package registry

import (
	"bytes"
	"context"
	"crypto/rsa"
	"crypto/x509"
	"encoding/gob"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"git.capotej.com/capotej/communique/config"
	"git.capotej.com/capotej/communique/models"
	"git.capotej.com/capotej/communique/urls"
	"git.capotej.com/capotej/communique/views"
	"github.com/go-fed/activity/streams"
	"github.com/go-fed/activity/streams/vocab"
	"github.com/go-fed/httpsig"
	"go.uber.org/zap"
)

type Handler struct {
	handlerCfg config.Handler
}

// TODO rename to controller and controller.go
type Registry struct {
	cfg        config.Config
	persister  *models.Persister
	handlerMap map[string]Handler
	log        *zap.SugaredLogger
}

func NewRegistry(cfg config.Config, persister *models.Persister, log *zap.SugaredLogger) (*Registry, error) {
	reg := Registry{cfg: cfg, persister: persister, log: log}
	reg.handlerMap = make(map[string]Handler)
	for _, v := range cfg.Handlers {
		reg.handlerMap[v.Name] = Handler{handlerCfg: v}
		err := generateKeypairIfNeeded(v, persister)
		if err != nil {
			return nil, err
		}
	}
	return &reg, nil
}

func generateKeypairIfNeeded(v config.Handler, p *models.Persister) error {
	kp, err := models.CreateKeypair(v)
	if err != nil {
		return err
	}
	err = p.Store(kp)
	if err != nil {
		return err
	}
	return nil
}

func (r *Registry) Actor(name string) (map[string]interface{}, error) {
	handler := r.findByName(name)
	if handler == nil {
		return nil, nil
	}
	aso := models.NewKeypair(handler.handlerCfg)
	result, err := r.persister.Find(aso)
	if err != nil {
		return nil, err
	}
	buf := bytes.NewBuffer(result)
	dec := gob.NewDecoder(buf)
	var keypair models.Keypair
	err = dec.Decode(&keypair)
	if err != nil {
		return nil, err
	}
	privKey := &keypair.PrivateKey
	pemdata := pem.EncodeToMemory(
		&pem.Block{
			Type:  "PUBLIC KEY",
			Bytes: x509.MarshalPKCS1PublicKey(&privKey.PublicKey),
		},
	)
	return views.RenderActor(handler.handlerCfg.Name, r.cfg.Domain, string(pemdata))
}

func (r *Registry) OutboxCollection(name string) (map[string]interface{}, error) {
	handler := r.findByName(name)
	if handler == nil {
		return nil, nil
	}
	aso := models.NewOutboxItem(handler.handlerCfg)
	page, err := r.persister.Collect(aso)
	if err != nil {
		return nil, err
	}
	var outboxItems []models.OutboxItem
	for _, v := range page { //TODO pagination
		buf := bytes.NewBuffer(v)
		dec := gob.NewDecoder(buf)
		var outboxItem models.OutboxItem
		err = dec.Decode(&outboxItem)
		if err != nil {
			return nil, err
		}
		outboxItems = append(outboxItems, outboxItem)
	}
	return views.RenderOutboxCollection(handler.handlerCfg.Name, r.cfg.Domain, outboxItems)
}

func (r *Registry) Following(name string) (map[string]interface{}, error) {
	handler := r.findByName(name)
	if handler == nil {
		return nil, nil
	}
	profile, err := urls.UrlProfile(name, r.cfg.Domain)
	if err != nil {
		return nil, err
	}
	following, err := urls.UrlFollowing(name, r.cfg.Domain)
	if err != nil {
		return nil, err
	}
	result := make(map[string]interface{})
	result["@context"] = "https://www.w3.org/ns/activitystreams"
	result["attributedTo"] = profile.String()
	result["id"] = following.String()
	result["totalItems"] = 0
	result["orderedItems"] = []bool{}
	result["type"] = "OrderedCollection"
	return result, nil
}

func (r *Registry) Followers(name string) (map[string]interface{}, error) {
	handler := r.findByName(name)
	if handler == nil {
		return nil, nil
	}
	profile, err := urls.UrlProfile(name, r.cfg.Domain)
	if err != nil {
		return nil, err
	}
	followers, err := urls.UrlFollowers(name, r.cfg.Domain)
	if err != nil {
		return nil, err
	}
	result := make(map[string]interface{})
	result["@context"] = "https://www.w3.org/ns/activitystreams"
	result["attributedTo"] = profile.String()
	result["id"] = followers.String()
	result["totalItems"] = 0
	result["orderedItems"] = []bool{}
	result["type"] = "OrderedCollection"
	return result, nil
}

func (r *Registry) Inbox(name string, req *http.Request) error {
	handler := r.findByName(name)
	if handler == nil {
		return nil
	}
	logger := r.log.With("type", "inbox")

	verifier, err := httpsig.NewVerifier(req)
	if err != nil {
		return err
	}

	keyId := verifier.KeyId()
	logger.With("keyId", keyId).Debugf("fetching")
	req, err = http.NewRequest("GET", keyId, nil)
	req.Header.Set("Accept", "application/json; charset=UTF-8")

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	keyPage, err := io.ReadAll(resp.Body)
	logger.With("keyId", keyId).With("response", string(keyPage)).Debugf("received response")
	var keyPageData map[string]interface{}
	err = json.Unmarshal(keyPage, &keyPageData)
	if err != nil {
		return err
	}

	var person vocab.ActivityStreamsPerson

	resolver, err := streams.NewJSONResolver(func(c context.Context, p vocab.ActivityStreamsPerson) error {
		// Store the person in the enclosing scope, for later.
		person = p
		return nil
	}, func(c context.Context, note vocab.ActivityStreamsNote) error {
		//TODO not needed, need to figure out how to only pass one func
		return nil
	})

	ctx := context.Background()
	err = resolver.Resolve(ctx, keyPageData)

	pubKeyProp := person.GetW3IDSecurityV1PublicKey()
	iter := pubKeyProp.At(0)
	pubKey := iter.Get()
	pemProp := pubKey.GetW3IDSecurityV1PublicKeyPem()
	pemStr := pemProp.Get()
	logger.With("keyId", keyId).With("pem", pemStr).Debugf("extracted pem")
	pemObj, _ := pem.Decode([]byte(pemStr))
	if pemObj == nil {
		return fmt.Errorf("no PEM block found")
	}
	decodedKey, err := x509.ParsePKIXPublicKey(pemObj.Bytes)
	if err != nil {
		return err
	}
	rsaPub, ok := decodedKey.(*rsa.PublicKey)
	if !ok {
		return fmt.Errorf("not an RSA public key")
	}
	algo := httpsig.RSA_SHA256
	return verifier.Verify(rsaPub, algo)
}

func (r *Registry) ActivityOrNote(activityOrNote, name, id string) (map[string]interface{}, error) {
	handler := r.findByName(name)
	if handler == nil {
		return nil, nil
	}
	lookup := models.NewOutboxItem(handler.handlerCfg)
	lookup.Id = []byte(id)
	result, err := r.persister.Find(lookup)
	if err != nil {
		return nil, err
	}
	if result == nil {
		return nil, nil
	}
	buf := bytes.NewBuffer(result)
	dec := gob.NewDecoder(buf)
	var outboxItem models.OutboxItem
	err = dec.Decode(&outboxItem)
	if err != nil {
		return nil, err
	}
	if activityOrNote == "activity" {
		return views.RenderActivity(handler.handlerCfg.Name, r.cfg.Domain, outboxItem)
	}
	return views.RenderNote(handler.handlerCfg.Name, r.cfg.Domain, outboxItem)
}

// This has to handle various lookup formats:
// ?resource=acct:actor@domain
// ?resource=actor@domain
// ?resource=actor
// ?resource=acct:actor
func (r *Registry) Webfinger(fqn string) (*views.WebfingerResource, error) {
	// Strip away acct: prefix, if found
	fqn = strings.TrimPrefix(fqn, "acct:")

	// Strip away @domain suffix, if found
	domainUrl, err := url.Parse(r.cfg.Domain)
	if err != nil {
		return nil, err
	}
	hostname := "@" + domainUrl.Hostname()
	fqn = strings.TrimSuffix(fqn, hostname)

	// We should just have $actor left
	handler := r.findByName(fqn)
	if handler == nil {
		return nil, nil
	}
	return views.RenderWebfinger(handler.handlerCfg.Name, r.cfg.Domain, hostname)
}

func (r *Registry) findByName(name string) *Handler {
	handler, ok := r.handlerMap[name]
	if !ok {
		return nil
	}
	return &handler
}