// Copyright 2019 Istio Authors
//
// 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.

package constraint

import (
	"encoding/json"
	"fmt"
)

// Check a single item for validation purposes.
type Check interface {
	ValidateItem(i interface{}, p Params) error
}

func parseChecks(rs []json.RawMessage) ([]Check, error) {
	var result []Check

	for _, r := range rs {
		c, err := parseCheck(r)
		if err != nil {
			return nil, err
		}

		result = append(result, c)
	}

	return result, nil
}

func parseCheck(r json.RawMessage) (Check, error) {
	m := make(map[string]interface{})
	err := json.Unmarshal(r, &m)
	if err != nil {
		return nil, err
	}

	if _, ok := m["select"]; ok {
		sel := &Select{}
		if err := json.Unmarshal(r, sel); err != nil {
			return nil, err
		}
		return sel, nil
	}

	if _, ok := m["equals"]; ok {
		eq := &Equals{}
		if err := json.Unmarshal(r, eq); err != nil {
			return nil, err
		}
		return eq, nil
	}

	return nil, fmt.Errorf("no recognized check clause found: %v", m)
}
