knazarov.com/bin/rss.sh

#!/usr/bin/env bash

remove_nbsp() {
    sed 's#\ # #g'
}

date_rfc_822() {
        if [[ "$OSTYPE" == "darwin"* ]]; then
                date -j '+%a, %d %b %Y %H:%M:%S %z'
        else
                date '+%a, %d %b %Y %H:%M:%S %z'
        fi
}

date_to_rfc_822() {
        if [[ "$OSTYPE" == "darwin"* ]]; then
                date -f "%Y-%m-%dT%H:%M:%SZ" -j '+%a, %d %b %Y %H:%M:%S %z' "$1T00:00:00Z"
        else
                date '+%a, %d %b %Y %H:%M:%S %z' -d "$1T00:00:00Z"
        fi
}

get_header() {
    HFILE="$1"
    HEADER="$2"

    FILTER="{ \
        if (match(\$0, /^$HEADER: /)) {print substr(\$0, RLENGTH+1, length(\$0) - RLENGTH)}; \
        if (\$0~/^$/) {exit}; \
        if (!\$0~/^[^ ]*: .*$/) {exit}; \
    }"

    awk "$FILTER" "$HFILE"
}

list_items() {
    DIR="$1"

    pushd "$DIR" > /dev/null
    find . ! -path . -type d  | while read -r FN
    do
        PAGE="$(echo "$FN" | sed 's/^\.\///g')"
        #echo "FILE: $PAGE"

        MD="$PAGE/note.md"
        if [ ! -f "$MD" ]; then
            echo "$MD doesn't exist"
            exit 1;
        fi

        SUBJECT="$(get_header "$MD" "Subject")"
        FDATE="$(get_header "$MD" "X-Date" | sed 's/T.*$//g')"

        if [ -z "$SUBJECT" ]; then
            echo "No subject in $MD"
            exit 1
        fi

        if [ -z "$FDATE" ] && [ "$NODATE" == "0" ]; then
            echo "No date in $MD"
            exit 1
        fi

        echo "$FDATE $PAGE $SUBJECT"
    done
    popd > /dev/null
}

render_item() {
    DIR="$1"
    base_url="$2"
    item="$3"

    site_url="$(echo "$base_url"| sed 's#\(.*//.*\)/.*#\1#')"

    date=$(echo "$item"|awk '{print $1}')
    page=$(echo "$item"|awk '{print $2}')
    title=$(echo "$item"| cut -d ' ' -f 3- )

    guid="$base_url/$(echo "$page" | sed 's#^/##')"
    content=$(cat $DIR/$page/note.md | ./bin/mdpage_plain.sh)

    cat <<-EOF
        <item>
        <guid>$guid</guid>
        <link>$guid</link>
        <pubDate>$(date_to_rfc_822 "$date")</pubDate>
        <title>$title</title>
        <description><![CDATA[$content]]></description>
        </item>

EOF
}

render_items() {
    DIR="$1"
    base_url="$2"

    while read -r i
    do render_item "$DIR" "$base_url" "$i"
    done
}

render_feed() {
    url="$1"
    title=$(echo "$2" | remove_nbsp)
    description="$3"

    base_url="$(echo "$url" | cut -d '/' -f1-3)"

    cat <<-EOF
<?xml version="1.0" encoding="UTF-8"?>
        <rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
        <channel>
        <atom:link href="$url" rel="self" type="application/rss+xml" />
        <title>$title</title>
        <description>$description</description>
        <link>$base_url/</link>
        <lastBuildDate>$(date_rfc_822)</lastBuildDate>
        $(cat)
        </channel></rss>
EOF
}

list_items "$1" | sort | tail -10 | render_items "$1" "$2$3" | render_feed "$2" "Konstantin Nazarov" "Konstantin Nazarov's blog"