/*
Copyright 2017-2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

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.
*/

// The CAcert board voting software.
package main

import (
	"context"
	"crypto/tls"
	"crypto/x509"
	"database/sql"
	"encoding/gob"
	"flag"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	"github.com/alexedwards/scs/sqlite3store"
	"github.com/alexedwards/scs/v2"
	"github.com/go-playground/form/v4"
	"github.com/jmoiron/sqlx"
	_ "github.com/mattn/go-sqlite3"

	"git.cacert.org/cacert-boardvoting/internal"
	"git.cacert.org/cacert-boardvoting/internal/models"
)

const sessionHours = 12

var (
	version = "undefined"
	commit  = "undefined"
	date    = "undefined"
)

type application struct {
	errorLog, infoLog *log.Logger
	users             *models.UserModel
	motions           *models.MotionModel
	jobScheduler      *JobScheduler
	mailNotifier      *MailNotifier
	mailConfig        *mailConfig
	templateCache     map[string]*template.Template
	sessionManager    *scs.SessionManager
	formDecoder       *form.Decoder
}

func main() {
	configFile := flag.String("config", "config.yaml", "Configuration file name")
	flag.Parse()

	infoLog := log.New(os.Stdout, "INFO\t", log.Ldate|log.Ltime)
	errorLog := log.New(os.Stderr, "ERROR\t", log.Ldate|log.Ltime)

	infoLog.Printf("CAcert Board Voting version %s, commit %s built at %s", version, commit, date)

	config, err := parseConfig(*configFile)
	if err != nil {
		errorLog.Fatal(err)
	}

	db, err := openDB(config.DatabaseFile)
	if err != nil {
		errorLog.Fatal(err)
	}

	defer func(db *sqlx.DB) {
		_ = db.Close()
	}(db)

	if err != nil {
		errorLog.Fatalf("could not setup decision model: %v", err)
	}

	templateCache, err := newTemplateCache()
	if err != nil {
		errorLog.Fatal(err)
	}

	sessionManager := scs.New()
	sessionManager.Store = sqlite3store.New(db.DB)
	sessionManager.Lifetime = sessionHours * time.Hour
	sessionManager.Cookie.SameSite = http.SameSiteStrictMode
	sessionManager.Cookie.Secure = true

	gob.Register([]FlashMessage{})

	app := &application{
		errorLog:       errorLog,
		infoLog:        infoLog,
		motions:        &models.MotionModel{DB: db},
		users:          &models.UserModel{DB: db},
		mailConfig:     config.MailConfig,
		templateCache:  templateCache,
		sessionManager: sessionManager,
	}

	err = internal.InitializeDb(db.DB, infoLog)
	if err != nil {
		errorLog.Fatal(err)
	}

	app.setupFormDecoder()

	app.NewMailNotifier()
	defer app.mailNotifier.Quit()

	go app.mailNotifier.Start()

	app.NewJobScheduler()
	defer app.jobScheduler.Quit()

	go app.jobScheduler.Schedule()

	infoLog.Printf("Starting server on %s", config.HTTPAddress)

	errChan := make(chan error, 1)

	infoLog.Printf("TLS config setup, starting TLS server on %s", config.HTTPSAddress)

	go setupHTTPRedirect(config, errChan)

	err = app.startHTTPSServer(config)
	if err != nil {
		errorLog.Fatalf("ListenAndServeTLS (HTTPS) failed: %v", err)
	}

	if err := <-errChan; err != nil {
		errorLog.Fatalf("ListenAndServe (HTTP) failed: %v", err)
	}
}

func (app *application) setupFormDecoder() {
	decoder := form.NewDecoder()

	decoder.RegisterCustomTypeFunc(func(values []string) (interface{}, error) {
		v, err := models.VoteTypeFromString(values[0])
		if err != nil {
			return nil, fmt.Errorf("could not convert value %s: %w", values[0], err)
		}

		return v, nil
	}, new(models.VoteType))
	decoder.RegisterCustomTypeFunc(func(values []string) (interface{}, error) {
		v, err := models.VoteChoiceFromString(values[0])
		if err != nil {
			return nil, fmt.Errorf("could not convert value %s: %w", values[0], err)
		}

		return v, nil
	}, new(models.VoteChoice))
	decoder.RegisterCustomTypeFunc(func(values []string) (interface{}, error) {
		userID, err := strconv.Atoi(values[0])
		if err != nil {
			return nil, fmt.Errorf("could not convert value %s to user ID: %w", values[0], err)
		}

		u, err := app.users.ByID(context.Background(), int64(userID))
		if err != nil {
			return nil, fmt.Errorf("could not convert value %s to user: %w", values[0], err)
		}

		return u, nil
	}, new(models.User))

	app.formDecoder = decoder
}

func (app *application) startHTTPSServer(config *Config) error {
	tlsConfig, err := setupTLSConfig(config)
	if err != nil {
		return fmt.Errorf("could not setup TLS configuration: %w", err)
	}

	srv := &http.Server{
		Addr:              config.HTTPSAddress,
		TLSConfig:         tlsConfig,
		ErrorLog:          app.errorLog,
		Handler:           app.routes(),
		IdleTimeout:       config.Timeouts.Idle,
		ReadHeaderTimeout: config.Timeouts.ReadHeader,
		ReadTimeout:       config.Timeouts.Read,
		WriteTimeout:      config.Timeouts.Write,
	}

	err = srv.ListenAndServeTLS(config.ServerCert, config.ServerKey)
	if err != nil {
		return fmt.Errorf("")
	}

	return nil
}

func (app *application) getVoter(ctx context.Context, w http.ResponseWriter, voterID int64) *models.User {
	voter, err := app.users.ByID(ctx, voterID, app.users.WithRoles())
	if err != nil {
		panic(err)
	}

	var isVoter bool

	if isVoter, err = voter.HasRole(models.RoleVoter); err != nil {
		panic(err)
	}

	if !isVoter {
		app.clientError(w, http.StatusBadRequest)

		return nil
	}

	return voter
}

func setupHTTPRedirect(config *Config, errChan chan error) {
	redirect := &http.Server{
		Addr: config.HTTPAddress,
		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			redirectURL := url.URL{
				Scheme: "https://",
				Host: strings.Join(
					[]string{
						strings.Split(r.URL.Host, ":")[0],
						strings.Split(config.HTTPSAddress, ":")[1],
					},
					":",
				),
				Path: r.URL.Path,
			}

			http.Redirect(w, r, redirectURL.String(), http.StatusMovedPermanently)
		}),
		IdleTimeout:       config.Timeouts.Idle,
		ReadHeaderTimeout: config.Timeouts.ReadHeader,
		ReadTimeout:       config.Timeouts.Read,
		WriteTimeout:      config.Timeouts.Write,
	}

	if err := redirect.ListenAndServe(); err != nil {
		errChan <- err
	}

	close(errChan)
}

func setupTLSConfig(config *Config) (*tls.Config, error) {
	caCert, err := os.ReadFile(config.ClientCACertificates)
	if err != nil {
		return nil, fmt.Errorf("could not read client certificate CAs %w", err)
	}

	caCertPool := x509.NewCertPool()
	if !caCertPool.AppendCertsFromPEM(caCert) {
		return nil, fmt.Errorf(
			"could not initialize client CA certificate pool from %s",
			config.ClientCACertificates,
		)
	}

	return &tls.Config{
		MinVersion: tls.VersionTLS12,
		ClientCAs:  caCertPool,
		ClientAuth: tls.VerifyClientCertIfGiven,
	}, nil
}

func openDB(dbFile string) (*sqlx.DB, error) {
	db, err := sql.Open("sqlite3", dbFile)
	if err != nil {
		return nil, fmt.Errorf("could not open database file %s: %w", dbFile, err)
	}

	if err = db.Ping(); err != nil {
		return nil, fmt.Errorf("could not ping database: %w", err)
	}

	return sqlx.NewDb(db, "sqlite3"), nil
}