import logging
from typing import List, Tuple

import psycopg2
from psycopg2.errorcodes import UNIQUE_VIOLATION


class DBAdapter:
    EXPECTED_TABLES = ['art', 'artist', 'tag', 'topic', 'presence', 'artist_to_topic', 'art_to_presence',
                       'art_to_tag', 'tag_alias', 'tag_implication', 'tag_category', 'art_collection',
                       'art_to_art_collection']

    def __init__(self, user: str, password: str, host: str = "localhost", port: int = 5432, database: str = "artnet"):
        self.db = None
        self.db_cursor = None
        try:
            self.db = psycopg2.connect(host=host, port=port, database=database, user=user, password=password,
                                       connect_timeout=3)
            self.db_cursor = self.db.cursor()

        except psycopg2.OperationalError as e:
            raise ValueError("Invalid DB credentials!")
        logging.debug("DB connection established to {0}:{1}/{2}".format(host, port, database))

        if not self.check_tables():
            logging.debug("Database schema check has failed! The expected tables have not been present.")
            raise ValueError("Invalid DB schema!")

    def check_tables(self) -> bool:
        """
        Check if all the expected tables are present in the connected database.
        :return:
        """
        try:
            self.db_cursor.execute("select relname from pg_class where relkind='r' and relname !~ '^(pg_|sql_)';")
            present_tables = self.db_cursor.fetchall()
        except psycopg2.DatabaseError as e:
            logging.error(f"Database error occured on check_tables(): {e}")
            self.db.rollback()
            return False
        unknown_tables = []
        missing = [x for x in DBAdapter.EXPECTED_TABLES]
        for table in present_tables:
            table = table[0]
            if table not in DBAdapter.EXPECTED_TABLES:
                unknown_tables.append(table)
            else:
                missing.remove(table)

        if len(missing) > 0:
            logging.error("The following tables are missing from the currently connected database: {0}".format(missing))
            return False

        if len(unknown_tables) > 0:
            logging.error(
                "The following tables are unknown and not expected inside the database: {0}".format(unknown_tables))

        return True

    def save_image(self, ID: str, title: str, authors: list, path: str, tags: list, link: str, md5_hash: str,
                   desc: str, collections: list):
        """
        Updates or saves the given image data to the DB
        :param ID:
        :param title:
        :param authors: list of presences List[Tuple[str, str]]
        :param path:
        :param tags:  list of tag names List[str]
        :param link:
        :param md5_hash: md5 hash as a hex digest
        :param desc: image description or None for empty
        :param collections: list of collections included by the image
        :return:
        """
        logging.debug("Saving Image {0}:{1} authors: {2} path: {3} tags: {4} link: {5} hash:{6} desc:{7}"
                      .format(ID, title, authors, path, [t["name"] for t in tags], link, md5_hash, desc))
        d = {"title": title, "path": path, "id": ID, "link": link, "hash": md5_hash, "desc": desc}  # TODO implement try/except for database errors and rollback!
        if self.get_art_by_path(path) is None:
            if ID is None:
                self.db_cursor.execute(
                    "INSERT INTO art (path, title, link, md5_hash, description) "
                    "VALUES (%(path)s, %(title)s, %(link)s, %(hash)s, %(desc)s)",
                    d)
                self.db.commit()
                ID = self.get_art_by_path(path)["ID"]
                d["id"] = ID
            elif self.get_tag_by_ID(ID) is None:
                self.db_cursor.execute(
                    "INSERT INTO art (path, title, link, md5_hash, description) "
                    "VALUES (%(path)s, %(title)s, %(link)s, %(hash)s, %(desc)s)", d)
                self.db.commit()
        else:
            self.db_cursor.execute("UPDATE art SET path = %(path)s, title = %(title)s, link = %(link)s, " +
                                   "md5_hash = %(hash)s, description = %(desc)s WHERE id = %(id)s", d)
            self.db.commit()

        if ID is None:
            ID = self.get_art_by_path(path)["ID"]
            assert (ID != None)  # was checked before, should never fail

        old_tags = [self.get_tag_by_ID(x)["name"].strip() for x in self.get_art_tags_by_ID(ID)]
        for tag in tags:
            if tag in old_tags:  # already present
                continue
            d = {"id": ID, "tag": tag["id"]}
            try:
                self.db_cursor.execute("INSERT INTO art_to_tag (art_id, tag_ID) VALUES (%(id)s, %(tag)s)", d)
                self.db.commit()
            except psycopg2.Error as e:
                if e.pgcode == UNIQUE_VIOLATION:  # tag was already set
                    logging.debug(e)
                    logging.info("Skipping Unique Violation ...")
                    self.db.rollback()
                else:
                    raise e

        for old_tag in old_tags:
            is_in_tags = False
            for t in tags:
                if t["name"] == old_tag:
                    is_in_tags = True
            if not is_in_tags:  # need to remove old tag
                self.remove_tag_from_image(art_ID=ID, tag_ID=self.get_tag_ID(old_tag))

        old_authors = self.get_authors_of_art_by_ID(ID)
        for author in authors:
            if author in old_authors:
                continue
            d = {"id": ID, "author_name": author[0], "author_domain": author[1]}
            self.db_cursor.execute("INSERT INTO art_to_presence (presence_name, presence_domain, art_ID) " +
                                   "VALUES (%(author_name)s, %(author_domain)s, %(id)s)", d)
            self.db.commit()
        for old_author_name, old_author_domain in old_authors:
            if (old_author_name, old_author_domain) not in authors:  # need to remove old author
                self.remove_artist_from_image(art_ID=ID, presence_name=old_author_name,
                                              presence_domain=old_author_domain)

        self.db.commit()

    def remove_image(self, hash: str):
        """
        Removes an image completely from the database.

        Does not affect tags or artists but removes art-tag, art-artist relations
        :param hash: md5 hash of the image to be deleted
        :return:
        """
        image_data = self.get_art_by_hash(hash)
        art_ID = image_data["ID"]
        logging.debug(f"Deleting image #{art_ID} {image_data['title']}")
        tags = self.get_art_tags_by_ID(art_ID)
        # for tag_ID in tags:
        #    pass
        # self.remove_tag_from_image(art_ID=art_ID, tag_ID=tag_ID)
        authors = self.get_authors_of_art_by_ID(art_ID)
        # for presence_name, presence_domain in authors:
        #    pass
        # self.remove_artist_from_image(art_ID=art_ID, presence_name=presence_name, presence_domain=presence_domain)

        # self.db_cursor.execute("DELETE FROM art WHERE md5_hash = %(hash)s", {"hash": hash})

    def remove_artist_from_image(self, art_ID, presence_name, presence_domain):
        """
        Removes the relationship between an artist and the image
        :param art_ID:
        :param presence_name:
        :param presence_domain:
        :return:
        """
        d = {"name": presence_name, "domain": presence_domain, "id": art_ID}
        self.db_cursor.execute("DELETE FROM art_to_presence " +
                               "WHERE presence_name = %(name)s and " +
                               "presence_domain = %(domain)s and art_ID = %(id)s",
                               d)

    def remove_tag_from_image(self, art_ID, tag_ID):
        """
        Remove the relationship between a tag and the image
        :param art_ID:
        :param tag_ID:
        :return:
        """
        d = {"id": art_ID, "tag": tag_ID}
        self.db_cursor.execute("DELETE FROM art_to_tag WHERE art_id = %(id)s and tag_id = %(tag)s", d)

    def save_presence(self, name: str, domain: str, artist_ID: int, link: str):
        """
        Save the presence entry with the given data.

        If it doesn't exist a new one will be created.
        If the artist ID is unknown an exception will be thrown
        :param name:
        :param domain:
        :param artist_ID:
        :param link:
        :return:
        """
        logging.debug("Saving Presence {0}:{1} Artist: {2} Link: {3}".format(name, domain, artist_ID, link))
        artist = self.get_artist(artist_ID)
        if artist is None or len(artist) == 0:
            raise Exception("Unknown Artist to create/update Presence with!")

        presence = self.get_presence(name, domain)
        d = {"name": name, "domain": domain, "artist": artist_ID, "link": link}
        if len(presence) == 0:  # presence does not exist yet
            self.db_cursor.execute("INSERT INTO presence (name, domain, artist_ID, link) " +
                                   "VALUES (%(name)s, %(domain)s, %(artist)s, %(link)s)", d)
        else:  # presence exists, update it
            self.db_cursor.execute("UPDATE presence SET artist_ID = %(artist)s, link = %(link)s" +
                                   "WHERE name = %(name)s and domain = %(domain)s", d)

        self.db.commit()

    def remove_presence(self, name: str, domain: str):
        """
        Remove a presence from the database
        :return:
        """
        logging.debug("Removing Presence {0}:{1}".format(name, domain))
        d = {"name": name, "domain": domain}
        self.db_cursor.execute("DELETE FROM presence WHERE name = %(name)s and domain = %(domain)s", d)
        self.db.commit()

    def get_presence(self, name: str, domain: str):
        """
        Queries the database for the presence and returns the result

        :param name:
        :param domain:
        :return:
        """
        d = {"name": name, "domain": domain}
        self.db_cursor.execute("SELECT name, domain, artist_ID, link FROM presence " +
                               "WHERE name = %(name)s and domain = %(domain)s",
                               d)
        rows = self.db_cursor.fetchall()
        new_rows = []
        for row in rows:
            new_rows.append((row[0].strip(), row[1].strip(), row[2], row[3]))

        return new_rows

    def save_artist(self, ID: int, name: str):
        """
        Save (or update if ID is already taken) an artist to the DB
        :param ID:
        :param name:
        :return:
        """
        logging.debug("Saving artist {0}:{1}".format(ID, name))
        d = {"id": ID, "name": name}
        if ID is None:  # no ID given, auto generate it
            self.db_cursor.execute("INSERT INTO artist (name) VALUES (%(name)s)", d)
        elif len(self.get_artist(ID)) != 0:  # artist exists already:
            self.db_cursor.execute("UPDATE artist SET name = %(name)s WHERE id = %(id)s", d)
        else:  # artist needs to be created
            self.db_cursor.execute("INSERT INTO artist (id, name) VALUES (%(id)s, %(name)s)", d)
        self.db.commit()

    def remove_artist(self, ID: int):
        """
        Deletes the artist from the DB
        :param ID:
        :return:
        """
        logging.debug("Deleting artist {0}".format(ID))
        d = {"id": ID}
        self.db_cursor.execute("DELETE FROM Artist WHERE ID = %(id)s", d)
        self.db.commit()

    def save_category(self, name: str):
        """
        Save the category to the DB.

        Does not check if the category already exists
        :param name:
        :return:
        """
        logging.debug("Saving category {0}!".format(name))
        d = {"name": name}
        self.db_cursor.execute("INSERT INTO tag_category (name) VALUES (%(name)s)", d)

        self.db.commit()

    def remove_category(self, name: str):
        """
        Remove the category from the DB.
        :param name:
        :return:
        """
        d = {"name": name}
        self.db_cursor.execute("DELETE FROM tag_category WHERE name = %(name)s", d)

        self.db.commit()

    def get_category_by_ID(self, id: int):
        """
        Queries the database for the category by its ID
        :param id:
        :return: (id, "name")
        """
        d = {"id": id}
        self.db_cursor.execute("SELECT category_id, name FROM tag_category WHERE category_id = %(id)s", d)

        r = self.db_cursor.fetchall()
        if len(r) == 0:
            return None

        nr = []
        for i in range(len(r[0])):
            if isinstance(r[0][i], str):
                nr.append(r[0][i].strip())
            else:
                nr.append(r[0][i])

        return nr

    def get_category_by_name(self, name: str):
        """
        Queries the database for the category by its name
        :return:
        """
        d = {"name": name}
        self.db_cursor.execute("SELECT category_id, name FROM tag_category WHERE name = %(name)s", d)

        r = self.db_cursor.fetchall()
        if len(r) == 0:
            return None

        return r[0]

    def get_artist(self, ID: int):
        """
        Queries the database for the artist (not presence) and returns the result
        :param ID:
        :return:
        """
        d = {"id": ID}
        self.db_cursor.execute("SELECT id, name FROM artist WHERE id = %(id)s", d)

        return self.db_cursor.fetchall()

    def get_artist_presences(self, id: int):
        """
        Queries the databse for all presences associated with the artist and returns the result
        :param id:
        :return:
        """
        d = {"id": id}
        self.db_cursor.execute("SELECT name, domain, artist_id FROM Presence WHERE artist_id = %(id)s", d)

        return self.db_cursor.fetchall()

    def get_all_artists(self):
        """
        Lists all available artists (not presences) and returns the result
        :return:
        """
        self.db_cursor.execute("SELECT id, name FROM artist")

    def get_art_by_ID(self, ID: int):
        """
        Queries the database for the art via its ID and returns it if available.
        """
        d = {"ID": ID}
        self.db_cursor.execute("SELECT id, path, title, link, md5_hash, description FROM art WHERE id = %(ID)s", d)

        result = self.db_cursor.fetchall()
        if len(result) == 0:
            return None
        else:
            result = result[0]
            image_data = {
                "ID": result[0],
                "path": result[1],
                "title": result[2],
                "link": result[3],
                "md5_hash": result[4],
                "description": result[5],
            }
            return image_data


    def get_art_by_hash(self, file_hash: str) -> dict:
        """
        Queries the database for the art via its hash and returns it if available.

        Currently uses an md5 hash
        :param file_hash:
        :return:
        """
        d = {"hash": file_hash}
        self.db_cursor.execute("SELECT id, path, title, link, md5_hash, description FROM art where md5_hash = %(hash)s",
                               d)

        result = self.db_cursor.fetchall()

        if len(result) == 0:
            return None
        else:
            result = result[0]
            image_data = {
                "ID": result[0],
                "path": result[1],
                "title": result[2],
                "link": result[3],
                "md5_hash": result[4],
                "description": result[5],
            }
            return image_data

    def get_art_by_path(self, path: str) -> dict:
        """
        Queries the database for the art via its path and returns it if available.

        Otherwise None
        :param path:
        :return:
        """
        d = {"path": path}
        self.db_cursor.execute("SELECT id, path, title, link, md5_hash FROM art where path = %(path)s", d)

        result = self.db_cursor.fetchall()

        if len(result) == 0:
            return None
        else:
            result = result[0]
            image_data = {
                "ID": result[0],
                "path": result[1],
                "title": result[2],
                "link": result[3],
                "md5_hash": result[4],
            }
            return image_data

    @DeprecationWarning
    def get_authors_of_art(self, path: str):
        """
        Get the authors (presence and author) of the given art.
        :param path:
        :return:
        """
        art_data = self.get_art_by_path(path)
        art_id: int = None
        if art_data is not None:
            art_id = art_data["ID"]
        if art_id is None:
            return None
        d = {"id": art_id}

        self.db_cursor.execute("SELECT presence_name, presence_domain FROM art_to_presence WHERE art_ID = %(id)s", d)
        presences = self.db_cursor.fetchall()

        result = []
        for name, domain in presences:
            result.append((name.strip(), domain.strip()))

        return result

    def get_authors_of_art_by_ID(self, id: int):
        """
        Get the authors (presence and author) of the given art.
        :param id:
        :return:
        """
        d = {"id": id}

        self.db_cursor.execute("SELECT presence_name, presence_domain FROM art_to_presence WHERE art_ID = %(id)s", d)
        presences = self.db_cursor.fetchall()

        result = []
        for name, domain in presences:
            result.append((name.strip(), domain.strip()))

        return result

    def get_art_tags_by_ID(self, art_ID: int):
        """
        Query the database for all tags associated with a given art ID
        :param art_ID:
        :return:
        """
        d = {"id": art_ID}
        self.db_cursor.execute("SELECT tag_ID FROM art_to_tag WHERE art_id = %(id)s", d)

        rows = self.db_cursor.fetchall()
        new_rows = []
        for row in rows:
            new_rows.append(row[0])
        return new_rows

    def search_art(self, tags: list, presences: list, resolve_tags: bool = True):
        """
        Search with the tags and given presences for fitting art.
        :param tags: List[int] list of tag ids that are to be present in the art. See resolve_tags for implication.
        :param presences: List[Tuple(str, str)] list of presences to be present in the art.
        :param resolve_tags: flag if tag implications should be resolved fully.
        """
        d = {"tags": tags, "presences": presences}
        l = list()
        for i in range(len(presences)):  # converting for psycopg2
            name, domain = presences[i]
            casted = [name, domain]
            l.append(casted)
        d["presences"] = l

        search_query = "SELECT art.id FROM art " \
                       "INNER JOIN art_to_tag ON art_to_tag.art_id = art.id " \
                       "INNER JOIN tag ON art_to_tag.tag_id = tag.id " \
                       "INNER JOIN art_to_presence as AtP ON art.id = AtP.art_id " \
                       "GROUP BY art.id " \
                       "HAVING array_agg(tag.name) @> %(tags)s::varchar[] AND " \
                       "array_agg(array[AtP.presence_name, AtP.presence_domain]) @> %(presences)s::varchar[]"

        # 1. Join all related tables
        # 2. Group them over art.id
        # 3. check which rows contain the searched tags or presences in the value arrays
        self.db_cursor.execute(search_query, d)
        result = self.db_cursor.fetchall()
        return result

    def search_fuzzy_presence(self, name: str, domain: str, all_if_empty: bool = False):
        """
        Search a list of presences fitting the (name, domain) fuzzy.
        :param name:
        :param domain:
        :param all_if_empty: return all presences (or a large selection) if an empty name and domain is given
        :return:
        """
        if all_if_empty and (name is None or len(name) == 0) and (domain is None or len(domain) == 0):
            self.db_cursor.execute("SELECT name, domain, artist_id FROM presence")
        else:
            d = {"name": "%" + name + "%", "domain": "%" + domain + "%"}
            self.db_cursor.execute("SELECT name, domain, artist_id FROM presence WHERE LOWER(name) LIKE "
                                   "LOWER(%(name)s) AND domain LIKE %(domain)s", d)
        rows = self.db_cursor.fetchall()

        result = []
        for row in rows:
            result.append((row[0].strip(), row[1].strip()))
        return result

    def get_presences_art(self, name, domain):
        """
        Query a list of all art that includes the given presence as their author
        :param name:
        :param domain:
        :return:
        """
        d = {"name": name, "domain": domain}
        self.db_cursor.execute(
            "SELECT art_ID FROM Art_Author WHERE presence_name = %(name)s and presence_domain = %(domain)s", d)

        return self.db_cursor.fetchall()

    def get_all_categories(self) -> list:
        """
        Return all categories in the database.
        :return:
        """
        self.db_cursor.execute("SELECT name FROM tag_category")

        rows = []
        for row in self.db_cursor.fetchall():
            rows.append(row[0].strip())

        return rows

    def search_fuzzy_categories(self, search: str) -> list:
        """
        Search a list of categories fitting search fuzzy.
        :param search:
        :return:
        """
        d = {"search": "%" + search + "%"}
        self.db_cursor.execute("SELECT name FROM tag_category WHERE LOWER(name) LIKE LOWER(%(search)s)", d)

        rows = []
        for row in self.db_cursor.fetchall():
            rows.append(row[0])

        return rows

    def search_fuzzy_tag(self, name: str, all_if_empty: bool = False) -> list:
        """
        Search a list of tags fitting name fuzzy.
        :param name:
        :param all_if_empty:
        :return:
        """
        if all_if_empty and len(name) == 0:
            self.db_cursor.execute("SELECT name, description, category_id, ID FROM tag")
        else:
            d = {"name": "%" + name + "%"}
            self.db_cursor.execute(
                "SELECT name, description, category_id, ID FROM tag WHERE LOWER(name) LIKE LOWER(%(name)s)", d)

        rows = self.db_cursor.fetchall()
        new_rows = []
        for i in range(len(rows)):
            new_rows.append([])
            for j in range(len(rows[i])):
                if rows[i][j] is None:
                    new_rows[i].append("")
                elif isinstance(rows[i][j], str):
                    new_rows[i].append(rows[i][j].strip())
                else:
                    new_rows[i].append(rows[i][j])

        return new_rows

    def search_fuzzy_artists(self, ID: int, name: str, all_if_empty: bool = False):
        """
        Search a list of fitting artists fuzzy.

        If ID is None it will search using the description
        :param ID:
        :param name:
        :param all_if_empty:
        :return:
        """
        if ID is not None:
            self.db_cursor.execute("SELECT id, name FROM artist WHERE id = %(id)s", {"id": ID})
        elif all_if_empty and ID is None and len(name) == 0:
            self.db_cursor.execute("SELECT id, name FROM artist")
        else:
            d = {"name": "%" + name + "%"}
            self.db_cursor.execute("SELECT id, name FROM artist WHERE LOWER(name) LIKE LOWER(%(name)s)", d)

        return self.db_cursor.fetchall()

    def create_tag(self, name: str, description: str, aliases: list, implications: list, category: str = None):
        name = name.strip()
        if aliases is None:
            aliases = []
        if implications is None:
            implications = []
        category_id = self.get_category_by_name(category)[0]
        d = {"name": name, "description": description, "category_id": category_id}
        self.db_cursor.execute("INSERT INTO tag (name, description, category_id) " +
                               "VALUES (LOWER(%(name)s), %(description)s, %(category_id)s)", d)

        for alias in aliases:
            self.add_alias_by_name(name, alias)
        for implicant in implications:
            self.add_implication_by_name(name, implicant)

        self.db.commit()

    def edit_tag(self, tag_id: int, name: str, description: str, aliases: list = None, implications: list = None,
                 category_id: int = None):
        """
        Edit a tag with the new given data
        :param tag_id: tag id to uniquely identify the tag
        :param name: unique tag name to apply edits to (distinct from old_tag)
        :param description: new description to apply, set to None to omit
        :param aliases: list of tag names to be the alias of this tag, set to None to omit
        :param implications: list of tag names to be implied by this tag, set to None to omit
        :param category_id:
        :return:
        """
        name = name.strip().lower()
        implications = [self.get_tag_ID(x) for x in implications]
        aliases = [self.get_tag_ID(x) for x in aliases]
        d = {
            "id": tag_id,
            "name": name,
            "description": description,
            "alias": aliases,
            "implications": implications,
            "category_id": category_id,
        }

        self.db_cursor.execute(
            "UPDATE tag SET description = %(description)s, category_id = %(category_id)s, name = %(name)s "
            "WHERE ID = %(id)s",
            d)

        if aliases is not None:
            old_aliases = self.get_tag_aliases_by_ID(tag_id)
            for alias in aliases:
                if alias in old_aliases:  # is this already set?
                    continue
                self.add_alias_by_ID(tag_id, alias)

            for old_alias in old_aliases:
                if old_alias not in aliases:  # got to delete an alias?
                    self.remove_alias_by_ID(tag_id, old_alias)

        if implications is not None:
            old_implicants = self.get_tag_implications_by_ID(tag_id)
            for implicant in implications:
                if implicant in old_implicants:  # is this already set?
                    continue
                self.add_implication_by_ID(tag_id, implicant)

            for old_implicant in old_implicants:
                if old_implicant not in implications:  # got to delete an implicant?
                    self.remove_implication_by_ID(tag_id, old_implicant)

    def add_alias_by_name(self, name: str, alias: str):
        """
        Add the alias pair to the database
        :param name: 
        :param alias: 
        :return: 
        """
        self.add_alias_by_ID(self.get_tag_ID(name), self.get_tag_ID(alias))

    def add_alias_by_ID(self, tag1: int, tag2: int):
        """
        Add the alias pair to the database
        :return:
        """
        d = {
            "tag1": tag1,
            "tag2": tag2
        }
        self.db_cursor.execute("INSERT INTO tag_alias (tag1, tag2) VALUES (%(tag1)s, %(tag2)s)", d)
        self.db.commit()

    def remove_alias_by_ID(self, tag1: int, tag2: int):
        """
        Remove alias pair from the database
        :param tag1:
        :param tag2:
        :return:
        """
        d = {
            "tag1": tag1,
            "tag2": tag2
        }
        self.db_cursor.execute("DELETE FROM tag_alias WHERE (tag1 = %(tag1)s and tag2 = %(tag2)s) or " +
                               "(tag1 = %(tag2)s and tag2 = %(tag1)s)", d)
        self.db.commit()

    def remove_alias_by_name(self, name: str, alias: str):
        """
        Remove alias pair from the database
        :param name:
        :param alias:
        :return:
        """
        self.remove_alias_by_ID(self.get_tag_ID(name), self.get_tag_ID(alias))

    def add_implication_by_ID(self, tag_id: int, implicant: int):
        """
        Add the implication to the database
        :param tag_id:
        :param implicant:
        :return:
        """
        d = {
            "tag": tag_id,
            "implicant": implicant
        }
        self.db_cursor.execute("INSERT INTO tag_implication (root_tag, implicate) VALUES (%(tag)s, %(implicant)s)",
                               d)
        self.db.commit()

    def add_implication_by_name(self, name: str, implicant: str):
        """
        Add the implication to the database
        :param name:
        :param implicant:
        :return:
        """
        self.add_implication_by_ID(self.get_tag_ID(name), self.get_tag_ID(implicant))

    def remove_implication_by_ID(self, tag: int, implicant: int):
        """
        Remove the implication pair from the database
        :param tag:
        :param implicant:
        :return:
        """
        d = {
            "tag": tag,
            "implicant": implicant
        }
        self.db_cursor.execute("DELETE FROM tag_implication WHERE root_tag = %(tag)s " +
                               "and implicate = %(implicant)s", d)
        self.db.commit()

    def remove_implication_by_name(self, name: str, implicant: str):
        """
        Remove the implication pair from the database
        :param name:
        :param implicant:
        :return:
        """
        self.remove_implication_by_ID(self.get_tag_ID(name), self.get_tag_ID(implicant))

    def remove_tag_by_ID(self, tag: int):
        """
        Remove the given tag from the database
        :param tag:
        :return:
        """
        d = {"tag": tag}
        self.db_cursor.execute("DELETE FROM tag WHERE id = %(tag)s", d)
        self.db.commit()

    def remove_tag_by_name(self, name: str):
        """
        Remove the given tag from the database
        :param name:
        :return:
        """
        self.remove_tag_by_ID(self.get_tag_ID(name))

    def get_tag_ID(self, name: str) -> int:
        """
        Get the tag ID by querying it by its unique name
        :param name:
        :return:
        """
        d = {"name": name}
        try:
            self.db_cursor.execute("SELECT ID FROM tag where LOWER(name) = LOWER(%(name)s)", d)

            rows = []
            for row in self.db_cursor.fetchall():
                rows.append(row[0])
        except psycopg2.DatabaseError as e:

            return None

        if len(rows) > 1:
            raise Exception("Found multiple tags by the same name!")
        elif len(rows) == 0:
            return None

        return rows[0]

    def get_tag_by_name(self, name: str) -> dict:
        """
        Search the tag in the DB via its name.

        Note: name is constrained to be unique by the DB
        :param name:
        :return: Returns the tag's name, description, category, tag ID
        """
        d = {"name": name}
        self.db_cursor.execute(
            "SELECT name, description, category_id, ID FROM tag where LOWER(name) = LOWER(%(name)s)", d)

        new_row = []
        row = self.db_cursor.fetchall()
        if len(row) == 0:
            return None
        row = row[0]
        for value in row:
            if value is None:
                new_row.append("")
            elif type(value) == str:
                new_row.append(value.strip())
            else:
                new_row.append(value)
        return {"name": new_row[0], "description": new_row[1], "category": new_row[2], "id": new_row[3]}

    def get_tag_by_ID(self, ID: int) -> dict:
        """
        Search the tag in the DB via its ID.

        Note: name is constrained to be unique by the DB
        :param ID:
        :return: Returns the tag's ID, name, description, category
        """
        d = {"ID": ID}
        self.db_cursor.execute("SELECT ID, name, description, category_id FROM tag where ID = %(ID)s", d)

        new_row = []
        rows = self.db_cursor.fetchall()
        if len(rows) != 1:
            raise Exception("Something went terribly wrong!")
        row = rows[0]
        for value in row:
            if value is None:
                new_row.append("")
            elif type(value) == str:
                new_row.append(value.strip())
            else:
                new_row.append(value)
        return {"name": new_row[1], "description": new_row[2], "category": new_row[3], "id": new_row[0]}

    def get_tag_aliases_by_name(self, name: str) -> List[dict]:
        """
        Search for the tag's aliases and the alias's aliases
        :param name:
        :return: List of tag Names that are aliases of this one
        """
        aliases = self.get_tag_aliases_by_ID(self.get_tag_ID(name))
        result = []
        for alias in aliases:
            tag_data = self.get_tag_by_ID(alias)
            if len(tag_data) > 0:  # tag exists
                result.append(tag_data)
        return result

    def get_tag_aliases_by_ID(self, tag_ID: int) -> list:
        """
        Search for the tag's aliases and the tag's aliases
        :param tag_ID:
        :return: List of tag IDs that are aliases of this one
        """
        marked = []
        to_search = [tag_ID]
        while len(to_search) != 0:
            curr_alias = to_search.pop()
            found_aliases = self.__get_tag_aliases_no_recurse(curr_alias)
            marked.append(curr_alias)

            for found_alias in found_aliases:
                if found_alias not in marked:
                    to_search.append(found_alias)

        marked.remove(tag_ID)
        return marked

    def get_all_tag_implications_by_name(self, name: str) -> list:
        """
        Search for the tag's implications and those that are implied by them.
        :param name:
        :return:
        """
        root_ID = self.get_tag_ID(name)
        collected_tags = self.get_tag_implications_by_ID(root_ID)
        collected_tags.append(root_ID)
        to_search = self.get_tag_implications_by_ID(root_ID)

        while len(to_search) != 0:
            curr_tag = to_search.pop()
            found_implications = self.get_tag_implications_by_ID(curr_tag)
            for found in found_implications:
                if found in collected_tags:
                    continue
                else:
                    collected_tags.append(found)
                    to_search.append(found)

        if root_ID in collected_tags:
            collected_tags.remove(root_ID)

        result = []
        for tag_ID in collected_tags:
            tag_data = self.get_tag_by_ID(tag_ID)
            if len(tag_data) != 0:
                result.append(tag_data)
        return result

    def get_all_tag_impliers_by_ID(self, ID: int) -> list:
        """
        Search for all tags that imply this one or imply a tag that implies this one.
        :param ID:
        :return:
        """
        collected_tags = self.get_tag_impliers_by_ID(ID)
        to_search = self.get_tag_impliers_by_ID(ID)
        collected_tags.append(ID)

        while len(to_search) != 0:
            curr_tag = to_search.pop()
            found_impliers = self.get_tag_impliers_by_ID(curr_tag)
            for found in found_impliers:
                if found in collected_tags:
                    continue
                else:
                    collected_tags.append(found)
                    to_search.append(found)

        if ID in collected_tags:
            collected_tags.remove(ID)

        return collected_tags

    def get_tag_implications_by_ID(self, ID: int) -> list:
        """
        Search for the tag's implications
        :param ID: ID of the tag
        :return: returns a list of IDs that are implied
        """
        d = {"ID": ID}
        if d["ID"] is None:
            return []

        self.db_cursor.execute("SELECT root_tag, implicate FROM Tag_Implication WHERE root_tag = %(ID)s", d)

        rows = self.db_cursor.fetchall()
        if len(rows) == 0:
            return []

        r = []
        for row in rows:
            r.append(row[1])

        return r

    def get_tag_implications(self, name: str) -> list:
        """
        Search for the tag's implications
        :param name:
        :param output_ID: Don't resolve the tag ids into names in the resulting list
        :return: List of tag ids
        """
        d = {"ID": self.get_tag_ID(name)}
        if d["ID"] is None:
            return []

        self.db_cursor.execute("SELECT root_tag, implicate FROM Tag_Implication WHERE root_tag = %(ID)s", d)

        rows = self.db_cursor.fetchall()
        if len(rows) == 0:
            return []

        r = []
        for row in rows:
            r.append(row[1])

        result = [self.get_tag_by_ID(v) for v in r]

        r = []
        for value in result:
            r.append(value[0][1].strip())

        return r

    def get_tag_impliers_by_ID(self, ID: int):
        """
        Search for tags that imply this one.
        :param ID:
        :return:
        """
        d = {"ID": ID}
        self.db_cursor.execute("SELECT root_tag FROM Tag_Implication WHERE implicate = %(ID)s", d)

        rows = self.db_cursor.fetchall()
        return rows

    def get_tag_impliers_by_name(self, name: str) -> list:
        """
        Search for tags that imply this one.
        :param name:
        :return:
        """
        d = {"ID": self.get_tag_ID(name)}
        self.db_cursor.execute("SELECT root_tag FROM Tag_Implication WHERE implicate = %(ID)s", d)

        rows = self.db_cursor.fetchall()
        return rows

    def __get_tag_aliases_no_recurse(self, tag_id: int) -> list:
        """
        Search for the tag's aliases
        :param tag_id:
        :return:
        """
        d = {"ID": tag_id}
        if d["ID"] is None:
            return []

        self.db_cursor.execute("SELECT tag1, tag2 FROM Tag_Alias "
                               "WHERE tag1 = %(ID)s or tag2 = %(ID)s", d)
        rows = self.db_cursor.fetchall()
        r = []
        for row in rows:
            if row[0] == tag_id:
                r.append(row[1])
            elif row[1] == tag_id:
                r.append(row[0])
            else:
                raise Exception("Something went terribly wrong!")

        return r

    def create_collection(self, collection_name: str, description: str) -> int:
        """
        Create the collection with name and description as given.
        """
        d = {"name": collection_name, "description": description}

        try:
            self.db_cursor.execute("INSERT INTO art_collection (name, description) VALUES (%(name)s, %(description)s) "
                                   "RETURNING id", d)
            self.db.commit()
        except psycopg2.DatabaseError as e:
            logging.error(f"Encountered database error on create_collection() with collection_name: {collection_name} "
                          f"description: {description}. Rolling it back now ...")
            logging.error(e)
            self.db.rollback()
            return None

        return self.db_cursor.fetchall()[0]

    def delete_collection(self, collection_id: int):
        """
        Delete the collection given by the id.
        """
        d = {"ID": collection_id}

        try:
            self.db_cursor.execute("DELETE FROM art_collection WHERE ID = %(ID)s", d)
            self.db.commit()
        except psycopg2.DatabaseError as e:
            logging.error(f"Encountered database error on delete_collection() ID: {collection_id}. "
                          f"Rolling it back now ...")
            logging.error(e)
            self.db.rollback()

    def get_collections_of_art_by_ID(self, art_id: int):
        """
        Queries the database for collections that include the given art_id

        :return: [(ID, name, description)]
        """
        d = {"art_id": art_id}

        self.db_cursor.execute("SELECT art_collection.id, art_collection.name, art_collection.description "
                               "FROM art_collection "
                               "INNER JOIN art_to_art_collection as atac ON art_collection.id = atac.collection_id "
                               "WHERE atac.art_id = %(art_id)s", d)

        return self.db_cursor.fetchall()

    def get_collection(self, collection_id: int):
        """
        Returns the collection given by the id.
        """
        d = {"ID": collection_id}

        self.db_cursor.execute("SELECT collection.id, collection.name, collection.description, array_agg(art.id), "
                               "array_agg(art.title), array_agg(art.path), array_agg(atac.ranking) "
                               "FROM art_collection as collection "
                               "LEFT OUTER JOIN art_to_art_collection as atac ON atac.collection_id = collection.id "
                               "LEFT OUTER JOIN art ON atac.art_id = art.id "
                               "WHERE collection.ID = %(ID)s "
                               "GROUP BY collection.id", d)
        r = self.db_cursor.fetchall()
        if len(r) > 0:
            r = r[0]
            collection = dict()
            collection["id"] = r[0]
            collection["name"] = r[1]
            collection["description"] = r[2]
            collection["entries"] = []
            for i in range(len(r[3])):
                art_data = {"id": r[3][i], "title": r[4][i], "path": r[5][i], "ranking": r[6][i]}
                if art_data["id"] is None:  # skipping non-existing art entries
                    continue  # might happen once when the collection has no entries
                collection["entries"].append(art_data)

        return collection

    def search_collections_by_name(self, name: str) -> List[Tuple[int, str]]:
        """
        Returns the collection by the given name
        """
        d = {"name": name}

        try:
            self.db_cursor.execute("SELECT art_collection.id, art_collection.name "
                                   "FROM art_collection "
                                   "WHERE art_collection.name = %(name)s", d)
        except psycopg2.DatabaseError as e:
            logging.error(f"Encountered database error on get_collection_by_name() name: {name}."
                          f"Rolling it back now ...")
            logging.error(e)
            self.db.rollback()
            return None

        return self.db_cursor.fetchall()

    def search_collections(self, collection_name: str = None, presence_name: str = None,
                           presence_domain: str = None, art_name: str = None):
        """
        Search for collections that contain the given parameters.

        Search is always fuzzy.
        :param collection_name:
        :param presence_name:
        :param presence_domain:
        :param art_name: Search for collections containing art with this title
        :result: List[collection_id, collection_name, collection_desc, List[art_id]]
        """
        d = {"collection_name": "%"+collection_name+"%", "presence_name": "%"+presence_name+"%",
             "presence_domain": "%"+presence_domain+"%", "art_name": "%"+art_name+"%"}

        try:
            self.db_cursor.execute("SELECT "
                                   "(art_collection.id) as collection_id, "
                                   "(art_collection.name) as collection_name, "
                                   "(art_collection.description) as collection_desc, "
                                   "array_agg(art.id) as art_ID, array_agg(art.title) as art_titles, "
                                   "array_agg(art_to_presence.presence_name) as presence_names, "
                                   "array_agg(art_to_presence.presence_domain) as presence_domains "
                                   "FROM art_collection "
                                   "LEFT OUTER JOIN art_to_art_collection On art_to_art_collection.collection_id = art_collection.id "
                                   "LEFT OUTER JOIN art ON art_to_art_collection.art_id = art.id "
                                   "LEFT OUTER JOIN art_to_presence ON art_to_presence.art_ID = art.id "
                                   "WHERE LOWER(art_collection.name) LIKE LOWER(%(collection_name)s) "
                                   "GROUP BY art_collection.id "
                                   "HAVING LOWER(array_to_string(array_agg(art_to_presence.presence_name), '|', '')) LIKE LOWER(%(presence_name)s) "
                                   "AND LOWER(array_to_string(array_agg(art_to_presence.presence_domain), '|', '')) LIKE LOWER(%(presence_domain)s) "
                                   "AND LOWER(array_to_string(array_agg(art.title), '|', '')) LIKE LOWER(%(art_name)s);",
                                   d)
        except psycopg2.DatabaseError as e:
            logging.error(f"Encountered database error on search_collections(): {e}")
            self.db.rollback()
            raise e

        return self.db_cursor.fetchall()