// NGnius 2020-02-27

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
)

const (
	defaultPassword = ""
	defaultEntryURL = "http://localhost:1337/record"
	defaultPort     = "9000"
	defaultDir      = "criterias"
)

var (
	// cli params
	password string
	entryURL string
	port     string
	dir      string
	// internal
	server            *http.Server
	client            *http.Client
	isClosing         bool
	referenceCriteria map[string]Criteria
)

// json structs

// NewEntryJSON a new entry to be saved to a leaderboard
type NewEntryJSON struct { // from leadercraft-s
	Score    int64
	PlayerID int64
	BoardID  int64
	Password string
}

// Criteria a set of values that must be met
type Criteria struct {
	Location    [2][3]float64 // (min coords (x,y,z), max coords (x,y,z))
	Time        int64         // time since start of game (seconds)
	GameID      int64         // game/board id in leadercraft-s and in Gamecraft (workshop ID?)
	PlayerID    int64         // player id in leadercraft-s and in Gamecraft (steam ID)
	Coefficient float64       // coefficient for calculating the score
	Complete    bool          // game has been completed
	Points      int64         // points scored in game
	ScoreMode   string        // score calculation mode
}

func (c *Criteria) Meets(c2 *Criteria) bool {
	meets := false
	if c2.Location[0][0] != 0.0 && c2.Location[0][1] != 0.0 && c2.Location[0][2] != 0.0 &&
		c2.Location[1][0] != 0.0 && c2.Location[1][1] != 0.0 && c2.Location[1][2] != 0.0 {
		// criteria is location-based
		meets = c.Location[0][0] >= c2.Location[0][0] && c.Location[0][1] >= c2.Location[0][1] && c.Location[0][2] >= c2.Location[0][2]
		meets = meets && c.Location[1][0] <= c2.Location[1][0] && c.Location[1][1] <= c2.Location[1][1] && c.Location[1][2] <= c2.Location[1][2]
		return meets
	}
	if c2.Complete {
		return c.Complete && (c.Points >= c2.Points)
	}
	return meets
}

func (c *Criteria) Score(c2 *Criteria) int64 {
	if c2.ScoreMode == "time" {
        time := float64(c.Time)
        if time < 1 {
            time = 1
        }
		return int64(c2.Coefficient / float64(c.Time))
	}
	if c2.ScoreMode == "points" {
		return int64(c2.Coefficient * float64(c.Points))
	}
	return 0
}

func init() {
	flag.StringVar(&password, "entry-pwd", defaultPassword, "Password for new entry POST requests")
	flag.StringVar(&entryURL, "url", defaultEntryURL, "URL for new entry POST requests")
	flag.StringVar(&port, "port", defaultPort, "Port to listen on")
	flag.StringVar(&dir, "dir", defaultDir, "Working directory")
}

func main() {
	flag.Parse()
	serverMux := http.NewServeMux()
	serverMux.HandleFunc("/criteria", criteriaHandler)
	signalChan := make(chan os.Signal)
	signal.Notify(signalChan, os.Interrupt)
	go func() {
		s := <-signalChan
		fmt.Println("Received terminate signal " + s.String())
		isClosing = true
		server.Close()
	}()
	server = &http.Server{
		Addr:    ":" + port,
		Handler: serverMux,
	}
	client = &http.Client{}
	fmt.Println("Starting on " + server.Addr)
	err := server.ListenAndServe()
	if err != nil && !isClosing {
		fmt.Println(err)
	}
}

// criteria POST request handler
// this also sends a new entry to leadercraft-s when the criteria is met
func criteriaHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		w.WriteHeader(405)
		return
	}
	authHeader := r.Header.Get("Authorization")
	w.Header().Add("Content-Type", "application/json")
	//w.Header().Add("Access-Control-Allow-Origin", "*")
	data, readErr := ioutil.ReadAll(r.Body)
	if readErr != nil {
		// body could not be read properly
		w.WriteHeader(500)
		return
	}
	reqCriteria := &Criteria{}
	unmarshErr := json.Unmarshal(data, reqCriteria)
	if unmarshErr != nil {
		// body could not be interpreted as json
		w.WriteHeader(400)
		return
	}
	if reqCriteria.GameID < 2 {
		//fmt.Println("404 -- GameID too low")
		w.WriteHeader(404)
		return
	}
	criteriaFilename := filepath.Join(dir, fmt.Sprintf("criteria-%d.json", reqCriteria.GameID))
	//fmt.Println(criteriaFilename)
	realCriteria := &Criteria{}
	realCriteriaF, openErr := os.Open(criteriaFilename)
	if openErr != nil {
		// file not found (or not accessible)
		//fmt.Println("404 -- criteria file not accessible: %s", openErr.Error())
		w.WriteHeader(404)
		return
	}
	realCritData, realCritReadErr := ioutil.ReadAll(realCriteriaF)
	if realCritReadErr != nil {
		// internal read error
		w.WriteHeader(500)
		return
	}
	unmarshCritErr := json.Unmarshal(realCritData, realCriteria)
	if unmarshCritErr != nil {
		// criteria file is invalid json
		//fmt.Printf("404 -- Invalid criteria file json: %s", unmarshCritErr.Error())
		w.WriteHeader(404)
		return
	}
	// TODO check if criteria matches
	if !reqCriteria.Meets(realCriteria) {
		// if criteria does not match, stop
		//fmt.Println("400 -- Criteria does not meet required criteria")
		w.WriteHeader(400)
		return
	}
	// if criteria matches, send new entry to leadercraft-s
	entry := NewEntryJSON{
		Score:    reqCriteria.Score(realCriteria),
		PlayerID: reqCriteria.PlayerID,
		BoardID:  realCriteria.GameID,
		Password: password,
	}
	echoData, marshErr := json.Marshal(entry)
	if marshErr != nil {
		//fmt.Println("500 -- Unable to marshal entry into JSON for leaderboard-s endpoint")
		w.WriteHeader(500)
		return
	}
	echoBody := bytes.NewReader(echoData)
	entryReq, reqErr := http.NewRequest("POST", entryURL, echoBody)
	if reqErr != nil {
		// malformed request parameters
		//fmt.Println("500 -- Malformed request detected during initialization")
		w.WriteHeader(500)
		return
	}
	entryReq.Header.Add("Authorization", authHeader)
	entryReq.Header.Add("Content-Type", "application/json")
	echoResp, postErr := client.Do(entryReq)
	if postErr != nil {
		// bad communication or malformed request
		//fmt.Println("500 -- Bad communication for leadercraft-s")
		w.WriteHeader(500)
		return
	}
	// echo new entry request response to original sender
	w.WriteHeader(echoResp.StatusCode)
	echoRespData, echoReadErr := ioutil.ReadAll(echoResp.Body)
	if echoReadErr != nil {
		// body read error (should never occur)
		//fmt.Println("!!! Error reading response body from leadercraft-s")
		return
	}
	w.Write(echoRespData)
}