# Copyright (C) 2011 The Android Open Source Project
#
# 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.
#

# This script is used to generate a shell script that will be
# run by the NDK build system to process dependency files generated by
# GCC on Windows, and convert them to a format that is suitable for
# Cygwin's GNU Make.
#
# The main issue to solve here is that the dependency files generated
# by GCC use native windows path names, as in:
#
#    C:/Foo/foo.o: \
#      C:/Foo/src/foo.h \
#      C:/Foo/src/foo.c \
#      D:/Bar/bar/bar.h
#
# And the file needs to be processed to convert each such path into
# a Cygwin-specific one, as in:
#
#    /cygdrive/c/Foo/foo.o: \
#      /cygdrive/c/Foo/src/foo.h \
#      /cygdrive/c/Foo/src/foo.c \
#      /cygdrive/d/Bar/bar/bar.h
#
# Previously, this conversion was done with an awk script that assumed
# that the cygwin drive prefix was always 'cygdrive'. This didn't work
# well when this was not the case, or when using drive-less mounts
# (e.g. when  /home/mnt would map to //server/subdir)
#
# To solve the issue correctly, we need to parse the output of the
# Cygwin mount table (i.e. the output of the 'mount' command), and
# build a sed script that will properly replace host paths into the
# corresponding cygwin equivalent.
#
# NOTE: The sed script will be run during command execution, not during the
# parse phase.
#
# This awk script expects its input to be the output of the Cygwin "mount" command
# as in:
#
#  C:/cygwin/bin on /usr/bin type ntfs (binary,auto)
#  C:/cygwin/lib on /usr/lib type ntfs (binary,auto)
#  C:/cygwin on / type ntfs (binary,auto)
#  C: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
#  D: on /cygdrive/d type udf (binary,posix=0,user,noumount,auto)
#  //server/subdir on /home/mnt.2$ type ....
#
# It first builds a sed script that convert all windows path in the
# an input file into the cygwin equivalent. For example, this would look
# like the following (but all on a single line):
#
#  s!^//server/subdir!/home/mnt\.2\$!ig;
#  s! //server/subdir! /home/mnt\.2\$!ig;
#  s!^C:/cygwin/bin!/usr/bin!ig;
#  s! C:/cygwin/bin! /usr/bin!ig;
#  s!^C:/cygwin/lib!/usr/lib!ig;
#  s! C:/cygwin/lib! /usr/lib!ig;
#  s!^C:/cygwin/!/!ig;
#  s! C:/cygwin/! /!ig;
#  s!^C:!/cygdrive/c!ig;
#  s! C:! /cygdrive/c!ig;
#  s!^D:!/cygdrive/d!ig;
#  s! D:! /cygdrive/d!ig;
#
# Note that we properly escape regex meta characters like . or $
# to avoid confusing sed. Also deal with the cases where the path
# is the first in the line, or prefixed with a space in the deps file.
#
# After this, the sed invokation is hard-coded into a generated shell
# script that can be invoked directly at build time.
#
BEGIN {
  # setup our count
  count = 0
}

$2 == "on" {
    # record a new (host-path,cygwin-path) pair
    count ++

    # Convert backwards slashes into forward ones in the host path.
    # This is to support MSys' mount command, which outputs Windows-style
    # separators, unlike Cygwin's version of the same tool.
    gsub("\\\\","/",$1)

    host[count] = $1
    cygwin[count] = $3
}

END {
    # We have recorded all (host,cygwin) path pairs,
    # now try to sort them so that the ones with the longest host path
    # appear first
    for (ii = 2; ii <= count; ii++) {
        for (jj = ii-1; jj > 0; jj--) {
            if (length(host[jj]) > length(host[jj+1])) {
                break;
            }
            if (length(host[jj]) == length(host[jj+1]) &&
                host[jj] > host[jj+1]) {
                break
            }
            tmp = cygwin[jj]
            cygwin[jj] = cygwin[jj+1]
            cygwin[jj+1] = tmp
            tmp = host[jj]
            host[jj] = host[jj+1]
            host[jj+1] = tmp
        }
    }

    # build/ndk/init.mk defines VERBOSE to 1 when it needs to dump the
    # list of substitutions in a human-friendly format, generally when
    # NDK_LOG is defined in the environment
    #
    # Otherwise, just generate the corresponding sed script
    #
    if (VERBOSE == 1) {
        for (nn = 1; nn <= count; nn++) {
            printf( "$(info %s => %s)", cygwin[nn], host[nn]);
        }
    } else {
        RESULT = ""
        for (nn = 1; nn <= count; nn++) {
            add_drive_rule(host[nn], cygwin[nn])
        }

        # Note: the role of the generated shell script is to first check
        #       that $1.org exists. If this is not the case, this simply
        #       means that GCC didn't generate a depedency file (e.g. when
        #       compiling an assembler file).
        #
        #       If the file exists, it is processed with our sed script,
        #       the output is written to $1, and we remove the original $1.org
        #
        print "#!/bin/sh"
        print "# AUTO-GENERATED FILE, DO NOT EDIT!"
        print "if [ -f $1.org ]; then"
        print "  sed -e '" RESULT "' $1.org > $1 && rm -f $1.org"
        print "fi"
    }
}

# We need to quote some characters so that 'sed' doesn't
# believe they are regex operators. For example, if a path
# contains a dot (.), we need to escape it into "\."
#
function sed_quote_path (str)
{
    # Windows path names cannot contain any of: <>:"|?*
    # see msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
    #
    # Anything else is valid. The regex meta characters are: ^.[]$()|*+?{}\
    #
    # This means we need to escape these when they appear in path names: ^.[]$()+{}\
    #
    gsub("\\^","\\^",str)
    gsub("\\.","\\.",str)
    gsub("\\[","\\[",str)
    gsub("\\]","\\]",str)
    gsub("\\$","\\$",str)
    gsub("\\(","\\(",str)
    gsub("\\)","\\)",str)
    gsub("\\+","\\+",str)
    gsub("\\{","\\{",str)
    gsub("\\}","\\}",str)

    return str
}

function add_drive_rule (hostpath,cygpath)
{
    hostpath = sed_quote_path(hostpath)
	cygpath = sed_quote_path(cygpath)
	
    # The root directory is a special case, because we need
	# to add a slash at the end of the corresponding host path
	# otherwise c:/cygwin/foo will be translated into //foo
	# instead of /foo.
	#
    if (cygpath == "/") {
        hostpath = hostpath "/"
    }
	# when the hostpath starts the line
    RESULT = RESULT "s!^" hostpath "!" cygpath "!ig;"

	# when the hostpath does not start the line (it will always be after a space)
	RESULT = RESULT "s! " hostpath "! " cygpath "!ig;"
}