#! /bin/sh
# 
# Copyright 1999-2010 University of Chicago
# 
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# 
# http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
if [ -x /usr/bin/getconf ]; then
    PATH="$PATH:`/usr/bin/getconf PATH 2> /dev/null`"
else
    PATH="$PATH:/usr/bin:/bin:/sbin"
fi
PATH="$PATH:$GLOBUS_LOCATION/bin"
export PATH

if [ $# -lt 6 ]; then
    printf "Usage: $0 tag jobid stream tailopt followopt url\n" 1>&2
    exit `[ $1 = "-help" -o $1 = "-usage" -o $1 = "-h" ]`
fi

tag="$1"
jobid="$2"
stream="$3"
tailopt="$4"
followopt="$5"
url="$6"

if [ "$tailopt" != no -a "$followopt" != no ]; then
    printf "Error: can't have both -f and -t command-line options\n" 1>&2
    exit 1
fi

out_path="`globus-gass-cache -query -t \"$tag\" \"x-gass-cache://${jobid}${stream}\"`"
if [ $? -ne 0 -o "$out_path" = "" ]; then
    printf "Error locating $stream for job $jobid\n" 1>&2
    exit 1
fi

subject=""
# For https transfers, we'll assume self-authz to a GASS server; otherwise
# we'll use the default authz (none for http)
if expr "$url" : https > /dev/null; then
    subject="`grid-proxy-info -identity 2> /dev/null`"
    if [ $? -ne 0 -o "$subject" = "" ]; then
        printf "Error determining subject\n" 1>&2
        exit 1
    fi
fi

# Seconds between instances of the loop. We only care about this for -f mode
sleeptime=0

# This is the last value of the length of the file, so we can avoid doing
# the (potentially) more expensive wc -l below. We initialize this to 0 so
# that the first time through, we will attempt to send data if there are any
# lines
out_file_size=0

# We want to keep track of the length of the file in lines for each poll
# If the client asked to tail the last N lines (via globus-job-get-output -t N
# or globus-job-get-output -f N) then we'll subtract that off of this lenght and
# stream from that point. If we are just doing a cat of the file, we'll ignore
# the file length value
if [ $tailopt != no ]; then
    out_line_count="`wc -l \"$out_path\" | awk '{print \$1}'`"
    out_line_count="`expr $out_line_count - $tailopt`"
elif [ $followopt != no ]; then
    out_line_count="`wc -l \"$out_path\" | awk '{print \$1}'`"
    out_line_count="`expr $out_line_count - $followopt`"
    sleeptime=1
else
    out_line_count=0
fi

# Don't allow silly values to confuse the tail commands below
if [ $out_line_count -lt 0 ]; then
    out_line_count=0
fi

# Loop will run forever if -f N is used, otherwise it will run 1 time
first=1
while [ $followopt != no -o $first = 1 ]; do
    first=0

    # Check if the file has grown since the last time through this loop. If not
    # we'll just continue on
    new_out_file_size="`wc -c \"$out_path\" | awk '{print \$1}'`"
    if [ $new_out_file_size -le $out_file_size ]; then
        sleep $sleeptime
        continue
    fi
    if [ $tailopt = 'no' -a $followopt = 'no' ]; then
        # "cat" case
        if [ "$subject" != "" ]; then
            globus-url-copy -s "$subject" file:"$out_path" "$url/dev/stdout"
        else
            globus-url-copy file:"$out_path" "$url/dev/stdout"
        fi
    elif [ $new_out_file_size -gt $out_file_size ]; then
        # this ends up parsing $out_path for \n, so it's expensive.
        new_out_line_count="`wc -l \"$out_path\" | awk '{print \$1}'`"
        # only send complete lines that have arrived since the last check
        out_skip_lines=`expr $new_out_line_count - $out_line_count`
        if [ $out_skip_lines -gt 0 ]; then
            head -$new_out_line_count "$out_path" | tail -$out_skip_lines | \
                (if [ "$subject" != "" ]; then
                    globus-url-copy -s "$subject" file:/dev/stdin \
                            "$url/dev/stdout"
                else
                    globus-url-copy file:/dev/stdin "$url/dev/stdout"
                fi)
            out_line_count=$new_out_line_count
        fi
        out_file_size=$new_out_file_size
    fi

    sleep $sleeptime
done