package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
)

type Match struct {
	WhitePlayer string
	BlackPlayer string
}

func getPlayerlist() []string {
	var playerList []string
	file, err := os.Open("players.txt")
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		playerList = append(playerList, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}
	return playerList
}

func main() {
	playerList := getPlayerlist()
	matchList := getMatchs(playerList)
	printMatchList(matchList)
	checkMatchList(matchList, playerList)
}

func getMatchs(playerList []string) []Match {
	if len(playerList) == 0 {
		return nil
	}
	var matchList []Match
	subList := playerList[1:]
	for i, player := range subList {
		whitePlayer := playerList[0]
		blackPlayer := player
		if i%2 == 0 {
			whitePlayer = player
			blackPlayer = playerList[0]
		}
		matchList = append(matchList, Match{whitePlayer, blackPlayer})
	}
	return append(matchList, getMatchs(subList)...)
}

func printMatchList(matchList []Match) {
	for _, match := range matchList {
		fmt.Printf("%s,%s\n", match.WhitePlayer, match.BlackPlayer)
	}
}

func checkMatchList(matchList []Match, playerList []string) {
	for _, player := range playerList {
		countWhitePlayer := countWhitePlayer(matchList, player)
		countBlackPlayer := countBlackPlayer(matchList, player)
		fmt.Fprintf(os.Stderr, "%s has %d games with white pieces and %d with black pieces.\n", player, countWhitePlayer, countBlackPlayer)
	}
}

func countWhitePlayer(matchList []Match, player string) int {
	c := 0
	for _, match := range matchList {
		if match.WhitePlayer == player {
			c++
		}
	}
	return c
}

func countBlackPlayer(matchList []Match, player string) int {
	c := 0
	for _, match := range matchList {
		if match.BlackPlayer == player {
			c++
		}
	}
	return c
}