package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"strings"
	"time"

	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
)

const discordRequestTimeout = 2 * time.Second

type (
	createChannelInviteReq struct {
		MaxAge    int64 `json:"max_age"`
		MaxUses   int64 `json:"max_uses"`
		Temporary bool  `json:"temporary"`
		Unique    bool  `json:"unique"`
		// more unsupported params
	}

	createChannelInviteResp struct {
		Code string `json:"code"`
		// more unsupported params
	}
)

func createInvite() (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), discordRequestTimeout)
	defer cancel()

	var (
		body   = new(bytes.Buffer)
		err    error
		reqURL = fmt.Sprintf("https://discord.com/api/channels/%s/invites", cfg.ChannelID)
	)

	if err = json.NewEncoder(body).Encode(createChannelInviteReq{
		MaxAge:    int64(cfg.ExpireIn / time.Second),
		MaxUses:   cfg.Uses,
		Temporary: false,
		Unique:    true,
	}); err != nil {
		return "", errors.Wrap(err, "encoding request body")
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, reqURL, body)
	if err != nil {
		return "", errors.Wrap(err, "creating request")
	}

	req.Header.Set("Authorization", strings.Join([]string{"Bot", cfg.DiscordBotToken}, " "))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-Audit-Log-Reason", fmt.Sprintf("twitch-bot-tools/dc-invite requested for %s", cfg.SendTo))

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", errors.Wrap(err, "executing request")
	}
	defer func() {
		if err := resp.Body.Close(); err != nil {
			logrus.WithError(err).Error("closing response body (leaked fd)")
		}
	}()

	if resp.StatusCode != http.StatusOK {
		return "", errors.Errorf("unexpected status %d", resp.StatusCode)
	}

	var invite createChannelInviteResp
	if err = json.NewDecoder(resp.Body).Decode(&invite); err != nil {
		return "", errors.Wrap(err, "decoding invite response")
	}

	return invite.Code, nil
}