linkinfo/linkinfo.go

package linkinfo

import (
	"net/http"
	"net/url"
	"time"
)

type LinkHandler struct {
	Hosts   []string
	Handler func(link string) (*LinkInfo, error)
}

type LinkInfoApi struct {
	Client *http.Client

	Imgur        *ImgurInfoApi
	Youtube      *YoutubeInfoApi
	Twitter      *TwitterInfoApi
	linkHandlers []*LinkHandler
}

type LinkInfo struct {
	Title         string   `json:"title"`
	Description   string   `json:"description"`
	ContentType   string   `json:"type"`
	ContentLength int64    `json:"contentLength"`
	Duration      string   `json:"duration,omitempty"`
	Redirects     []string `json:"redirects,omitempty"`
}

func New(opts ...Option) *LinkInfoApi {
	api := &LinkInfoApi{
		Client: &http.Client{
			Timeout: 60 * time.Second,
		},
	}

	for _, opt := range opts {
		switch opt.(type) {
		case *ImgurOptions:
			api.Imgur = &ImgurInfoApi{api, opt.(*ImgurOptions)}
		case *YoutubeOptions:
			api.Youtube = &YoutubeInfoApi{api, opt.(*YoutubeOptions)}
		case *TwitterOptions:
			api.Twitter = &TwitterInfoApi{opts: opt.(*TwitterOptions)}
			api.Twitter.Init()
		}
	}

	api.registerDefaultHandlers()

	return api
}

func (i *LinkInfoApi) registerDefaultHandlers() {
	i.linkHandlers = make([]*LinkHandler, 0)

	if i.Imgur != nil {
		i.linkHandlers = append(i.linkHandlers, &LinkHandler{
			Hosts:   imgurHosts,
			Handler: i.Imgur.Handler,
		})
	}

	if i.Youtube != nil {
		i.linkHandlers = append(i.linkHandlers, &LinkHandler{
			Hosts:   youtubeHosts,
			Handler: i.Youtube.Handler,
		})
	}

	if i.Twitter != nil {
		i.linkHandlers = append(i.linkHandlers, &LinkHandler{
			Hosts:   twitterHosts,
			Handler: i.Twitter.Handler,
		})
	}
}

func (i *LinkInfoApi) AddHandler(handler *LinkHandler) {
	i.linkHandlers = append(i.linkHandlers, handler)
}

func (i *LinkInfoApi) Retrieve(link string) (*LinkInfo, error) {
	u, err := url.Parse(link)

	if err != nil {
		return nil, err
	}

	for _, handler := range i.linkHandlers {
		for _, host := range handler.Hosts {
			if host == u.Hostname() {
				return handler.Handler(link)
			}
		}
	}

	return i.DefaultLinkHandler(link)
}