// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

// Integration Action Flow
//
// 1. An integration creates an interactive message button or menu.
// 2. A user clicks on a button or selects an option from the menu.
// 3. The client sends a request to server to complete the post action, calling DoPostAction below.
// 4. DoPostAction will send an HTTP POST request to the integration containing contextual data, including
// an encoded and signed trigger ID. Slash commands also include trigger IDs in their payloads.
// 5. The integration performs any actions it needs to and optionally makes a request back to the MM server
// using the trigger ID to open an interactive dialog.
// 6. If that optional request is made, OpenInteractiveDialog sends a WebSocket event to all connected clients
// for the relevant user, telling them to display the dialog.
// 7. The user fills in the dialog and submits it, where SubmitInteractiveDialog will submit it back to the
// integration for handling.

package app

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"path"
	"path/filepath"
	"strings"

	"github.com/gorilla/mux"

	"github.com/mattermost/mattermost-server/v6/app/request"
	"github.com/mattermost/mattermost-server/v6/model"
	"github.com/mattermost/mattermost-server/v6/shared/i18n"
	"github.com/mattermost/mattermost-server/v6/shared/mlog"
	"github.com/mattermost/mattermost-server/v6/store"
	"github.com/mattermost/mattermost-server/v6/utils"
)

func (a *App) DoPostAction(c *request.Context, postID, actionId, userID, selectedOption string) (string, *model.AppError) {
	return a.DoPostActionWithCookie(c, postID, actionId, userID, selectedOption, nil)
}

func (a *App) DoPostActionWithCookie(c *request.Context, postID, actionId, userID, selectedOption string, cookie *model.PostActionCookie) (string, *model.AppError) {

	// PostAction may result in the original post being updated. For the
	// updated post, we need to unconditionally preserve the original
	// IsPinned and HasReaction attributes, and preserve its entire
	// original Props set unless the plugin returns a replacement value.
	// originalXxx variables are used to preserve these values.
	var originalProps map[string]any
	originalIsPinned := false
	originalHasReactions := false

	// If the updated post does contain a replacement Props set, we still
	// need to preserve some original values, as listed in
	// model.PostActionRetainPropKeys. remove and retain track these.
	remove := []string{}
	retain := map[string]any{}

	datasource := ""
	upstreamURL := ""
	rootPostId := ""
	upstreamRequest := &model.PostActionIntegrationRequest{
		UserId: userID,
		PostId: postID,
	}

	// See if the post exists in the DB, if so ignore the cookie.
	// Start all queries here for parallel execution
	pchan := make(chan store.StoreResult, 1)
	go func() {
		post, err := a.Srv().Store.Post().GetSingle(postID, false)
		pchan <- store.StoreResult{Data: post, NErr: err}
		close(pchan)
	}()

	cchan := make(chan store.StoreResult, 1)
	go func() {
		channel, err := a.Srv().Store.Channel().GetForPost(postID)
		cchan <- store.StoreResult{Data: channel, NErr: err}
		close(cchan)
	}()

	userChan := make(chan store.StoreResult, 1)
	go func() {
		user, err := a.Srv().Store.User().Get(context.Background(), upstreamRequest.UserId)
		userChan <- store.StoreResult{Data: user, NErr: err}
		close(userChan)
	}()

	result := <-pchan
	if result.NErr != nil {
		if cookie == nil {
			var nfErr *store.ErrNotFound
			switch {
			case errors.As(result.NErr, &nfErr):
				return "", model.NewAppError("DoPostActionWithCookie", "app.post.get.app_error", nil, nfErr.Error(), http.StatusNotFound)
			default:
				return "", model.NewAppError("DoPostActionWithCookie", "app.post.get.app_error", nil, result.NErr.Error(), http.StatusInternalServerError)
			}
		}
		if cookie.Integration == nil {
			return "", model.NewAppError("DoPostActionWithCookie", "api.post.do_action.action_integration.app_error", nil, "no Integration in action cookie", http.StatusBadRequest)
		}

		if postID != cookie.PostId {
			return "", model.NewAppError("DoPostActionWithCookie", "api.post.do_action.action_integration.app_error", nil, "postId doesn't match", http.StatusBadRequest)
		}

		channel, err := a.Srv().Store.Channel().Get(cookie.ChannelId, true)
		if err != nil {
			var nfErr *store.ErrNotFound
			switch {
			case errors.As(err, &nfErr):
				return "", model.NewAppError("DoPostActionWithCookie", "app.channel.get.existing.app_error", nil, nfErr.Error(), http.StatusNotFound)
			default:
				return "", model.NewAppError("DoPostActionWithCookie", "app.channel.get.find.app_error", nil, err.Error(), http.StatusInternalServerError)
			}
		}

		upstreamRequest.ChannelId = cookie.ChannelId
		upstreamRequest.ChannelName = channel.Name
		upstreamRequest.TeamId = channel.TeamId
		upstreamRequest.Type = cookie.Type
		upstreamRequest.Context = cookie.Integration.Context
		datasource = cookie.DataSource

		retain = cookie.RetainProps
		remove = cookie.RemoveProps
		rootPostId = cookie.RootPostId
		upstreamURL = cookie.Integration.URL
	} else {
		post := result.Data.(*model.Post)
		result = <-cchan
		if result.NErr != nil {
			return "", model.NewAppError("DoPostActionWithCookie", "app.channel.get_for_post.app_error", nil, result.NErr.Error(), http.StatusInternalServerError)
		}
		channel := result.Data.(*model.Channel)

		action := post.GetAction(actionId)
		if action == nil || action.Integration == nil {
			return "", model.NewAppError("DoPostActionWithCookie", "api.post.do_action.action_id.app_error", nil, fmt.Sprintf("action=%v", action), http.StatusNotFound)
		}

		upstreamRequest.ChannelId = post.ChannelId
		upstreamRequest.ChannelName = channel.Name
		upstreamRequest.TeamId = channel.TeamId
		upstreamRequest.Type = action.Type
		upstreamRequest.Context = action.Integration.Context
		datasource = action.DataSource

		// Save the original values that may need to be preserved (including selected
		// Props, i.e. override_username, override_icon_url)
		for _, key := range model.PostActionRetainPropKeys {
			value, ok := post.GetProps()[key]
			if ok {
				retain[key] = value
			} else {
				remove = append(remove, key)
			}
		}
		originalProps = post.GetProps()
		originalIsPinned = post.IsPinned
		originalHasReactions = post.HasReactions

		if post.RootId == "" {
			rootPostId = post.Id
		} else {
			rootPostId = post.RootId
		}

		upstreamURL = action.Integration.URL
	}

	teamChan := make(chan store.StoreResult, 1)

	go func() {
		defer close(teamChan)

		// Direct and group channels won't have teams.
		if upstreamRequest.TeamId == "" {
			return
		}

		team, err := a.Srv().Store.Team().Get(upstreamRequest.TeamId)
		teamChan <- store.StoreResult{Data: team, NErr: err}
	}()

	ur := <-userChan
	if ur.NErr != nil {
		var nfErr *store.ErrNotFound
		switch {
		case errors.As(ur.NErr, &nfErr):
			return "", model.NewAppError("DoPostActionWithCookie", MissingAccountError, nil, nfErr.Error(), http.StatusNotFound)
		default:
			return "", model.NewAppError("DoPostActionWithCookie", "app.user.get.app_error", nil, ur.NErr.Error(), http.StatusInternalServerError)
		}
	}
	user := ur.Data.(*model.User)
	upstreamRequest.UserName = user.Username

	tr, ok := <-teamChan
	if ok {
		if tr.NErr != nil {
			var nfErr *store.ErrNotFound
			switch {
			case errors.As(tr.NErr, &nfErr):
				return "", model.NewAppError("DoPostActionWithCookie", "app.team.get.find.app_error", nil, nfErr.Error(), http.StatusNotFound)
			default:
				return "", model.NewAppError("DoPostActionWithCookie", "app.team.get.finding.app_error", nil, tr.NErr.Error(), http.StatusInternalServerError)
			}
		}

		team := tr.Data.(*model.Team)
		upstreamRequest.TeamName = team.Name
	}

	if upstreamRequest.Type == model.PostActionTypeSelect {
		if selectedOption != "" {
			if upstreamRequest.Context == nil {
				upstreamRequest.Context = map[string]any{}
			}
			upstreamRequest.DataSource = datasource
			upstreamRequest.Context["selected_option"] = selectedOption
		}
	}

	clientTriggerId, _, appErr := upstreamRequest.GenerateTriggerId(a.AsymmetricSigningKey())
	if appErr != nil {
		return "", appErr
	}

	var resp *http.Response
	if strings.HasPrefix(upstreamURL, "/warn_metrics/") {
		appErr = a.doLocalWarnMetricsRequest(c, upstreamURL, upstreamRequest)
		if appErr != nil {
			return "", appErr
		}
		return "", nil
	}
	requestJSON, jsonErr := json.Marshal(upstreamRequest)
	if jsonErr != nil {
		return "", model.NewAppError("DoPostActionWithCookie", "api.marshal_error", nil, jsonErr.Error(), http.StatusInternalServerError)
	}
	resp, appErr = a.DoActionRequest(c, upstreamURL, requestJSON)
	if appErr != nil {
		return "", appErr
	}
	defer resp.Body.Close()

	var response model.PostActionIntegrationResponse
	respBytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", model.NewAppError("DoPostActionWithCookie", "api.post.do_action.action_integration.app_error", nil, "err="+err.Error(), http.StatusBadRequest)
	}

	if len(respBytes) > 0 {
		if err = json.Unmarshal(respBytes, &response); err != nil {
			return "", model.NewAppError("DoPostActionWithCookie", "api.post.do_action.action_integration.app_error", nil, "err="+err.Error(), http.StatusBadRequest)
		}
	}

	if response.Update != nil {
		response.Update.Id = postID

		// Restore the post attributes and Props that need to be preserved
		if response.Update.GetProps() == nil {
			response.Update.SetProps(originalProps)
		} else {
			for key, value := range retain {
				response.Update.AddProp(key, value)
			}
			for _, key := range remove {
				response.Update.DelProp(key)
			}
		}
		response.Update.IsPinned = originalIsPinned
		response.Update.HasReactions = originalHasReactions

		if _, appErr = a.UpdatePost(c, response.Update, false); appErr != nil {
			return "", appErr
		}
	}

	if response.EphemeralText != "" {
		ephemeralPost := &model.Post{
			Message:   response.EphemeralText,
			ChannelId: upstreamRequest.ChannelId,
			RootId:    rootPostId,
			UserId:    userID,
		}

		if !response.SkipSlackParsing {
			ephemeralPost.Message = model.ParseSlackLinksToMarkdown(response.EphemeralText)
		}

		for key, value := range retain {
			ephemeralPost.AddProp(key, value)
		}
		a.SendEphemeralPost(userID, ephemeralPost)
	}

	return clientTriggerId, nil
}

// Perform an HTTP POST request to an integration's action endpoint.
// Caller must consume and close returned http.Response as necessary.
// For internal requests, requests are routed directly to a plugin ServerHTTP hook
func (a *App) DoActionRequest(c *request.Context, rawURL string, body []byte) (*http.Response, *model.AppError) {
	inURL, err := url.Parse(rawURL)
	if err != nil {
		return nil, model.NewAppError("DoActionRequest", "api.post.do_action.action_integration.app_error", nil, err.Error(), http.StatusBadRequest)
	}

	rawURLPath := path.Clean(rawURL)
	if strings.HasPrefix(rawURLPath, "/plugins/") || strings.HasPrefix(rawURLPath, "plugins/") {
		return a.DoLocalRequest(c, rawURLPath, body)
	}

	req, err := http.NewRequest("POST", rawURL, bytes.NewReader(body))
	if err != nil {
		return nil, model.NewAppError("DoActionRequest", "api.post.do_action.action_integration.app_error", nil, err.Error(), http.StatusBadRequest)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json")

	// Allow access to plugin routes for action buttons
	var httpClient *http.Client
	subpath, _ := utils.GetSubpathFromConfig(a.Config())
	siteURL, _ := url.Parse(*a.Config().ServiceSettings.SiteURL)
	if (inURL.Hostname() == "localhost" || inURL.Hostname() == "127.0.0.1" || inURL.Hostname() == siteURL.Hostname()) && strings.HasPrefix(inURL.Path, path.Join(subpath, "plugins")) {
		req.Header.Set(model.HeaderAuth, "Bearer "+c.Session().Token)
		httpClient = a.HTTPService().MakeClient(true)
	} else {
		httpClient = a.HTTPService().MakeClient(false)
	}

	resp, httpErr := httpClient.Do(req)
	if httpErr != nil {
		return nil, model.NewAppError("DoActionRequest", "api.post.do_action.action_integration.app_error", nil, "err="+httpErr.Error(), http.StatusBadRequest)
	}

	if resp.StatusCode != http.StatusOK {
		return resp, model.NewAppError("DoActionRequest", "api.post.do_action.action_integration.app_error", nil, fmt.Sprintf("status=%v", resp.StatusCode), http.StatusBadRequest)
	}

	return resp, nil
}

type LocalResponseWriter struct {
	data    []byte
	headers http.Header
	status  int
}

func (w *LocalResponseWriter) Header() http.Header {
	if w.headers == nil {
		w.headers = make(http.Header)
	}
	return w.headers
}

func (w *LocalResponseWriter) Write(bytes []byte) (int, error) {
	w.data = make([]byte, len(bytes))
	copy(w.data, bytes)
	return len(w.data), nil
}

func (w *LocalResponseWriter) WriteHeader(statusCode int) {
	w.status = statusCode
}

func (a *App) doPluginRequest(c *request.Context, method, rawURL string, values url.Values, body []byte) (*http.Response, *model.AppError) {
	return a.ch.doPluginRequest(c, method, rawURL, values, body)
}

func (ch *Channels) doPluginRequest(c *request.Context, method, rawURL string, values url.Values, body []byte) (*http.Response, *model.AppError) {
	rawURL = strings.TrimPrefix(rawURL, "/")
	inURL, err := url.Parse(rawURL)
	if err != nil {
		return nil, model.NewAppError("doPluginRequest", "api.post.do_action.action_integration.app_error", nil, "err="+err.Error(), http.StatusBadRequest)
	}
	result := strings.Split(inURL.Path, "/")
	if len(result) < 2 {
		return nil, model.NewAppError("doPluginRequest", "api.post.do_action.action_integration.app_error", nil, "err=Unable to find pluginId", http.StatusBadRequest)
	}
	if result[0] != "plugins" {
		return nil, model.NewAppError("doPluginRequest", "api.post.do_action.action_integration.app_error", nil, "err=plugins not in path", http.StatusBadRequest)
	}
	pluginID := result[1]

	path := strings.TrimPrefix(inURL.Path, "plugins/"+pluginID)

	base, err := url.Parse(path)
	if err != nil {
		return nil, model.NewAppError("doPluginRequest", "api.post.do_action.action_integration.app_error", nil, "err="+err.Error(), http.StatusBadRequest)
	}

	// merge the rawQuery params (if any) with the function's provided values
	rawValues := inURL.Query()
	if len(rawValues) != 0 {
		if values == nil {
			values = make(url.Values)
		}
		for k, vs := range rawValues {
			for _, v := range vs {
				values.Add(k, v)
			}
		}
	}
	if values != nil {
		base.RawQuery = values.Encode()
	}

	w := &LocalResponseWriter{}
	r, err := http.NewRequest(method, base.String(), bytes.NewReader(body))
	if err != nil {
		return nil, model.NewAppError("doPluginRequest", "api.post.do_action.action_integration.app_error", nil, "err="+err.Error(), http.StatusBadRequest)
	}
	r.Header.Set("Mattermost-User-Id", c.Session().UserId)
	r.Header.Set(model.HeaderAuth, "Bearer "+c.Session().Token)
	params := make(map[string]string)
	params["plugin_id"] = pluginID
	r = mux.SetURLVars(r, params)

	ch.ServePluginRequest(w, r)

	resp := &http.Response{
		StatusCode: w.status,
		Proto:      "HTTP/1.1",
		ProtoMajor: 1,
		ProtoMinor: 1,
		Header:     w.headers,
		Body:       ioutil.NopCloser(bytes.NewReader(w.data)),
	}
	if resp.StatusCode == 0 {
		resp.StatusCode = http.StatusOK
	}

	return resp, nil
}

func (a *App) doLocalWarnMetricsRequest(c *request.Context, rawURL string, upstreamRequest *model.PostActionIntegrationRequest) *model.AppError {
	_, err := url.Parse(rawURL)
	if err != nil {
		return model.NewAppError("doLocalWarnMetricsRequest", "api.post.do_action.action_integration.app_error", nil, err.Error(), http.StatusBadRequest)
	}

	warnMetricId := filepath.Base(rawURL)
	if warnMetricId == "" {
		return model.NewAppError("doLocalWarnMetricsRequest", "api.post.do_action.action_integration.app_error", nil, "", http.StatusBadRequest)
	}

	license := a.Srv().License()
	if license != nil {
		mlog.Debug("License is present, skip this call")
		return nil
	}

	user, appErr := a.GetUser(c.Session().UserId)
	if appErr != nil {
		return appErr
	}

	botPost := &model.Post{
		UserId:       upstreamRequest.Context["bot_user_id"].(string),
		ChannelId:    upstreamRequest.ChannelId,
		HasReactions: true,
	}

	isE0Edition := (model.BuildEnterpriseReady == "true") // license == nil was already validated upstream
	_, warnMetricDisplayTexts := a.getWarnMetricStatusAndDisplayTextsForId(warnMetricId, i18n.T, isE0Edition)
	botPost.Message = ":white_check_mark: " + warnMetricDisplayTexts.BotSuccessMessage

	if isE0Edition {
		if appErr = a.RequestLicenseAndAckWarnMetric(c, warnMetricId, true); appErr != nil {
			botPost.Message = ":warning: " + i18n.T("api.server.warn_metric.bot_response.start_trial_failure.message")
		}
	} else {
		forceAck := upstreamRequest.Context["force_ack"].(bool)
		if appErr = a.NotifyAndSetWarnMetricAck(warnMetricId, user, forceAck, true); appErr != nil {
			if forceAck {
				return appErr
			}
			mailtoLinkText := a.buildWarnMetricMailtoLink(warnMetricId, user)
			botPost.Message = ":warning: " + i18n.T("api.server.warn_metric.bot_response.notification_failure.message")
			actions := []*model.PostAction{}
			actions = append(actions,
				&model.PostAction{
					Id:   "emailUs",
					Name: i18n.T("api.server.warn_metric.email_us"),
					Type: model.PostActionTypeButton,
					Options: []*model.PostActionOptions{
						{
							Text:  "WarnMetricMailtoUrl",
							Value: mailtoLinkText,
						},
						{
							Text:  "TrackEventId",
							Value: warnMetricId,
						},
					},
					Integration: &model.PostActionIntegration{
						Context: model.StringInterface{
							"bot_user_id": botPost.UserId,
							"force_ack":   true,
						},
						URL: fmt.Sprintf("/warn_metrics/ack/%s", model.SystemWarnMetricNumberOfActiveUsers500),
					},
				},
			)
			attachments := []*model.SlackAttachment{{
				AuthorName: "",
				Title:      "",
				Actions:    actions,
				Text:       i18n.T("api.server.warn_metric.bot_response.notification_failure.body"),
			}}
			model.ParseSlackAttachment(botPost, attachments)
		}
	}

	if _, err := a.CreatePostAsUser(c, botPost, c.Session().Id, true); err != nil {
		return err
	}

	return nil
}

type MailToLinkContent struct {
	MetricId      string `json:"metric_id"`
	MailRecipient string `json:"mail_recipient"`
	MailCC        string `json:"mail_cc"`
	MailSubject   string `json:"mail_subject"`
	MailBody      string `json:"mail_body"`
}

func (mlc *MailToLinkContent) ToJSON() string {
	b, _ := json.Marshal(mlc)
	return string(b)
}

func (a *App) buildWarnMetricMailtoLink(warnMetricId string, user *model.User) string {
	T := i18n.GetUserTranslations(user.Locale)
	_, warnMetricDisplayTexts := a.getWarnMetricStatusAndDisplayTextsForId(warnMetricId, T, false)

	mailBody := warnMetricDisplayTexts.EmailBody
	mailBody += T("api.server.warn_metric.bot_response.mailto_contact_header", map[string]any{"Contact": user.GetFullName()})
	mailBody += "\r\n"
	mailBody += T("api.server.warn_metric.bot_response.mailto_email_header", map[string]any{"Email": user.Email})
	mailBody += "\r\n"

	registeredUsersCount, err := a.Srv().Store.User().Count(model.UserCountOptions{})
	if err != nil {
		mlog.Warn("Error retrieving the number of registered users", mlog.Err(err))
	} else {
		mailBody += i18n.T("api.server.warn_metric.bot_response.mailto_registered_users_header", map[string]any{"NoRegisteredUsers": registeredUsersCount})
		mailBody += "\r\n"
	}

	mailBody += T("api.server.warn_metric.bot_response.mailto_site_url_header", map[string]any{"SiteUrl": a.GetSiteURL()})
	mailBody += "\r\n"

	mailBody += T("api.server.warn_metric.bot_response.mailto_diagnostic_id_header", map[string]any{"DiagnosticId": a.TelemetryId()})
	mailBody += "\r\n"

	mailBody += T("api.server.warn_metric.bot_response.mailto_footer")

	mailToLinkContent := &MailToLinkContent{
		MetricId:      warnMetricId,
		MailRecipient: model.MmSupportAdvisorAddress,
		MailCC:        user.Email,
		MailSubject:   T("api.server.warn_metric.bot_response.mailto_subject"),
		MailBody:      mailBody,
	}

	return mailToLinkContent.ToJSON()
}

func (a *App) DoLocalRequest(c *request.Context, rawURL string, body []byte) (*http.Response, *model.AppError) {
	return a.doPluginRequest(c, "POST", rawURL, nil, body)
}

func (a *App) OpenInteractiveDialog(request model.OpenDialogRequest) *model.AppError {
	clientTriggerId, userID, err := request.DecodeAndVerifyTriggerId(a.AsymmetricSigningKey())
	if err != nil {
		return err
	}

	request.TriggerId = clientTriggerId

	jsonRequest, _ := json.Marshal(request)

	message := model.NewWebSocketEvent(model.WebsocketEventOpenDialog, "", "", userID, nil)
	message.Add("dialog", string(jsonRequest))
	a.Publish(message)

	return nil
}

func (a *App) SubmitInteractiveDialog(c *request.Context, request model.SubmitDialogRequest) (*model.SubmitDialogResponse, *model.AppError) {
	url := request.URL
	request.URL = ""
	request.Type = "dialog_submission"

	b, jsonErr := json.Marshal(request)
	if jsonErr != nil {
		return nil, model.NewAppError("SubmitInteractiveDialog", "app.submit_interactive_dialog.json_error", nil, jsonErr.Error(), http.StatusBadRequest)
	}

	resp, err := a.DoActionRequest(c, url, b)
	if err != nil {
		return nil, err
	}

	defer resp.Body.Close()

	var response model.SubmitDialogResponse
	if err := json.NewDecoder(resp.Body).Decode(&response); err != nil {
		// Don't fail, an empty response is acceptable
		return &response, nil
	}

	return &response, nil
}