/*
 * Copyright (C) 2008-2020, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.juick.www.api.activity;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.juick.model.Message;
import com.juick.model.User;
import com.juick.util.formatters.PlainTextFormatter;
import com.juick.model.CommandResult;
import com.juick.ActivityPubManager;
import com.juick.CommandsManager;
import com.juick.KeystoreManager;
import com.juick.www.api.activity.model.Activity;
import com.juick.www.api.activity.model.Context;
import com.juick.www.api.activity.model.activities.Announce;
import com.juick.www.api.activity.model.activities.Create;
import com.juick.www.api.activity.model.activities.Delete;
import com.juick.www.api.activity.model.activities.Flag;
import com.juick.www.api.activity.model.activities.Follow;
import com.juick.www.api.activity.model.activities.Like;
import com.juick.www.api.activity.model.activities.Undo;
import com.juick.www.api.activity.model.objects.Actor;
import com.juick.www.api.activity.model.objects.Application;
import com.juick.www.api.activity.model.objects.Image;
import com.juick.www.api.activity.model.objects.Key;
import com.juick.www.api.activity.model.objects.Note;
import com.juick.www.api.activity.model.objects.OrderedCollection;
import com.juick.www.api.activity.model.objects.OrderedCollectionPage;
import com.juick.www.api.activity.model.objects.Person;
import com.juick.www.api.activity.model.objects.Tombstone;
import com.juick.util.HttpNotFoundException;
import com.juick.www.WebApp;
import com.juick.service.MessagesService;
import com.juick.service.UserService;
import com.juick.service.activities.AnnounceEvent;
import com.juick.service.activities.DirectMessageEvent;
import com.juick.service.activities.FollowEvent;
import com.juick.service.activities.UndoAnnounceEvent;
import com.juick.service.activities.UndoFollowEvent;
import com.juick.service.security.annotation.Visitor;
import com.overzealous.remark.Remark;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.text.StringEscapeUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
import org.springframework.web.util.UriComponentsBuilder;

import javax.inject.Inject;
import java.io.InputStream;
import java.net.URI;
import java.nio.charset.StandardCharsets;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

@RestController
public class Profile {
    private static final Logger logger = LoggerFactory.getLogger("ActivityPub");
    @Inject
    private UserService userService;
    @Inject
    private MessagesService messagesService;
    @Inject
    private KeystoreManager keystoreManager;
    @Inject
    private ActivityPubManager activityPubManager;
    @Inject
    private ApplicationEventPublisher applicationEventPublisher;
    @Inject
    private CommandsManager commandsManager;
    @Value("${web_domain:localhost}")
    private String domain;
    @Value("${ap_base_uri:http://localhost:8080/}")
    private String baseUri;
    @Inject
    private ObjectMapper jsonMapper;
    @Inject
    private WebApp webApp;
    @Inject
    private Remark remarkConverter;

    @GetMapping(value = "/u/{userName}", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE, Context.FALLBACK_JSON_MEDIA_TYPE })
    public Actor getUser(@PathVariable String userName) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            Actor profile = userService.isServiceUser(user) ? new Application() : new Person();
            profile.setId(activityPubManager.personUri(user));
            profile.setUrl(activityPubManager.personWebUri(user));
            profile.setName(userName);
            profile.setPreferredUsername(userName);
            Key publicKey = new Key();
            publicKey.setId(profile.getId() + "#main-key");
            publicKey.setOwner(profile.getId());
            publicKey.setPublicKeyPem(keystoreManager.getPublicKeyPem());
            profile.setPublicKey(publicKey);
            profile.setInbox(activityPubManager.inboxUri());
            profile.setOutbox(activityPubManager.outboxUri(user));
            profile.setFollowers(activityPubManager.followersUri(user));
            profile.setFollowing(activityPubManager.followingUri(user));
            Image avatar = new Image();
            avatar.setUrl(webApp.getAvatarUrl(user));
            avatar.setMediaType("image/png");
            profile.setIcon(avatar);
            return (Actor) Context.build(profile);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/blog/toc", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollection getOutbox(@PathVariable String userName) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(baseUri);
            OrderedCollection blog = new OrderedCollection();
            blog.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            blog.setTotalItems(userService.getStatsMessages(user.getUid()));
            blog.setFirst(uriComponentsBuilder.path(String.format("/u/%s/blog", userName)).toUriString());
            return (OrderedCollection) Context.build(blog);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/blog", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollectionPage getOutboxPage(@Visitor User visitor, @PathVariable String userName,
            @RequestParam(required = false, defaultValue = "0") int before) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous() && !user.isBanned()) {
            UriComponentsBuilder uri = UriComponentsBuilder.fromUriString(baseUri);
            String personUri = uri.path(String.format("/u/%s", userName)).toUriString();
            List<Integer> mids = messagesService.getUserBlog(user.getUid(), 0, before);
            List<Note> notes = messagesService.getMessages(visitor, mids).stream().map(activityPubManager::makeNote)
                    .collect(Collectors.toList());
            OrderedCollectionPage page = new OrderedCollectionPage();
            page.setPartOf(uri.replacePath(String.format("/u/%s/blog/toc", userName)).toUriString());
            page.setFirst(uri.replacePath(String.format("/u/%s/blog", userName)).toUriString());
            page.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            page.setOrderedItems(notes.stream().map(a -> {
                Create create = new Create();
                create.setId(a.getId() + "#Create");
                create.setTo(a.getTo());
                create.setActor(personUri);
                create.setObject(a);
                create.setPublished(a.getPublished());
                return create;
            }).collect(Collectors.toList()));
            int beforeNext = mids.stream().reduce((fst, second) -> second).orElse(0);
            if (beforeNext > 0) {
                page.setNext(uri.queryParam("before", beforeNext).toUriString());
            }
            page.setLast(uri.replaceQueryParam("before", "1").toUriString());
            return (OrderedCollectionPage) Context.build(page);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/followers/toc", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollection getFollowers(@PathVariable String userName) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(baseUri);
            OrderedCollection followers = new OrderedCollection();
            followers.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            followers.setTotalItems(userService.getStatsMyReaders(user.getUid()));
            followers.setFirst(uriComponentsBuilder.path(String.format("/u/%s/followers", userName)).toUriString());
            return (OrderedCollection) Context.build(followers);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/followers", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollectionPage getFollowersPage(@PathVariable String userName,
            @RequestParam(required = false, defaultValue = "0") int page) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(baseUri);
            uriComponentsBuilder.path(String.format("/u/%s/followers", userName));
            List<User> followers = userService.getUserReaders(user.getUid());
            Stream<User> followersPage = followers.stream().skip(20 * page).limit(20);

            OrderedCollectionPage result = new OrderedCollectionPage();
            result.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            result.setOrderedItems(followersPage.map(a -> {
                Person follower = new Person();
                follower.setName(a.getName());
                follower.setPreferredUsername(a.getName());
                follower.setUrl(activityPubManager.personWebUri(a));
                return follower;
            }).collect(Collectors.toList()));
            boolean hasNext = followers.size() <= 20 * page;
            if (hasNext) {
                result.setNext(uriComponentsBuilder.queryParam("page", page + 1).toUriString());
            }
            return (OrderedCollectionPage) Context.build(result);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/following/toc", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollection getFollowing(@PathVariable String userName) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(baseUri);
            OrderedCollection following = new OrderedCollection();
            following.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            following.setTotalItems(userService.getUserFriends(user.getUid()).size());
            following.setFirst(uriComponentsBuilder.path(String.format("/u/%s/followers", userName)).toUriString());
            return (OrderedCollection) Context.build(following);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/u/{userName}/following", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public OrderedCollectionPage getFollowingPage(@PathVariable String userName,
            @RequestParam(required = false, defaultValue = "0") int page) {
        User user = userService.getUserByName(userName);
        if (!user.isAnonymous()) {
            UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(baseUri);
            uriComponentsBuilder.path(String.format("/u/%s/following", userName));
            List<User> following = userService.getUserFriends(user.getUid());
            Stream<User> followingPage = following.stream().skip(20 * page).limit(20);

            OrderedCollectionPage result = new OrderedCollectionPage();
            result.setId(ServletUriComponentsBuilder.fromCurrentRequestUri().toUriString());
            result.setOrderedItems(followingPage.map(a -> {
                Person follower = new Person();
                follower.setName(a.getName());
                follower.setPreferredUsername(a.getName());
                follower.setUrl(activityPubManager.personWebUri(a));
                return follower;
            }).collect(Collectors.toList()));
            boolean hasNext = following.size() <= 20 * page;
            if (hasNext) {
                result.setNext(uriComponentsBuilder.queryParam("page", page + 1).toUriString());
            }
            return (OrderedCollectionPage) Context.build(result);
        }
        throw new HttpNotFoundException();
    }

    @GetMapping(value = "/n/{mid}-{rid}", produces = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public Context showNote(@PathVariable int mid, @PathVariable int rid) {
        if (rid > 0) {
            // reply
            return Context.build(activityPubManager.makeNote(messagesService.getReply(mid, rid)));
        }
        return Context.build(
                activityPubManager.makeNote(messagesService.getMessage(mid).orElseThrow(IllegalStateException::new)));
    }

    @PostMapping(value = "/api/inbox", consumes = { Context.LD_JSON_MEDIA_TYPE,
            Context.ACTIVITYSTREAMS_PROFILE_MEDIA_TYPE })
    public ResponseEntity<CommandResult> processInbox(@Visitor User visitor, InputStream inboxData) throws Exception {
        String inbox = IOUtils.toString(inboxData, StandardCharsets.UTF_8);
        Activity activity = jsonMapper.readValue(inbox, Activity.class);
        if ((StringUtils.isNotEmpty(visitor.getUri().toString())
                && visitor.getUri().equals(URI.create(activity.getActor()))) || !visitor.isAnonymous()) {
            if (activity instanceof Follow) {
                Follow followRequest = (Follow) activity;
                applicationEventPublisher.publishEvent(new FollowEvent(this, followRequest));
                return new ResponseEntity<>(CommandResult.fromString("Follow request accepted"), HttpStatus.ACCEPTED);
            }
            if (activity instanceof Undo) {
                Activity object = (Activity) activity.getObject();
                if (object instanceof Follow) {
                    applicationEventPublisher
                            .publishEvent(new UndoFollowEvent(this, activity.getActor(), object.getObject().getId()));
                    return new ResponseEntity<>(CommandResult.fromString("Undo follow request accepted"),
                            HttpStatus.OK);
                } else if (object instanceof Like || object instanceof Announce) {
                    applicationEventPublisher
                            .publishEvent(new UndoAnnounceEvent(this, activity.getActor(), object.getObject().getId()));
                    return new ResponseEntity<>(CommandResult.fromString("Undo like/announce request accepted"),
                            HttpStatus.OK);
                }
            }
            if (activity instanceof Create) {
                if (activity.getObject() instanceof Note) {
                    Note note = (Note) activity.getObject();
                    URI noteId = URI.create((String) note.getId());
                    if (messagesService.replyExists(noteId)) {
                        return new ResponseEntity<>(CommandResult.fromString("Reply already exists"), HttpStatus.OK);
                    } else {
                        String inReplyTo = (String) note.getInReplyTo();
                        if (StringUtils.isNotBlank(inReplyTo)) {
                            if (inReplyTo.startsWith(baseUri)) {
                                String postId = activityPubManager.postId(inReplyTo);
                                User user = new User();
                                user.setUri(URI.create(activity.getActor()));
                                String markdown = remarkConverter.convertFragment((String) note.getContent());
                                String commandBody = note.getAttachment() == null ? markdown
                                        : note.getAttachment().stream().map(attachment -> {
                                            String attachmentUrl = attachment.getUrl();
                                            String attachmentName = attachment.getName();
                                            return PlainTextFormatter.markdownUrl(attachmentUrl, attachmentName);
                                        }).reduce(markdown,
                                                (currentUrl, nextUrl) -> String.format("%s\n%s", currentUrl, nextUrl));

                                CommandResult result = commandsManager.processCommand(user,
                                        String.format("#%s %s", postId, commandBody), URI.create(StringUtils.EMPTY));
                                logger.info(jsonMapper.writeValueAsString(result));
                                if (result.getNewMessage().isPresent()) {
                                    messagesService.updateReplyUri(result.getNewMessage().get(), noteId);
                                    return new ResponseEntity<>(result, HttpStatus.OK);
                                } else {
                                    logger.warn("Invalid request: {}", inbox);
                                    return new ResponseEntity<>(result, HttpStatus.BAD_REQUEST);
                                }
                            } else {
                                Message reply = messagesService.getReplyByUri(inReplyTo);
                                if (reply != null) {
                                    User user = new User();
                                    user.setUri(URI.create(activity.getActor()));
                                    String markdown = remarkConverter.convertFragment((String) note.getContent());
                                    // combine note text with attachment urls
                                    String commandBody = note.getAttachment() == null ? markdown
                                            : note.getAttachment().stream().map(attachment -> {
                                                String attachmentUrl = attachment.getUrl();
                                                String attachmentName = attachment.getName();
                                                return PlainTextFormatter.markdownUrl(attachmentUrl, attachmentName);
                                            }).reduce(markdown, (currentUrl, nextUrl) -> String.format("%s\n%s",
                                                    currentUrl, nextUrl));
                                    CommandResult result = commandsManager.processCommand(user,
                                            String.format("#%d/%d %s", reply.getMid(), reply.getRid(), commandBody),
                                            URI.create(StringUtils.EMPTY));
                                    logger.info(jsonMapper.writeValueAsString(result));
                                    if (result.getNewMessage().isPresent()) {
                                        messagesService.updateReplyUri(result.getNewMessage().get(), noteId);
                                        return new ResponseEntity<>(result, HttpStatus.OK);
                                    }
                                }                                
                            }
                        } else {
                            if (note.getTo().stream().anyMatch(recipient -> recipient.startsWith(baseUri))) {
                                logger.warn("Possible direct message from {}", note.getAttributedTo());
                                applicationEventPublisher.publishEvent(new DirectMessageEvent(this, note));
                                return new ResponseEntity<>(CommandResult.fromString("Message accepted"), HttpStatus.ACCEPTED);
                            }
                        }
                        logger.warn("Request with invalid recipient from {}", activity.getActor());
                        return new ResponseEntity<>(CommandResult.fromString("Message accepted"), HttpStatus.ACCEPTED);
                    }
                }
            }
            if (activity instanceof Delete) {
                // Delete gone user
                // TODO: check if it is really deleted and remove copy-paste
                if (activity.getActor().equals(activity.getObject().getId())) {
                    return new ResponseEntity<>(CommandResult.fromString("Delete request accepted"),
                            HttpStatus.ACCEPTED);
                }

                if (activity.getObject() instanceof Tombstone) {
                    Tombstone tombstone = (Tombstone) activity.getObject();
                    URI actor = URI.create(activity.getActor());
                    URI reply = URI.create((String) tombstone.getId());
                    messagesService.deleteReply(actor, reply);
                    return new ResponseEntity<>(CommandResult.fromString("Delete request accepted"), HttpStatus.OK);
                }
            }
            if (activity instanceof Like || activity instanceof Announce) {
                String messageUri = activity.getObject().getId();
                applicationEventPublisher.publishEvent(new AnnounceEvent(this, activity.getActor(), messageUri));
                return new ResponseEntity<>(CommandResult.fromString("Like/announce request accepted"), HttpStatus.OK);
            }
            if (activity instanceof Flag) {
                URI actor = URI.create(activity.getActor());
                logger.info("{} flag some objects: {}", actor, activity.getObject());
                return new ResponseEntity<>(CommandResult.fromString("Report accepted"), HttpStatus.ACCEPTED);
            }
            logger.warn("Unknown activity: {}", jsonMapper.writeValueAsString(activity));
            return new ResponseEntity<>(CommandResult.fromString("Unknown activity"), HttpStatus.NOT_IMPLEMENTED);
        }
        if (activity instanceof Delete) {
            // Delete gone user
            if (activity.getActor().equals(activity.getObject().getId())) {
                return new ResponseEntity<>(CommandResult.fromString("Delete request accepted"), HttpStatus.ACCEPTED);
            }
        }
        return new ResponseEntity<>(CommandResult.fromString("Can not authenticate"), HttpStatus.UNAUTHORIZED);
    }

    @PostMapping(value = { "/u/", "/api/u/" }, produces = MediaType.APPLICATION_JSON_VALUE)
    public User fetchUser(@RequestParam URI uri) {
        return activityPubManager.personToUser(uri);
    }
}