# Function to find Azure services by IP address
function Find-AzureServiceByIP {
    param (
        [string]$ipAddress,
        [string]$jsonFilePath = ".data.json"
    )

    # Load the JSON file into a PowerShell object
    $serviceTags = Get-Content $jsonFilePath | ConvertFrom-Json

    # Loop through each service tag in the file
    foreach ($serviceTag in $serviceTags.values) {
        foreach ($addressPrefix in $serviceTag.properties.addressPrefixes) {
            # TODO: extract and add IPv6 support
            # Check if the addressPrefix is an IP range in CIDR format
            if ($addressPrefix -match "\d+\.\d+\.\d+\.\d+\/\d+") {
                # Use the 'IPAddress' class to check if the given IP is within the CIDR block
                if (Test-IpInRange -IpAddress $ipAddress -CIDR $addressPrefix) {
                    # If IP is found, output the service tag details
                    Write-Output ([pscustomobject]@{
                        Service    = $serviceTag.name
                        Region     = $serviceTag.properties.region
                        IPRange    = $addressPrefix
                    })
                }
            }
        }
    }
}

# Helper function to check if an IP address is within a CIDR block
function Test-IpInRange {
    param (
        [string]$IpAddress,
        [string]$CIDR
    )

    # Split CIDR into base IP and subnet mask bits
    $cidrParts = $CIDR -split "/"
    $baseIP = $cidrParts[0]
    $subnetBits = [int]$cidrParts[1]

    # Convert IP addresses to byte arrays
    $ipBytes = [System.Net.IPAddress]::Parse($IpAddress).GetAddressBytes()
    $baseIpBytes = [System.Net.IPAddress]::Parse($baseIP).GetAddressBytes()

    # Calculate the number of full bytes and partial bits in the subnet mask
    $fullBytes = [math]::Floor($subnetBits / 8)
    $remainingBits = $subnetBits % 8

    # Compare full bytes of the IP and base IP
    for ($i = 0; $i -lt $fullBytes; $i++) {
        if ($ipBytes[$i] -ne $baseIpBytes[$i]) {
            return $false
        }
    }

    # Compare the remaining bits in the last byte, if any
    if ($remainingBits -gt 0) {
        $mask = 0xFF -bxor (0xFF -shr $remainingBits)
        if (($ipBytes[$fullBytes] -band $mask) -ne ($baseIpBytes[$fullBytes] -band $mask)) {
            return $false
        }
    }

    return $true
}

function Download-ServiceTagsData {
    param(
        [string]$jsonFilePath = ".data.json"
    )
    $url = 'https://www.microsoft.com/en-us/download/confirmation.aspx?id=56519'
    $pageContent = Invoke-WebRequest -Uri $url
    if ($pageContent.Content -match 'href="(?<url>[a-zA-Z0-9/:\.\-_]*\.json?)"') { 
        $jsonUrl = $matches['url'] 
    }
    Write-Host "Downloading file from $jsonUrl"
    Invoke-RestMethod -Uri $jsonUrl -OutFile $jsonFilePath
}

# Example usage:
# Find-AzureServiceByIP -IpAddress "X.X.X.X" -jsonFilePath "C:\path\to\ServiceTags_Public_20240909.json"