/*
 Copyright 2020, 2021 Jan Dittberner


 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
*/

package main

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"encoding/base64"
	"fmt"
	"io/ioutil"
	"net/http"
	"time"

	"github.com/knadh/koanf/parsers/toml"
	"github.com/knadh/koanf/providers/confmap"
	log "github.com/sirupsen/logrus"

	"git.cacert.org/oidc_login/app/handlers"
	"git.cacert.org/oidc_login/app/services"
	commonHandlers "git.cacert.org/oidc_login/common/handlers"
	commonServices "git.cacert.org/oidc_login/common/services"
)

func main() {
	logger := log.New()
	config, err := commonServices.ConfigureApplication(
		logger,
		"RESOURCE_APP",
		map[string]interface{}{
			"server.port":        4000,
			"server.name":        "app.cacert.localhost",
			"server.key":         "certs/app.cacert.localhost.key",
			"server.certificate": "certs/app.cacert.localhost.crt.pem",
			"oidc.server":        "https://auth.cacert.localhost:4444/",
			"session.path":       "sessions/app",
			"i18n.languages":     []string{"en", "de"},
		})
	if err != nil {
		log.Fatalf("error loading configuration: %v", err)
	}

	oidcServer := config.MustString("oidc.server")
	oidcClientId := config.MustString("oidc.client-id")
	oidcClientSecret := config.MustString("oidc.client-secret")

	ctx := context.Background()
	ctx = commonServices.InitI18n(ctx, logger, config.Strings("i18n.languages"))
	services.AddMessages(ctx)

	sessionPath := config.MustString("session.path")
	sessionAuthKey, err := base64.StdEncoding.DecodeString(config.String("session.auth-key"))
	if err != nil {
		log.Fatalf("could not decode session auth key: %s", err)
	}
	sessionEncKey, err := base64.StdEncoding.DecodeString(config.String("session.enc-key"))
	if err != nil {
		log.Fatalf("could not decode session encryption key: %s", err)
	}

	generated := false
	if len(sessionAuthKey) != 64 {
		sessionAuthKey = commonServices.GenerateKey(64)
		generated = true
	}
	if len(sessionEncKey) != 32 {
		sessionEncKey = commonServices.GenerateKey(32)
		generated = true
	}

	if generated {
		_ = config.Load(confmap.Provider(map[string]interface{}{
			"session.auth-key": sessionAuthKey,
			"session.enc-key":  sessionEncKey,
		}, "."), nil)
		tomlData, err := config.Marshal(toml.Parser())
		if err != nil {
			log.Fatalf("could not encode session config")
		}
		log.Infof("put the following in your resource_app.toml:\n%s", string(tomlData))
	}

	tlsClientConfig := &tls.Config{
		MinVersion: tls.VersionTLS12,
	}
	if config.Exists("api-client.rootCAs") {
		rootCAFile := config.MustString("api-client.rootCAs")
		caCertPool := x509.NewCertPool()
		pemBytes, err := ioutil.ReadFile(rootCAFile)
		if err != nil {
			log.Fatalf("could not read CA certificate file: %v", err)
		}
		caCertPool.AppendCertsFromPEM(pemBytes)
		tlsClientConfig.RootCAs = caCertPool
	}

	apiTransport := &http.Transport{TLSClientConfig: tlsClientConfig}
	apiClient := &http.Client{Transport: apiTransport}

	if ctx, err = commonServices.DiscoverOIDC(ctx, logger, &commonServices.OidcParams{
		OidcServer:       oidcServer,
		OidcClientId:     oidcClientId,
		OidcClientSecret: oidcClientSecret,
		APIClient:        apiClient,
	}); err != nil {
		log.Fatalf("OpenID Connect discovery failed: %s", err)
	}

	services.InitSessionStore(logger, sessionPath, sessionAuthKey, sessionEncKey)

	authMiddleware := handlers.Authenticate(ctx, logger, oidcClientId)

	serverAddr := fmt.Sprintf("%s:%d", config.String("server.name"), config.Int("server.port"))

	indexHandler, err := handlers.NewIndexHandler(ctx, serverAddr)
	if err != nil {
		logger.Fatalf("could not initialize index handler: %v", err)
	}
	callbackHandler := handlers.NewCallbackHandler(ctx, logger)
	afterLogoutHandler := handlers.NewAfterLogoutHandler(logger)
	staticFiles := http.FileServer(http.Dir("static"))

	router := http.NewServeMux()
	router.Handle("/", authMiddleware(indexHandler))
	router.Handle("/callback", callbackHandler)
	router.Handle("/after-logout", afterLogoutHandler)
	router.Handle("/health", commonHandlers.NewHealthHandler())
	router.Handle("/images/", staticFiles)
	router.Handle("/css/", staticFiles)
	router.Handle("/js/", staticFiles)

	nextRequestId := func() string {
		return fmt.Sprintf("%d", time.Now().UnixNano())
	}

	tracing := commonHandlers.Tracing(nextRequestId)
	logging := commonHandlers.Logging(logger)
	hsts := commonHandlers.EnableHSTS()
	errorMiddleware, err := commonHandlers.ErrorHandling(
		ctx,
		logger,
		"templates/app",
	)
	if err != nil {
		logger.Fatalf("could not initialize request error handling: %v", err)
	}

	tlsConfig := &tls.Config{
		ServerName: config.String("server.name"),
		MinVersion: tls.VersionTLS12,
	}
	server := &http.Server{
		Addr:         serverAddr,
		Handler:      tracing(logging(hsts(errorMiddleware(router)))),
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 10 * time.Second,
		IdleTimeout:  15 * time.Second,
		TLSConfig:    tlsConfig,
	}

	commonHandlers.StartApplication(logger, ctx, server, config)
}