to web pages about the location
        string mySQL = "/*stackmap get urls*/ select url, " 
            + " (select url from stackMap_URLs where mapid = 'error') as failover " 
            + " from stackMap_URLs  where mapid = @ms ";
        bool runerror = false;
        using (SqlConnection conn = new SqlConnection(dbReader))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(mySQL, conn))
            {
                SqlParameter p = new SqlParameter();
                p.ParameterName = "ms";
                p.Value = MapID;
                cmd.Parameters.Add(p);

                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        _locationError[0] = reader[0].ToString();
                        _locationError[1] = reader[1].ToString();
                    }
                }
                else
                {
                    runerror = true;
                }
            }
            conn.Close();
            conn.Dispose();
        }
        // we store a URL in the database to the general library location page instead of hard coding it
        // in case we change the logic for this.        
        if (runerror)
        {
            mySQL = "/*stackmap get urls*/ select url from stackMap_URLs  where mapid = 'error' ";
            using (SqlConnection conn = new SqlConnection(dbReader))
            {
                conn.Open();
                using (SqlCommand cmd = new SqlCommand(mySQL, conn))
                {
                    SqlDataReader reader = cmd.ExecuteReader();
                    if (reader.HasRows)
                    {
                        while (reader.Read())
                        {
                            _locationError[1] = reader[0].ToString();
                        }
                    }
                }
                conn.Close();
                conn.Dispose();
            }
        }
    }
    private void setRange()
    {
        try
        {
            // basically we want the first bank of numbers from the call number, if any exist
            string temp = _callSplit[0];
            MatchCollection matches = Regex.Matches(temp, @"\d+");
            string _range = "0";
            if (matches.Count > 0)
                _range = matches[0].Groups[0].Value;
            Range = int.Parse(_range);
        }
        catch
        {
            // there's nothing to really catch, if this doesn't work, 
            // it's not the end of the world
        }
    }
    private void setPrefix()
    {
        // this is the heavy lifting method that will essentially decide the map section and map floor
        // it will loop the codes that are loaded to try and find an exact match
        Range = Range <= 0 ? 1 : Range;
        string temp = _callSplit[0];
        MatchCollection matches = Regex.Matches(temp, "[A-Z|a-z]+");
        if (matches.Count > 0)
            Prefix = matches[0].Groups[0].Value;
        string _prefix = Prefix.ToLower();
        if (_prefix.Length > 2)
            _prefix = _prefix.Substring(0, 2);
        bool foundOne = false;
        for (int i = 0; i < ccodes.Count; i++)
        {
            if (_prefix == ccodes[i].prefix.ToLower())
            {
                if (Range <= ccodes[i].callEnd && Range >= ccodes[i].callStart)
                {
                    MapSection = ccodes[i].mapSection;
                    MapFloor = ccodes[i].mapFloor;
                    foundOne = true;
                    break;
                }
            }
        }
        if (!foundOne)
        {
            // if an exact match is not found and there is only one match in the database,
            // it is probably right. it just means that the database didn't have the proper
            // range specified. 
            if (ccodes.Count == 1)
            {
                MapSection = ccodes[0].mapSection;
                MapFloor = ccodes[0].mapFloor;
            }
            else
            {
                for (int i = 0; i < ccodes.Count; i++)
                {
                    if (_prefix[0].ToString() == ccodes[i].prefix.ToLower())
                    {
                        if (Range <= ccodes[i].callEnd && Range >= ccodes[i].callStart)
                        {
                            MapSection = ccodes[i].mapSection;
                            MapFloor = ccodes[i].mapFloor;
                            foundOne = true;
                            break;
                        }
                    }
                }
            }
        }
    }
    private void checkFolio()
    {
        if (_callnumber.ToLower().IndexOf("folio") >= 0)
            folio = true;
        if (Classification == "YALE")
        {
            // This is rare, this would mean that a location overrode the classification type from LC
            // to Yale even though the regex match is LC = two upper case letters. In the Yale
            // class two upper case = folio. Luckily, Yale class folios are usually handled
            // in the location code and not the call number
            if (Regex.IsMatch(Prefix, "[A-Z]{2}"))
            {
                folio = true;
            }
            try
            {
                // alternatively, if position 2 in the call number split of a Yale call number is 00
                // it's a folio
                if (_callSplit[1].StartsWith("00"))
                {
                    folio = true;
                }
            }
            catch { }
        }
    }
    private void loadCodes()
    {
        // a very forgiving query retrieves all possible map sections no matter how unlikely they are to match
        // this is done to provide failover possibilities. Originally a more rigid query ran but failure rates 
        // to provide a map location were high forcing additional queries to run. 

        // an important note about the call prefix, start and end. All letter/number combinations are stored
        // even for call numbers that do not exist. This way all fail safe values are stored in SQL rather than
        // writing complex exception handling because Qz456.78 does not exist. Instead SQL assumes that it does
        // exist but if a map doesn't exist to handle, it fails gracefully. The alternative being some infinite
        // loop that can never find it.
        string mySQL = "/*stackmap load codes*/ select callprefix,callstart,callend,mapfloor,mapsection from stackmap "
            + " where calltype = @ct and mapid = @mapid and oversized = @ov and left(callprefix,1) = @pre ";
        string pre = "";
        string temp = _callSplit[0];
        for (int i = 0; i < temp.Length; i++)
        {
            if (Regex.IsMatch(temp[i].ToString(), "\\w"))
            {
                pre = temp[i].ToString();
                break;
            }
        }
        using (SqlConnection conn = new SqlConnection(dbReader))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(mySQL, conn))
            {
                SqlParameter p = new SqlParameter();
                p.ParameterName = "ct";
                p.Value = Classification;
                cmd.Parameters.Add(p);

                p = new SqlParameter();
                p.ParameterName = "mapid";
                p.Value = MapID;
                cmd.Parameters.Add(p);

                p = new SqlParameter();
                p.ParameterName = "ov";
                p.Value = isOversized;
                cmd.Parameters.Add(p);

                p = new SqlParameter();
                p.ParameterName = "pre";
                p.Value = pre;
                cmd.Parameters.Add(p);

                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.HasRows)
                {
                    while (reader.Read())
                    {
                        ccodes.Add(new cCode(
                            reader[0].ToString(),
                            reader.GetInt32(1),
                            reader.GetInt32(2), 
                            reader[3].ToString(),
                            reader[4].ToString()));
                    }
                }
            }
            conn.Close();
            conn.Dispose();
        }
    }
}

// helper classes 
public class cCoordinates
{
    // this amounts to the coordinates used to draw a highlghted box over the .GIF image on the web page
    public int Top;
    public int Left;
    public int Width;
    public int Height;
    // the offsets are literally the number of pixels from left and top that the .GIF image appears on the web page
    // if our web templates change, these number have to change as well. The image is placed using an absolute DIV tag
    // with top and left specified.
    private int xOff = 23;
    private int yOff = 121;
    public cCoordinates(int TOP, int LEFT, int WIDTH, int HEIGHT)
    {
        Top = TOP + yOff;
        Left = LEFT + xOff;
        Width = WIDTH;
        Height = HEIGHT;
    }
}

public class cCode
{
    // these values are all populated from a SQL table and 
    // used to try and find the best matching location code info
    public string prefix;
    public int callStart;
    public int callEnd;
    public string mapFloor;
    public string mapSection;

    public cCode(string PREFIX, int CALLSTART, int CALLEND, string MAPFLOOR, string MAPSECTION)
    {
        prefix = PREFIX;
        callStart = CALLSTART;
        callEnd = CALLEND;
        mapFloor = MAPFLOOR;
        mapSection = MAPSECTION;
    }
}

// SQL table setup
/*
 * [stackMap]
 * - id (unique)
 * - callPrefix (char)
 * - callStart (int)
 * - callEnd (int)
 * - callType (char)
 * - oversized (bit)
 * - mapID (char)
 * - mapFloor (char)
 * - mapSection (int)
 * 
 * example row: 120|PL|1|2652|LC|0|SML|2M|40
 * 
 * 
 * [stackMap_coordinates]
 * - id (unique id)
 * - mapSection (int)
 * - cssTop (int)
 * - cssLeft (int)
 * - cssWidth (int)
 * - cssHeight (int)
 * 
 * example row: 61|40|629|257|107|94
 * 
 * 
 * [stackMap_locationCode]
 * - id (unique)
 * - location_code (nvarchar - imported from Voyager table)
 * - location_name (nvarchar - imported from Voyager table)
 * - display_name (nvarchar - imported from Voyager table)
 * - mapID (char)
 * - defaultClassification (char)
 * 
 * example row: 1136|smly|smly|SML, Stacks, Yale Classification|sml|YALE
 * 
 * 
 * [stackMap_URLs]
 * - id (unique)
 * - MapID (char)
 * - URL (nvarchar)
 * 
 * example row: 17|medical|http://library.medicine.yale.edu/about/floor
*/