#!/bin/sh

# Copyright (c) Victor Porton 2004.
# Extreme Code Software (http://ex-code.com) - VERY CHEAP custom software.
# Bashisms & typos fixed by Reuben Thomas

usage_msg='inplace [-vin] [-s <suffix>] [-d <diff>] "cmd \$IN \$OUT" <file> [<file> ...]'

usage () {
    echo "$usage_msg"
    exit 1
}

help () {
    echo "$usage_msg"
    cat << EOF

Performs inplace transformation of file(s).
  --help       Show help
  --version    Show version info
  -i           Interactively ask confirmation
  -n           Don't backup
  -s <suffix>  Backup suffix (default .bak)
  -d <diffcmd> Comparison command (default "cmp -s", can be e.g. "diff -u")
  -v           Be verbose
  
Example: inplace -v "sed -e s/John/Paul/g \\\$IN > \\\$OUT" file.txt

--
Extreme Code (http://www.ex-code.com, support@ex-code.com)
VERY CHEAP custom software.
EOF
    exit 0;
}

case "$1" in
    -h|--help) help;;
    --version) echo "inplace 1.0.1 by Extreme Code (http://ex-code.com)."; exit 1;
esac

file=""
suffix=".bak"
backup=true
confirm=false
verbose=false
diff="cmp -s"

while test $# -gt 1; do
    case "$1" in
        -v) verbose=true
            ;;
        -i) confirm=true
            ;;
        -n) backup=false
            ;;
        -s) suffix="$2"; shift
            if test -z "$suffix"; then
                echo "Suffix can't be empty" >&2
                exit 1
            fi
            ;;
        -d) diff="$2"; shift
            if test -z "$diff"; then
                echo "Diff command can't be empty" >&2
                exit 1
            fi
            ;;
        -*) usage
            ;;
        *)  cmd="$1"; shift
            break
            ;;
    esac
    shift
done

if test -z "$cmd" || test $# -lt 1; then usage; fi

OUT=`tempfile -s .tmp`

while test $# -ge 1; do
    file=$1
    IN="$file"
    if ! test -f "$IN"; then
        echo "File $IN doesn't exist!" >&2
        exit 2
    fi
    if test $backup = true; then
        cp "$IN" "$IN$suffix" || exit 2
    fi
    export IN OUT
    if ! sh -c "$cmd"; then
        status=$?
        echo "** Command failed" >&2
        if test -f "$OUT"; then rm "$OUT"; fi
        exit 2
    fi
    if ! test -f "$OUT"; then
        echo "Transformation of file $file isn't created!" >&2
        continue
    fi
    $diff -s "$IN" "$OUT"
    case $? in
        0) if test $verbose = true; then echo "$file unchanged."; fi
           ;;
        1) if test $confirm = true; then
               overwrite=""
               while test -z $overwrite; do
                   echo "Overwrite? \c"; read
                   case $REPLY in
                       y|Y|yes|true|t|T|Yes|True|YES|TRUE|1)
                           overwrite=true  ;;
                       n|N|no|false|f|F|No|False|NO|FALSE|0)
                           overwrite=false ;;
                   esac
               done
               if test $overwrite = true; then
                   mv "$OUT" "$IN" || rm "$OUT" # for the case of not writable $IN
               else
                   rm "$OUT"
               fi
           else
               if test $verbose = true; then echo "$file changed."; fi
               mv "$OUT" "$IN" || rm "$OUT" # for the case of not writable $IN
           fi
           ;;
        2) echo "Can't compare files $IN and $OUT" >&2
           rm "$OUT"
           exit 2
           ;;
    esac
    shift
done