/*
 * Copyright (C) 2008-2023, 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.service;

import com.juick.model.Tag;
import com.juick.model.TagStats;
import com.juick.model.User;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.tuple.Pair;
import org.springframework.jdbc.core.BatchPreparedStatementSetter;
import org.springframework.jdbc.core.PreparedStatementCallback;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.time.Instant;
import java.time.ZoneOffset;
import java.time.temporal.ChronoUnit;
import java.util.*;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Created by aalexeev on 11/13/16.
 */
@Repository
public class TagServiceImpl extends BaseJdbcService implements TagService {

    private class TagMapper implements RowMapper<Tag> {
        @Override
        public Tag mapRow(ResultSet rs, int rowNum) throws SQLException {
            Tag tag = new Tag(rs.getString(3));
            tag.setId(rs.getInt(1));
            tag.setSynonymId(rs.getInt(2));
            tag.setNotIndexed(rs.getInt("noindex") > 0);
            tag.setHiddenFromTop(rs.getInt("notop") > 0);
            tag.setSubscribed(rs.getInt("subscribed") > 0);
            tag.setIgnored(rs.getInt("ignored") > 0);
            return tag;
        }
    }

    private final TagMapper tagMapper = new TagMapper();

    @Override
    public Tag getTag(int tid) {
        return getTag(0, tid);
    }

    @Transactional(readOnly = true)
    @Override
    public Tag getTag(int userId, int tid) {
        List<Tag> list = namedParameterJdbcTemplate.query("""
                        SELECT tag_id, synonym_id, name, noindex, notop,
                        COALESCE((SELECT 1 FROM bl_tags WHERE tag_id=:tagId AND user_id=:userId), 0) ignored,
                        COALESCE((SELECT 1 FROM subscr_tags WHERE tag_id=:tagId AND suser_id=:userId), 0) subscribed
                        FROM tags WHERE tag_id = :tagId""",
                new MapSqlParameterSource()
                        .addValue("userId", userId)
                        .addValue("tagId", tid),
                tagMapper);

        return list.isEmpty() ? null : list.get(0);
    }

    @Override
    public Tag getTag(final String tagName, boolean autoCreate) {
        return getTag(0, tagName, autoCreate);
    }

    @Transactional
    @Override
    public Tag getTag(int userId, final String tagName, boolean autoCreate) {
        if (StringUtils.isBlank(tagName))
            return null;
        List<Tag> list = namedParameterJdbcTemplate.query("""
                    SELECT t.tag_id, t.synonym_id, t.name, t.noindex, t.notop,
                    COALESCE((SELECT 1 FROM bl_tags WHERE tag_id=t.tag_id AND user_id=:userId), 0) ignored,
                    COALESCE((SELECT 1 FROM subscr_tags WHERE tag_id=t.tag_id AND suser_id=:userId), 0) subscribed
                    FROM (SELECT tag_id, synonym_id, name, noindex, notop FROM tags) t
                    WHERE name = :tagName""",
                new MapSqlParameterSource()
                        .addValue("userId", userId)
                        .addValue("tagName", tagName),
                tagMapper);

        Tag ret = list.isEmpty() ? null : list.get(0);

        if (ret == null && autoCreate) {
            ret = new Tag(tagName);
            ret.setId(createTag(tagName));
        }

        return ret;
    }

    @Override
    public List<Tag> getTags(Stream<String> tags, final boolean autoCreate) {
        return getTags(0, tags, autoCreate);
    }

    @Override
    public List<Tag> getTags(int userId, Stream<String> tags, final boolean autoCreate) {
        return tags.filter(StringUtils::isNotBlank).map(tag -> getTag(tag, autoCreate)).filter(Objects::nonNull)
                .distinct()
                .toList();
    }

    @Transactional
    @Override
    public int createTag(final String name) {
        return getJdbcTemplate().execute(returningId("INSERT INTO tags(name)",  "VALUES (?)", "tag_id"),
                (PreparedStatementCallback<Integer>) stmt -> {
                    stmt.setString(1, name);
                    try (var resultSet = stmt.executeQuery()) {
                        if (resultSet.next()) {
                            return resultSet.getInt(1);
                        }
                        return 0;
                    }
                });
    }

    private class TagStatsMapper implements RowMapper<TagStats> {

        @Override
        public TagStats mapRow(ResultSet rs, int rowNum) throws SQLException {
            Tag t = new Tag(rs.getString(1));
            TagStats s = new TagStats();
            s.setTag(t);
            s.setUsageCount(rs.getInt(2));
            return s;
        }
    }

    private final TagStatsMapper tagStatsMapper = new TagStatsMapper();

    @Transactional(readOnly = true)
    @Override
    public List<TagStats> getUserTagStats(final int uid) {
        return getJdbcTemplate().query(
                "SELECT tags.name,COUNT(messages.message_id) " +
                        "FROM (messages INNER JOIN messages_tags ON (messages.user_id=? " +
                        "AND messages.message_id=messages_tags.message_id)) " +
                        "INNER JOIN tags ON messages_tags.tag_id=tags.tag_id GROUP BY tags.tag_id, tags.name ORDER BY tags.name ASC",
                tagStatsMapper,
                uid);
    }

    @Transactional(readOnly = true)
    @Override
    public List<String> getUserBLTags(final int uid) {
        return getJdbcTemplate().queryForList(
                "SELECT tags.name FROM tags INNER JOIN bl_tags " +
                        "ON (bl_tags.user_id = ? AND bl_tags.tag_id = tags.tag_id) ORDER BY tags.name",
                String.class, uid);
    }

    @Transactional(readOnly = true)
    @Override
    public List<String> getPopularTags() {
        return getJdbcTemplate().queryForList("""
                select name from tags where noindex=0
                order by stat_messages desc
                """ + limit(20), String.class);
    }

    @Transactional(readOnly = true)
    @Override
    public List<TagStats> getTagStats() {
        var ts = Instant.now().minus(14, ChronoUnit.DAYS);
        var sql = """
                SELECT tags.name,COUNT(DISTINCT messages.user_id) AS cnt
                FROM (messages INNER JOIN messages_tags ON (messages.ts > :ts
                AND messages.message_id=messages_tags.message_id))
                INNER JOIN tags ON messages_tags.tag_id=tags.tag_id
                WHERE tags.tag_id NOT IN (SELECT tag_id FROM tags_ignore)
                GROUP BY tags.tag_id, tags.name HAVING COUNT(DISTINCT messages.user_id) > 1
                ORDER BY cnt DESC
                """ + limit(20);
        return getNamedParameterJdbcTemplate()
                .query(sql, new MapSqlParameterSource()
                        .addValue("ts", toDateTime(ts.atOffset(ZoneOffset.UTC)), dateTimeType()),
                        tagStatsMapper);
    }

    @Transactional
    @Override
    public Set<Tag> updateTags(final int mid, final Collection<Tag> newTags) {
        Set<Tag> currentTags = getMessageTags(mid).stream()
                .map(TagStats::getTag).collect(Collectors.toSet());
        if (CollectionUtils.isEmpty(newTags))
            return currentTags;

        List<Integer> idsForDelete = newTags.stream()
                .filter(currentTags::contains)
                .map(Tag::getId)
                .toList();
        if (newTags.size() - idsForDelete.size() >= 5) {
            return currentTags;
        }

        if (!idsForDelete.isEmpty())
            getNamedParameterJdbcTemplate().update(
                    "DELETE FROM messages_tags WHERE message_id = :mid AND tag_id in (:ids)",
                    new MapSqlParameterSource().addValue("ids", idsForDelete).addValue("mid", mid));

        List<Tag> addedTags = newTags.stream().filter(t -> !currentTags.contains(t)).toList();
        getJdbcTemplate().batchUpdate("INSERT INTO messages_tags(message_id,tag_id) VALUES (?,?)",
                new BatchPreparedStatementSetter() {
                    @Override
                    public void setValues(PreparedStatement ps, int i) throws SQLException {
                        ps.setInt(1, mid);
                        ps.setInt(2, addedTags.get(i).getId());
                    }

                    @Override
                    public int getBatchSize() {
                        return addedTags.size();
                    }
                });

        return getMessageTags(mid).stream()
                .map(TagStats::getTag).collect(Collectors.toSet());
    }

    @Override
    public Pair<String, Set<Tag>> fromString(final String txt) {
        String firstLine = txt.split("\\n", 2)[0];
        Supplier<Stream<String>> tagsStream = () -> Arrays.stream(firstLine.split(" "))
                .takeWhile(t -> t.matches("\\*\\S+|#\\S*\\D\\S*"));
        int tagsLength = tagsStream.get().collect(Collectors.joining(" ")).length();
        String body = txt.substring(tagsLength);
        Set<Tag> tags = tagsStream.get().map(t -> getTag(t.substring(1), true)).collect(Collectors.toSet());
        return Pair.of(body, tags);
    }

    @Override
    public List<TagStats> getMessageTags(final int mid) {
        return getJdbcTemplate().query(
                "SELECT tags.tag_id,synonym_id,name,stat_messages FROM tags " +
                        "INNER JOIN messages_tags ON (messages_tags.message_id = ? AND messages_tags.tag_id = tags.tag_id)",
                (rs, num) -> {
                    Tag t = new Tag(rs.getString(3));
                    t.setId(rs.getInt(1));
                    t.setSynonymId(rs.getInt(2));
                    TagStats s = new TagStats();
                    s.setTag(t);
                    s.setUsageCount(rs.getInt(4));
                    return s;
                }, mid);
    }

    @Override
    public boolean blacklistTag(User user, Tag tag) {
        int rowcount = getNamedParameterJdbcTemplate().update(
                "DELETE FROM bl_tags WHERE tag_id = :tid AND user_id = :uid",
                new MapSqlParameterSource().addValue("tid", tag.getId()).addValue("uid", user.getUid()));
        return rowcount <= 0 && getNamedParameterJdbcTemplate()
                .update("INSERT INTO bl_tags(user_id, tag_id) VALUES(:uid,:tid)",
                        new MapSqlParameterSource().addValue("tid", tag.getId())
                                .addValue("uid", user.getUid())) > 0;
    }
}