/*
   Copyright 2014 CoreOS, Inc.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package network

import (
	"encoding/json"
	"fmt"
	"log"
	"net"

	"github.com/coreos/coreos-cloudinit/datasource/metadata/digitalocean"
)

func ProcessDigitalOceanNetconf(config string) ([]InterfaceGenerator, error) {
	log.Println("Processing DigitalOcean network config")
	if config == "" {
		return nil, nil
	}

	var cfg digitalocean.Metadata
	if err := json.Unmarshal([]byte(config), &cfg); err != nil {
		return nil, err
	}

	log.Println("Parsing nameservers")
	nameservers, err := parseNameservers(cfg.DNS)
	if err != nil {
		return nil, err
	}
	log.Printf("Parsed %d nameservers\n", len(nameservers))

	log.Println("Parsing interfaces")
	generators, err := parseInterfaces(cfg.Interfaces, nameservers)
	if err != nil {
		return nil, err
	}
	log.Printf("Parsed %d network interfaces\n", len(generators))

	log.Println("Processed DigitalOcean network config")
	return generators, nil
}

func parseNameservers(cfg digitalocean.DNS) ([]net.IP, error) {
	nameservers := make([]net.IP, 0, len(cfg.Nameservers))
	for _, ns := range cfg.Nameservers {
		if ip := net.ParseIP(ns); ip == nil {
			return nil, fmt.Errorf("could not parse %q as nameserver IP address", ns)
		} else {
			nameservers = append(nameservers, ip)
		}
	}
	return nameservers, nil
}

func parseInterfaces(cfg digitalocean.Interfaces, nameservers []net.IP) ([]InterfaceGenerator, error) {
	generators := make([]InterfaceGenerator, 0, len(cfg.Public)+len(cfg.Private))
	for _, iface := range cfg.Public {
		if generator, err := parseInterface(iface, nameservers, true); err == nil {
			generators = append(generators, &physicalInterface{*generator})
		} else {
			return nil, err
		}
	}
	for _, iface := range cfg.Private {
		if generator, err := parseInterface(iface, []net.IP{}, false); err == nil {
			generators = append(generators, &physicalInterface{*generator})
		} else {
			return nil, err
		}
	}
	return generators, nil
}

func parseInterface(iface digitalocean.Interface, nameservers []net.IP, useRoute bool) (*logicalInterface, error) {
	routes := make([]route, 0)
	addresses := make([]net.IPNet, 0)
	if iface.IPv4 != nil {
		var ip, mask, gateway net.IP
		if ip = net.ParseIP(iface.IPv4.IPAddress); ip == nil {
			return nil, fmt.Errorf("could not parse %q as IPv4 address", iface.IPv4.IPAddress)
		}
		if mask = net.ParseIP(iface.IPv4.Netmask); mask == nil {
			return nil, fmt.Errorf("could not parse %q as IPv4 mask", iface.IPv4.Netmask)
		}
		addresses = append(addresses, net.IPNet{
			IP:   ip,
			Mask: net.IPMask(mask),
		})

		if useRoute {
			if gateway = net.ParseIP(iface.IPv4.Gateway); gateway == nil {
				return nil, fmt.Errorf("could not parse %q as IPv4 gateway", iface.IPv4.Gateway)
			}
			routes = append(routes, route{
				destination: net.IPNet{
					IP:   net.IPv4zero,
					Mask: net.IPMask(net.IPv4zero),
				},
				gateway: gateway,
			})
		}
	}
	if iface.IPv6 != nil {
		var ip, gateway net.IP
		if ip = net.ParseIP(iface.IPv6.IPAddress); ip == nil {
			return nil, fmt.Errorf("could not parse %q as IPv6 address", iface.IPv6.IPAddress)
		}
		addresses = append(addresses, net.IPNet{
			IP:   ip,
			Mask: net.CIDRMask(iface.IPv6.Cidr, net.IPv6len*8),
		})

		if useRoute {
			if gateway = net.ParseIP(iface.IPv6.Gateway); gateway == nil {
				return nil, fmt.Errorf("could not parse %q as IPv6 gateway", iface.IPv6.Gateway)
			}
			routes = append(routes, route{
				destination: net.IPNet{
					IP:   net.IPv6zero,
					Mask: net.IPMask(net.IPv6zero),
				},
				gateway: gateway,
			})
		}
	}

	hwaddr, err := net.ParseMAC(iface.MAC)
	if err != nil {
		return nil, err
	}

	if nameservers == nil {
		nameservers = []net.IP{}
	}

	return &logicalInterface{
		hwaddr: hwaddr,
		config: configMethodStatic{
			addresses:   addresses,
			nameservers: nameservers,
			routes:      routes,
		},
	}, nil
}