package main

import (
	"crypto/x509"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"net/http"
	"strings"
)

func hostMetaHandler(w http.ResponseWriter, r *http.Request) {
	headers := w.Header()
	headers.Add("Content-Type", "application/xrd+xml")
	headers.Add("Content-Type", "charset=utf-8")
	fmt.Fprintf(w, `<?xml version="1.0" encoding="UTF-8"?><XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0"><Link rel="lrdd" template="https://%s/.well-known/webfinger?resource={uri}" type="application/xrd+xml" /></XRD>`, host)
}

func handlerUserPage(w http.ResponseWriter, r *http.Request) {
	parts := strings.SplitN(strings.Trim(r.URL.Path, " /"), "/", 2)
	if len(parts) < 2 {
		http.Error(w, "page not found", http.StatusNotFound)
		return
	}
	name := parts[1]
	app, ok := apps[name]
	if !ok {
		http.Error(w, "page not found", http.StatusNotFound)
		return
	}
	userURL := fmt.Sprintf("%s/u/%s", fullhost, name)

	contextes := []string{
		"https://www.w3.org/ns/activitystreams",
	}

	var pubkey *pubKeyBlock = nil
	if app.PublicKey != nil {
		pubKeyBytes := x509.MarshalPKCS1PublicKey(app.PublicKey)
		pubKeyPem := string(pem.EncodeToMemory(&pem.Block{
			Type:  "PUBLIC KEY",
			Bytes: pubKeyBytes,
		}))
		contextes = append(contextes, "https://w3id.org/security/v1")
		pubkey = &pubKeyBlock{
			ID:    userURL + "#main-key",
			Owner: userURL,
			PEM:   pubKeyPem,
		}
	}
	headers := w.Header()
	headers.Add("Content-Type", "application/activity+json")
	headers.Add("Content-Type", "charset=utf-8")
	err := json.NewEncoder(w).Encode(profilePage{
		Context:           contextes,
		ID:                userURL,
		Type:              "Person",
		PreferredUsername: name,
		Name:              app.Name,
		Inbox:             fmt.Sprintf("%s/inbox", fullhost),
		Followers:         fmt.Sprintf("%s/followers", userURL),
		PublicKey:         pubkey,
	})
	if err != nil {
		http.Error(w, "Error encoding page: "+err.Error(), http.StatusInternalServerError)
	}
}

func handlerWebFinger(w http.ResponseWriter, r *http.Request) {
	params := r.URL.Query()
	resource := params.Get("resource")
	if resource == "" {
		http.Error(w, "must include a valid resource", http.StatusBadRequest)
		return
	}

	parts := strings.SplitN(resource, ":", 2)
	if len(parts) < 2 {
		http.Error(w, "invalid resource specified", http.StatusBadRequest)
		return
	}
	switch parts[0] {
	case "acct":
		// Split user by host
		userParts := strings.SplitN(parts[1], "@", 2)
		if len(userParts) < 2 || strings.ToLower(userParts[1]) != host {
			http.Error(w, "Invalid user specified", http.StatusBadRequest)
			return
		}
		// Check if user is a registered app
		_, ok := apps[userParts[0]]
		if !ok {
			http.Error(w, "user not found", http.StatusNotFound)
			return
		}
		headers := w.Header()
		headers.Add("Content-Type", "application/json")
		headers.Add("Content-Type", "charset=utf-8")

		err := json.NewEncoder(w).Encode(profileWebFingerData{
			Subject: resource,
			Links: []profileLink{
				{
					Rel:  "self",
					Type: "application/activity+json",
					Href: fmt.Sprintf("%s/u/%s", fullhost, userParts[0]),
				},
			},
		})

		if err != nil {
			http.Error(w, "Error encoding webfinger: "+err.Error(), http.StatusInternalServerError)
		}
	}
}