#!/bin/bash

assert_is_instance() {
  local usage=$1
  local name=$2
  local instance=$3
  local check_link=$4

  if [ -z "$name" ]
  then
    $usage "Missing required option -n."
  fi

  if [ -z "$instance" ]
  then
    $usage "Missing required option -i."
  fi

  # Use $APPSH_APPS as prefix if it's set
  local x=""
  if [ ! -z "$APPSH_APPS" ]
  then
    x="$APPSH_APPS/"
  fi

  if [ ! -d $x$name/$instance ]
  then
    echo "No such instance: $name/$instance."  >&2
    exit 1
  fi

  if [ "$check_link" != "no" ]
  then
    if [ ! -e $x$name/$instance/current ]
    then
      echo "Missing 'current' link." >&2
      exit 1
    fi
  fi
}

list_apps() {
  filter_name=$1; shift
  filter_instnace=$1; shift
  vars="$@"

  sort $apps/.app/var/list | while read line
  do
    echo $line | (IFS=:; while read name instance version junk
    do
      if [ -n "$filter_name" -a "$filter_name" != "$name" ]
      then
        continue
      fi

      if [ -n "$filter_instance" -a "$filter_instance" != "$instance" ]
      then
        continue
      fi

      local line=""
      IFS=" "; for var in $vars
      do
        case $var in
          name) x=$name;;
          instance) x=$instance;;
          version) x=$version;;
          current_version) x=`find_current_version $name $instance`;;
          *) x="";;
        esac

        if [ -z "$line" ]
        then
          line="$line$x"
        else
          line="$line:$x"
        fi
      done
      echo $line
    done)
  done
}

find_current_version() {
  name=$1
  instance=$2

  if [ ! -L $apps/$name/$instance/current ]
  then
    return 0
  fi

  (
    cd $apps/$name/$instance
    ls -l current | sed -n "s,.* current -> versions/\(.*\)/root,\1,p"
  )
}

find_versions() {
  name=$1
  instance=$2

  if [ ! -d $apps/$name/$instance/versions ]
  then
    return 0
  fi

  (
    cd $apps/$name/$instance/versions
    ls -1d *
  )
}

# TODO: set ulimit
# TODO: set umask
# TODO: change group newgrp/sg
run_app() {
  local name=$1; shift
  local instance=$1; shift
  local bin=$1; shift
  local method=$1; shift

  assert_is_instance operate_usage "$name" "$instance"

  local x=""
  if [ ! -z "$APPSH_APPS" ]
  then
    x="$APPSH_APPS/"
  fi

  (
    cd $x$name/$instance
    APPSH_INSTANCE_HOME=`pwd`
    cd current

    e="`get_conf_in_group $apps $name $instance env`"
    # This magically get the expansion of $u correct.
    IFS="
"

    # Set a default PATH which can be overridden by the application's settings
    set +e
    env -i \
      PATH=/bin:/usr/bin \
      $e \
      PWD=$PWD \
      APPSH_METHOD=$method \
      APPSH_APPS=$apps \
      APPSH_HOME=$APPSH_HOME \
      APPSH_NAME=$name \
      APPSH_INSTANCE=$instance \
      APPSH_INSTANCE_HOME=$APPSH_INSTANCE_HOME \
      $bin "$@"
    local ret=$?
    set +x
    set -e

    exit $ret
  )
}