/*
Copyright 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

    https://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 handlers

import (
	"context"
	"fmt"
	"html/template"
	"io"
	"log/slog"
	"net/http"
	"sort"
	"strings"
	"time"

	"github.com/gorilla/csrf"
	"github.com/nicksnyder/go-i18n/v2/i18n"
	client "github.com/ory/hydra-client-go/v2"

	"code.cacert.org/cacert/oidc-idp/internal/services"
)

type IndexHandler struct {
	logger    *slog.Logger
	trans     *services.I18NService
	templates TemplateCache
}

func (h *IndexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)

		return
	}

	localizer := getLocalizer(h.trans, r)

	if r.URL.Path != "/" {
		http.Error(w, h.trans.LookupHTTPErrorMessage(http.StatusNotFound, localizer), http.StatusNotFound)

		return
	}

	h.templates.render(h.logger, w, Index, map[string]interface{}{
		"Title": h.trans.LookupMessage("IndexTitle", nil, localizer),
		"WelcomeMessage": template.HTML(h.trans.LookupMarkdownMessage( //nolint:gosec
			"IndexWelcomeMessage",
			map[string]interface{}{"ManageConsentHRef": "/manage-consent"},
			localizer,
		)),
	})
}

func NewIndex(logger *slog.Logger, templateCache TemplateCache, trans *services.I18NService) *IndexHandler {
	return &IndexHandler{logger: logger, trans: trans, templates: templateCache}
}

type ManageConsentHandler struct {
	logger    *slog.Logger
	trans     *services.I18NService
	adminAPI  client.OAuth2API
	templates TemplateCache
}

func (h *ManageConsentHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)

		return
	}

	localizer := getLocalizer(h.trans, r)

	allSessions := make(ConsentSessions, 0)

	var (
		sessions []client.OAuth2ConsentSession
		ok       bool
	)

	for _, s := range GetAuthenticatedAddresses(r) {
		if sessions, ok = h.getConsentSessions(w, r, s); !ok {
			return
		}

		for _, session := range sessions {
			allSessions = append(allSessions, ConsentSession{Subject: s, Session: session})
		}
	}

	sort.Sort(allSessions)

	requestSession, err := GetSession(r)
	if err != nil {
		h.logger.Error("could not get session for request", "error", err)

		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	h.logger.Debug("got session for request", "new_session", requestSession.IsNew)

	h.templates.render(h.logger, w, ManageConsent, map[string]interface{}{
		"Title": h.trans.LookupMessage("ManageConsentTitle", nil, localizer),
		"Description": template.HTML(h.trans.LookupMarkdownMessage( //nolint:gosec
			"ManageConsentDescription",
			nil,
			localizer,
		)),
		"NoConsentGiven":    h.trans.LookupMessage("NoConsentGiven", nil, localizer),
		"Flashes":           requestSession.Flashes("messages"),
		"ConsentSessions":   allSessions,
		"ButtonTitleRevoke": h.trans.LookupMessage("ButtonTitleRevoke", nil, localizer),
		"ApplicationTitle":  h.trans.LookupMessage("ColumnNameApplication", nil, localizer),
		"ActionsTitle":      h.trans.LookupMessage("ColumnNameActions", nil, localizer),
		"SubjectTitle":      h.trans.LookupMessage("ColumnNameSubject", nil, localizer),
		"GrantedTitle":      h.trans.LookupMessage("ColumnNameGranted", nil, localizer),
		"ExpiresTitle":      h.trans.LookupMessage("ColumnNameExpires", nil, localizer),
		"LabelUnknown":      h.trans.LookupMessage("LabelUnknown", nil, localizer),
		"LabelNever":        h.trans.LookupMessage("LabelNever", nil, localizer),
	})
}

type ConsentSession struct {
	Subject string
	Session client.OAuth2ConsentSession
}

func (s ConsentSession) GetClientName() string {
	if !s.Session.HasConsentRequest() {
		return ""
	}

	request := s.Session.GetConsentRequest()
	if !request.HasClient() {
		return ""
	}

	consentClient := request.GetClient()

	return consentClient.GetClientName()
}

func (s ConsentSession) GetID() string {
	if consent, ok := s.Session.GetConsentRequestOk(); ok {
		if app, ok := consent.GetClientOk(); ok {
			return app.GetClientId()
		}
	}

	return ""
}

func (s ConsentSession) GrantedAt() *time.Time {
	if grantedAt, ok := s.Session.GetHandledAtOk(); ok {
		return grantedAt
	}

	return nil
}

func (s ConsentSession) Expires() *time.Time {
	if expiresAt, ok := s.Session.GetExpiresAtOk(); ok {
		if grantedAt := s.GrantedAt(); grantedAt != nil {
			return expiresAt.AccessToken
		}
	}

	return nil
}

type ConsentSessions []ConsentSession

func (c ConsentSessions) Len() int {
	return len(c)
}

func (c ConsentSessions) Less(i, j int) bool {
	return c[i].Subject < c[j].Subject && c[i].GetClientName() < c[j].GetClientName()
}

func (c ConsentSessions) Swap(i, j int) {
	c[i], c[j] = c[j], c[i]
}

func (h *ManageConsentHandler) getConsentSessions(
	w http.ResponseWriter, r *http.Request, subject string,
) ([]client.OAuth2ConsentSession, bool) {
	sessions, response, err := h.adminAPI.ListOAuth2ConsentSessions(r.Context()).Subject(subject).Execute()
	if err != nil {
		h.logger.Error("error getting consent session list", "error", err)

		// h.fillAcceptLoginRequestErrorBucket(r, err)
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return nil, false
	}

	defer func(response *http.Response) { _ = response.Body.Close() }(response)

	h.logger.Debug(
		"got response for AcceptOAuth2LoginRequest",
		"response", response.Status, "consent_sessions", sessions,
	)

	if h.logger.Enabled(r.Context(), slog.LevelDebug) {
		if rb, err := io.ReadAll(response.Body); err == nil {
			h.logger.Debug("response body from Hydra", "response_body", rb)
		}
	}

	return sessions, true
}

func NewManageConsent(
	logger *slog.Logger, tc TemplateCache, trans *services.I18NService, adminAPI client.OAuth2API,
) *ManageConsentHandler {
	return &ManageConsentHandler{logger: logger, trans: trans, adminAPI: adminAPI, templates: tc}
}

type RevokeConsentHandler struct {
	logger    *slog.Logger
	trans     *services.I18NService
	adminAPI  client.OAuth2API
	templates TemplateCache
}

func (h *RevokeConsentHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	localizer := getLocalizer(h.trans, r)

	if r.Method != http.MethodGet && r.Method != http.MethodPost {
		http.Error(
			w, h.trans.LookupHTTPErrorMessage(http.StatusMethodNotAllowed, localizer), http.StatusMethodNotAllowed,
		)

		return
	}

	clientID, _ := strings.CutPrefix(r.URL.Path, "/revoke-consent/")
	subject := r.URL.Query().Get("subject")

	if clientID == "" || subject == "" {
		http.Error(w, h.trans.LookupHTTPErrorMessage(http.StatusNotFound, localizer), http.StatusNotFound)

		return
	}

	if r.Method == http.MethodGet {
		h.handleGet(w, r, clientID, localizer, subject)

		return
	}

	h.handlePost(w, r, clientID, subject, localizer)
}

func (h *RevokeConsentHandler) handleGet(
	w http.ResponseWriter, r *http.Request, clientID string, localizer *i18n.Localizer, subject string,
) {
	clientApp, found, err := h.getClient(r.Context(), clientID)
	if err != nil {
		h.logger.Error("could not get client", "error", err)

		http.Error(
			w, h.trans.LookupHTTPErrorMessage(http.StatusInternalServerError, localizer),
			http.StatusInternalServerError,
		)

		return
	}

	if !found {
		http.Error(w, h.trans.LookupHTTPErrorMessage(http.StatusNotFound, localizer), http.StatusNotFound)

		return
	}

	h.templates.render(h.logger, w, ConfirmRevoke, map[string]interface{}{
		"Title":             h.trans.LookupMessage("ConfirmRevokeTitle", nil, localizer),
		"ButtonTitleRevoke": h.trans.LookupMessage("ButtonTitleConfirmRevoke", nil, localizer),
		"ButtonTitleCancel": h.trans.LookupMessage("ButtonTitleCancel", nil, localizer),
		"CancelLink":        "/manage-consent",
		csrf.TemplateTag:    csrf.TemplateField(r),
		"Explanation": template.HTML(h.trans.LookupMarkdownMessage( //nolint:gosec
			"ConfirmRevokeExplanation", map[string]interface{}{
				"ApplicationID": template.URLQueryEscaper(clientApp.GetClientId()),
				"Application":   template.HTMLEscapeString(clientApp.GetClientName()),
				"Subject":       subject,
			}, localizer)),
	})
}

func (h *RevokeConsentHandler) handlePost(
	w http.ResponseWriter, r *http.Request, clientID string, subject string, localizer *i18n.Localizer,
) {
	err := h.revokeConsent(r.Context(), clientID, subject)
	if err != nil {
		h.logger.Error("could not revoke consent", "error", err)

		http.Error(
			w, h.trans.LookupHTTPErrorMessage(http.StatusInternalServerError, localizer),
			http.StatusInternalServerError,
		)

		return
	}

	http.Redirect(w, r, "/manage-consent", http.StatusFound)
}

func (h *RevokeConsentHandler) getClient(ctx context.Context, clientID string) (*client.OAuth2Client, bool, error) {
	clientApp, response, err := h.adminAPI.GetOAuth2Client(ctx, clientID).Execute()
	if err != nil {
		return nil, false, fmt.Errorf("error getting client application: %w", err)
	}

	defer func(response *http.Response) { _ = response.Body.Close() }(response)

	h.logger.Debug(
		"got response for GetOAuth2Client",
		"response", response.Status, "client_app", clientApp,
	)

	if h.logger.Enabled(ctx, slog.LevelDebug) {
		if rb, err := io.ReadAll(response.Body); err == nil {
			h.logger.Debug("response body from Hydra", "response_body", rb)
		}
	}

	return clientApp, true, nil
}

func (h *RevokeConsentHandler) revokeConsent(ctx context.Context, clientID, subject string) error {
	response, err := h.adminAPI.RevokeOAuth2ConsentSessions(ctx).Client(clientID).Subject(subject).Execute()
	if err != nil {
		return fmt.Errorf("could not revoke consent: %w", err)
	}

	defer func(response *http.Response) { _ = response.Body.Close() }(response)

	h.logger.Debug("got response for RevokeOAuth2ConsentSessions", "response", response.Status)

	if h.logger.Enabled(ctx, slog.LevelDebug) {
		if rb, err := io.ReadAll(response.Body); err == nil {
			h.logger.Debug("response body from Hydra", "response_body", rb)
		}
	}

	return nil
}

func NewRevokeConsent(
	logger *slog.Logger, tc TemplateCache, trans *services.I18NService, adminAPI client.OAuth2API,
) *RevokeConsentHandler {
	return &RevokeConsentHandler{logger: logger, trans: trans, adminAPI: adminAPI, templates: tc}
}