#!/bin/bash

TG_TOKEN="$1"
USER_ID="$2"
API_URL="https://api.telegram.org/bot$TG_TOKEN"

OFFSET_FILE="tg_bot_offset.dat"

send_message() {
    local chat_id="$1"
    local text="$2"
    curl -s -X POST "$API_URL/sendMessage" -d chat_id="$chat_id" -d text="$text" --max-time 10 > /dev/null
}

get_system_status() {
    {
        echo "Hostname: $(hostname)"
        echo "Uptime: $(uptime -p)"
        echo "Memory:"
        free -h
        echo
        echo "Disk:"
        df -h /
        echo
        echo "Load average:"
        cat /proc/loadavg
    } | sed 's/\\n/\n/g'
}

run_command() {
    local cmd="$1"
    output="$(bash -c "$cmd" 2>&1)"
    echo "\$ $cmd"
    echo "$output"
}

get_updates() {
    local offset="$1"
    curl -s "$API_URL/getUpdates?timeout=30&offset=$offset" --max-time 35
}

main_loop() {
    local offset=0
    if [ -f "$OFFSET_FILE" ]; then
        offset=$(cat "$OFFSET_FILE")
    fi

    while true; do
        updates=$(get_updates "$offset")
        [ -z "$updates" ] && sleep 2 && continue

        new_offset="$offset"

        echo "$updates" | jq -c '.result[]' | while read -r update; do
            update_id=$(echo "$update" | jq '.update_id')
            [ "$update_id" -ge "$new_offset" ] && new_offset=$((update_id + 1))

            chat_id=$(echo "$update" | jq '.message.chat.id')
            from_id=$(echo "$update" | jq '.message.from.id')
            text=$(echo "$update" | jq -r '.message.text // empty')

            [ "$from_id" != "$USER_ID" ] && continue

            if [[ "$text" =~ ^/status ]]; then
                status="$(get_system_status)"
                send_message "$chat_id" "$status"
            elif [[ "$text" =~ ^/c[[:space:]]+(.+) ]]; then
                cmd="${text:3}"
                result="$(run_command "$cmd")"
                [ -z "$result" ] && result="(no output)"
                # Truncate if message is too long for Telegram
                result=$(echo "$result" | head -c 4000)
                send_message "$chat_id" "\`\`\`
$result
\`\`\`"
            fi
        done

        echo "$new_offset" > "$OFFSET_FILE"
        offset="$new_offset"
    done
}

# Entrypoint
if [[ -z "$TG_TOKEN" || -z "$USER_ID" ]]; then
    echo "Usage: $0 <telegram_token> <user_id>"
    exit 1
fi

main_loop