#!/bin/bash
#
# Copyright (c) 2011-2015 Ryan Prichard
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to
# deal in the Software without restriction, including without limitation the
# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
# sell copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.

#
# findTool(desc, commandList)
#
# Searches commandLine for the first command in the PATH and returns it.
# Prints an error and aborts the script if no match is found.
#
FINDTOOL_OUT=""
function findTool {
    DESC=$1
    OPTIONS=$2
    for CMD in ${OPTIONS}; do
        if (which $CMD &>/dev/null) then
            echo "Found $DESC: $CMD"
            FINDTOOL_OUT="$CMD"
            return
        fi
    done
    echo "Error: could not find $DESC.  One of these should be in your PATH:"
    for CMD in ${OPTIONS}; do
        echo " * $CMD"
    done
    exit 1
}

IS_CYGWIN=0
IS_MSYS=0

# Link parts of the Cygwin binary statically to aid in redistribution?  The
# binary still links dynamically against the main DLL.  The MinGW binaries are
# also statically linked and therefore depend only on Windows DLLs.  I started
# linking the Cygwin/MSYS binary statically, because G++ 4.7 changed the
# Windows C++ ABI.
UNIX_LDFLAGS_STATIC='-static -static-libgcc -static-libstdc++'

# Detect the environment -- Cygwin or MSYS.
case $(uname -s) in
    CYGWIN*)
        echo 'uname -s identifies a Cygwin environment.'
        IS_CYGWIN=1
	    case $(uname -m) in
            i686)
                echo 'uname -m identifies an i686 environment.'
                UNIX_CXX=i686-pc-cygwin-g++
                MINGW_CXX="i686-w64-mingw32-g++ i686-pc-mingw32-g++"
                ;;
            x86_64)
                echo 'uname -m identifies an x86_64 environment.'
                UNIX_CXX=x86_64-pc-cygwin-g++
                MINGW_CXX=x86_64-w64-mingw32-g++
                ;;
            *)
                echo 'Error: uname -m did not match either i686 or x86_64.'
                exit 1
                ;;
	    esac
        ;;
    MSYS*|MINGW*)
        # MSYS2 notes:
        #  - MSYS2 offers two shortcuts to open an environment:
        #     - MinGW-w64 Win32 Shell.  This env reports a `uname -s` of
        #       MINGW32_NT-6.1 on 32-bit Win7.  The MinGW-w64 compiler
        #       (i686-w64-mingw32-g++.exe) is in the PATH.
        #     - MSYS2 Shell.  `uname -s` instead reports MSYS_NT-6.1.
        #       The i686-w64-mingw32-g++ compiler is not in the PATH.
        #  - MSYS2 appears to use MinGW-w64, not the older mingw.org.
        # MSYS notes:
        #  - `uname -s` is always MINGW32_NT-6.1 on Win7.
        echo 'uname -s identifies an MSYS/MSYS2 environment.'
        IS_MSYS=1
        case $(uname -m) in
            i686)
                echo 'uname -m identifies an i686 environment.'
                UNIX_CXX=i686-pc-msys-g++
                MINGW_CXX='i686-w64-mingw32-g++.exe mingw32-g++'
                if echo "$(uname -r)" | grep '^1[.]' > /dev/null; then
                    # The MSYS-targeting compiler for the original 32-bit-only
                    # MSYS does not recognize the -static-libstdc++ flag, and
                    # it does not work with -static, because it tries to link
                    # statically with the core MSYS library and fails.
                    #
                    # Distinguish between the two using the major version
                    # number of `uname -r`:
                    #
                    #   MSYS uname -r:  1.0.18(0.48/3/2)
                    #   MSYS2 uname -r: 2.0.0(0.284/5/3)
                    #
                    # This is suboptimal because MSYS2 is not actually the
                    # second version of MSYS--it's a brand-new fork of Cygwin.
                    #
                    UNIX_LDFLAGS_STATIC=
                fi
                ;;
            x86_64)
                echo 'uname -m identifies an x86_64 environment.'
                UNIX_CXX=x86_64-pc-msys-g++
                MINGW_CXX=x86_64-w64-mingw32-g++
                ;;
            *)
                echo 'Error: uname -m did not match either i686 or x86_64.'
                exit 1
                ;;
        esac
        ;;
    *)
        echo 'Error: uname -s did not match either CYGWIN* or MINGW*.'
        exit 1
        ;;
esac

# Search the PATH and pick the first match.
findTool "Cygwin/MSYS G++ compiler" "$UNIX_CXX"
UNIX_CXX=$FINDTOOL_OUT
findTool "MinGW G++ compiler" "$MINGW_CXX"
MINGW_CXX=$FINDTOOL_OUT

# Write config files.
echo Writing config.mk
echo UNIX_CXX=$UNIX_CXX > config.mk
echo UNIX_LDFLAGS_STATIC=$UNIX_LDFLAGS_STATIC >> config.mk
echo MINGW_CXX=$MINGW_CXX >> config.mk

# Figure out how to embed build info (e.g. git commit) into the binary.
if test -f BUILD_INFO.txt; then
    echo "Build info: source package"
    eval $(grep '^VERSION_SUFFIX=' BUILD_INFO.txt | tr -d '\r')
    eval $(grep '^COMMIT_HASH=' BUILD_INFO.txt | tr -d '\r')
    echo "VERSION_SUFFIX ?= ${VERSION_SUFFIX}" >> config.mk
    echo "COMMIT_HASH ?= ${COMMIT_HASH}" >> config.mk
    echo "BUILD_INFO_DEP = config.mk" >> config.mk
elif test -d .git && git rev-parse HEAD >&/dev/null; then
    echo "Build info: git"
    echo 'VERSION_SUFFIX ?= -dev' >> config.mk
    echo 'COMMIT_HASH ?= $$(git rev-parse HEAD)' >> config.mk
    echo 'BUILD_INFO_DEP = config.mk .git/HEAD' >> config.mk
else
    echo "Build info: none"
    echo 'VERSION_SUFFIX ?= -dev' >> config.mk
    echo 'COMMIT_HASH ?= none' >> config.mk
    echo 'BUILD_INFO_DEP = config.mk' >> config.mk
fi