package configuration

import (
	. "antoine-roux.tk/kafka/internal/kafka"
	. "antoine-roux.tk/kafka/internal/kafka/provider"
	"crypto/tls"
	"crypto/x509"
	"flag"
	"fmt"
	"github.com/Shopify/sarama"
	"gopkg.in/yaml.v3"
	"os"
	"path/filepath"
	"strings"
)

const usage = `
Usage of %s:
  -c, --configuration path to yaml configuration file
  -h, --help prints help information
`

type AuthType string

const (
	MTLS_AUTH AuthType = "mtls"
	SRAM_AUTH AuthType = "scram-sha-512"
)

var configurationPath string

type Configuration interface {
	IsVerbose() bool
	CreateApplication() (application *Application)
}

type kafkaConfiguration struct {
	Version   string   `yaml:"version"`
	Brokers   string   `yaml:"brokers"`
	AuthType  AuthType `yaml:"auth-type"`
	UserName  *string  `yaml:"username"`
	Password  *string  `yaml:"password"`
	Cert      *string  `yaml:"cert"`
	Key       *string  `yaml:"key"`
	Ca        string   `yaml:"ca"`
	GroupName string   `yaml:"group-name"`
	Topics    struct {
		In  string `yaml:"in"`
		Out string `yaml:"out"`
	}
}

type configuration struct {
	Verbose bool `yaml:"verbose"`
	Kafka   kafkaConfiguration
}

func NewConfiguration() Configuration {

	flag.StringVar(&configurationPath, "configuration", "./configuration.yaml", "configuration path")
	flag.StringVar(&configurationPath, "c", "./configuration.yaml", "configuration path")
	flag.Usage = func() { fmt.Printf(usage, os.Args[0]) }
	flag.Parse()

	filename, _ := filepath.Abs(configurationPath)

	configurationFile, err := os.ReadFile(filename)
	if err != nil {
		panic("Invalid configuration file path, fail to read it")
	}

	var configuration configuration

	err = yaml.Unmarshal(configurationFile, &configuration)
	return &configuration
}

func (c *configuration) IsVerbose() bool {
	return c.Verbose
}

func (c *configuration) CreateApplication() (application *Application) {
	producerConfigurationFactory := newKafkaProducerConfigurationFactory(c.Kafka)
	consumerConfigurationFactory := newKafkaConsumerConfigurationFactory(c.Kafka)

	application = &Application{}

	application.ProducerProvider = NewProducerProvider(
		strings.Split(c.Kafka.Brokers, ","),
		producerConfigurationFactory,
	)
	application.ConsumerProvider = NewConsumerProvider(
		strings.Split(c.Kafka.Brokers, ","),
		c.Kafka.GroupName,
		consumerConfigurationFactory,
	)

	if len(c.Kafka.Topics.In) == 0 {
		panic("no input In topic given to be consumed, please set kafka.topics.in")
	}
	application.ReceiverTopic = Topic(c.Kafka.Topics.In)

	if len(c.Kafka.Topics.Out) == 0 {
		panic("no input Out topic given to produce to, please set kafka.topics.out")
	}
	application.EmitterTopic = Topic(c.Kafka.Topics.Out)

	return
}

func newKafkaConsumerConfigurationFactory(kafkaConfiguration kafkaConfiguration) func() *sarama.Config {
	version, err := sarama.ParseKafkaVersion(kafkaConfiguration.Version)
	if err != nil {
		panic(fmt.Sprintf("Error parsing Kafka Version: %v\n", err))
	}
	if len(kafkaConfiguration.Brokers) == 0 {
		panic("no Kafka bootstrap brokers defined, please set Kafka.brokers in configuration file")
	}

	if kafkaConfiguration.AuthType == SRAM_AUTH {
		if kafkaConfiguration.UserName == nil || len(*kafkaConfiguration.UserName) == 0 {
			panic("no Kafka scram username defined, please set Kafka.username in configuration file")
		}
		if kafkaConfiguration.Password == nil || len(*kafkaConfiguration.Password) == 0 {
			panic("no Kafka scram password defined, please set Kafka.password in configuration file")
		}
	} else if kafkaConfiguration.AuthType == MTLS_AUTH {
		if kafkaConfiguration.Cert == nil {
			panic("no Kafka mtls cert defined, please set Kafka.cert in configuration file")
		}
		if kafkaConfiguration.Key == nil {
			panic("no Kafka mtls key defined, please set Kafka.key in configuration file")
		}
	} else {
		panic("invalid kafka auth type in configuration file")
	}

	configuration := sarama.NewConfig()

	return func() *sarama.Config {
		configuration.Version = version
		configuration.ClientID = "client_id"
		configuration.Metadata.Full = true

		configuration.Net.MaxOpenRequests = 1
		configuration.Net.TLS.Enable = true

		caCertPool := x509.NewCertPool()
		caCertPool.AppendCertsFromPEM([]byte(kafkaConfiguration.Ca))
		configuration.Net.TLS.Config = &tls.Config{
			RootCAs:            caCertPool,
			InsecureSkipVerify: false,
		}

		if kafkaConfiguration.AuthType == SRAM_AUTH {
			configuration.Net.SASL.Enable = true
			configuration.Net.SASL.User = *kafkaConfiguration.UserName
			configuration.Net.SASL.Password = *kafkaConfiguration.Password
			configuration.Net.SASL.Handshake = true
			configuration.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient { return &XDGSCRAMClient{HashGeneratorFcn: SHA512} }
			configuration.Net.SASL.Mechanism = sarama.SASLTypeSCRAMSHA512
		} else {
			cert, err := tls.X509KeyPair([]byte(*kafkaConfiguration.Cert), []byte(*kafkaConfiguration.Key))
			if err != nil {
				panic("Invalid configuration failed to read client certificates")
			}
			configuration.Net.TLS.Config.Certificates = []tls.Certificate{cert}
		}

		return configuration
	}
}

func newKafkaProducerConfigurationFactory(kafkaConfiguration kafkaConfiguration) func() *sarama.Config {
	version, err := sarama.ParseKafkaVersion(kafkaConfiguration.Version)
	if err != nil {
		panic(fmt.Sprintf("Error parsing Kafka Version: %v\n", err))
	}
	if len(kafkaConfiguration.Brokers) == 0 {
		panic("no Kafka bootstrap brokers defined, please set Kafka.brokers in configuration file")
	}

	if kafkaConfiguration.AuthType == SRAM_AUTH {
		if kafkaConfiguration.UserName == nil || len(*kafkaConfiguration.UserName) == 0 {
			panic("no Kafka scram username defined, please set Kafka.username in configuration file")
		}
		if kafkaConfiguration.Password == nil || len(*kafkaConfiguration.Password) == 0 {
			panic("no Kafka scram password defined, please set Kafka.password in configuration file")
		}
	} else if kafkaConfiguration.AuthType == MTLS_AUTH {
		if kafkaConfiguration.Cert == nil {
			panic("no Kafka mtls cert defined, please set Kafka.cert in configuration file")
		}
		if kafkaConfiguration.Key == nil {
			panic("no Kafka mtls key defined, please set Kafka.key in configuration file")
		}
	} else {
		panic("invalid kafka auth type in configuration file")
	}

	configuration := sarama.NewConfig()

	return func() *sarama.Config {
		configuration.Version = version
		configuration.ClientID = "client_id"
		configuration.Metadata.Full = true

		configuration.Producer.Idempotent = true
		configuration.Producer.Return.Errors = true
		configuration.Producer.RequiredAcks = sarama.WaitForAll
		configuration.Producer.Partitioner = sarama.NewRoundRobinPartitioner
		configuration.Producer.Transaction.Retry.Backoff = 10
		configuration.Producer.Transaction.ID = "txn_producer"
		configuration.Producer.Retry.Max = 1
		configuration.Producer.Return.Successes = true

		configuration.Net.MaxOpenRequests = 1
		configuration.Net.TLS.Enable = true

		caCertPool := x509.NewCertPool()
		caCertPool.AppendCertsFromPEM([]byte(kafkaConfiguration.Ca))
		configuration.Net.TLS.Config = &tls.Config{
			RootCAs:            caCertPool,
			InsecureSkipVerify: false,
		}

		if kafkaConfiguration.AuthType == SRAM_AUTH {
			configuration.Net.SASL.Enable = true
			configuration.Net.SASL.User = *kafkaConfiguration.UserName
			configuration.Net.SASL.Password = *kafkaConfiguration.Password
			configuration.Net.SASL.Handshake = true
			configuration.Net.SASL.SCRAMClientGeneratorFunc = func() sarama.SCRAMClient { return &XDGSCRAMClient{HashGeneratorFcn: SHA512} }
			configuration.Net.SASL.Mechanism = sarama.SASLTypeSCRAMSHA512
		} else {
			cert, err := tls.X509KeyPair([]byte(*kafkaConfiguration.Cert), []byte(*kafkaConfiguration.Key))
			if err != nil {
				panic("Invalid configuration failed to read client certificates")
			}
			configuration.Net.TLS.Config.Certificates = []tls.Certificate{cert}
		}

		return configuration
	}
}

type Topic string

type Application struct {
	ProducerProvider Provider[sarama.SyncProducer]
	ConsumerProvider Provider[sarama.ConsumerGroup]
	ReceiverTopic    Topic
	EmitterTopic     Topic
}