package mongo

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/cenkalti/backoff/v4"
	"github.com/spf13/viper"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"sync"
	"time"
)

var AppName = "crawlab-db"

var _clientMap = map[string]*mongo.Client{}
var _mu sync.Mutex

func GetMongoClient(opts ...ClientOption) (c *mongo.Client, err error) {
	// client options
	_opts := &ClientOptions{}
	for _, op := range opts {
		op(_opts)
	}
	if _opts.Uri == "" {
		_opts.Uri = viper.GetString("mongo.uri")
	}
	if _opts.Host == "" {
		_opts.Host = viper.GetString("mongo.host")
		if _opts.Host == "" {
			_opts.Host = "localhost"
		}
	}
	if _opts.Port == 0 {
		_opts.Port = viper.GetInt("mongo.port")
		if _opts.Port == 0 {
			_opts.Port = 27017
		}
	}
	if _opts.Db == "" {
		_opts.Db = viper.GetString("mongo.db")
		if _opts.Db == "" {
			_opts.Db = "admin"
		}
	}
	if len(_opts.Hosts) == 0 {
		_opts.Hosts = viper.GetStringSlice("mongo.hosts")
	}
	if _opts.Username == "" {
		_opts.Username = viper.GetString("mongo.username")
	}
	if _opts.Password == "" {
		_opts.Password = viper.GetString("mongo.password")
	}
	if _opts.AuthSource == "" {
		_opts.AuthSource = viper.GetString("mongo.authSource")
		if _opts.AuthSource == "" {
			_opts.AuthSource = "admin"
		}
	}
	if _opts.AuthMechanism == "" {
		_opts.AuthMechanism = viper.GetString("mongo.authMechanism")
	}
	if _opts.AuthMechanismProperties == nil {
		_opts.AuthMechanismProperties = viper.GetStringMapString("mongo.authMechanismProperties")
	}

	// client options key json string
	_optsKeyBytes, err := json.Marshal(_opts)
	if err != nil {
		return nil, err
	}
	_optsKey := string(_optsKeyBytes)

	// attempt to get client by client options
	c, ok := _clientMap[_optsKey]
	if ok {
		return c, nil
	}

	// create new mongo client
	c, err = newMongoClient(_opts)
	if err != nil {
		logger.Errorf("create mongo client error: %v", err)
		return nil, err
	}

	// add to map
	_mu.Lock()
	_clientMap[_optsKey] = c
	_mu.Unlock()

	return c, nil
}

func newMongoClient(_opts *ClientOptions) (c *mongo.Client, err error) {
	// mongo client options
	mongoOpts := &options.ClientOptions{
		AppName: &AppName,
	}

	if _opts.Uri != "" {
		// uri is set
		mongoOpts.ApplyURI(_opts.Uri)
	} else {
		// uri is unset
		if _opts.Username != "" && _opts.Password != "" {
			// username and password are set
			mongoOpts.SetAuth(options.Credential{
				AuthMechanism:           _opts.AuthMechanism,
				AuthMechanismProperties: _opts.AuthMechanismProperties,
				AuthSource:              _opts.AuthSource,
				Username:                _opts.Username,
				Password:                _opts.Password,
				PasswordSet:             true,
			})
		}

		if len(_opts.Hosts) > 0 {
			// hosts are set
			mongoOpts.SetHosts(_opts.Hosts)
		} else {
			// hosts are unset
			mongoOpts.ApplyURI(fmt.Sprintf("mongodb://%s:%d/%s", _opts.Host, _opts.Port, _opts.Db))
		}
	}

	// attempt to connect with retry
	op := func() error {
		ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
		defer cancel()

		logger.Infof("connecting to mongo")
		c, err = mongo.Connect(ctx, mongoOpts)
		if err != nil {
			return err
		}
		err = c.Ping(ctx, nil)
		if err != nil {
			logger.Errorf("ping mongo error: %v", err)
			return err
		}
		logger.Infof("connected to mongo")
		return nil
	}
	b := backoff.NewExponentialBackOff()
	n := func(err error, duration time.Duration) {
		logger.Errorf("connect to mongo error: %v. retrying in %.1fs", err, duration.Seconds())
	}
	err = backoff.RetryNotify(op, b, n)
	if err != nil {
		logger.Errorf("connect to mongo error: %v", err)
		return nil, err
	}

	return c, nil
}