use opnsense_config_xml::Range;
use opnsense_config_xml::StaticMap;
use std::cmp::Ordering;
use std::net::Ipv4Addr;

use opnsense_config_xml::OPNsense;

pub struct DhcpConfig<'a> {
    opnsense: &'a mut OPNsense,
}

#[derive(Debug)]
pub enum DhcpError {
    InvalidMacAddress(String),
    InvalidIpAddress(String),
    IpAddressAlreadyMapped(String),
    MacAddressAlreadyMapped(String),
    IpAddressOutOfRange(String),
}

impl std::fmt::Display for DhcpError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            DhcpError::InvalidMacAddress(mac) => write!(f, "Invalid MAC address format: {}", mac),
            DhcpError::InvalidIpAddress(ip) => write!(f, "Invalid IP address format: {}", ip),
            DhcpError::IpAddressAlreadyMapped(ip) => {
                write!(f, "IP address {} is already mapped", ip)
            }
            DhcpError::MacAddressAlreadyMapped(mac) => {
                write!(f, "MAC address {} is already mapped", mac)
            }
            DhcpError::IpAddressOutOfRange(ip) => {
                write!(f, "IP address {} is out of interface range", ip)
            }
        }
    }
}

impl std::error::Error for DhcpError {}

impl<'a> DhcpConfig<'a> {
    pub fn new(opnsense: &'a mut OPNsense) -> Self {
        Self { opnsense }
    }

    pub fn add_static_mapping(
        &mut self,
        mac: &str,
        ipaddr: Ipv4Addr,
        hostname: &str,
    ) -> Result<(), DhcpError> {
        let mac = mac.to_string();
        let hostname = hostname.to_string();
        let range = &self.opnsense.dhcpd.lan.range;

        if !Self::is_valid_mac(&mac) {
            return Err(DhcpError::InvalidMacAddress(mac));
        }

        if !Self::is_ip_in_range(&ipaddr, range) {
            return Err(DhcpError::IpAddressOutOfRange(ipaddr.to_string()));
        }

        let existing_mappings = &self.opnsense.dhcpd.lan.staticmaps;

        if existing_mappings.iter().any(|m| {
            m.ipaddr
                .parse::<Ipv4Addr>()
                .expect("Mapping contains invalid ipv4")
                == ipaddr
        }) {
            return Err(DhcpError::IpAddressAlreadyMapped(ipaddr.to_string()));
        }

        if existing_mappings.iter().any(|m| m.mac == mac) {
            return Err(DhcpError::MacAddressAlreadyMapped(mac));
        }

        let static_map = StaticMap {
            mac,
            ipaddr: ipaddr.to_string(),
            hostname,
            descr: Default::default(),
            winsserver: Default::default(),
            dnsserver: Default::default(),
            ntpserver: Default::default(),
        };

        self.opnsense.dhcpd.lan.staticmaps.push(static_map);
        Ok(())
    }

    pub fn get_static_mappings(&self) -> &[StaticMap] {
        &self.opnsense.dhcpd.lan.staticmaps
    }

    fn is_valid_mac(mac: &str) -> bool {
        let parts: Vec<&str> = mac.split(':').collect();
        if parts.len() != 6 {
            return false;
        }

        parts
            .iter()
            .all(|part| part.len() == 2 && part.chars().all(|c| c.is_ascii_hexdigit()))
    }

    fn is_ip_in_range(ip: &Ipv4Addr, range: &Range) -> bool {
        let range_start = range
            .from
            .parse::<Ipv4Addr>()
            .expect("Invalid DHCP range start");
        let range_end = range.to.parse::<Ipv4Addr>().expect("Invalid DHCP range to");

        let start_compare = range_start.cmp(ip);
        let end_compare = range_end.cmp(ip);

        if (Ordering::Less == start_compare || Ordering::Equal == start_compare)
            && (Ordering::Greater == end_compare || Ordering::Equal == end_compare)
        {
            return true;
        } else {
            return false;
        }
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use pretty_assertions::assert_eq;
    use std::net::Ipv4Addr;

    #[test]
    fn test_ip_in_range() {
        let range = Range {
            from: "192.168.1.100".to_string(),
            to: "192.168.1.200".to_string(),
        };

        // Test IP within range
        let ip = "192.168.1.150".parse::<Ipv4Addr>().unwrap();
        assert_eq!(DhcpConfig::is_ip_in_range(&ip, &range), true);

        // Test IP at start of range
        let ip = "192.168.1.100".parse::<Ipv4Addr>().unwrap();
        assert_eq!(DhcpConfig::is_ip_in_range(&ip, &range), true);

        // Test IP at end of range
        let ip = "192.168.1.200".parse::<Ipv4Addr>().unwrap();
        assert_eq!(DhcpConfig::is_ip_in_range(&ip, &range), true);

        // Test IP before range
        let ip = "192.168.1.99".parse::<Ipv4Addr>().unwrap();
        assert_eq!(DhcpConfig::is_ip_in_range(&ip, &range), false);

        // Test IP after range
        let ip = "192.168.1.201".parse::<Ipv4Addr>().unwrap();
        assert_eq!(DhcpConfig::is_ip_in_range(&ip, &range), false);
    }

}