threads.sh

#!/bin/bash

# This file provides functions for accessing threads.

. ./config
. ./bans.sh
. ./admins.sh

list_threads() {
    # use grep to make sure we only get numbers
    # shellcheck disable=SC2010
    ls -1 "$THREAD_DIR" | grep '[0-9]\+'
}

list_posts() {
    # shellcheck disable=SC2010
    ls -1 "$THREAD_DIR/$1/" | grep '[0-9]\+' | sort -g
}

# This function finds the next thread's id by listing files in the thread dir,
# sorting them, and adding one to the highest number.
next_thread_id() {
    # shellcheck disable=SC2010
    last_id=$(ls -1A "$THREAD_DIR" | grep '\.\?[0-9]\+' | sed 's/\.//g' | sort -rg | head -n 1)
    if [ -z "$last_id" ]; then
        echo 0
    else
        echo "$last_id + 1" | bc
    fi
}

next_post_id() {
    # This function uses ls and sed instead of list_posts so that it also
    # considers the dot-prefixed files left behind by the remove post
    # function. This prevents removed post IDs from being reused.
    # shellcheck disable=SC2010
    last_id=$(ls -1A "$THREAD_DIR/$1" | grep '\.\?[0-9]\+' | sed 's/\.//g' | sort -rg | head -n 1)
    if [ -z "$last_id" ]; then
        echo 0
    else
        echo "$last_id + 1" | bc
    fi
}

# This function checks the entry in the lastpost file for the current IP and,
# if the post time is more than $POST_COOLDOWN seconds ago, exits success and
# sets the last post time for the current IP to now. Exits 1 if the post is
# rate limited.
try_post_limit() {
    if is_mod; then
        # mods and admins aren't rate limited
        return 0;
    fi

    if [ -f "$THREAD_DIR/lastpost" ] && grep -q "$ip" "$THREAD_DIR/lastpost"; then
        now="$(date '+%s')"

        lastpost="$(grep "$ip" "$THREAD_DIR/lastpost" | awk '{ print $2; }')"
        if [ "$(echo "$lastpost + $POST_COOLDOWN" | bc)" -lt "$now" ]; then
            # If the last post was less than $POST_COOLDOWN ago, set it to now
            # and return 0.
            sed 's/^\('"$ip"'\) .\+/\1 '"$now"'/' -i "$THREAD_DIR/lastpost"
            return 0
        else
            return 1
        fi
    else
        echo "$ip $now" >> "$THREAD_DIR/lastpost"
        return 0
    fi
}

# This function makes a new thread and prints its id.
new_thread() {
    # This chan is anonymous, but we need a way to ban people, so we track some
    # form of identification (currently IP address).
    ip="$1"
    poster="$2"
    first_post="$3"

    if is_banned "$ip"; then
        error="You are banned from posting"
        return 1
    fi

    if ! try_post_limit; then
        export error="You've posted a thread too recently. Just chill for a bit."
        return 1
    fi

    id=$(next_thread_id)
    dir="$THREAD_DIR/$id"
    mkdir "$dir"

    if new_post "$id" "$ip" "$poster" "$first_post"; then
        echo "$id"
    else
        rmdir "$dir"
        return 1
    fi
}

# Writes a new post in the given thread. Returns nonzero and sets an error
# message in the "error" variable if posting fails for some reason.
new_post() {
    thid="$1"
    ip="$2"
    poster="$3"
    post="$4"

    if is_banned "$ip"; then
        error="You are banned from posting"
        return 1
    fi

    if [ -z "$post" ]; then
        error="Can't post empty text"
        return 1
    fi

    # If the post is too long.
    if [ "${#post}" -gt "$MAX_POST_LEN" ]; then
        error="Post can't be longer than $MAX_POST_LEN characters."
        return 1
    fi

    thdir="$THREAD_DIR/$thid"
    postid=$(next_post_id "$thid")

    cat <<EOF > "$thdir/$postid"
poster=$poster
ip=$ip
date=$(date +%s)
----
$post
EOF
}

# Moves a post to $DATA_DIR/removed/<thread>-<post>. In the original folder,
# creates a file called '.<postid>', which prevents the post's ID from being
# re-used.
remove_post() {
    thid="$1"
    postid="$2"

    mv "$THREAD_DIR/$thid/$postid" "$THREAD_DIR/$thid/.$postid"

    # If the thread now has no posts, remove it too.
    if [ -z "$(ls -1 "$THREAD_DIR/$thid/")" ]; then
        mv "$THREAD_DIR/$thid" "$THREAD_DIR/.$thid"
    fi
}

# Prints the text of a post.
post_text() {
    thid="$1"
    postid="$2"

    sed -n '/----/,$p' "$THREAD_DIR/$thid/$postid" | tail -n +2
}

# Loads the metadata of a post into environment variables.
post_meta() {
    thid="$1"
    postid="$2"

    file="$THREAD_DIR/$thid/$postid"
    poster=$(grep "poster=" "$file" | head -n 1 | sed 's/poster=//')
    ip=$(grep "ip=" "$file" | head -n 1 | sed 's/ip=//')
    date=$(grep "date=" "$file" | head -n 1 | sed 's/date=//')
}

# Renders a post as html
post_html() {
    thid="$1"
    post="$2"
    post_meta "$thid" "$post"
    cat <<EOF
<div class="post">
<p>#$post by $poster on $(date -d "@$date")
EOF
    if is_mod; then
        cat <<EOF
<a href="$URL_ROOT/admin/ban.cgi?${thid}-${post}" target="_blank">ban</a> |
<a href="$URL_ROOT/admin/rm-post.cgi?${thid}-${post}" target="_blank">remove</a>
EOF
    fi
    cat <<EOF
</p>
<pre>
$(post_text "$thid" "$post")
</pre>
</div>
EOF
}