func (m schemaMap) validate(
	k string,
	schema *Schema,
	c *terraform.ResourceConfig) ([]string, []error) {
	raw, ok := c.Get(k)
	if !ok && schema.DefaultFunc != nil {
		// We have a dynamic default. Check if we have a value.
		var err error
		raw, err = schema.DefaultFunc()
		if err != nil {
			return nil, []error{fmt.Errorf(
				"%q, error loading default: %s", k, err)}
		}

		// We're okay as long as we had a value set
		ok = raw != nil
	}
	if !ok {
		if schema.Required {
			return nil, []error{fmt.Errorf(
				"%q: required field is not set", k)}
		}

		return nil, nil
	}

	if !schema.Required && !schema.Optional {
		// This is a computed-only field
		return nil, []error{fmt.Errorf(
			"%q: this field cannot be set", k)}
	}

	return m.validateType(k, raw, schema, c)
}

func (m schemaMap) validateObject(
	k string,
	schema map[string]*Schema,
	c *terraform.ResourceConfig) ([]string, []error) {
	var ws []string
	var es []error
	for subK, s := range schema {
		key := subK
		if k != "" {
			key = fmt.Sprintf("%s.%s", k, subK)
		}

		ws2, es2 := m.validate(key, s, c)
		if len(ws2) > 0 {
			ws = append(ws, ws2...)
		}
		if len(es2) > 0 {
			es = append(es, es2...)
		}
	}

	// Detect any extra/unknown keys and report those as errors.
	raw, _ := c.Get(k)
	if m, ok := raw.(map[string]interface{}); ok {
		for subk, _ := range m {
			if _, ok := schema[subk]; !ok {
				es = append(es, fmt.Errorf(
					"%s: invalid or unknown key: %s", k, subk))
			}
		}
	}

	return ws, es
}

func (m schemaMap) validateMap(
	k string,
	raw interface{},
	schema *Schema,
	c *terraform.ResourceConfig) ([]string, []error) {
	// We use reflection to verify the slice because you can't
	// case to []interface{} unless the slice is exactly that type.
	rawV := reflect.ValueOf(raw)
	switch rawV.Kind() {
	case reflect.String:
		// If raw and reified are equal, this is a string and should
		// be rejected.
		reified, reifiedOk := c.Get(k)
		log.Printf("[jen20] reified: %s", spew.Sdump(reified))
		log.Printf("[jen20]     raw: %s", spew.Sdump(raw))
		if reifiedOk && raw == reified && !c.IsComputed(k) {
			return nil, []error{fmt.Errorf("%s: should be a map", k)}
		}
		// Otherwise it's likely raw is an interpolation.
		return nil, nil
	case reflect.Map:
	case reflect.Slice:
	default:
		return nil, []error{fmt.Errorf("%s: should be a map", k)}
	}

	// If it is not a slice, it is valid
	if rawV.Kind() != reflect.Slice {
		return nil, nil
	}

	// It is a slice, verify that all the elements are maps
	raws := make([]interface{}, rawV.Len())
	for i, _ := range raws {
		raws[i] = rawV.Index(i).Interface()
	}

	for _, raw := range raws {
		v := reflect.ValueOf(raw)
		if v.Kind() != reflect.Map {
			return nil, []error{fmt.Errorf(
				"%s: should be a map", k)}
		}
	}

	if schema.ValidateFunc != nil {
		validatableMap := make(map[string]interface{})
		for _, raw := range raws {
			for k, v := range raw.(map[string]interface{}) {
				validatableMap[k] = v
			}
		}

		return schema.ValidateFunc(validatableMap, k)
	}

	return nil, nil
}

func (m schemaMap) validatePrimitive(
	k string,
	raw interface{},
	schema *Schema,
	c *terraform.ResourceConfig) ([]string, []error) {
	if c.IsComputed(k) {
		// If the key is being computed, then it is not an error
		return nil, nil
	}

	var decoded interface{}
	switch schema.Type {
	case TypeBool:
		// Verify that we can parse this as the correct type
		var n bool
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeInt:
		// Verify that we can parse this as an int
		var n int
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeFloat:
		// Verify that we can parse this as an int
		var n float64
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeString:
		// Verify that we can parse this as a string
		var n string
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	default:
		panic(fmt.Sprintf("Unknown validation type: %#v", schema.Type))
	}

	if schema.ValidateFunc != nil {
		return schema.ValidateFunc(decoded, k)
	}

	return nil, nil
}

func (m schemaMap) validateConflictingAttributes(
	k string,
	schema *Schema,
	c *terraform.ResourceConfig) error {

	if len(schema.ConflictsWith) == 0 {
		return nil
	}

	for _, conflicting_key := range schema.ConflictsWith {
		if value, ok := c.Get(conflicting_key); ok {
			return fmt.Errorf(
				"%q: conflicts with %s (%#v)", k, conflicting_key, value)
		}
	}

	return nil
}

func (m schemaMap) validate(
	k string,
	schema *Schema,
	c *terraform.ResourceConfig) ([]string, []error) {
	raw, ok := c.Get(k)
	if !ok {
		if schema.Required {
			return nil, []error{fmt.Errorf(
				"%s: required field is not set", k)}
		}

		return nil, nil
	}

	if !schema.Required && !schema.Optional {
		// This is a computed-only field
		return nil, []error{fmt.Errorf(
			"%s: this field cannot be set", k)}
	}

	return m.validatePrimitive(k, raw, schema, c)
}

func (m schemaMap) validatePrimitive(
	k string,
	raw interface{},
	schema *Schema,
	c *terraform.ResourceConfig) ([]string, []error) {

	// Catch if the user gave a complex type where a primitive was
	// expected, so we can return a friendly error message that
	// doesn't contain Go type system terminology.
	switch reflect.ValueOf(raw).Type().Kind() {
	case reflect.Slice:
		return nil, []error{
			fmt.Errorf("%s must be a single value, not a list", k),
		}
	case reflect.Map:
		return nil, []error{
			fmt.Errorf("%s must be a single value, not a map", k),
		}
	default: // ok
	}

	if c.IsComputed(k) {
		// If the key is being computed, then it is not an error as
		// long as it's not a slice or map.
		return nil, nil
	}

	var decoded interface{}
	switch schema.Type {
	case TypeBool:
		// Verify that we can parse this as the correct type
		var n bool
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeInt:
		// Verify that we can parse this as an int
		var n int
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeFloat:
		// Verify that we can parse this as an int
		var n float64
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	case TypeString:
		// Verify that we can parse this as a string
		var n string
		if err := mapstructure.WeakDecode(raw, &n); err != nil {
			return nil, []error{err}
		}
		decoded = n
	default:
		panic(fmt.Sprintf("Unknown validation type: %#v", schema.Type))
	}

	if schema.ValidateFunc != nil {
		return schema.ValidateFunc(decoded, k)
	}

	return nil, nil
}