// Copyright 2016 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 gce

import (
	"fmt"
	"net"
	"net/http"
	"strconv"
	"strings"

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

const (
	apiVersion   = "computeMetadata/v1/"
	metadataPath = apiVersion
	userdataPath = apiVersion + "instance/attributes/user-data"
)

type metadataService struct {
	metadata.MetadataService
}

func NewDatasource(root string) *metadataService {
	return &metadataService{metadata.NewDatasource(root, apiVersion, userdataPath, metadataPath, http.Header{"Metadata-Flavor": {"Google"}})}
}

func (ms metadataService) FetchMetadata() (datasource.Metadata, error) {
	public, err := ms.fetchIP("instance/network-interfaces/0/access-configs/0/external-ip")
	if err != nil {
		return datasource.Metadata{}, err
	}
	local, err := ms.fetchIP("instance/network-interfaces/0/ip")
	if err != nil {
		return datasource.Metadata{}, err
	}
	hostname, err := ms.fetchString("instance/hostname")
	if err != nil {
		return datasource.Metadata{}, err
	}

	projectSshKeys, err := ms.fetchString("project/attributes/sshKeys")
	if err != nil {
		return datasource.Metadata{}, err
	}
	instanceSshKeys, err := ms.fetchString("instance/attributes/sshKeys")
	if err != nil {
		return datasource.Metadata{}, err
	}

	keyStrings := strings.Split(projectSshKeys+"\n"+instanceSshKeys, "\n")

	sshPublicKeys := map[string]string{}
	i := 0
	for _, keyString := range keyStrings {
		keySlice := strings.SplitN(keyString, ":", 2)
		if len(keySlice) == 2 {
			key := strings.TrimSpace(keySlice[1])
			if key != "" {
				sshPublicKeys[strconv.Itoa(i)] = strings.TrimSpace(keySlice[1])
				i++
			}
		}
	}

	return datasource.Metadata{
		PublicIPv4:    public,
		PrivateIPv4:   local,
		Hostname:      hostname,
		SSHPublicKeys: sshPublicKeys,
	}, nil
}

func (ms metadataService) Type() string {
	return "gce-metadata-service"
}

func (ms metadataService) fetchString(key string) (string, error) {
	data, err := ms.FetchData(ms.MetadataUrl() + key)
	if err != nil {
		return "", err
	}

	return string(data), nil
}

func (ms metadataService) fetchIP(key string) (net.IP, error) {
	str, err := ms.fetchString(key)
	if err != nil {
		return nil, err
	}

	if str == "" {
		return nil, nil
	}

	if ip := net.ParseIP(str); ip != nil {
		return ip, nil
	} else {
		return nil, fmt.Errorf("couldn't parse %q as IP address", str)
	}
}

func (ms metadataService) FetchUserdata() ([]byte, error) {
	data, err := ms.FetchData(ms.UserdataUrl())
	if err != nil {
		return nil, err
	}
	if len(data) == 0 {
		data, err = ms.FetchData(ms.MetadataUrl() + "instance/attributes/startup-script")
		if err != nil {
			return nil, err
		}
	}
	return data, nil
}