package chunk

import (
	"github.com/flashmob/go-guerrilla/backends"
	"github.com/flashmob/go-guerrilla/mail"
	"github.com/flashmob/go-guerrilla/mail/smtp"
	"io"
	"net"
	"time"
)

func init() {
	StorageEngines = make(map[string]StorageEngineConstructor)
}

// Storage defines an interface to the storage layer (the database)
type Storage interface {
	// OpenMessage is used to begin saving an email. An email id is returned and used to call CloseMessage later
	OpenMessage(
		queuedID mail.Hash128,
		from string,
		helo string,
		recipient string,
		ipAddress IPAddr,
		returnPath string,
		protocol mail.Protocol,
		transport smtp.TransportType) (mailID uint64, err error)
	// CloseMessage finalizes the writing of an email. Additional data collected while parsing the email is saved
	CloseMessage(
		mailID uint64,
		size int64,
		partsInfo *PartsInfo,
		subject string,
		to string,
		from string) error
	// AddChunk saves a chunk of bytes to a given hash key
	AddChunk(data []byte, hash []byte) error
	// GetEmail returns an email that's been saved
	GetMessage(mailID uint64) (*Email, error)
	// GetChunks loads in the specified chunks of bytes from storage
	GetChunks(hash ...HashKey) ([]*Chunk, error)
	// Initialize is called when the backend is started
	Initialize(cfg backends.ConfigGroup) error
	// Shutdown is called when the backend gets shutdown.
	Shutdown() (err error)
}

// StorageEngines contains the constructors for creating instances that implement Storage
// To add your own Storage, create your own Storage struct, then add your constructor to
// this `StorageEngines` map. Enable it via the configuration (the `storage_engine` setting)
var StorageEngines map[string]StorageEngineConstructor

type StorageEngineConstructor func() Storage

// Email represents an email
type Email struct {
	mailID     uint64
	createdAt  time.Time
	size       int64
	from       string // from stores the email address found in the "From" header field
	to         string // to stores the email address found in the "From" header field
	partsInfo  PartsInfo
	helo       string // helo message given by the client when the message was transmitted
	subject    string // subject stores the value from the first "Subject" header field
	queuedID   string
	recipient  string             // recipient is the email address that the server received from the RCPT TO command
	ipv4       IPAddr             // set to a value if client connected via ipv4
	ipv6       IPAddr             // set to a value if client connected via ipv6
	returnPath string             // returnPath is the email address that the server received from the MAIL FROM command
	protocol   mail.Protocol      // protocol such as SMTP, ESTMP, ESMTPS
	transport  smtp.TransportType // transport what type of transport the message uses, eg 8bitmime
}

type Chunk struct {
	modifiedAt     time.Time
	referenceCount uint // referenceCount counts how many emails reference this chunk
	data           io.Reader
}

type IPAddr struct {
	net.IPAddr
}