submit.go

package main

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"log"
	"mime/multipart"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"golang.org/x/net/html"
)

type probCode struct {
	contest int
	task    string
}

// guess not defined args
func (cf *cf) guessArgs(file *string, prob probCode, lang *int) error {
	f, l := *file, *lang
	needExt := len(f) < 3

	if l == 0 && needExt {
		// search over disk
		f += "."
		var match []string
		for k := range cf.config {
			if st, err := os.Stat(f + k); err == nil && !st.IsDir() {
				match = append(match, k)
			}
		}
		if len(match) == 0 {
			return fmt.Errorf("submit: could not found solution file for problem %q", prob.task)
		}
		if len(match) > 1 {
			buf := bytes.NewBufferString("submit: more than one file looks like solution for problem ")
			fmt.Fprintf(buf, "%v, candidates (with lang IDs):", prob.task)
			for _, k := range match {
				fmt.Fprintf(buf, "\n%s%v (%s)", f, k, cf.config[k])
			}
			return errors.New(buf.String() + "\n\nremove all but one of those files, or\n" +
				" remove all but one of those extensions in conf, or\n specify lang at command line")
		}

		*file = f + match[0]
		l, err := strconv.Atoi(cf.config[match[0]])
		*lang = l
		return err
	}

	if l != 0 && needExt {
		s := strconv.Itoa(l)
		for k, v := range cf.config {
			if v == s {
				*file += "." + k
				return nil
			}
		}
		return fmt.Errorf("submit: extension must be specified for lang %q", l)
	}

	if l == 0 {
		ext := filepath.Ext(f)
		if len(ext) < 2 {
			return errors.New("submit: lang must be specified")
		}
		s, ok := cf.config[ext[1:]]
		if !ok {
			return fmt.Errorf("submit: unknown file extension %q, (you may add it in conf)", ext)
		}
		l, err := strconv.Atoi(s)
		if err != nil {
			return err
		}
		*lang = l
	}
	return nil
}

func (cf *cf) submit(file string, prob probCode, lang int) error {
	if _, ok := cf.config["user"]; !ok {
		return errors.New("submit: user must be configured (and logged in)")
	}

	err := cf.guessArgs(&file, prob, &lang)
	if err != nil {
		return err
	}

	err = cf.initClient()
	if err != nil {
		return err
	}

	f, err := os.Open(file)
	if err != nil {
		return err
	}
	defer f.Close()

	submitURL := contestURL(prob)
	resp, err := cf.client.Get(submitURL)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if !strings.Contains(resp.Request.URL.String(), "/problem/") {
		return errors.New("submit: probably not logged in or login expired; was redirected to: " + resp.Request.URL.String())
	}

	tree, err := html.Parse(resp.Body)
	if err != nil {
		return err
	}
	if tree == nil {
		return errors.New("submit: could not parse html response for /problem")
	}

	submitForm := selSubmit.MatchFirst(tree)
	if submitForm == nil {
		return errors.New("submit: could not match submit form\nnote that you could not submit during system testing (right after the contest)")
	}
	action := formAction(submitForm)
	fields := form(selInput.MatchAll(submitForm))
	fields.Del("sourceFile")
	fields.Set("submittedProblemIndex", prob.task)
	fields.Set("programTypeId", fmt.Sprintf("%d", lang))

	buf := &bytes.Buffer{}
	w := multipart.NewWriter(buf)
	for k, vs := range fields {
		for _, v := range vs {
			w.WriteField(k, v)
		}
	}
	fw, err := w.CreateFormFile("sourceFile", filepath.Base(file))
	if err != nil {
		return err
	}
	if _, err = io.Copy(fw, f); err != nil {
		return err
	}
	w.Close()

	// http://codeforces.com/contest/1436/problem/B?csrf_token=1d130cd435e8bf4e59f8888974641a3f
	// action starts at '?'
	req, err := http.NewRequest("POST", submitURL+action, buf)
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", w.FormDataContentType())
	resp, err = cf.client.Do(req)
	if err != nil {
		return err
	}
	resp.Body.Close()
	if resp.StatusCode == 200 || resp.StatusCode == 100 {
		log.Println("code submitted properly, you could safely kill this program from now on (by ^C)")
	} else {
		log.Printf("code submitted, response HTTP status: %d, you could safely kill this program from now on (by ^C)\n", resp.StatusCode)
	}

	cf.status(prob)
	return nil
}

func contestURL(prob probCode) string {
	contestOrGym := "contest"
	if prob.contest >= 100000 { // just guessing here
		contestOrGym = "gym"
	}
	return fmt.Sprintf(CFURL+"/%s/%d/problem/%s", contestOrGym, prob.contest, prob.task)
}