#!/usr/bin/env bash

# Dateien
INPUT_FILE="sites.json"
LOG_FILE="sites.log"

# Curl-Optionen
CURL_OPTS=(
    --silent
    --max-time 10
    --location
    --max-redirs 10
    --fail
    --output /dev/null
)

# Telegram-Bot-Configuration
TELEGRAM_BOT_TOKEN="${TELEGRAM_BOT_TOKEN:-<Your-Bot-Token>}"
TELEGRAM_CHAT_ID="${TELEGRAM_CHAT_ID:-<Your-Chat-ID>}"

# Function: Send Telegram-Messages
send_telegram_message() {
    local chat_id="$1"
    local message="$2"
    curl -s -X POST "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendMessage" \
        -d chat_id="${chat_id}" \
        -d text="$message" \
        > /dev/null
}

# Function: Describe HTTP-Statuscode
http_status_description() {
    local status="$1"
    case "$status" in
        200) echo "OK" ;;
        301) echo "Moved Permanently" ;;
        302) echo "Found" ;;
        400) echo "Bad Request" ;;
        401) echo "Unauthorized" ;;
        403) echo "Forbidden" ;;
        404) echo "Not Found" ;;
        408) echo "Request Timeout" ;;
        429) echo "Too Many Requests" ;;
        500) echo "Internal Server Error" ;;
        502) echo "Bad Gateway" ;;
        503) echo "Service Unavailable" ;;
        504) echo "Gateway Timeout" ;;
        *) echo "Unknown Status" ;;
    esac
}

# Function: Check Site Status
check_site() {
    local site="$1"
    curl "${CURL_OPTS[@]}" --write-out "%{http_code}" "$site" 2>/dev/null
}

# Function: Telegram-Command `/check URL` execution
process_telegram_updates() {
    local update_url="https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/getUpdates"
    local last_update_id=0

    while true; do
        # Check for Updates
        response=$(curl -s "${update_url}?offset=${last_update_id}")
        messages=$(echo "$response" | jq -c '.result[]')

        for message in $messages; do
            # Extract Message Details
            update_id=$(echo "$message" | jq -r '.update_id')
            chat_id=$(echo "$message" | jq -r '.message.chat.id')
            text=$(echo "$message" | jq -r '.message.text')

            # Command `/check URL` run
            if [[ "$text" == /check* ]]; then
                url=$(echo "$text" | awk '{print $2}')
                if [[ -z "$url" ]]; then
                    send_telegram_message "$chat_id" "❗ Error: Please provide a valid URL after /check."
                else
                    status=$(check_site "$url")
                    description=$(http_status_description "$status")

                    send_telegram_message "$chat_id" "🌐 URL: $url
HTTP-Status: $status ($description)"
                fi
            fi

            # Update-ID Increasing, to avoid double messages
            last_update_id=$((update_id + 1))
        done

        # Check Intervall
        sleep 5
    done
}

# Function: Automatic Monitoring
monitor_sites() {
    local urls=$(jq -r '.urls[]' "$INPUT_FILE")

    if [[ -z "$urls" ]]; then
        echo "Error: No URL set."
        exit 1
    fi

    for site in $urls; do
        status=$(check_site "$site")
        description=$(http_status_description "$status")

        # Show Only The Error
        if [[ "$status" != "200" ]]; then
            send_telegram_message "$TELEGRAM_CHAT_ID" "❗ Website-Monitoring Error:
🌐 URL: $site
HTTP-Status: $status ($description)"
        fi
    done
}

# Main
case "$1" in
    listen)
        echo "Start Telegram-Bot-Listeners..."
        process_telegram_updates
        ;;
    monitor)
        echo "Start Auto Monitoring..."
        monitor_sites
        ;;
    *)
        echo "Usage: $0 {listen|monitor}"
        exit 1
        ;;
esac