package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"path"
	"strconv"
	"strings"
)

type SubmissionHandler struct{}

func (SubmissionHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	log.Printf("Handling %s request from %s: %s [%s]\n", r.Method, r.RemoteAddr, r.URL.Path, r.UserAgent())

	w.Header().Set("Content-Type", "application/json")


	// Check request type and size
	if r.Method != "POST" {
		http.Error(w, "{errmsg:\"Bad request.\"}", http.StatusBadRequest)
		return
	} else if r.ContentLength < 0 || r.ContentLength > 255 {
		http.Error(w, "{errmsg:\"Request too large or request size unknown\"}", http.StatusRequestEntityTooLarge)
		return
	}


	// Extract URL arguments
	var sURL = strings.Split(r.URL.Path, "/")

	if len(sURL) != 3 && len(sURL) != 4 {
		http.Error(w, "{errmsg:\"Bad request.\"}", http.StatusBadRequest)
		return
	}

	// Parse arguments
	if team, err := strconv.Atoi(sURL[1]); err != nil {
		http.Error(w, "{errmsg:\"Bad request.\"}", http.StatusBadRequest)
		return
	} else if exercice, err := strconv.Atoi(sURL[2]); err != nil {
		http.Error(w, "{errmsg:\"Bad request.\"}", http.StatusBadRequest)
		return
	} else {
		if _, err := os.Stat(path.Join(SubmissionDir, fmt.Sprintf("%d", team))); os.IsNotExist(err) {
			log.Println("Creating submission directory for", team)
			if err := os.MkdirAll(path.Join(SubmissionDir, fmt.Sprintf("%d", team)), 0777); err != nil {
				log.Println("Unable to create submission directory: ", err)
				http.Error(w, "{errmsg:\"Internal server error. Please retry in few seconds.\"}", http.StatusInternalServerError)
				return
			}
		}


		// Previous submission not treated
		if _, err := os.Stat(path.Join(SubmissionDir, fmt.Sprintf("%d", team), fmt.Sprintf("%d", exercice))); !os.IsNotExist(err) {
			http.Error(w, "{errmsg:\"Calm-down. A solution is already being processed.\"}", http.StatusPaymentRequired)
			return
		}


		// Read request body
		var body []byte
		if r.ContentLength > 0 {
			tmp := make([]byte, 1024)
			for {
				n, err := r.Body.Read(tmp)
				for j := 0; j < n; j++ {
					body = append(body, tmp[j])
				}
				if err != nil || n <= 0 {
					break
				}
			}
		}


		// Store content in file
		if file, err := os.Create(path.Join(SubmissionDir, fmt.Sprintf("%d", team), fmt.Sprintf("%d", exercice))); err != nil {
			log.Println("Unable to open exercice file:", err)
			http.Error(w, "{errmsg:\"Internal server error. Please retry in few seconds.\"}", http.StatusInternalServerError)
			return
		} else {
			file.Write(body)
			file.Close()
		}
		http.Error(w, "{errmsg:\"Submission accepted, please wait...\"}", http.StatusAccepted)
	}
}