package linkinfo

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"path/filepath"
	"regexp"
	"strings"
)

const imgurApiUrl = "https://api.imgur.com/3/%s/%s.json"

var (
	imgurHosts = []string{"imgur.com", "i.imgur.com"}

	imgurAlbumRegexp = regexp.MustCompile("^/(a|gallery)/")
)

type ImgurOptions struct {
	Option

	ClientId string
}

type ImgurInfoApi struct {
	api  *LinkInfoApi
	opts *ImgurOptions
}

type imgurResponse struct {
	Success bool      `json:"success"`
	Data    imgurData `json:"data"`
}

type imgurData struct {
	Type        string `json:"type"`
	Title       string `json:"title"`
	Description string `json:"description"`
	Width       int    `json:"width"`
	Height      int    `json:"height"`
	Animated    bool   `json:"animated"`
	Nsfw        bool   `json:"nsfw"`
}

func (i *ImgurInfoApi) Handler(link string) (*LinkInfo, error) {
	if i.opts.ClientId == "" {
		return nil, errors.New("invalid client id")
	}

	u, err := url.Parse(link)

	if err != nil {
		return nil, err
	}

	id := filepath.Base(u.Path)

	extension := filepath.Ext(id)

	if extension != "" {
		id = id[0 : len(id)-len(extension)]
	}

	imageType := "image"

	if imgurAlbumRegexp.MatchString(link) {
		imageType = "album"
	}

	req, err := http.NewRequest("GET", fmt.Sprintf(imgurApiUrl, imageType, id), nil)

	if err != nil {
		return nil, err
	}

	req.Header.Set("Authorization", "Client-ID "+i.opts.ClientId)

	res, err := i.api.Client.Do(req)

	if err != nil {
		return nil, err
	}

	defer res.Body.Close()

	var response imgurResponse

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

	if !response.Success {
		return nil, errors.New("imgur api returned success=false")
	}

	var title string

	if response.Data.Title != "" {
		title = "Imgur - " + response.Data.Title
	} else {
		title = "Imgur - " + id

		switch response.Data.Type {
		case "image/jpeg":
			title += ".jpg"
		case "image/png":
			title += ".png"
		case "image/gif":
			title += ".gif"
		}
	}

	attribs := make([]string, 0)

	if imageType == "album" {
		attribs = append(attribs, "Album")
	} else {
		attribs = append(attribs, fmt.Sprintf("%dx%d", response.Data.Width, response.Data.Height))

		if response.Data.Animated {
			attribs = append(attribs, "Animated")
		}
	}

	title += " (" + strings.Join(attribs, ", ") + ")"

	if response.Data.Nsfw {
		attribs = append(attribs, "NSFW")
	}

	info := &LinkInfo{
		Title:       title,
		Description: response.Data.Description,
	}

	return info, nil
}