/*
Copyright 2016 The Fission Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package client

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"mime/multipart"
	"net/http"
	"net/url"
	"os"
	"strings"

	"go.opencensus.io/plugin/ochttp"
	"golang.org/x/net/context/ctxhttp"

	"github.com/fission/fission/storagesvc"
)

type (
	Client struct {
		url        string
		httpClient *http.Client
	}
)

// Client creates a storage service client.
func MakeClient(url string) *Client {
	return &Client{
		url: strings.TrimSuffix(url, "/") + "/v1",
		httpClient: &http.Client{
			Transport: &ochttp.Transport{},
		},
	}
}

// Upload sends the local file pointed to by filePath to the storage
// service, along with the metadata.  It returns a file ID that can be
// used to retrieve the file.
func (c *Client) Upload(ctx context.Context, filePath string, metadata *map[string]string) (string, error) {
	fi, err := os.Stat(filePath)
	if err != nil {
		return "", err
	}
	fileSize := fi.Size()

	buf := &bytes.Buffer{}
	bodyWriter := multipart.NewWriter(buf)
	fileWriter, err := bodyWriter.CreateFormFile("uploadfile", filePath)
	if err != nil {
		return "", err
	}

	f, err := os.Open(filePath)
	if err != nil {
		return "", err
	}

	_, err = io.Copy(fileWriter, f)
	if err != nil {
		return "", err
	}

	contentType := bodyWriter.FormDataContentType()
	bodyWriter.Close()

	req, err := http.NewRequest(http.MethodPost, c.url+"/archive", buf)
	if err != nil {
		return "", err
	}
	req.Header["X-File-Size"] = []string{fmt.Sprintf("%v", fileSize)}
	req.Header["Content-Type"] = []string{contentType}

	resp, err := ctxhttp.Do(ctx, c.httpClient, req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}
	if resp.StatusCode != http.StatusOK {
		msg := fmt.Sprintf("Upload error %v", resp.Status)
		return "", errors.New(msg)
	}

	var ur storagesvc.UploadResponse
	err = json.Unmarshal(body, &ur)
	if err != nil {
		return "", err
	}

	return ur.ID, nil
}

// GetUrl returns an HTTP URL that can be used to download the file pointed to by ID
func (c *Client) GetUrl(id string) string {
	return fmt.Sprintf("%v/archive?id=%v", c.url, url.PathEscape(id))
}

// Download fetches the file identified by ID to the local file path.
// filePath must not exist.
func (c *Client) Download(ctx context.Context, id string, filePath string) error {
	// url for id
	url := c.GetUrl(id)

	// quit if file exists
	_, err := os.Stat(filePath)
	if err == nil || !os.IsNotExist(err) {
		return errors.New(fmt.Sprintf("file already exists: %v", filePath))
	}

	// create
	f, err := os.Create(filePath)
	if err != nil {
		return err
	}
	defer f.Close()

	// make request
	resp, err := ctxhttp.Get(ctx, c.httpClient, url)
	if err != nil {
		fmt.Println(err)
		os.Remove(filePath)
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		msg := fmt.Sprintf("HTTP error %v", resp.StatusCode)
		os.Remove(filePath)
		return errors.New(msg)
	}

	// download and write data
	_, err = io.Copy(f, resp.Body)
	if err != nil {
		return err
	}

	return nil
}

func (c *Client) Delete(ctx context.Context, id string) error {
	url := c.GetUrl(id)

	req, err := http.NewRequest(http.MethodDelete, url, nil)
	if err != nil {
		return err
	}

	resp, err := ctxhttp.Do(ctx, c.httpClient, req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return errors.New(fmt.Sprintf("HTTP error %v", resp.StatusCode))
	}

	return nil
}