#!/bin/sh

set -e -x -v
set -o pipefail || true

# set some local defaults
web_server="${web_server:-'appserver'}"
db_server="${db_server:-'replication1'}"
database="${database:-'xe150'}"
cubrid="${cubrid:-'false'}"

# parse command line
case "$#" in
(0)
    echo Syntax:
    echo "	$0"	"webserver[:port] [ dbserver[:port] [db] ]"
    echo "	$0"	"webserver[:port] db@dbserver[:port]"
    echo
    exit 1;;
(1)
    if test "$1" = "--help" -o "$1" == "--usage"
    then
	"$0"
	exit
    else
	web_server="$1"
    fi;;
(2)
    web_server="$1"

    if echo "$2" | grep '@' -l>/dev/null
    then
	cubrid=true
	db_server="$2"
	database="$(echo "$2" | sed 's#^\([a-zA-Z_0-9]*\)@.*$#\1#')"
    else
	db_server="$2"
    fi;;
(3)
    web_server="$1"
    db_server="$2"
    database="$3";;
(*)
    "$0"
    exit 1;;
esac

if echo "$db_server" | grep ':' -l>/dev/null
then
    db_port="$(echo "$db_server" | sed 's#^[a-zA-Z0-9.]*:\([0-9]\{2,5\}\)$#\1#')"
    db_server="$(echo "$db_server" | sed 's#^\([a-zA-Z0-9.]*\):[0-9]\{2,5\}$#\1#')"
else
    db_port=3306    # default mysql port number
fi

# generate a set of pipes/processes
sets=
a=0
b=0

while [ $a -lt 2 ]  # 20 processes (and pipes)
do
    while [ $b -lt 10 ]
    do
	sets="${sets}${sets:+ }$a$b"
	b=$(($b+1))
    done

    b=0
    a=$(($a+1))
done


(
    # remove all pipes on exit
    trap 'rm -rf "/tmp/visit_boards"' EXIT

    mkdir "/tmp/visit_boards"

    pids_list=

    # create pipes
    # start wget processes for the read ends of the pipes
    # open shell output file descriptors for the write ends of the pipes
    for p in $sets
    do
	fdp="${p#0}"    # convert 08 to 8
	fdp=$(($fdp+5))    # first 3 file descriptiors are reserved, so start with the 4th
	fdp_bit=$(($fdp % 2))

	# create pipe
	mkfifo "/tmp/visit_boards/pipe_$p"

	# connect a new wget process to the read end of the pipe
	wget --server-response --spider --output-file="visit_$p.log" --input-file="/tmp/visit_boards/pipe_$p" &
	pids_list="$pids_list${pids_list:+ }$!"

	# connect the current shell process to the write end of the pipe
	echo exec "$fdp>>/tmp/visit_boards/pipe_$p">"/tmp/visit_boards/shell_script_pipe"
	. "/tmp/visit_boards/shell_script_pipe"
    done

    # output URLs to the pipes, one line into each pipe in turn
    if $cubrid
    then
	csql -u dba -p arniarules --command='SELECT "domain" FROM xe_sites WHERE site_srl != 0' "$db_server" |
		sed -n 's#^[[:space:]]*'\''\([a-zA-Z0-9_]*\)'\''$#\1#p'
    else
	echo "SELECT domain FROM xe_sites WHERE site_srl != 0" |
	    mysql -u dba --password=arniarules -h "$db_server" -P "$db_port" --skip-column-names "$database"
    fi \
	|
    {
	sh_flags="$-"
	set +x
	a=0
	b=0

	while read -r board_name
	do
	    # output the current site URL to the current file descriptor
	    # (connected to one of the pipes)
	    p="$a$b"
	    fdp="${p#0}"
	    fdp=$(($fdp+5))
	    fdp_bit=$(($fdp%2))

	    echo "http://$web_server/$database/$board_name" >&$fdp

	    # advance (a, b) to the next pipe or cycle back to the
	    # first one (0, 0) if (2, 0) is reached
	    b=$(($b+1))
	    if [ $b -eq 10 ]
	    then
		b=0
		a=$(($a+1))
		if [ $a -eq 2 ]
		then
		    a=0
		fi
	    fi
	done

	set "-$sh_flags"
    }

    if [ "$?" -ne "0" ]
    then
	# Old versions of bash (still current on CentOS) do not exit after
	# errors from the nested (inner) pipe, even with set -e -o pipefail,
	# but "$?" still indicates a non-zero status
	exit 4;
    fi

    # list the open file descriptors for the process
    for OPEN_FD in /dev/fd/*
    do
	open_fds="${open_fds}${open_fds:+ }${OPEN_FD#/dev/fd/}"
    done
    echo "$open_fds"

    # close write end for all pipes
    a=0
    b=0
    while [ $a -lt 2 ]
    do
	while [ $b -lt 10 ]
	do
	    p="$a$b"
	    fdp="${p#0}"
	    fdp=$(($fdp+5))

	    # a redirection like 9>&- is defined to close file descriptor 9
	    echo exec "$fdp>&-" >"/tmp/visit_boards/shell_script_pipe"
	    . "/tmp/visit_boards/shell_script_pipe"

	    b=$(($b+1))
	done
	
	b=0
	a=$(($a+1))
    done

    # list the open file descriptors for the process
    open_fds=
    for OPEN_FD in /dev/fd/*
    do
	open_fds="${open_fds}${open_fds:+ }${OPEN_FD#/dev/fd/}"
    done
    echo "$open_fds"

    watch_pid=
    if [ -t 0 -a -t 1 ]
    then
	watch -n 1 ls -l visit_[0-1][0-9].log &
	watch_pid="$!"
    fi

    error=
    for pid in $pids_list
    do
	wait $pid

	if [ "$?" -ne 0 ]
	then
	    error="$error${error:+ }$pid"
	fi
    done

    if test -n "$watch_pid"
    then
	# `watch` utility will run until interrupted
	kill -s INT "$watch_pid"
    fi

    if test -n "$error"
    then
	echo Child processes "($error)" returned errors.
	exit 2
    fi


    # EXIT trap shall now remove pipes
)