package server

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"

	"github.com/sirupsen/logrus"

	"gitlab.com/mstarongitlab/linstrom/config"
	"gitlab.com/mstarongitlab/linstrom/server/middlewares"
	"gitlab.com/mstarongitlab/linstrom/storage"
)

type webfingerUrl struct {
	Relation string `json:"rel"`
	Type     string `json:"type"`
	Url      string `json:"href"`
}

// NOTE: Unused for now
// Reason: No endpoint for eg follow authorisation yet
type webfingerTemplate struct {
	Relation string `json:"rel"`
	Template string `json:"template"`
}

type webfingerResponse struct {
	Subject string `json:"subject"`
	// Any because it's either a webfingerTemplate or webfingerUrl
	Links []any `json:"links"`
}

// Mount under /.well-known/webfinger
// Handles webfinger requests which are used to determine whether an account exists on this server
// Additionally, a sucessful query will return a set of links related to that account, such as the activitypub view and the web view
func webfingerHandler(w http.ResponseWriter, r *http.Request) {
	logEntry, ok := r.Context().Value(middlewares.CONTEXT_KEY_LOGRUS).(*logrus.Entry)
	if !ok {
		http.Error(w, "couldn't get logging entry from context", http.StatusInternalServerError)
		return
	}
	store := storage.Storage{}

	requestedResource := r.FormValue("resource")
	if requestedResource == "" {
		http.Error(w, "bad request. Include \"resource\" parameter", http.StatusBadRequest)
		logEntry.Infoln("No resource parameter. Cancelling")
		return
	}
	accName := strings.TrimPrefix(requestedResource, "acc:")
	acc, err := store.FindLocalAccount(accName)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		logEntry.WithError(err).Warningln("couldn't find account")
		return
	}
	finger, err := accToWebfinger(acc)
	if err != nil {
		http.Error(w, "failed to build webfinger", http.StatusInternalServerError)
		return
	}
	data, err := json.Marshal(finger)
	if err != nil {
		http.Error(w, "failed to build json", http.StatusInternalServerError)
		return
	}
	fmt.Fprint(w, string(data))
}

func accToWebfinger(acc *storage.User) (*webfingerResponse, error) {
	// First ensure config is set
	if config.Global == nil {
		return nil, config.ErrGlobalConfigNotSet
	}
	// Then build the ap link
	apLink := webfingerUrl{
		Relation: "self",
		Type:     "application/activity+json",
		Url:      config.Global.General.FullDomain,
	}
	if config.Global.General.PublicPort != 80 &&
		config.Global.General.PublicPort != 443 {
		apLink.Url += fmt.Sprintf(":%d", config.Global.General.PublicPort)
	}
	apLink.Url += "/api/ap/user/" + acc.ID

	// Now the web view
	viewLink := webfingerUrl{
		Relation: "http://webfinger.net/rel/profile-page",
		Type:     "text/html",
		Url:      config.Global.General.FullDomain,
	}
	if config.Global.General.PublicPort != 80 &&
		config.Global.General.PublicPort != 443 {
		viewLink.Url += fmt.Sprintf(":%d", config.Global.General.PublicPort)
	}
	viewLink.Url += "/@" + acc.GetHandleNameOnly()

	// TODO: Add follow authorisation template once the endpoint is available

	response := webfingerResponse{
		Subject: fmt.Sprintf("acct:%s", strings.TrimPrefix(acc.Handle, "@")),
		Links: []any{
			apLink,
			viewLink,
		},
	}

	return &response, nil
}