package gupta

import (
	"encoding/json"
	"fmt"
	"time"
)

const version = "0.0.1"

func Hello() string {
	return fmt.Sprintf("Welcome to gupta version %s", version)
}

type GuptaReport struct {
	Time        time.Time
	LoadAvarage float64
	CPUUsage    *CPUStat `json:"cpu usage, omitempty"`
	MemoryUsage *Memory  `json:"memory,omitempty"`
}

// usually you'd want a g GuptaReport reciever here ...
// but than you could now check for the object properties ...
func (g *GuptaReport) MarshalJSON() ([]byte, error) {
	report := []byte(fmt.Sprintf("{\"timestamp\": \"%d\", \"metrics\": [",
		g.Time.Unix()))
	if g.CPUUsage != nil {
		usage, _ := json.Marshal(g.CPUUsage)
		report = append(report, usage...)
	}

	if g.MemoryUsage != nil {
		if g.CPUUsage != nil {
			report = append(report, []byte(",")...)
		}
		usage, _ := json.Marshal(g.MemoryUsage)
		report = append(report, usage...)
	}

	report = append(report, []byte("]}")...)
	return report, nil
}