def analyse(config: ConfigParser) -> None:
    """
    Does a bunch of analysis over the toots. Returns a dict with the results suitable for
    sending to [post()](module-post.md). The whole process is described in more detail in
    the [methodology documentation](../methodology.md).

    # Parameters
    - **config**: A ConfigParser object from the [config](module-config.md) module

    # Config Parameters Used

    | Option | Description |
    | ------- | ------- |
    | `analyse:botusername` | Exclude toots from this ID |
    | `analyse:journaldir` | Directory to read JSON files from  |
    | `analyse:journalfile` | Template for files to read  |
    | `analyse:top_n` | How many top toots to report |
    | `analyse:timezone` | What timezone to convert times to |
    | `analyse:tag_users` | Whether we tag users with an @ or not |

    # Returns

    Dict that includes a few elements:
    - `preamble`: A bit of information about the analysis. Hashtag and when it was generated.
    - `num_toots`: A few lines of text that describe the analysis: total number of toots, servers, participants, etc.
    - `most_toots`: A line about the person that posted the most toots.
    - `max_boosts`, `max_faves`, and `max_replies`: pandas DataFrames that contain the `top_n` toots in each of these categories.

    """
    hashtag = config.get('analyse', 'hashtag')
    debug = config.getint('analyse', 'debug')
    top_n = config.getint('analyse', 'top_n')
    timezone = config.get('analyse', 'timezone')
    tag_users = config.getboolean('analyse', 'tag_users')

    logger = logging.getLogger(__name__)
    logging.basicConfig(format='%(levelname)s\t%(message)s')
    logger.setLevel(debug)

    df = get_toots_df(config)
    if len(df) <= 0:
       return None

    earliest, latest = get_dates(config)
    analysis = dict()
    # some old data files don't have data for fields we expect
    df = df.replace(nan, None)
    # top poster
    most_toots_id = df['userid'].value_counts().idxmax()
    most_toots_name = df.loc[df['userid'] == most_toots_id][:1]['account.display_name'].values[0]
    most_toots_count = len(df.loc[df['userid'] == most_toots_id])

    # Some overall statistics
    num_servers = df['server'].nunique()
    max_server = df['server'].value_counts().idxmax()
    max_server_toots = len(df.loc[df['server'] == max_server])

    # do the max_boosts stuff last because it is destructive. I remove selected toots
    # from the dataframe so that they can't appear twice. i.e., if you're the most
    # boosted toot, you're taken out of the running for most favourites and most replies,
    # even if you DO have the most favourites and most replies.
    maxdf = df.copy(deep=True)
    max_boosts = maxdf.sort_values(
        by=['reblogs_count', 'favourites_count', 'replies_count'], ascending=False).head(top_n)

    # drop from df all the toots that are in the max_boosts df
    maxdf.drop(maxdf[maxdf['uri'].isin(max_boosts['uri'])].index, inplace=True)
    max_faves = maxdf.sort_values(
        by=['favourites_count', 'reblogs_count', 'replies_count'], ascending=False).head(top_n)

    # drop from df all the toots that are in the max_faves df
    maxdf.drop(maxdf[maxdf['uri'].isin(max_faves['uri'])].index, inplace=True)

    # Count how many replies to each post are from the post's original author
    # Group by the original post ID and count replies where the author is the same
    if 'in_reply_to_account_id' in df.columns and 'account.id' in df.columns:
    # Create a copy of the dataframe to work with for calculating external replies
        replies_df = df.copy()
        logger.debug(f"removing self-replies")

        # Create a new column for external replies (total replies minus self-replies)
        # First, identify self-replies (where author replies to their own post)
        self_replies = replies_df[replies_df['in_reply_to_account_id'] == replies_df['account.id']]

        # Count self-replies per original post
        self_reply_counts = self_replies.groupby('in_reply_to_account_id').size().reset_index(name='self_reply_count')

        # Merge this count back to the main dataframe
        replies_df = replies_df.merge(self_reply_counts, left_on='account.id', right_on='in_reply_to_account_id', how='left')

        # Fill NaN values with 0 (posts with no self-replies)
        replies_df['self_reply_count'] = replies_df['self_reply_count'].fillna(0)

        # Calculate external replies (total replies minus self-replies)
        replies_df['external_replies_count'] = replies_df['replies_count'] - replies_df['self_reply_count']

        # Sort by external replies count instead of total replies
        max_replies = replies_df.sort_values(
            by=['external_replies_count', 'reblogs_count', 'favourites_count'], ascending=False).head(top_n)
        print(replies_df[['id', 'replies_count', 'self_reply_count', 'external_replies_count']])
    else:
        # Fallback to original behavior if we don't have the necessary columns
        logger.debug(f"NOT removing self-replies")
        logger.debug(df.columns.tolist())
        max_replies = df.sort_values(
            by=['replies_count', 'reblogs_count', 'favourites_count'], ascending=False).head(top_n)
    # Prepare the analysis
    # convert config strings into datetime structs
    tag = "@" if tag_users else ""
    timezone = pytimezone(timezone)
    start_time = earliest.strftime("%a %e %b %Y %H:%M %Z")
    end_time = latest.strftime("%a %e %b %Y %H:%M %Z")
    right_now = datetime.datetime.now(
        tz=timezone).strftime("%a %e %b %Y %H:%M %Z")
    analysis['preamble'] = f"<p>Summary of #{hashtag} generated at {right_now}.</p>"
    analysis['num_toots'] = f"We looked at {len(df)} toots posted between {start_time} and "\
        f"{end_time} by {df['userid'].nunique()} " +\
        f"different participants across {num_servers} different servers. {max_server} " +\
        f"contributed the most toots at {max_server_toots}"
    analysis['most_toots'] = f"Most toots were from '{most_toots_name}' ({tag}{most_toots_id}) who posted {most_toots_count}"
    analysis['max_boosts'] = max_boosts.to_dict(orient='records', )
    analysis['max_faves'] = max_faves.to_dict(orient='records')
    analysis['max_replies'] = max_replies.to_dict(orient='records')
    analysis['unique_ids'] = df['userid'].nunique()
    analysis['top_n'] = top_n
    analysis['hashtag'] = hashtag
    analysis['top_n'] = top_n
    analysis['generated'] = right_now
    analysis['event_start'] = start_time
    analysis['gross_toots'] = len(df)
    analysis['event_end'] = end_time
    analysis['num_servers'] = num_servers
    analysis['max_server'] = {}
    analysis['max_server']['name'] = max_server
    analysis['max_server']['num'] = max_server_toots
    analysis['most_posts'] = {}
    analysis['most_posts']['name'] = most_toots_name
    analysis['most_posts']['id'] = most_toots_id
    analysis['most_posts']['count'] = most_toots_count

    write_json(config, 'analysis', analysis)

def get_dates(config):
    """
    Given a config, it does a bunch of timezone math and returns a list of
    two datetime objects, the earliest and latest dates we analyse. Right now
    there's a hard-coded 1-hour time that is subtracted from the start and added
    to the end. E.g., if you sent start_time = 12:00 and end_time = 14:00, this function
    currently returns 11:00 and 15:00 as the two times.

    # Parameters
    - **config**: A ConfigParser object from the [config](module-config.md) module

    # Config Parameters Used
    - `analyse:start_time`: start time for the event
    - `analyse:end_time`: end time for the event
    - `analyse:timezone`: the time zone to localise all the times to
    - `analyse:hours_margin`: How many days to go back for analysis. You might have
       fetched toots from days ago, but then want to restrict analysis to toots from today.

    # Returns

    List of two `datetime` objects: the earliest possible time and latest possible time

    """
    start_time = config.get('analyse', 'start_time')
    end_time = config.get('analyse', 'end_time')
    timezone = config.get('analyse', 'timezone')
    hours_margin = config.getint('analyse', 'hours_margin')

    timezone = pytimezone(timezone)
    start_time = datetime.datetime.fromisoformat(
        start_time).astimezone(tz=timezone)
    end_time = datetime.datetime.fromisoformat(
        end_time).astimezone(tz=timezone)
    earliest = start_time - datetime.timedelta(hours=hours_margin)
    latest = end_time + datetime.timedelta(hours=hours_margin)

    return [earliest, latest]

def get_toots_df(config) -> pd.DataFrame:
    """
    Opens the journal files from a hierarchical directory structure, parses the toots,
    and does a bunch of analysis over the toots. Returns a df with the results.
    This is its own method because the graph() module calls it.

    # Parameters
    - **config**: A ConfigParser object from the [config](module-config.md) module

    # Config Parameters Used
    - `analyse:botusername`: Exclude toots from this ID
    - `analyse:journaldir`: Base directory to read JSON files from
    - `analyse:journalfile`: Template for files to read
    - `analyse:top_n`: How many top toots to report
    - `mastoscore:event_year`: Year of the event (YYYY)
    - `mastoscore:event_month`: Month of the event (MM)
    - `mastoscore:event_day`: Day of the event (DD)

    # Returns

    Pandas DataFrame with all the toots pulled in and converted to normalised types.
    """
    botusername = config.get('analyse', 'botusername')
    journaldir = config.get('analyse', 'journaldir')
    journalfile = config.get('analyse', 'journalfile')
    debug = config.getint('analyse', 'debug')
    top_n = config.getint('analyse', 'top_n')

    logger = logging.getLogger(__name__)
    logging.basicConfig(format='%(levelname)s\t%(message)s')
    logger.setLevel(debug)

    # Get date components from config
    try:
        year = config.get('mastoscore', 'event_year')
        month = config.get('mastoscore', 'event_month')
        day = config.get('mastoscore', 'event_day')
        date_path = os.path.join(year, month, day)
        logger.info(f"Looking for journal files in date path: {date_path}")
    except Exception as e:
        logger.error(f"Failed to get date components from config: {e}")
        logger.error("Falling back to flat directory structure")
        date_path = ""

    df = pd.DataFrame([])
    # journal is now a template. Read all the matching files into a big data frame
    max_toots = 0
    max_toots_file = "none"
    nfiles = 0

    # Build the path to search for journal files
    if date_path:
        search_path = os.path.join(journaldir, date_path)
        p = Path(search_path).resolve()
        if not p.exists():
            logger.error(f"Directory {search_path} does not exist")
            # Try falling back to the base directory
            logger.info(f"Falling back to base directory: {journaldir}")
            p = Path(journaldir).resolve()
            # Look for files in the hierarchical structure
            pattern = f"**/{journalfile}-*.json"
        else:
            pattern = f"{journalfile}-*.json"
    else:
        p = Path(journaldir).resolve()
        # Look for files in the hierarchical structure
        pattern = f"**/{journalfile}-*.json"

    logger.info(f"Searching for files matching pattern: {pattern} in {p}")
    filelist = list(p.glob(pattern))

    if not filelist:
        logger.warning(f"No files found matching pattern {pattern} in {p}")
        # Try a more general search if specific path failed
        if date_path:
            logger.info("Trying broader search in entire journal directory")
            p = Path(journaldir).resolve()
            filelist = list(p.glob(f"**/{journalfile}-*.json"))

    for jfile in filelist:
        try:
            logger.debug(f"Attempting to read {jfile}")
            newdf = pd.read_json(jfile)
        except Exception as e:
            logger.critical(f"Failed to open {jfile}")
            logger.critical(e)
            continue
        if len(newdf) > max_toots:
            max_toots_file = jfile
            max_toots = len(newdf)
        nfiles = nfiles+1
        df = pd.concat([df, newdf])
        logger.debug(f"Loaded {len(newdf)} toots from {jfile.name}")
        del newdf

    logger.info(f"Loaded {len(df)} total toots from {nfiles} JSON files")
    logger.info(f"Biggest was {max_toots} toots from {max_toots_file}")
    assert(len(df) > 0)
    # Now exclude toots that are too old or too new
    earliest, latest = get_dates(config)
    df = df.loc[df['created_at'] >= earliest]
    df = df.loc[df['created_at'] <= latest]
    # gather up the set we want to work on
    # 1. local toots
    # 2. remote toots where we didn't get a local version
    local_toots = df.loc[df['local'] == True]
    sources = local_toots['source'].unique()
    non_local_toots = df.loc[df['server'] != df['source']]
    # drop all toots from servers we successfully contacted
    non_local_toots = non_local_toots.loc[~non_local_toots['server'].isin(
        sources)]
    # There will be more than one copy of non-local toots.
    # Iterate over each uri, find the copy of it that has the highest numbers
    # and keep it, deleting the others
    non_local_keepers = pd.DataFrame([])
    for uri in non_local_toots['uri'].unique():
        minidf = non_local_toots[non_local_toots['uri'] == uri]
        # logger.debug(f"{len(minidf)} toots for {uri}")
        minidf = minidf.sort_values(
            by=['reblogs_count', 'favourites_count', 'replies_count'], ascending=False).head(1)
        non_local_keepers = pd.concat([non_local_keepers, minidf])
    logger.info(
        f"{len(local_toots)} local toots and {len(non_local_keepers)} non-local toots")
    df = pd.concat([local_toots, non_local_keepers])
    orig_len = len(df)
    df = df[df['userid'] != botusername]
    final_len = len(df)
    logger.debug(
        f"Excluded {orig_len-final_len} posts from ourselves ('{botusername}')")
    # Quick check to make sure we don't have duplicates. Number of rows in the final
    # DataFrame and the number of unique URIs should be the same. If they're not, we
    # have duplicates somewhere.
    num_unique = len(df['uri'].unique())
    if num_unique != final_len:
        logger.error(
            f"We have {final_len} toots, but {num_unique} URIs. Likely duplicates!")
    else:
        logger.debug(
            f"Number of unique URIs ({num_unique}) == Number of rows ({final_len}). All good.")
    return df