#!/usr/bin/env bash

# nf (netfinger): A netcat-based finger client.

# Copyright 2025-2026 640kb.neocities.org
# Blue Oak Model License 1.0.0 <https://blueoakcouncil.org/license/1.0.0>

# Features: user@host and finger:// queries, HTML/Markdown render, smart wrap,
# blocklists, custom shortcuts, ANSI Art viewer, classic 7-bit mode and more.

# Requirements: nc, awk, less, fold (standard on most Linux systems)
# Optional: pandoc, lynx (for Markdown support), GUI browser (for --mdg)

# 2026-08-12: Latest update (classic mode, width variable, restructuring)
# 2025-11-24: Initial release

# ===========================================================================
# CONFIGURATION: START
# ===========================================================================
# NOTE: Use lowercase true/false only. (Uppercase breaks the script.)
# ===========================================================================

# The wrap width (in columns) when WRAP_MODE is set to "true" or when the
# -w | --wrap flags are used. Default is 80.
WRAP_WIDTH=80

# When "true", enables permanent wrapping via wrap_text() function (uses "less").
# Default is 80 columns. The -w | --wrap flags achieves this on a per-request basis.
WRAP_MODE=false

# When set to "true", wraps output in basic HTML tags and converts plain text
# URLs (http, https, gemini, finger, spartan, gopher) into clickable links.
# The -r | --render flag achieves this on a per-request basis.
RENDER_MODE=false

# When "true", renders Markdown output using pandoc and displays in lynx (text
# browser). The -m | --md flag achieves this on a per-request basis.
MD_MODE=false

# When "true", renders Markdown output using pandoc and opens in GUI browser
# (firefox by default). The --mdg flag achieves this on a per-request basis.
MDG_MODE=false

# CLASSIC_MODE: Set to true for permanent 7-bit ASCII filtering (pre-parser).
# Filters 8-bit bytes immediately after nc reception, before any built-in script
# parser (awk, pandoc, lynx, etc) touches them. Matches the BSD finger behavior:
# parsers never see 8-bit data. DEFAULT: false (process full 8-bit stream)
CLASSIC_MODE=false

# GUI Browsers for --mdg mode:
GUI_BROWSER="firefox"

# ===========================================================================
# CONFIGURATION: END
# ===========================================================================

# ===========================================================================
# SHORTCUTS: BEGIN
# ===========================================================================
# Some examples below. Adjust for personal use or you can delete this entire
# section without affecting the script's core function.
# ===========================================================================

case "$1" in
    --ansi)
        "$0" ansi@happynetbox.com | head -n -2 | echo -e "$(cat)"
        exit 0
        ;;

    --verse) 
        "$0" fingerverse@happynetbox.com | less
        exit 0
        ;;

    --text)
        "$0" textfile@typed-hole.org | less
        exit 0
        ;;

    --say)
        "$0" say@happynetbox.com | head -n 25
        exit 0
        ;;

# ---------------------------------------------------------------------------
# happynetbox.com shortcut (--hnb) with BLOCKLIST option
# Edit the "grep -v..." lines to add/remove usernames from your blocklist
# ---------------------------------------------------------------------------

    --hnb)
        "$0" @happynetbox.com \
            | tail -n +5 | head -n -7 \
            | grep -v -i -w trollacct1 \
            | grep -v -i -w spammer1 \
            | grep -v -i -w trollacct2
        exit 0
        ;;

# ---------------------------------------------------------------------------
# plan.cat shortcut (--plan) with BLOCKLIST option
# Edit the "grep -v..." lines to add/remove usernames from your blocklist
# ---------------------------------------------------------------------------

    --plan)
        "$0" @plan.cat \
            | head -n 20 \
            | grep -v -i -w trollacct1 \
            | grep -v -i -w spammer1 \
            | grep -v -i -w trollacct2
        exit 0
        ;;

# ---------------------------------------------------------------------------

    -l|--list)
        printf "%s\n" --ansi --verse --text --say --hnb --plan --list
        exit 0
        ;;
esac

# ===========================================================================
# SHORTCUTS: END
# ===========================================================================

if [ $# -eq 1 ] && [[ "$1" =~ ^(-h|--help|/\?|-\?)$ ]]; then
    echo
    echo " .-------------------------------------------------------------."
    echo " | nf (netfinger): A finger client using netcat.               |"
    echo " |-------------------------------------------------------------|"
    echo " | Usage:    nf user@domain.com                                |"
    echo " |           nf finger://domain.com/user                       |"
    echo " |-------------------------------------------------------------|"
    echo " | Options:  -w  --wrap     Smart wrap using fold & less       |"
    echo " |           -r  --render   HTML as <pre> with clickable links |"
    echo " |           -m  --md       Render Markdown with Pandoc & Lynx |"
    echo " |               --mdg      Render Markdown (GUI Browser)      |"
    echo " |           -c  --classic  Only 7-bit ASCII is parsed         |"
    echo " |                                                             |"
    echo " |           -l  --list     Displays all shortcuts (see code)  |"
    echo " |-------------------------------------------------------------|"
    echo " | Examples: nf echo@plan.cat                                  |"
    echo " |           nf @plan.cat | head -n 20                         |"
    echo " |           nf finger://happynetbox.com/spartanware           |"
    echo " |                                                             |"
    echo " |           nf -w bot@happynetbox.com                         |"
    echo " |           nf -r bot@happynetbox.com | chawan -T text/html   |"
    echo " |           nf -m markdown@happynetbox.com                    |"
    echo " |           nf -c codepage437@happynetbox.com                 |"
    echo " |                                                             |"
    echo " |           nf -l       (list shortcuts)                      |"
    echo " |           nf --ansi   (shortcut to ansi@happynetbox.com)    |"
    echo " |-------------------------------------------------------------|"
    echo " | See the configuration section at the top of the script for: |"
    echo " |                                                             |"
    echo " | Wrap width, classic mode, render, gui browser and more.     |"
    echo " '-------------------------------------------------------------'"
    echo
    exit 0
fi

FINGER_TARGET=""

while [[ $# -gt 0 ]]; do
    case "$1" in
        -w|--wrap)
            WRAP_MODE=true
            shift
            ;;
        -r|--render)
            RENDER_MODE=true
            shift
            ;;
        -m|--md)
            MD_MODE=true
            shift
            ;;
        --mdg)
            MDG_MODE=true
            shift
            ;;
        -c|--classic)
            CLASSIC_MODE=true
            shift
            ;;
        -*)
            echo "Error: Unknown flag $1" >&2
            exit 1
            ;;
        *)
            if [ -z "$FINGER_TARGET" ]; then
                FINGER_TARGET="$1"
                shift
            else
                echo "Error: Multiple finger targets specified" >&2
                exit 1
            fi
            ;;
    esac
done

if [ -z "$FINGER_TARGET" ]; then
    echo
    echo " Error: Missing finger target" >&2
    echo " Use 'nf -h' for help" >&2
    echo
    exit 1
fi

input="$FINGER_TARGET"

if [[ "$input" == finger://* ]]; then
    path="${input#finger://}"
    
    if [[ "$path" == */* ]]; then
        host="${path%%/*}"
        user="${path#*/}"
    else
        host="$path"
        user=""
    fi
    
    if [ -n "$user" ]; then
        input="$user@$host"
    else
        input="@$host"
    fi
fi

if [[ "$input" == *://* ]]; then
    protocol="${input%%://*}"
    echo "Error: Only finger protocol is supported (got $protocol:// instead)" >&2
    exit 1
fi

wrap_text() {
    fold -s -w "${1:-$WRAP_WIDTH}" | less
}

render_html() {
    awk '{
        while(match($0, /(https?|gemini|finger|spartan|gopher):\/\/[^[:space:]<>"'"'"']*/)) {
            url = substr($0, RSTART, RLENGTH)
            after = substr($0, RSTART + RLENGTH)
            
            # ver 3.5 update: Strip trailing punctuation from all URLs EXCEPT Wikipedia.
            if (url ~ /[.,;:!?)]$/ && !(url ~ /wikipedia\.org/)) {
                after = substr(url, length(url)) after
                url = substr(url, 1, length(url) - 1)
            }
            
            printf "%s<a href=\"%s\">%s</a>", substr($0, 1, RSTART - 1), url, url
            $0 = after
        }
        print
    }'
}

fetch_finger() {
    local host="$1"
    local user="$2"
    local data
    
    if [ -n "$user" ]; then
        data=$(printf '%s\r\n' "$user" | nc "$host" 79 2>/dev/null || echo "$user" | nc "$host" 79 2>/dev/null)
    else
        data=$(printf '\r\n' | nc "$host" 79 2>/dev/null || echo | nc "$host" 79 2>/dev/null)
    fi
    
    if $CLASSIC_MODE; then
        data=$(echo "$data" | tr -cd '\000-\177')
    fi
    
    printf '%s' "$data"
}

if [[ "$input" == @* ]]; then
    host="${input#@}"
    output=$(fetch_finger "$host" "")
elif [[ "$input" == *@* ]]; then
    user="${input%@*}"
    host="${input#*@}"
    output=$(fetch_finger "$host" "$user")
else
    echo "Error: Input must be in format user@host or finger://host/user" >&2
    exit 1
fi

if $MDG_MODE; then
    TMP=$(mktemp --suffix=.html) && echo "$output" | pandoc -s -f markdown -t html -o "$TMP" && $GUI_BROWSER "$TMP" && rm "$TMP"
elif $MD_MODE; then
    echo "$output" | pandoc -s -f markdown -t html | lynx -stdin

elif $RENDER_MODE; then
    echo "<html><pre>"
    echo "$output" | render_html
    echo "</pre></html>"
elif $WRAP_MODE; then
    echo "$output" | wrap_text "$WRAP_WIDTH"
else
    echo "$output"
    echo # blank line for improved readability of finger query
fi