#!/bin/bash
#
# MKPatch 2.0.0: Simple patch program to .mkbuild models
# feedback: rudsonaalves at yahoo.com.br | gpl
#
#  mkbuild is free software; you can redistribute it and/or modify it under the
#  terms of the GNU General Public License as published by the Free Software
#  Foundation; either version 2 of the License, or any later version.
#
#  mkbuild is distributed in the hope that it will be useful, but WITHOUT ANY
#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
#  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License along with
#  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
#  Place - Suite 330, Boston, MA 02111-1307, USA
#
# Input:
#   - $1 Diff_File
#   - #2 Source_File
#
# Version:
PROG_VERSION=2.0
BASENAME=`basename $0`

# Errors codes. From common.sh
ERROR_FILE_NOTFOUND=${ERROR_FILE_NOTFOUND:=100}
ERROR_PAR_NUMBER=${ERROR_PAR_NUMBER:=102}
ERROR_MKPATCH=${ERROR_MKPATCH:=600}

# check input arguments
if [ "$1" = "--help" -o "$1" = "-h" ]; then
    echo "Use: $BASENAME <diff_file> <source_file>"
    exit $ERROR_HELP
fi

# check number of parameters
[ $# -ne 2 ] && exit $ERROR_PAR_NUMBER

# check diff_file exit
[ ! -e $1 ] && exit $ERROR_FILE_NOTFOUND

# check source_file exit
[ ! -e $2 ] && exit $ERROR_FILE_NOTFOUND

# Change IFS value to <ENTER> only
OLD_IFS=$IFS
IFS='
'

# Read vector from patch file
index=0
while read line; do
    Diff_lines[index]="`echo $line | cut -c2-`"
    Diff_action[index]="`echo $line | cut -c1`"
    let index++
done < $1
let Diff_n_lines=index-1

# Read vector from source file
index=0
while read line; do
    Source_lines[index]="$line"
    let index++
done < $2
let Source_n_lines=index-1

# Rescue IFS value
IFS=$OLD_IFS

# Stating variables
Source_index=0
Diff_index=0
Diff_pointer=0
Status_diff=0

# Output vector
Output=""
Output_index=0

# Apply patch
while [ $Source_index -le $Source_n_lines -a $Diff_index -le $Diff_n_lines ]; do
    # make Actions
    case "${Diff_action[Diff_index]}" in
        '-')
            if [ "${Source_lines[Source_index]}" == "${Diff_lines[Diff_index]}" ]; then
                Status_diff=1
                let Diff_index++
            else
                Diff_index=$Diff_pointer
                Status_diff=0
                Output[Output_index]="${Source_lines[Souce_index]}"
                let Output_index++
            fi
            let Source_index++
            ;;
        '+')
            Output[Output_index]="${Diff_lines[Diff_index]}"
            let Diff_index++
            let Output_index++
            ;;
        ' ')
            if [ "${Source_lines[Source_index]}" == "${Diff_lines[Diff_index]}" ]; then
                Status_diff=1
                let Diff_index++
            else
                Status_diff=0
                Diff_index=$Diff_pointer
            fi
            Output[Output_index]="${Source_lines[Source_index]}"
            let Output_index++
            let Source_index++
            ;;
        '=')
            let Diff_index++
            Status_diff=0
            Diff_pointer=$Diff_index
            ;;
        '*')
            echo "Invalid diff action."
            exit $ERROR_MKPATCH
            ;;
    esac
done

# Check end of file mkSlackBuild
if [ $Diff_index -gt $Diff_n_lines -a $Source_index -le $Source_n_lines ]; then
    # write the rest of mkSlackBuild in Output vector
    for index in `seq $Source_index $Source_n_lines`; do
        Output[Output_index]="${Source_lines[index]}"
        let Output_index++
    done
elif [ $Diff_index -le $Diff_n_lines ]; then
    # Write others addlines, "+", in Output vector
    while [ "${Diff_Action[Diff_index]}" == "+" ]; do
        Output[Output_index]="${Diff_lines[Diff_index]}"
        let Diff_index++
        let Output_index++
    done
fi

# Print Output file
for index in `seq 1 $Output_index`; do
    echo "${Output[$index-1]}"
done