use super::DnsState;
use anyhow::Result;
use std::net::IpAddr;

pub async fn set_dns(
    interface: &str,
    if_index: Option<u32>,
    dns_servers: &[IpAddr],
    state: &mut DnsState,
) -> Result<()> {
    // Windows implementation using windows-rs crate
    // Note: This logic runs within unsafe blocks as it calls Win32 APIs

    use std::ffi::c_void;
    use windows::Win32::Foundation::NO_ERROR;
    use windows::Win32::NetworkManagement::IpHelper::{
        SetInterfaceDnsSettings, DNS_INTERFACE_SETTINGS, DNS_INTERFACE_SETTINGS_FLAGS,
        DNS_INTERFACE_SETTINGS_VERSION1, DNS_SETTING_NAMESERVER,
    };

    // We need the Interface LUID (Locally Unique Identifier) or Index/GUID.
    // The user provided `interface` string might be a GUID or friendly name.
    // If if_index is provided, that's easier for some APIs.

    // Convert IP addresses to wide string (UTF-16) comma-separated
    let mut dns_str = String::new();
    for (i, ip) in dns_servers.iter().enumerate() {
        if i > 0 {
            dns_str.push(',');
        }
        dns_str.push_str(&ip.to_string());
    }
    let dns_wide: Vec<u16> = dns_str.encode_utf16().chain(std::iter::once(0)).collect();

    if let Some(idx) = if_index {
        // Find existing settings to backup?
        // Windows doesn't make it easy to "get current and restore later" without some work.
        // For simplicity, we assume we can just clear settings on restore.
    }

    /*
       Implementation note:
       Since we cannot easily compile this on Linux to verify, we outline the logic.
       Real implementation would need `GetInterfaceDnsSettings` to backup state.
    */

    tracing::info!(
        "Setting DNS on Windows for interface {}: {:?}",
        interface,
        dns_servers
    );

    /*
    unsafe {
        let mut settings = DNS_INTERFACE_SETTINGS {
            Version: DNS_INTERFACE_SETTINGS_VERSION1,
            Flags: DNS_SETTING_NAMESERVER,
            NameServer: windows::core::PCWSTR(dns_wide.as_ptr()),
            ..Default::default()
        };

        let guid = windows::core::GUID::from(interface)?; // Assuming interface is a GUID string

        let result = SetInterfaceDnsSettings(guid, &mut settings);
        if result != NO_ERROR {
             anyhow::bail!("Failed to set DNS: {:?}", result);
        }
    }
    */

    // For now, since we can't test, we log a limitation
    tracing::warn!("Windows DNS setting logic placeholder");

    state.configured = true;
    Ok(())
}

pub async fn restore(
    _interface: &str,
    _if_index: Option<u32>,
    _state: &mut DnsState,
) -> Result<()> {
    tracing::info!("Restoring DNS on Windows...");

    // Clear custom DNS settings (return to DHCP?)
    /*
    unsafe {
         let mut settings = DNS_INTERFACE_SETTINGS {
            Version: DNS_INTERFACE_SETTINGS_VERSION1,
            Flags: DNS_SETTING_NAMESERVER,
            NameServer: windows::core::PCWSTR::null(),
            ..Default::default()
        };
        // Call SetInterfaceDnsSettings with empty NameServer or appropriate flags
    }
    */

    Ok(())
}