# Rjarshi Guha <rguha@indiana.edu>
# 08/17/2006
#

require(XML)

vot2df <- function(doc, url=FALSE, isString=FALSE) {
  tlist <- list()
  tcount <- 1

  if (isString) {
    tn <- tempfile('votmp')
    con <- file(tn, open='w')
    cat(doc, file=con)
    close(con)
    x <- xmlTreeParse(tn)
  } else {
    x <- xmlTreeParse(doc, isURL=url)
  }
  
  root <- xmlRoot(x)
  tables <- xmlElementsByTagName(root, 'TABLE', recursive=TRUE)

  for (aTable in tables) {
    
    fields <- xmlElementsByTagName(aTable, 'FIELD')
    fieldnames <- lapply(fields, xmlGetAttr, name='name')
    fieldtypes <- lapply(fields, xmlGetAttr, name='datatype', default='char')

    tdata <- xmlElementsByTagName(aTable, 'TABLEDATA', recursive=TRUE)
    if (length(tdata) == 0) {
      warn("Looks like I couldn't find a table")
    }
    rowdata <- xmlElementsByTagName(tdata[[1]], 'TR')

    tmp <- list()
    i <- 1
    for (aRow in rowdata) {
      items <- xmlElementsByTagName(aRow, 'TD') # the TD elements
      tmp[[i]] <- lapply( items, function(x) {
        val <- xmlValue(x)
        if (is.null(val)) val <- NA
        return(val)
        }) # value of the TD elements, NA is value missing
      i <- i+1
    }

    ncol <- unique(sapply(tmp, length))
    if (length(ncol) > 1) {
      warn("A table had non-uniform rows!")
    }

    ## make the initial data.frame
    tmp <- as.data.frame(do.call(rbind, tmp))

    ## set the column names
    if (length(fieldnames) > 0) names(tmp) <- fieldnames

    ## set column types
    for (i in 1:length(fieldtypes)) {
      col <- unlist(tmp[,i])
      if (fieldtypes[i] %in% c('double', 'float', 'long', 'short')) tmp[,i] <- as.double(col)
      else if (fieldtypes[i] == 'int') tmp[,i] <- as.integer(col)
      else if (fieldtypes[i] == 'char') tmp[,i] <- col
      else if (fieldtypes[i] == 'boolean') tmp[,i] <- ifelse( col %in% c('T','t','1'), TRUE, FALSE )
    }

    # get the table description
    desc <- xmlElementsByTagName(aTable, 'DESCRIPTION')
    if (length(desc)) attr(tmp, 'description') <- xmlValue(desc[[1]])
    
    tlist[[tcount]] <- tmp
    tcount <- tcount + 1

  }

  if (length(tlist) == 1) {
    return(tlist[[1]])
  } else {
    return(tlist)
  }
  
}