package main

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"runtime"
	"strings"
)

// reused by GoRuntinesStatus()
var buffer []byte

// Get Go Routines and map the Status.  See GStatus.
func GoRoutinesStatus() string {
	var result string
	// Map status to letter.
	var GStatus = map[string]string{
		"idle":         "I",
		"runnable":     "r",
		"running":      "R",
		"syscall":      "s",
		"waiting":      "W",
		"dead":         "D",
		"copystack":    "C",
		"preempted":    "P",
		"sleep":        "S",
		"select":       "s", // missing
		"chan receive": "<", // missing
		"chan send":    ">", // missing
	}
	// 2K works, we don't have to grow any more.
	if buffer == nil {
		buffer = make([]byte, 2048)
	}
	read := runtime.Stack(buffer, true)

	if read == cap(buffer) {
		log.Printf("Increasing buffer from (%d bytes)\n", cap(buffer))
		buffer = make([]byte, cap(buffer)+1024)
		return GoRoutinesStatus()
	}

	// fmt.Println(string(buffer[0:read]))

	var reader = bytes.NewReader(buffer[0:read])
	var scanner = bufio.NewScanner(reader)
	for scanner.Scan() {
		var text = scanner.Text()
		if strings.HasPrefix(text, "goroutine ") {
			// fmt.Println(text)
			// goroutine 20 [runnable]:
			// goroutine 1 [select, 1 minutes]:
			// goroutine 17 [chan receive]:

			// Get ID and get Status.
			parts := strings.SplitN(text, " ", 3)
			/*
				gid, err := strconv.Atoi(parts[1])
				if err != nil {
					continue
				}
			*/
			status := parts[2][1 : len(parts[2])-2]
			if strings.Contains(status, ",") {
				status = strings.Split(status, ",")[0]
			}
			rstatus, ok := GStatus[status]
			if ok {
				result += rstatus
			} else {
				log.Printf("Status %s not found.\n[%s]\n", rstatus, text)
			}
		}
	}
	return result
}

// Return a nicely formatted string representing memory usage.
func ReprMem(size uint64) string {
	var value float64 = float64(size)
	var units string = ""

	if value > 1024 {
		// In KB
		units = "K"
		value /= 1024
	}
	if value > 1024 {
		// In MB
		units = "M"
		value /= 1024
	}
	if value > 1024 {
		// Im GB
		units = "G"
		value /= 1024
	}
	var test = fmt.Sprintf("%0.2f", value)
	if len(test) > 4 {
		test = fmt.Sprintf("%0.1f", value)
	}
	if len(test) > 4 {
		test = fmt.Sprintf("%0.0f", value)
	}
	return test + units
}

// Return array of memory usage information
func Memory() map[string]string {
	var memstats runtime.MemStats
	var result map[string]string = make(map[string]string, 7)
	runtime.ReadMemStats(&memstats)
	result["Heap"] = ReprMem(memstats.HeapAlloc)
	result["HeapInUse"] = ReprMem(memstats.HeapInuse)
	result["HeapSys"] = ReprMem(memstats.HeapSys)
	result["Sys"] = ReprMem(memstats.Sys)
	result["StackInUse"] = ReprMem(memstats.StackInuse)
	result["StackSys"] = ReprMem(memstats.StackSys)
	result["GCSys"] = ReprMem(memstats.GCSys)
	return result
}