package main

import (
	"flag"
	"fmt"
	"os"
	"runtime"
	"time"

	"github.com/shirou/gopsutil/v3/load"
	"github.com/shirou/gopsutil/v3/mem"
)

type Format struct {
	Default, Warning string
}

var defaultFormat = Format{}
var tmuxFormat = Format{Default: "#[default]", Warning: "#[bg=colour208]"}

var binarySuffixes = []string{"B", "KiB", "MiB", "GiB", "TiB"}

const binaryFactor = 1024

func HBin(a uint64, precision int) string {
	f := float64(a)
	var suffix string
	for _, suffix = range binarySuffixes {
		if f < binaryFactor {
			break
		}
		f /= binaryFactor
	}
	return fmt.Sprintf("%.*f%s", precision, f, suffix)
}

func usage() {
	fmt.Fprintln(os.Stderr, "Usage:", os.Args[0], "<window_width>")
	os.Exit(2)
}

func printLoad(format Format, precision int) {
	l, err := load.Avg()
	if err != nil {
		panic(err) // fixme
	}

	if l.Load1 > float64(runtime.NumCPU()) {
		fmt.Print(format.Warning)
	}
	fmt.Printf("[%.[1]*[2]f %.[1]*[3]f %.[1]*[4]f]",
		precision, l.Load1, l.Load5, l.Load15)
}

func printMem(format Format, absolute, percent bool) {
	if !(absolute || percent) {
		return
	}

	v, err := mem.VirtualMemory()
	if err != nil {
		panic(err) //fixme
	}

	if v.UsedPercent > 90 {
		fmt.Print(format.Warning, "[")
	} else {
		fmt.Print(format.Default, "[")
	}
	if absolute {
		fmt.Printf("%s/%s", HBin(v.Used, 1), HBin(v.Total, 1))
		if percent {
			fmt.Print(" ")
		}
	}
	if percent {
		fmt.Printf("%.0f%%", v.UsedPercent)
	}
	fmt.Print("]")
}

func printTime(format Format, timeFormat string) {
	now := time.Now()

	fmt.Print(format.Default, now.Format(timeFormat))
}

func main() {
	cols := flag.Uint("c", 0, "Window width in columns. 0 prints everything.")
	mode := flag.String("style", "none", "Include style directives in output. Valid values: none tmux")
	flag.Parse()

	format := defaultFormat
	switch *mode {
	case "", "none":
	case "tmux":
		format = tmuxFormat
	default:
		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
		flag.PrintDefaults()
		os.Exit(2)
	}

	if *cols == 0 || *cols >= 150 {
		printLoad(format, 2)
		printMem(format, true, true)
		printTime(format, " Mon 2006-01-02 15:04")
	} else if *cols >= 120 {
		printLoad(format, 2)
		printMem(format, false, true)
		printTime(format, " 15:04")
	} else if *cols >= 100 {
		printLoad(format, 0)
		printMem(format, false, true)
		printTime(format, " 15:04")
	} else if *cols >= 80 {
		printTime(format, "15:04")
	}
}