package main

import (
	"encoding/binary"
	"fmt"
	"io"
	"os"
)

/*
first word
high 8 bits is ee, which is an invalid address on amd64. 
next 8 bits is protocol version
next 16 bits is unused, MBZ. Later, we can make it a packet type. 
next 16 bits is core id
next 8 bits is unused
next 8 bits is # words following.

second word is time in ns. (soon to be tsc ticks)

Third and following words are PCs, there must be at least one of them. 
 */
type sample struct {
	Wordcount,_ uint8
	Coreid uint16
	_ uint16
	Version, Marker uint8
	Ns uint64
}

type backtrace struct {
	Pcs []uint64
}

/* the docs lie. Perl expects Count to be zero. I only wasted a day figuring this out. */
type hdr struct {
	Count, Slots, Format, Period, Padding uint64
}

type record struct {
	Count, Size uint64
	Pcs []uint64
}

type trailer struct {
	Zero, One, Zeroh uint64
}

func main() {
	var s sample
	
	r := io.Reader(os.Stdin)
	w := io.Writer(os.Stdout)

	records := make(map[string]uint64, 16384)
	backtraces := make(map[string][]uint64,1024)

	/* ignore the documentation, it's wrong, first word must be zero.
	 * the perl code that figures word length depends on it.
	 */
	hdr := hdr{0,3,0,10000,0}
	trailer := trailer{0,1,0}
	start := uint64(0)
	end := start
	nsamples := end
	for binary.Read(r, binary.LittleEndian, &s) == nil {
		numpcs := int(s.Wordcount)
		bt := make([]uint64, numpcs)
		binary.Read(r, binary.LittleEndian, &bt)
		//fmt.Printf("%v\n", bt)
		record := ""
		/* Fix the symbols. pprof was unhappy about the 0xfffffff.
		 * N.B. The fact that we have to mess with the bt values
		 * is the reason we did not write a stringer for bt.
		 */
		for i := range(bt) {
			bt[i] = bt[i] & ((uint64(1)<<32)-1)
			record = record + fmt.Sprintf("0x%x ",bt[i])
		}
		records[record]++
		backtraces[record] = bt
		//fmt.Printf("%v %d %d %x %v record %v\n", s, s.Wordcount, s.Coreid, s.Ns, bt, record)
		/* how sad, once we go to ticks this gets ugly. */
		if start == 0 {
			start = s.Ns
		}
		end = s.Ns
		nsamples ++
	}
	/* we'll need to fix this once we go to ticks. */
	hdr.Period = (end - start) / nsamples
	hdr.Count = uint64(0) // !@$@!#$!@#$len(records))
	//fmt.Printf("start %v end %v nsamples %d period %d\n", start, end, nsamples, hdr.Period)
	binary.Write(w, binary.LittleEndian, &hdr)
	out := make([]uint64, 2)
	/* note that the backtrace length varies. But we're good with that. */
	for key, v := range(records) {
		bt := backtraces[key]
		out[0] = v
		out[1] = uint64(len(bt))
		dump := append(out, bt...)
		//fmt.Printf("dump %v\n", dump)
		binary.Write(w, binary.LittleEndian, &dump)
	}
	binary.Write(w, binary.LittleEndian, &trailer)

}