package api

import (
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/service/cloudwatch"
	"github.com/aws/aws-sdk-go/service/ec2"
	"github.com/grafana/grafana/pkg/middleware"
)

func ProxyCloudWatchDataSourceRequest(c *middleware.Context) {
	body, _ := ioutil.ReadAll(c.Req.Request.Body)

	reqInfo := &struct {
		Region  string `json:"region"`
		Service string `json:"service"`
		Action  string `json:"action"`
	}{}
	json.Unmarshal([]byte(body), reqInfo)

	switch reqInfo.Service {
	case "CloudWatch":
		svc := cloudwatch.New(&aws.Config{Region: aws.String(reqInfo.Region)})

		switch reqInfo.Action {
		case "GetMetricStatistics":
			reqParam := &struct {
				Parameters struct {
					Namespace  string                  `json:"Namespace"`
					MetricName string                  `json:"MetricName"`
					Dimensions []*cloudwatch.Dimension `json:"Dimensions"`
					Statistics []*string               `json:"Statistics"`
					StartTime  int64                   `json:"StartTime"`
					EndTime    int64                   `json:"EndTime"`
					Period     int64                   `json:"Period"`
				} `json:"parameters"`
			}{}
			json.Unmarshal([]byte(body), reqParam)

			params := &cloudwatch.GetMetricStatisticsInput{
				Namespace:  aws.String(reqParam.Parameters.Namespace),
				MetricName: aws.String(reqParam.Parameters.MetricName),
				Dimensions: reqParam.Parameters.Dimensions,
				Statistics: reqParam.Parameters.Statistics,
				StartTime:  aws.Time(time.Unix(reqParam.Parameters.StartTime, 0)),
				EndTime:    aws.Time(time.Unix(reqParam.Parameters.EndTime, 0)),
				Period:     aws.Int64(reqParam.Parameters.Period),
			}

			resp, err := svc.GetMetricStatistics(params)
			if err != nil {
				c.JsonApiErr(500, "Unable to call AWS API", err)
				return
			}

			respJson, _ := json.Marshal(resp)
			fmt.Fprint(c.RW(), string(respJson))
		case "ListMetrics":
			reqParam := &struct {
				Parameters struct {
					Namespace  string                        `json:"Namespace"`
					MetricName string                        `json:"MetricName"`
					Dimensions []*cloudwatch.DimensionFilter `json:"Dimensions"`
				} `json:"parameters"`
			}{}
			json.Unmarshal([]byte(body), reqParam)

			params := &cloudwatch.ListMetricsInput{
				Namespace:  aws.String(reqParam.Parameters.Namespace),
				MetricName: aws.String(reqParam.Parameters.MetricName),
				Dimensions: reqParam.Parameters.Dimensions,
			}

			resp, err := svc.ListMetrics(params)
			if err != nil {
				c.JsonApiErr(500, "Unable to call AWS API", err)
				return
			}

			respJson, _ := json.Marshal(resp)
			fmt.Fprint(c.RW(), string(respJson))
		default:
			c.JsonApiErr(500, "Unexpected CloudWatch action", errors.New(reqInfo.Action))
		}
	case "EC2":
		svc := ec2.New(&aws.Config{Region: aws.String(reqInfo.Region)})

		switch reqInfo.Action {
		case "DescribeInstances":
			reqParam := &struct {
				Parameters struct {
					Filters     []*ec2.Filter `json:"Filters"`
					InstanceIds []*string     `json:"InstanceIds"`
				} `json:"parameters"`
			}{}
			json.Unmarshal([]byte(body), reqParam)

			params := &ec2.DescribeInstancesInput{}
			if len(reqParam.Parameters.Filters) > 0 {
				params.Filters = reqParam.Parameters.Filters
			}
			if len(reqParam.Parameters.InstanceIds) > 0 {
				params.InstanceIDs = reqParam.Parameters.InstanceIds
			}

			resp, err := svc.DescribeInstances(params)
			if err != nil {
				c.JsonApiErr(500, "Unable to call AWS API", err)
				return
			}

			respJson, _ := json.Marshal(resp)
			fmt.Fprint(c.RW(), string(respJson))
		default:
			c.JsonApiErr(500, "Unexpected EC2 action", errors.New(reqInfo.Action))
		}
	default:
		c.JsonApiErr(500, "Unexpected service", errors.New(reqInfo.Service))
	}
}