gitech

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// Copyright 2021 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package lfs
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import (
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	"bytes"
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	"context"
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	"errors"
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	"fmt"
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	"io"
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	"net/http"
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	"net/url"
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	"strings"
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	"code.gitea.io/gitea/modules/json"
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	"code.gitea.io/gitea/modules/log"
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	"code.gitea.io/gitea/modules/proxy"
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)
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const httpBatchSize = 20
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// HTTPClient is used to communicate with the LFS server
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// https://github.com/git-lfs/git-lfs/blob/main/docs/api/batch.md
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type HTTPClient struct {
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	client    *http.Client
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	endpoint  string
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	transfers map[string]TransferAdapter
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}
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// BatchSize returns the preferred size of batchs to process
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func (c *HTTPClient) BatchSize() int {
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	return httpBatchSize
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}
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func newHTTPClient(endpoint *url.URL, httpTransport *http.Transport) *HTTPClient {
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	if httpTransport == nil {
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		httpTransport = &http.Transport{
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			Proxy: proxy.Proxy(),
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		}
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	}
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	hc := &http.Client{
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		Transport: httpTransport,
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	}
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	basic := &BasicTransferAdapter{hc}
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	client := &HTTPClient{
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		client:   hc,
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		endpoint: strings.TrimSuffix(endpoint.String(), "/"),
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		transfers: map[string]TransferAdapter{
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			basic.Name(): basic,
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		},
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	}
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	return client
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}
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func (c *HTTPClient) transferNames() []string {
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	keys := make([]string, len(c.transfers))
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	i := 0
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	for k := range c.transfers {
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		keys[i] = k
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		i++
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	}
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	return keys
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}
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func (c *HTTPClient) batch(ctx context.Context, operation string, objects []Pointer) (*BatchResponse, error) {
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	log.Trace("BATCH operation with objects: %v", objects)
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	url := fmt.Sprintf("%s/objects/batch", c.endpoint)
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	request := &BatchRequest{operation, c.transferNames(), nil, objects}
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	payload := new(bytes.Buffer)
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	err := json.NewEncoder(payload).Encode(request)
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	if err != nil {
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		log.Error("Error encoding json: %v", err)
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		return nil, err
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	}
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	req, err := createRequest(ctx, http.MethodPost, url, map[string]string{"Content-Type": MediaType}, payload)
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	if err != nil {
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		return nil, err
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	}
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	res, err := performRequest(ctx, c.client, req)
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	if err != nil {
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		return nil, err
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	}
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	defer res.Body.Close()
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	var response BatchResponse
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	err = json.NewDecoder(res.Body).Decode(&response)
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	if err != nil {
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		log.Error("Error decoding json: %v", err)
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		return nil, err
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	}
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	if len(response.Transfer) == 0 {
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		response.Transfer = "basic"
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	}
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	return &response, nil
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}
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// Download reads the specific LFS object from the LFS server
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func (c *HTTPClient) Download(ctx context.Context, objects []Pointer, callback DownloadCallback) error {
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	return c.performOperation(ctx, objects, callback, nil)
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}
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// Upload sends the specific LFS object to the LFS server
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func (c *HTTPClient) Upload(ctx context.Context, objects []Pointer, callback UploadCallback) error {
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	return c.performOperation(ctx, objects, nil, callback)
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}
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func (c *HTTPClient) performOperation(ctx context.Context, objects []Pointer, dc DownloadCallback, uc UploadCallback) error {
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	if len(objects) == 0 {
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		return nil
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	}
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	operation := "download"
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	if uc != nil {
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		operation = "upload"
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	}
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	result, err := c.batch(ctx, operation, objects)
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	if err != nil {
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		return err
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	}
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	transferAdapter, ok := c.transfers[result.Transfer]
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	if !ok {
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		return fmt.Errorf("TransferAdapter not found: %s", result.Transfer)
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	}
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	for _, object := range result.Objects {
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		if object.Error != nil {
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			objectError := errors.New(object.Error.Message)
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			log.Trace("Error on object %v: %v", object.Pointer, objectError)
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			if uc != nil {
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				if _, err := uc(object.Pointer, objectError); err != nil {
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					return err
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				}
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			} else {
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				if err := dc(object.Pointer, nil, objectError); err != nil {
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					return err
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				}
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			}
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			continue
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		}
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		if uc != nil {
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			if len(object.Actions) == 0 {
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				log.Trace("%v already present on server", object.Pointer)
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				continue
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			}
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			link, ok := object.Actions["upload"]
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			if !ok {
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				log.Debug("%+v", object)
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				return errors.New("missing action 'upload'")
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			}
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			content, err := uc(object.Pointer, nil)
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			if err != nil {
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				return err
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			}
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			err = transferAdapter.Upload(ctx, link, object.Pointer, content)
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			if err != nil {
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				return err
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			}
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			link, ok = object.Actions["verify"]
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			if ok {
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				if err := transferAdapter.Verify(ctx, link, object.Pointer); err != nil {
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					return err
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				}
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			}
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		} else {
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			link, ok := object.Actions["download"]
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			if !ok {
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				log.Debug("%+v", object)
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				return errors.New("missing action 'download'")
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			}
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			content, err := transferAdapter.Download(ctx, link)
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			if err != nil {
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				return err
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			}
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			if err := dc(object.Pointer, content, nil); err != nil {
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				return err
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			}
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		}
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	}
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	return nil
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}
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// createRequest creates a new request, and sets the headers.
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func createRequest(ctx context.Context, method, url string, headers map[string]string, body io.Reader) (*http.Request, error) {
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	log.Trace("createRequest: %s", url)
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	req, err := http.NewRequestWithContext(ctx, method, url, body)
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	if err != nil {
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		log.Error("Error creating request: %v", err)
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		return nil, err
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	}
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	for key, value := range headers {
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		req.Header.Set(key, value)
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	}
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	req.Header.Set("Accept", MediaType)
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	return req, nil
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}
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// performRequest sends a request, optionally performs a callback on the request and returns the response.
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// If the status code is 200, the response is returned, and it will contain a non-nil Body.
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// Otherwise, it will return an error, and the Body will be nil or closed.
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func performRequest(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
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	log.Trace("performRequest: %s", req.URL)
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	res, err := client.Do(req)
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	if err != nil {
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		select {
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		case <-ctx.Done():
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			return res, ctx.Err()
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		default:
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		}
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		log.Error("Error while processing request: %v", err)
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		return res, err
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	}
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	if res.StatusCode != http.StatusOK {
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		defer res.Body.Close()
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		return res, handleErrorResponse(res)
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	}
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	return res, nil
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}
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func handleErrorResponse(resp *http.Response) error {
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	var er ErrorResponse
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	err := json.NewDecoder(resp.Body).Decode(&er)
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	if err != nil {
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		if err == io.EOF {
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			return io.ErrUnexpectedEOF
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		}
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		log.Error("Error decoding json: %v", err)
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		return err
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	}
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	log.Trace("ErrorResponse: %v", er)
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	return errors.New(er.Message)
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}
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