#!/usr/bin/ruby

NONSTANDARD_SDKS = {
    '10.3.9' => '10.3',
    '10.4u' => '10.4'
}

def standardize_sdk(sdk_name)
    NONSTANDARD_SDKS[sdk_name] || sdk_name
end

def macosx_to_darwin_version(macosx_version)
    macosx_version =~ /^10\.(\d+)$/
    $1.to_i + 4
end

MINIMUM_DARWIN_VERSION_BY_ARCH = {
    'ppc' => 7,
    'i386' => 8,
    'ppc64' => 9,
    'x86_64' => 9,
}

MAXIMUM_DARWIN_VERSION_BY_ARCH = {
    'ppc' => 9,
    'ppc64' => 9,
}

def current_darwin_version()
    `uname -r` =~ /^(\d+).*$/
    $1.to_i
end

def possible_darwin_versions(arch)
    min = MINIMUM_DARWIN_VERSION_BY_ARCH[arch]
    max = MAXIMUM_DARWIN_VERSION_BY_ARCH[arch] || current_darwin_version()
    min..max
end

def available_sdks()
    Hash[*(Dir['/Developer/SDKs/*.sdk'].map { |sdk|
        sdk =~ /.*MacOSX(.*)\.sdk/
        sdk_name = $1
        [macosx_to_darwin_version(standardize_sdk(sdk_name)), sdk_name]
    }.flatten)]
end

MIN_OS_VERSION_BY_DARWIN_VERSION = {
    7 => '10.3.9',
    8 => '10.4.11',
}

def min_os_version_from_darwin_version(version)
    MIN_OS_VERSION_BY_DARWIN_VERSION[version] || "10.#{version - 4}"
end

def choose_sdk(arch)
    sdks = available_sdks()
    versions = possible_darwin_versions(arch)
    possible_darwin_versions = versions.find_all { |v| sdks[v] }
    version = possible_darwin_versions[0]
    <<EOF
SDK                = /Developer/SDKs/MacOSX#{sdks[version]}.sdk
MACOSX_VERSION_MIN = #{min_os_version_from_darwin_version(version)}
EOF
end

puts choose_sdk(ARGV[0])