From 39118f3fe085fceede9594bbb7b561fd09ed3d25 Mon Sep 17 00:00:00 2001
From: Ant Zucaro <azucaro@gmail.com>
Date: Sun, 29 Oct 2017 16:56:44 -0400
Subject: [PATCH] Add command line and config file parsing.

---
 xonstat/util/xs_glicko.go | 74 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/xonstat/util/xs_glicko.go b/xonstat/util/xs_glicko.go
index 67821f5..8bdcca4 100644
--- a/xonstat/util/xs_glicko.go
+++ b/xonstat/util/xs_glicko.go
@@ -1,9 +1,81 @@
 package main
 
 import (
+	"encoding/json"
+	"flag"
 	"fmt"
+	"log"
+	"os"
 )
 
+const DefaultStartGameID = 0
+const DefaultEndGameID = -1
+const DefaultRankingWindowDays = 7
+
+type Config struct {
+	// database connection string
+	ConnStr string
+
+	// the starting game_id in the games table
+	StartGameID int
+
+	// the ending game_id in the games table
+	EndGameID int
+
+	// the number of days constituting the ranking window
+	RankingWindowDays int
+}
+
+func loadConfig(path string) (*Config, error) {
+	config := new(Config)
+
+	// defaults
+	config.ConnStr = "user=xonstat host=localhost dbname=xonstatdb sslmode=disable"
+	config.StartGameID = DefaultStartGameID
+	config.EndGameID = DefaultEndGameID
+	config.RankingWindowDays = DefaultRankingWindowDays
+
+	file, err := os.Open(path)
+	if err != nil {
+		fmt.Println("Failed opening the file.")
+		return config, err
+	}
+
+	decoder := json.NewDecoder(file)
+
+	// overwrite in-mem config with new values
+	err = decoder.Decode(config)
+	if err != nil {
+		fmt.Println("Failed to decode the JSON.")
+		return config, err
+	}
+
+	return config, nil
+}
+
 func main() {
-	fmt.Println("Hello, world")
+	path := flag.String("config", "xs_glicko.json", "configuration file path")
+	start := flag.Int("start", DefaultStartGameID, "starting game_id")
+	end := flag.Int("end", DefaultEndGameID, "ending game_id")
+	days := flag.Int("days", DefaultRankingWindowDays, "number of days in the ranking window")
+	flag.Parse()
+
+	config, err := loadConfig(*path)
+	if err != nil {
+		log.Fatalf("Unable to load config file: %s.\n", err)
+	}
+
+	if *start != DefaultStartGameID {
+		config.StartGameID = *start
+	}
+
+	if *end != DefaultEndGameID {
+		config.EndGameID = *end
+	}
+
+	if *days != DefaultRankingWindowDays {
+		config.RankingWindowDays = *days
+	}
+
+	fmt.Printf("%+v\n", config)
 }
-- 
2.39.2