package main

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"strings"
	"unicode"

	log "github.com/sirupsen/logrus"
	"golang.org/x/crypto/nacl/secretbox"

	. "git.deuxfleurs.fr/Deuxfleurs/easybridge/connector"
)

const EASYBRIDGE_SYSTEM_PROTOCOL string = "✯◡✯"

func ezbrMxId() string {
	return fmt.Sprintf("@%s:%s", registration.SenderLocalpart, config.MatrixDomain)
}

func ezbrSystemRoom(user_mx_id string) (string, error) {
	mx_room_id, err := dbGetMxPmRoom(EASYBRIDGE_SYSTEM_PROTOCOL, UserID("Easybridge"), ezbrMxId(), user_mx_id, "easybridge")
	if err != nil {
		return "", err
	}

	widget_kv_key := "ezbr_widget_on:" + mx_room_id
	if config.WebURL != "" && dbKvGet(widget_kv_key) != "yes" {
		widget := map[string]interface{}{
			"type": "m.easybridge",
			"url":  config.WebURL,
			"name": "Easybridge account configuration dashboard",
		}
		err = mx.PutStateAs(mx_room_id, "im.vector.modular.widgets", "ezbr_widget", widget, ezbrMxId())
		if err == nil {
			dbKvPut(widget_kv_key, "yes")
		}
	}

	return mx_room_id, nil
}

func ezbrSystemSend(user_mx_id string, msg string) {
	mx_room_id, err := ezbrSystemRoom(user_mx_id)
	if err == nil {
		err = mx.SendMessageAs(mx_room_id, "m.text", msg, ezbrMxId())
	}
	if err != nil {
		log.Warnf("(%s) %s", user_mx_id, msg)
	}
}

func ezbrSystemSendf(user_mx_id string, format string, args ...interface{}) {
	ezbrSystemSend(user_mx_id, fmt.Sprintf(format, args...))
}

// ----

func roomAlias(protocol string, id RoomID) string {
	what := fmt.Sprintf("%s_%s", safeStringForId(string(id)), protocol)
	return strings.Replace(config.NameFormat, "{}", what, 1)
}

func userMxId(protocol string, id UserID) string {
	what := fmt.Sprintf("%s_%s", safeStringForId(string(id)), protocol)
	return strings.Replace(config.NameFormat, "{}", what, 1)
}

func safeStringForId(in string) string {
	id2 := ""
	for _, c := range in {
		if c == '@' {
			id2 += "__"
		} else if c == ':' {
			id2 += "_"
		} else if unicode.IsDigit(c) || unicode.IsLetter(c) || c == '.' || c == '-' || c == '_' {
			id2 += string(c)
		}
	}
	return id2
}

func isBridgedIdentifier(mxid string) bool {
	if mxid[0] == '@' || mxid[0] == '#' {
		return isBridgedIdentifier(mxid[1:])
	}

	if strings.Contains(mxid, ":") {
		sp := strings.Split(mxid, ":")
		return (sp[1] == config.MatrixDomain) && isBridgedIdentifier(sp[0])
	}

	nameformat_fixed_part := strings.Replace(config.NameFormat, "{}", "", 1)
	if strings.HasPrefix(config.NameFormat, "{}") {
		return strings.HasSuffix(mxid, nameformat_fixed_part)
	} else if strings.HasSuffix(config.NameFormat, "{}") {
		return strings.HasPrefix(mxid, nameformat_fixed_part)
	} else {
		// This is not supported
		log.Fatalf("Invalid name format %s, please put {} at the beginning or at the end", config.NameFormat)
		return false
	}
}

// ---- Encoding and encryption of account config

func encryptAccountConfig(config map[string]string, key *[32]byte) string {
	bytes, err := json.Marshal(config)
	if err != nil {
		log.Fatal(err)
	}

	var nonce [24]byte
	_, err = rand.Read(nonce[:])
	if err != nil {
		log.Fatal(err)
	}

	crypto := secretbox.Seal([]byte{}, bytes, &nonce, key)
	all := append(nonce[:], crypto...)
	return base64.StdEncoding.EncodeToString(all)
}

func decryptAccountConfig(data string, key *[32]byte) (map[string]string, error) {
	bytes, err := base64.StdEncoding.DecodeString(data)
	if err != nil {
		return nil, err
	}

	var nonce [24]byte
	copy(nonce[:], bytes[:24])

	decoded, ok := secretbox.Open([]byte{}, bytes[24:], &nonce, key)
	if !ok {
		return nil, fmt.Errorf("Invalid key")
	}

	var config map[string]string
	err = json.Unmarshal(decoded, &config)
	return config, err
}