package main

import (
	"bufio"
	"compress/gzip"
	"fmt"
	"os"
	"time"

	xmlparser "github.com/tamerh/xml-stream-parser"
	// Dá se získat pomocí "go get -u github.com/tamerh/xml-stream-parser"
)

// Funkce na vytáhnutí tagu daného elementu
func getTag(el *xmlparser.XMLElement, name string) (string, bool) {
	for _, tag := range el.Childs["tag"] {
		if tag.Attrs["k"] == name {
			return tag.Attrs["v"], true
		}
	}
	return "", false
}

// Funkce na kontrolu jestli má tag daný element (bez kontroly hodnoty)
func hasTag(el *xmlparser.XMLElement, name string) bool {
	_, found := getTag(el, name)
	return found
}

func die(exitcode int, format string, a ...interface{}) {
	fmt.Fprintf(os.Stderr, format, a...)
	os.Exit(1)
}

func main() {
	if len(os.Args) != 2 {
		die(1, "Usage: %s <file.xml.gz>\n", os.Args[0])
	}
	// 1. Otevřeme soubor
	file, err := os.Open(os.Args[1])
	if err != nil {
		die(1, "Cannot open file: %v\n", err)
	}
	// 2. Gzip streamový reader
	gzipReader, err := gzip.NewReader(file)
	if err != nil {
		die(1, "Cannot construct gzip stream reader: %v\n", err)
	}

	// 3. XML streamový parser
	buffer := bufio.NewReaderSize(gzipReader, 1024*1024*256)
	parser := xmlparser.NewXMLParser(buffer, "node", "way", "relation")

	streets := map[string]int{}

	nodes, ways, relations := 0, 0, 0
	start := time.Now()
	// funkce na vypisování statistiky
	printStat := func() {
		megabytes := float64(parser.TotalReadSize) / 1024 / 1024
		elapsed := time.Now().Sub(start)
		fmt.Fprintf(os.Stderr,
			"Elapsed: %-20s Read: %10.2fMB (%.2fMB/s)\tNodes: %8d\tWays: %8d\tRelations: %8d\tFound streets: %8d\r",
			elapsed, megabytes, megabytes/time.Now().Sub(start).Seconds(), nodes, ways, relations, len(streets),
		)
	}

	// 4. Čteme element po elementu
	for xml := range parser.Stream() {
		switch xml.Name {
		case "node":
			nodes++
		case "way":
			ways++

			if hasTag(xml, "highway") {
				if name, found := getTag(xml, "name"); found {
					streets[name]++
				}
			}
		case "relation":
			relations++
		}

		// Vypíšeme statistiku každých 10000 načtených elementů
		if (nodes+ways+relations)%10000 == 0 {
			printStat()
		}
	}

	printStat()
	fmt.Fprintf(os.Stderr, "\n\nTotal time: %v\nTotal unique streets: %d\n", time.Now().Sub(start), len(streets))

	for street, count := range streets {
		fmt.Printf("%s\t%d\n", street, count)
	}
}