lib

var (
	// ConcatFunc returns the concatenation of two string arguments.
	ConcatFunc = function.New(&function.Spec{
		VarParam: nil,
		Params: []function.Parameter{
			{
				Name: "first",
				Type: cty.String,
			},
			{
				Name: "second",
				Type: cty.String,
			},
		},
		Type: func(args []cty.Value) (cty.Type, error) { return cty.String, nil },
		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
			var first, second string
			if err := gocty.FromCtyValue(args[0], &first); err != nil {
				return cty.StringVal(""), err
			}
			if err := gocty.FromCtyValue(args[1], &second); err != nil {
				return cty.StringVal(""), err
			}
			return cty.StringVal(first + second), nil
		},
	})
)

var FunctionRunAsUnitTestOption = func(oa *functionOptionArg) { oa.runAsUnitTest = true }

var (
	// HostnameFunc attempts to determine the current system's hostname as the
	// environment variable HOSTNAME is not available on every platform.
	HostnameFunc = function.New(&function.Spec{
		VarParam: nil,
		Params:   nil,
		Type:     func(args []cty.Value) (cty.Type, error) { return cty.String, nil },
		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
			if hostname, ok := os.LookupEnv("HOSTNAME"); ok {
				return cty.StringVal(hostname), nil
			}
			if hostname, err := os.Hostname(); err == nil && len(hostname) > 0 {
				return cty.StringVal(hostname), nil
			}
			hostname, _ := os.LookupEnv("HOST")
			return cty.StringVal(hostname), nil
		},
	})
)

var (
	// RandomFunc generates length cryptographically secure random bytes and returns
	// an encoding encoded string.
	RandomFunc = function.New(&function.Spec{
		VarParam: nil,
		Params: []function.Parameter{
			{
				Name: "length",
				Type: cty.Number,
			},
			{
				Name: "encoding",
				Type: cty.String,
			},
		},
		Type: func(args []cty.Value) (cty.Type, error) { return cty.String, nil },
		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
			var length int
			var encoding string
			if err := gocty.FromCtyValue(args[0], &length); err != nil {
				return cty.StringVal(""), err
			}
			if err := gocty.FromCtyValue(args[1], &encoding); err != nil {
				return cty.StringVal(""), err
			}
			encodingF, ok := encodingMap[encoding]
			if !ok {
				return cty.StringVal(""), base.NewErrInvalidArg(
					"invalid or unsupported encoding scheme %q", encoding)
			}
			b := make([]byte, length)
			if _, err := rand.Read(b); err != nil {
				return cty.StringVal(""), err
			}
			return cty.StringVal(encodingF(b)), nil
		},
	})
)