/*
 * Copyright 2019 Intel Corporation, Inc
 *
 * 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 config

import (
	"encoding/json"
	"log"
	"os"
	"reflect"
)

// Configuration loads up all the values that are used to configure
// backend implementations
type Configuration struct {
	CAFile            string `json:"ca-file"`
	ServerCert        string `json:"server-cert"`
	ServerKey         string `json:"server-key"`
	Password          string `json:"password"`
	DatabaseAddress   string `json:"database-address"`
	DatabaseType      string `json:"database-type"`
	PluginDir         string `json:"plugin-dir"`
	EtcdIP            string `json:"etcd-ip"`
	EtcdCert          string `json:"etcd-cert"`
	EtcdKey           string `json:"etcd-key"`
	EtcdCAFile        string `json:"etcd-ca-file"`
	OVNCentralAddress string `json:"ovn-central-address"`
	ServicePort       string `json:"service-port"`
}

// Config is the structure that stores the configuration
var gConfig *Configuration

// readConfigFile reads the specified smsConfig file to setup some env variables
func readConfigFile(file string) (*Configuration, error) {
	f, err := os.Open(file)
	if err != nil {
		return defaultConfiguration(), err
	}
	defer f.Close()

	// Setup some defaults here
	// If the json file has values in it, the defaults will be overwritten
	conf := defaultConfiguration()

	// Read the configuration from json file
	decoder := json.NewDecoder(f)
	err = decoder.Decode(conf)
	if err != nil {
		return conf, err
	}

	return conf, nil
}

func defaultConfiguration() *Configuration {
	cwd, err := os.Getwd()
	if err != nil {
		log.Println("Error getting cwd. Using .")
		cwd = "."
	}

	return &Configuration{
		CAFile:            "ca.cert",
		ServerCert:        "server.cert",
		ServerKey:         "server.key",
		Password:          "",
		DatabaseAddress:   "127.0.0.1",
		DatabaseType:      "mongo",
		PluginDir:         cwd,
		EtcdIP:            "127.0.0.1",
		EtcdCert:          "etcd.cert",
		EtcdKey:           "etcd.key",
		EtcdCAFile:        "etcd-ca.cert",
		OVNCentralAddress: "127.0.0.1",
		ServicePort:       "9015",
	}
}

// GetConfiguration returns the configuration for the app.
// It will try to load it if it is not already loaded.
func GetConfiguration() *Configuration {
	if gConfig == nil {
		conf, err := readConfigFile("k8sconfig.json")
		if err != nil {
			log.Println("Error loading config file. Using defaults.")
		}
		gConfig = conf
	}

	return gConfig
}

// SetConfigValue sets a value in the configuration
// This is mostly used to customize the application and
// should be used carefully.
func SetConfigValue(key string, value string) *Configuration {
	c := GetConfiguration()
	if value == "" || key == "" {
		return c
	}

	v := reflect.ValueOf(c).Elem()
	if v.Kind() == reflect.Struct {
		f := v.FieldByName(key)
		if f.IsValid() {
			if f.CanSet() {
				if f.Kind() == reflect.String {
					f.SetString(value)
				}
			}
		}
	}
	return c
}