From 3d25882d6bf689740506b9c569f6e0d30da6f6a5 Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Fri, 27 Sep 2019 21:55:40 -0400
Subject: [PATCH] Add response handling and 304 support to fetchJson.

---
 packages/ethers/src.ts/utils.ts |  3 +-
 packages/web/src.ts/index.ts    | 81 ++++++++++++++++++++++-----------
 2 files changed, 56 insertions(+), 28 deletions(-)

diff --git a/packages/ethers/src.ts/utils.ts b/packages/ethers/src.ts/utils.ts
index 060eaa2eb1..826633c2d2 100644
--- a/packages/ethers/src.ts/utils.ts
+++ b/packages/ethers/src.ts/utils.ts
@@ -33,7 +33,7 @@ import { UnicodeNormalizationForm } from "@ethersproject/strings";
 
 import { CoerceFunc } from "@ethersproject/abi";
 import { Bytes, BytesLike, Hexable } from "@ethersproject/bytes"
-import { ConnectionInfo, OnceBlockable, PollOptions } from "@ethersproject/web";
+import { ConnectionInfo, FetchJsonResponse, OnceBlockable, PollOptions } from "@ethersproject/web";
 import { EncryptOptions, ProgressCallback } from "@ethersproject/json-wallets";
 
 ////////////////////////
@@ -164,6 +164,7 @@ export {
     ConnectionInfo,
     OnceBlockable,
     PollOptions,
+    FetchJsonResponse,
 
     EncryptOptions,
     ProgressCallback
diff --git a/packages/web/src.ts/index.ts b/packages/web/src.ts/index.ts
index ca5e4c259a..b5d4a32a00 100644
--- a/packages/web/src.ts/index.ts
+++ b/packages/web/src.ts/index.ts
@@ -33,11 +33,16 @@ export type PollOptions = {
     onceBlock?: OnceBlockable
 };
 
+export type FetchJsonResponse = {
+    statusCode: number;
+    status: string;
+    headers: { [ header: string ]: string };
+};
 
 
 type Header = { key: string, value: string };
 
-export function fetchJson(connection: string | ConnectionInfo, json?: string, processFunc?: (value: any) => any): Promise<any> {
+export function fetchJson(connection: string | ConnectionInfo, json?: string, processFunc?: (value: any, response: FetchJsonResponse) => any): Promise<any> {
     let headers: { [key: string]: Header } = { };
 
     let url: string = null;
@@ -52,6 +57,8 @@ export function fetchJson(connection: string | ConnectionInfo, json?: string, pr
         referrer: "client",         // no-referrer, *client
     };
 
+    let allow304 = false;
+
     let timeout = 2 * 60 * 1000;
 
     if (typeof(connection) === "string") {
@@ -71,6 +78,9 @@ export function fetchJson(connection: string | ConnectionInfo, json?: string, pr
         if (connection.headers) {
             for (let key in connection.headers) {
                 headers[key.toLowerCase()] = { key: key, value: String(connection.headers[key]) };
+                if (["if-none-match", "if-modified-since"].indexOf(key.toLowerCase()) >= 0) {
+                    allow304 = true;
+                }
             }
         }
 
@@ -124,42 +134,59 @@ export function fetchJson(connection: string | ConnectionInfo, json?: string, pr
 
         return fetch(url, options).then((response) => {
             return response.text().then((body) => {
-                if (!response.ok) {
+
+                let json: any = null;
+
+                if (allow304 && response.status === 304) {
+                    // Leave json as null
+
+                } else if (!response.ok) {
                     logger.throwError("bad response", Logger.errors.SERVER_ERROR, {
                         status: response.status,
                         body: body,
                         type: response.type,
                         url: response.url
                     });
-                }
 
-                return body;
-            });
-
-        }).then((text) => {
-            let json: any = null;
-            try {
-                json = JSON.parse(text);
-            } catch (error) {
-                logger.throwError("invalid JSON", Logger.errors.SERVER_ERROR, {
-                    body: text,
-                    error: error,
-                    url: url
-                });
-            }
+                } else {
+                    try {
+                        json = JSON.parse(body);
+                    } catch (error) {
+                        logger.throwError("invalid JSON", Logger.errors.SERVER_ERROR, {
+                            body: body,
+                            error: error,
+                            url: url
+                        });
+                    }
+                }
 
-            if (processFunc) {
-                try {
-                    json = processFunc(json);
-                } catch (error) {
-                    logger.throwError("processing response error", Logger.errors.SERVER_ERROR, {
-                        body: json,
-                        error: error
-                    });
+                if (processFunc) {
+                    try {
+                        const headers: { [ header: string ]: string } = { };
+                        if (response.headers.forEach) {
+                            response.headers.forEach((value, key) => {
+                                headers[key.toLowerCase()] = value;
+                            });
+                        } else {
+                            (<() => Array<string>>((<any>(response.headers)).keys))().forEach((key) => {
+                                headers[key.toLowerCase()] = response.headers.get(key);
+                            });
+                        }
+                        json = processFunc(json, {
+                            statusCode: response.status,
+                            status: response.statusText,
+                            headers: headers
+                        });
+                    } catch (error) {
+                        logger.throwError("processing response error", Logger.errors.SERVER_ERROR, {
+                            body: json,
+                            error: error
+                        });
+                    }
                 }
-            }
 
-            return json;
+                return json;
+           });
 
         }, (error) => {
             throw error;