package pprof

import (
	"bytes"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"runtime/pprof"
	"strconv"
	"strings"
	"time"

	"github.com/projectdiscovery/utils/env"
)

const (
	PPROFSwitchENV = "PPROF"
	MemProfileENV  = "MEM_PROFILE_DIR"
	CPUProfileENV  = "CPU_PROFILE_DIR"
	PPROFTimeENV   = "PPROF_TIME"
	MemProfileRate = "MEM_PROFILE_RATE"
)

func init() {
	if env.GetEnvOrDefault(PPROFSwitchENV, 0) == 1 {
		startDefaultProfiler()
	}
}

func startDefaultProfiler() {
	log.Printf("[+] GOOS: %v\n", runtime.GOOS)
	log.Printf("[+] GOARCH: %v\n", runtime.GOARCH)
	log.Printf("[+] Command: %v\n", strings.Join(os.Args, " "))
	log.Println("Available PPROF Config Options:")
	log.Printf("%-16v - directory to write memory profiles to\n", MemProfileENV)
	log.Printf("%-16v - directory to write cpu profiles to\n", CPUProfileENV)
	log.Printf("%-16v - polling time for cpu and memory profiles (with unit ex: 10s)\n", PPROFTimeENV)
	log.Printf("%-16v - memory profiling rate (default 4096)\n", MemProfileRate)

	memProfilesDir := env.GetEnvOrDefault(MemProfileENV, "memdump")
	cpuProfilesDir := env.GetEnvOrDefault(CPUProfileENV, "cpuprofile")
	pprofTimeDuration := env.GetEnvOrDefault(PPROFTimeENV, time.Duration(3)*time.Second)
	pprofRate := env.GetEnvOrDefault(MemProfileRate, 4096)

	_ = os.MkdirAll(memProfilesDir, 0755)
	_ = os.MkdirAll(cpuProfilesDir, 0755)

	runtime.MemProfileRate = pprofRate
	log.Printf("profile: memory profiling enabled (rate %d), %s\n", runtime.MemProfileRate, memProfilesDir)
	log.Printf("profile: ticker enabled (rate %s)\n", pprofTimeDuration)

	// cpu ticker and profiler
	go func() {
		ticker := time.NewTicker(pprofTimeDuration)
		count := 0
		buff := bytes.Buffer{}
		log.Printf("profile: cpu profiling enabled (ticker %s)\n", pprofTimeDuration)
		for {
			err := pprof.StartCPUProfile(&buff)
			if err != nil {
				log.Fatalf("profile: could not start cpu profile: %s\n", err)
			}
			<-ticker.C
			pprof.StopCPUProfile()
			if err := os.WriteFile(filepath.Join(cpuProfilesDir, "cpuprofile-t"+strconv.Itoa(count)+".out"), buff.Bytes(), 0755); err != nil {
				log.Fatalf("profile: could not write cpu profile: %s\n", err)
			}
			buff.Reset()
			count++
		}
	}()

	// memory ticker and profiler
	go func() {
		ticker := time.NewTicker(pprofTimeDuration)
		count := 0
		log.Printf("profile: memory profiling enabled (ticker %s)\n", pprofTimeDuration)
		for {
			<-ticker.C
			var buff bytes.Buffer
			if err := pprof.WriteHeapProfile(&buff); err != nil {
				log.Printf("profile: could not write memory profile: %s\n", err)
			}
			err := os.WriteFile(filepath.ToSlash(filepath.Join(memProfilesDir, "memprofile-t"+strconv.Itoa(count)+".out")), buff.Bytes(), 0755)
			if err != nil {
				log.Printf("profile: could not write memory profile: %s\n", err)
			}
			count++
		}
	}()
}