package channels

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

	"github.com/google/go-querystring/query"
	"go.fifitido.net/twitch/api/endpoint"
	"go.fifitido.net/twitch/api/types"
)

type GetChannelFollowersParams struct {
	// A user’s ID. Use this parameter to see whether the user follows this broadcaster.
	// If specified, the response contains this user if they follow the broadcaster.
	// If not specified, the response contains all users that follow the broadcaster.
	//
	// Using this parameter requires both a user access token with the moderator:read:followers scope and the user ID
	// in the access token match the broadcaster_id or be the user ID for a moderator of the specified broadcaster.
	UserID *string `url:"user_id,omitempty"`

	// The broadcaster’s ID. Returns the list of users that follow this broadcaster.
	BroadcasterID string `url:"broadcaster_id"`

	// The maximum number of items to return per page in the response. The minimum page size is 1 item per page and the maximum is 100. The default is 20.
	First *int `url:"first,omitempty"`

	// The cursor used to get the next page of results. The Pagination object in the response contains the cursor’s value.
	// Read more: https://dev.twitch.tv/docs/api/guide#pagination
	After *types.Cursor `url:"after,omitempty"`
}

type GetChannelFollowersResponse struct {
	// The list of users that follow the specified broadcaster. The list is in descending order by followed_at (with the most recent follower first).
	// The list is empty if nobody follows the broadcaster, the specified user_id isn’t in the follower list,
	// the user access token is missing the moderator:read:followers scope, or the user isn’t the broadcaster or moderator for the channel.
	Data []ChannelFollower `json:"data"`

	// Contains the information used to page through the list of results. The object is empty if there are no more pages left to page through.
	// Read more: https://dev.twitch.tv/docs/api/guide#pagination
	Pagination types.Pagination `json:"pagination"`

	// The total number of users that follow this broadcaster.
	// As someone pages through the list, the number of users may change as users follow or unfollow the broadcaster.
	Total int `json:"total"`
}

type ChannelFollower struct {
	// An ID that uniquely identifies the user that’s following the broadcaster.
	UserID string `json:"user_id"`

	// The user’s login name.
	UserLogin string `json:"user_login"`

	// The user’s display name.
	UserName string `json:"user_name"`

	// The UTC timestamp when the user started following the broadcaster.
	FollowedAt time.Time `json:"followed_at"`
}

// Gets a list of users that follow the specified broadcaster. You can also use this endpoint to see whether a specific user follows the broadcaster.
//
// - Requires a user access token that includes the moderator:read:followers scope.
//
// - The ID in the broadcaster_id query parameter must match the user ID in the access token or the user ID in the access token must be a moderator for the specified broadcaster.
//
// This endpoint will return specific follower information only if both of the above are true.
// If a scope is not provided or the user isn’t the broadcaster or a moderator for the specified channel,
// only the total follower count will be included in the response.
func (c *Channels) GetChannelFollowers(ctx context.Context, params *GetChannelFollowersParams) (*GetChannelFollowersResponse, error) {
	v, _ := query.Values(params)

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint.Make(c.baseUrl, "channels/followers", v), nil)
	if err != nil {
		return nil, err
	}

	res, err := c.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 get channel followers (%d)", res.StatusCode)
	}

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

	return &data, nil
}