// Copyright 2017 HootSuite Media Inc.
//
// 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.
// Modified hereafter by contributors to runatlantis/atlantis.
//
// Package server handles the web server and executing commands that come in
// via webhooks.
package server

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/elazarl/go-bindata-assetfs"
	"github.com/gorilla/mux"
	"github.com/lkysow/go-gitlab"
	"github.com/pkg/errors"
	"github.com/runatlantis/atlantis/server/events"
	"github.com/runatlantis/atlantis/server/events/locking"
	"github.com/runatlantis/atlantis/server/events/locking/boltdb"
	"github.com/runatlantis/atlantis/server/events/models"
	"github.com/runatlantis/atlantis/server/events/runtime"
	"github.com/runatlantis/atlantis/server/events/terraform"
	"github.com/runatlantis/atlantis/server/events/vcs"
	"github.com/runatlantis/atlantis/server/events/webhooks"
	"github.com/runatlantis/atlantis/server/events/yaml"
	"github.com/runatlantis/atlantis/server/logging"
	"github.com/runatlantis/atlantis/server/static"
	"github.com/urfave/cli"
	"github.com/urfave/negroni"
)

const (
	// LockViewRouteName is the named route in mux.Router for the lock view.
	// The route can be retrieved by this name, ex:
	//   mux.Router.Get(LockViewRouteName)
	LockViewRouteName = "lock-detail"
	// LockViewRouteIDQueryParam is the query parameter needed to construct the lock view
	// route. ex:
	//   mux.Router.Get(LockViewRouteName).URL(LockViewRouteIDQueryParam, "my id")
	LockViewRouteIDQueryParam = "id"
)

// Server runs the Atlantis web server.
type Server struct {
	AtlantisVersion    string
	Router             *mux.Router
	Port               int
	CommandRunner      *events.DefaultCommandRunner
	Logger             *logging.SimpleLogger
	Locker             locking.Locker
	AtlantisURL        string
	EventsController   *EventsController
	LocksController    *LocksController
	IndexTemplate      TemplateWriter
	LockDetailTemplate TemplateWriter
	SSLCertFile        string
	SSLKeyFile         string
}

// UserConfig holds config values passed in by the user.
// The mapstructure tags correspond to flags in cmd/server.go and are used when
// the config is parsed from a YAML file.
type UserConfig struct {
	AllowForkPRs        bool   `mapstructure:"allow-fork-prs"`
	AtlantisURL         string `mapstructure:"atlantis-url"`
	DataDir             string `mapstructure:"data-dir"`
	GithubHostname      string `mapstructure:"gh-hostname"`
	GithubToken         string `mapstructure:"gh-token"`
	GithubUser          string `mapstructure:"gh-user"`
	GithubWebHookSecret string `mapstructure:"gh-webhook-secret"`
	GitlabHostname      string `mapstructure:"gitlab-hostname"`
	GitlabToken         string `mapstructure:"gitlab-token"`
	GitlabUser          string `mapstructure:"gitlab-user"`
	GitlabWebHookSecret string `mapstructure:"gitlab-webhook-secret"`
	LogLevel            string `mapstructure:"log-level"`
	Port                int    `mapstructure:"port"`
	RepoWhitelist       string `mapstructure:"repo-whitelist"`
	// RequireApproval is whether to require pull request approval before
	// allowing terraform apply's to be run.
	RequireApproval bool            `mapstructure:"require-approval"`
	SlackToken      string          `mapstructure:"slack-token"`
	SSLCertFile     string          `mapstructure:"ssl-cert-file"`
	SSLKeyFile      string          `mapstructure:"ssl-key-file"`
	Webhooks        []WebhookConfig `mapstructure:"webhooks"`
}

// Config holds config for server that isn't passed in by the user.
type Config struct {
	AllowForkPRsFlag string
	AtlantisVersion  string
}

// WebhookConfig is nested within UserConfig. It's used to configure webhooks.
type WebhookConfig struct {
	// Event is the type of event we should send this webhook for, ex. apply.
	Event string `mapstructure:"event"`
	// WorkspaceRegex is a regex that is used to match against the workspace
	// that is being modified for this event. If the regex matches, we'll
	// send the webhook, ex. "production.*".
	WorkspaceRegex string `mapstructure:"workspace-regex"`
	// Kind is the type of webhook we should send, ex. slack.
	Kind string `mapstructure:"kind"`
	// Channel is the channel to send this webhook to. It only applies to
	// slack webhooks. Should be without '#'.
	Channel string `mapstructure:"channel"`
}

// NewServer returns a new server. If there are issues starting the server or
// its dependencies an error will be returned. This is like the main() function
// for the server CLI command because it injects all the dependencies.
func NewServer(userConfig UserConfig, config Config) (*Server, error) {
	var supportedVCSHosts []models.VCSHostType
	var githubClient *vcs.GithubClient
	var gitlabClient *vcs.GitlabClient
	if userConfig.GithubUser != "" {
		supportedVCSHosts = append(supportedVCSHosts, models.Github)
		var err error
		githubClient, err = vcs.NewGithubClient(userConfig.GithubHostname, userConfig.GithubUser, userConfig.GithubToken)
		if err != nil {
			return nil, err
		}
	}
	if userConfig.GitlabUser != "" {
		supportedVCSHosts = append(supportedVCSHosts, models.Gitlab)
		gitlabClient = &vcs.GitlabClient{
			Client: gitlab.NewClient(nil, userConfig.GitlabToken),
		}
		// If not using gitlab.com we need to set the URL to the API.
		if userConfig.GitlabHostname != "gitlab.com" {
			// Check if they've also provided a scheme so we don't prepend it
			// again.
			scheme := "https"
			schemeSplit := strings.Split(userConfig.GitlabHostname, "://")
			if len(schemeSplit) > 1 {
				scheme = schemeSplit[0]
				userConfig.GitlabHostname = schemeSplit[1]
			}
			apiURL := fmt.Sprintf("%s://%s/api/v4/", scheme, userConfig.GitlabHostname)
			if err := gitlabClient.Client.SetBaseURL(apiURL); err != nil {
				return nil, errors.Wrapf(err, "setting GitLab API URL: %s", apiURL)
			}
		}
	}
	var webhooksConfig []webhooks.Config
	for _, c := range userConfig.Webhooks {
		config := webhooks.Config{
			Channel:        c.Channel,
			Event:          c.Event,
			Kind:           c.Kind,
			WorkspaceRegex: c.WorkspaceRegex,
		}
		webhooksConfig = append(webhooksConfig, config)
	}
	webhooksManager, err := webhooks.NewMultiWebhookSender(webhooksConfig, webhooks.NewSlackClient(userConfig.SlackToken))
	if err != nil {
		return nil, errors.Wrap(err, "initializing webhooks")
	}
	vcsClient := vcs.NewDefaultClientProxy(githubClient, gitlabClient)
	commitStatusUpdater := &events.DefaultCommitStatusUpdater{Client: vcsClient}
	terraformClient, err := terraform.NewClient(userConfig.DataDir)
	// The flag.Lookup call is to detect if we're running in a unit test. If we
	// are, then we don't error out because we don't have/want terraform
	// installed on our CI system where the unit tests run.
	if err != nil && flag.Lookup("test.v") == nil {
		return nil, errors.Wrap(err, "initializing terraform")
	}
	markdownRenderer := &events.MarkdownRenderer{}
	boltdb, err := boltdb.New(userConfig.DataDir)
	if err != nil {
		return nil, err
	}
	lockingClient := locking.NewClient(boltdb)
	workingDirLocker := events.NewDefaultAtlantisWorkingDirLocker()
	workingDir := &events.FileWorkspace{
		DataDir: userConfig.DataDir,
	}
	projectLocker := &events.DefaultProjectLocker{
		Locker: lockingClient,
	}
	underlyingRouter := mux.NewRouter()
	router := &Router{
		AtlantisURL:               userConfig.AtlantisURL,
		LockViewRouteIDQueryParam: LockViewRouteIDQueryParam,
		LockViewRouteName:         LockViewRouteName,
		Underlying:                underlyingRouter,
	}
	pullClosedExecutor := &events.PullClosedExecutor{
		VCSClient:  vcsClient,
		Locker:     lockingClient,
		WorkingDir: workingDir,
	}
	logger := logging.NewSimpleLogger("server", nil, false, logging.ToLogLevel(userConfig.LogLevel))
	eventParser := &events.EventParser{
		GithubUser:  userConfig.GithubUser,
		GithubToken: userConfig.GithubToken,
		GitlabUser:  userConfig.GitlabUser,
		GitlabToken: userConfig.GitlabToken,
	}
	commentParser := &events.CommentParser{
		GithubUser:  userConfig.GithubUser,
		GithubToken: userConfig.GithubToken,
		GitlabUser:  userConfig.GitlabUser,
		GitlabToken: userConfig.GitlabToken,
	}
	defaultTfVersion := terraformClient.Version()
	commandRunner := &events.DefaultCommandRunner{
		VCSClient:                vcsClient,
		GithubPullGetter:         githubClient,
		GitlabMergeRequestGetter: gitlabClient,
		CommitStatusUpdater:      commitStatusUpdater,
		EventParser:              eventParser,
		MarkdownRenderer:         markdownRenderer,
		Logger:                   logger,
		AllowForkPRs:             userConfig.AllowForkPRs,
		AllowForkPRsFlag:         config.AllowForkPRsFlag,
		ProjectCommandBuilder: &events.DefaultProjectCommandBuilder{
			ParserValidator:  &yaml.ParserValidator{},
			ProjectFinder:    &events.DefaultProjectFinder{},
			VCSClient:        vcsClient,
			WorkingDir:       workingDir,
			WorkingDirLocker: workingDirLocker,
			RequireApproval:  userConfig.RequireApproval,
		},
		ProjectCommandRunner: &events.DefaultProjectCommandRunner{
			Locker:           projectLocker,
			LockURLGenerator: router,
			InitStepRunner: runtime.InitStepRunner{
				TerraformExecutor: terraformClient,
				DefaultTFVersion:  defaultTfVersion,
			},
			PlanStepRunner: runtime.PlanStepRunner{
				TerraformExecutor: terraformClient,
				DefaultTFVersion:  defaultTfVersion,
			},
			ApplyStepRunner: runtime.ApplyStepRunner{
				TerraformExecutor: terraformClient,
			},
			RunStepRunner: runtime.RunStepRunner{
				DefaultTFVersion: defaultTfVersion,
			},
			PullApprovedChecker: vcsClient,
			WorkingDir:          workingDir,
			Webhooks:            webhooksManager,
			WorkingDirLocker:    workingDirLocker,
		},
	}
	repoWhitelist := &events.RepoWhitelistChecker{
		Whitelist: userConfig.RepoWhitelist,
	}
	locksController := &LocksController{
		AtlantisVersion:    config.AtlantisVersion,
		Locker:             lockingClient,
		Logger:             logger,
		VCSClient:          vcsClient,
		LockDetailTemplate: lockTemplate,
	}
	eventsController := &EventsController{
		CommandRunner:                commandRunner,
		PullCleaner:                  pullClosedExecutor,
		Parser:                       eventParser,
		CommentParser:                commentParser,
		Logger:                       logger,
		GithubWebHookSecret:          []byte(userConfig.GithubWebHookSecret),
		GithubRequestValidator:       &DefaultGithubRequestValidator{},
		GitlabRequestParserValidator: &DefaultGitlabRequestParserValidator{},
		GitlabWebHookSecret:          []byte(userConfig.GitlabWebHookSecret),
		RepoWhitelistChecker:         repoWhitelist,
		SupportedVCSHosts:            supportedVCSHosts,
		VCSClient:                    vcsClient,
	}
	return &Server{
		AtlantisVersion:    config.AtlantisVersion,
		Router:             underlyingRouter,
		Port:               userConfig.Port,
		CommandRunner:      commandRunner,
		Logger:             logger,
		Locker:             lockingClient,
		AtlantisURL:        userConfig.AtlantisURL,
		EventsController:   eventsController,
		LocksController:    locksController,
		IndexTemplate:      indexTemplate,
		LockDetailTemplate: lockTemplate,
		SSLKeyFile:         userConfig.SSLKeyFile,
		SSLCertFile:        userConfig.SSLCertFile,
	}, nil
}

// Start creates the routes and starts serving traffic.
func (s *Server) Start() error {
	s.Router.HandleFunc("/", s.Index).Methods("GET").MatcherFunc(func(r *http.Request, rm *mux.RouteMatch) bool {
		return r.URL.Path == "/" || r.URL.Path == "/index.html"
	})
	s.Router.PathPrefix("/static/").Handler(http.FileServer(&assetfs.AssetFS{Asset: static.Asset, AssetDir: static.AssetDir, AssetInfo: static.AssetInfo}))
	s.Router.HandleFunc("/events", s.EventsController.Post).Methods("POST")
	s.Router.HandleFunc("/locks", s.LocksController.DeleteLock).Methods("DELETE").Queries("id", "{id:.*}")
	s.Router.HandleFunc("/lock", s.LocksController.GetLock).Methods("GET").
		Queries(LockViewRouteIDQueryParam, fmt.Sprintf("{%s}", LockViewRouteIDQueryParam)).Name(LockViewRouteName)
	n := negroni.New(&negroni.Recovery{
		Logger:     log.New(os.Stdout, "", log.LstdFlags),
		PrintStack: false,
		StackAll:   false,
		StackSize:  1024 * 8,
	}, NewRequestLogger(s.Logger))
	n.UseHandler(s.Router)

	// Ensure server gracefully drains connections when stopped.
	stop := make(chan os.Signal, 1)
	// Stop on SIGINTs and SIGTERMs.
	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)

	server := &http.Server{Addr: fmt.Sprintf(":%d", s.Port), Handler: n}
	go func() {
		s.Logger.Warn("Atlantis started - listening on port %v", s.Port)

		var err error
		if s.SSLCertFile != "" && s.SSLKeyFile != "" {
			err = server.ListenAndServeTLS(s.SSLCertFile, s.SSLKeyFile)
		} else {
			err = server.ListenAndServe()
		}

		if err != nil {
			// When shutdown safely, there will be no error.
			s.Logger.Err(err.Error())
		}
	}()
	<-stop

	s.Logger.Warn("Received interrupt. Safely shutting down")
	ctx, _ := context.WithTimeout(context.Background(), 5*time.Second) // nolint: vet
	if err := server.Shutdown(ctx); err != nil {
		return cli.NewExitError(fmt.Sprintf("while shutting down: %s", err), 1)
	}
	return nil
}

// Index is the / route.
func (s *Server) Index(w http.ResponseWriter, _ *http.Request) {
	locks, err := s.Locker.List()
	if err != nil {
		w.WriteHeader(http.StatusServiceUnavailable)
		fmt.Fprintf(w, "Could not retrieve locks: %s", err)
		return
	}

	var lockResults []LockIndexData
	for id, v := range locks {
		lockURL, _ := s.Router.Get(LockViewRouteName).URL("id", url.QueryEscape(id))
		lockResults = append(lockResults, LockIndexData{
			LockURL:      lockURL.String(),
			RepoFullName: v.Project.RepoFullName,
			PullNum:      v.Pull.Num,
			Time:         v.Time,
		})
	}
	// nolint: errcheck
	s.IndexTemplate.Execute(w, IndexData{
		Locks:           lockResults,
		AtlantisVersion: s.AtlantisVersion,
	})
}