package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"sort"
	"strings"
)

type ImageCompression interface {
	Compress(url string) (location string, err error)
}

// Tinify
type Tinify struct {
	// API Key
	key string
}

func (t *Tinify) Compress(url string) (location string, err error) {
	fileExtension := func() string {
		spliced := strings.Split(url, ".")
		return spliced[len(spliced)-1]
	}()
	supportedTypes := []string{"jpg", "jpeg", "png"}
	sort.Strings(supportedTypes)
	i := sort.SearchStrings(supportedTypes, strings.ToLower(fileExtension))
	if !(i < len(supportedTypes) && supportedTypes[i] == strings.ToLower(fileExtension)) {
		err = errors.New("file not supported")
		return
	}
	// Shrink
	shrinkedUrl, e := t.shrink(url)
	if e != nil {
		err = errors.New("failed to compress file")
		return
	}
	// Create temp file
	file, e := ioutil.TempFile("", "tiny-*."+fileExtension)
	if e != nil {
		err = errors.New("failed to create temporary file")
		return
	}
	defer func() {
		// Cleanup
		_ = file.Close()
		_ = os.Remove(file.Name())
	}()
	// Resize and download image
	e = t.resize(shrinkedUrl, file)
	if e != nil {
		err = errors.New("failed to resize file or save compressed file")
		return
	}
	hashFile, e := os.Open(file.Name())
	defer func() { _ = hashFile.Close() }()
	if e != nil {
		err = errors.New("failed to open temporary file")
		return
	}
	fileName, err := getSHA256(hashFile)
	if err != nil {
		return
	}
	location, err = SelectedMediaStorage.Upload(fileName+"."+fileExtension, file)
	return
}

func (t *Tinify) shrink(source string) (string, error) {
	type Source struct {
		Url string `json:"url"`
	}
	data := struct {
		Source Source `json:"source"`
	}{
		Source: Source{
			Url: source,
		},
	}
	body := new(bytes.Buffer)
	err := json.NewEncoder(body).Encode(data)
	if err != nil {
		return "", err
	}
	req, err := http.NewRequest("POST", "https://api.tinify.com/shrink", body)
	if err != nil {
		return "", err
	}
	req.SetBasicAuth("api", t.key)
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", err
	}
	if resp.StatusCode != 201 {
		return "", errors.New("not 201 response code")
	}
	return resp.Header.Get("Location"), nil
}

func (t *Tinify) resize(output string, file *os.File) error {
	type Resize struct {
		Method string `json:"method"`
		Width  int    `json:"width"`
	}
	data := struct {
		Resize Resize `json:"resize"`
	}{
		Resize: Resize{
			Method: "scale",
			Width:  2000,
		},
	}
	body := new(bytes.Buffer)
	err := json.NewEncoder(body).Encode(data)
	if err != nil {
		return err
	}
	req, err := http.NewRequest("POST", output, body)
	if err != nil {
		return err
	}
	req.SetBasicAuth("api", t.key)
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	if resp.StatusCode != 200 {
		return errors.New("not 201 response code")
	}
	defer resp.Body.Close()
	_, err = io.Copy(file, resp.Body)
	return err
}