From 562662dcaf9ec186bb20458d9ed07d3d4ab61b3e Mon Sep 17 00:00:00 2001
From: Robin Jarry <robin@jarry.cc>
Date: Mon, 25 Nov 2024 16:09:26 +0100
Subject: [PATCH] graphql: add support for multipart file uploads

Inspire from the python implementation in core.sr.ht.

Link: https://git.sr.ht/~sircmpwn/core.sr.ht/tree/7bcbc8ba8f4e/item/srht/graphql/client.py
Signed-off-by: Robin Jarry <robin@jarry.cc>
---
 client/graphql.go | 106 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 95 insertions(+), 11 deletions(-)

diff --git a/client/graphql.go b/client/graphql.go
index 59ce62e8dfeba275c3786b8f1abe2e8ef4aeb250..6ccb71307905bcfd5cd321f6ca3afcdce2d9d2c6 100644
--- a/client/graphql.go
+++ b/client/graphql.go
@@ -5,18 +5,23 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
+	"mime/multipart"
 	"net/http"
+	"net/textproto"
 
 	"git.sr.ht/~sircmpwn/core-go/config"
 	"git.sr.ht/~sircmpwn/core-go/crypto"
 
+	"github.com/99designs/gqlgen/graphql"
 	"github.com/vektah/gqlparser/v2/gqlerror"
 )
 
 type GraphQLQuery struct {
-	Query     string                 `json:"query"`
-	Variables map[string]interface{} `json:"variables"`
+	Query     string                    `json:"query"`
+	Variables map[string]interface{}    `json:"variables"`
+	Uploads   map[string]graphql.Upload `json:"-"`
 }
 
 type InternalAuth struct {
@@ -26,13 +31,8 @@ type InternalAuth struct {
 }
 
 func Do(ctx context.Context, username string, svc string,
-	query GraphQLQuery, result interface{}) error {
-
-	body, err := json.Marshal(query)
-	if err != nil {
-		panic(err) // Programmer error
-	}
-
+	query GraphQLQuery, result interface{},
+) error {
 	conf := config.ForContext(ctx)
 	origin, _ := conf.Get(svc, "api-origin")
 	if origin == "" {
@@ -42,13 +42,97 @@ func Do(ctx context.Context, username string, svc string,
 		panic(fmt.Errorf("No %s origin specified in config.ini", svc))
 	}
 
-	reader := bytes.NewBuffer(body)
+	var (
+		contentType string
+		reader      io.Reader
+	)
+
+	if len(query.Uploads) > 0 {
+		var (
+			body    *multipart.Writer
+			buf     bytes.Buffer
+			filemap map[string][]string
+			uploads []graphql.Upload
+			h       textproto.MIMEHeader
+		)
+
+		// Prepare the "map" field which associates the index of each
+		// uploaded file to a variable name. Related 'null' values are
+		// required in the variables map.
+		filemap = make(map[string][]string)
+		uploads = make([]graphql.Upload, 0, len(query.Uploads))
+		i := 0
+		for name, upload := range query.Uploads {
+			filemap[fmt.Sprintf("%d", i)] = []string{
+				fmt.Sprintf("variables.%s", name),
+			}
+			query.Variables[name] = nil
+			uploads = append(uploads, upload)
+			i++
+		}
+
+		// Create a new multipart body
+		body = multipart.NewWriter(&buf)
+
+		// Add the GraphQLQuery object serialized as JSON as a first
+		// multipart field named "operations".
+		h = make(textproto.MIMEHeader)
+		h.Add("Content-Disposition", `form-data; name="operations"`)
+		h.Add("Content-Type", "application/json")
+		pw, _ := body.CreatePart(h)
+		if err := json.NewEncoder(pw).Encode(query); err != nil {
+			panic(err) // Programmer error
+		}
+
+		// The second multipart field is the filemap we created
+		// previously. The field name must be "map" and be serialized
+		// as JSON.
+		h = make(textproto.MIMEHeader)
+		h.Add("Content-Disposition", `form-data; name="map"`)
+		h.Add("Content-Type", "application/json")
+		pw, _ = body.CreatePart(h)
+		if err := json.NewEncoder(pw).Encode(filemap); err != nil {
+			panic(err) // Programmer error
+		}
+
+		// Finally, add one multipart field per upload. Use the upload
+		// index as field name. The filename value is optional and can
+		// remain empty. If the content-type is not set, assume
+		// application/octet-stream as default.
+		for i, upload := range uploads {
+			h = make(textproto.MIMEHeader)
+			h.Add("Content-Disposition", fmt.Sprintf(
+				`form-data; name="%d"; filename=%q`, i, upload.Filename))
+			if upload.ContentType == "" {
+				upload.ContentType = "application/octet-stream"
+			}
+			h.Add("Content-Type", upload.ContentType)
+			pw, _ = body.CreatePart(h)
+			if _, err := io.Copy(pw, upload.File); err != nil {
+				return err
+			}
+		}
+		if err := body.Close(); err != nil {
+			return err
+		}
+		reader = &buf
+		contentType = fmt.Sprintf(
+			"multipart/form-data; boundary=%s", body.Boundary())
+	} else {
+		body, err := json.Marshal(query)
+		if err != nil {
+			panic(err) // Programmer error
+		}
+		reader = bytes.NewBuffer(body)
+		contentType = "application/json"
+	}
+
 	req, err := http.NewRequestWithContext(ctx,
 		"POST", fmt.Sprintf("%s/query", origin), reader)
 	if err != nil {
 		return err
 	}
-	req.Header.Add("Content-Type", "application/json")
+	req.Header.Add("Content-Type", contentType)
 	auth := InternalAuth{
 		Name:     username,
 		ClientID: config.ServiceName(ctx),