package ads

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"go.fifitido.net/twitch/api/endpoint"
)

type StartCommercialRequest struct {
	// The ID of the partner or affiliate broadcaster that wants to run the commercial. This ID must match the user ID found in the OAuth token.
	BroadcasterID string `json:"broadcaster_id"`

	// The length of the commercial to run, in seconds.
	// Twitch tries to serve a commercial that’s the requested length, but it may be shorter or longer.
	// The maximum length you should request is 180 seconds.
	Duration int `json:"duration"`
}

type StartCommercialResponse struct {
	// An array that contains a single object with the status of your start commercial request.
	Data []StartCommercialData `json:"data"`
}

type StartCommercialData struct {
	// The length of the commercial you requested. If you request a commercial that’s longer than 180 seconds, the API uses 180 seconds.
	Length int `json:"length"`

	// A message that indicates whether Twitch was able to serve an ad.
	Message string `json:"message"`

	// The number of seconds you must wait before running another commercial.
	RetryAfter int `json:"retry_after"`
}

// Starts a commercial on the specified channel.
//
// NOTE: Only partners and affiliates may run commercials and they must be streaming live at the time.
//
// NOTE: Only the broadcaster may start a commercial; the broadcaster’s editors and moderators may not start commercials on behalf of the broadcaster.
//
// Requires a user access token that includes the channel:edit:commercial scope.
func (a *Ads) StartCommercial(ctx context.Context, body *StartCommercialRequest) (*StartCommercialResponse, error) {

	r, w := io.Pipe()

	go func() {
		if err := json.NewEncoder(w).Encode(body); err != nil {
			w.CloseWithError(err)
		} else {
			w.Close()
		}
	}()

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint.Make(a.baseUrl, "channels/commercial"), r)
	if err != nil {
		return nil, err
	}

	res, err := a.client.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	statusOK := res.StatusCode >= 200 && res.StatusCode < 300
	if !statusOK {
		return nil, fmt.Errorf("failed to start commercial (%d)", res.StatusCode)
	}

	var data StartCommercialResponse
	if err := json.NewDecoder(res.Body).Decode(&data); err != nil {
		return nil, err
	}

	return &data, nil
}