docs_: better usage docs for status-backend (#5955)

README.md

@@ -11,7 +11,8 @@
 - [How to run a Bootnode](BOOTNODE.md)
 - [How to run a Mailserver](MAILSERVER.md)
 - [How to run a Waku node](./_examples/README.md#run-waku-node)
-- [How to configure status-go](/config)
+- [How to configure status-go](/config/README.md)
+- [How to run status-go as HTTP server](/cmd/status-backend/README.md)
 
 ## Policies
 

cmd/status-backend/README.md

@@ -1,4 +1,4 @@
-# Description
+# 📝Description
 
 Welcome to `status-backend`. This is a tool for debugging and testing `status-go`.
 In contrast to existing `statusd` and `status-cli`, the `status-backend` exposes full status-go API through HTTP.
@@ -13,17 +13,87 @@ This allows to communicate with status-go through HTTP the same way as `status-d
 - subscribe to status-go signals
 - etc.
 
-# status-go API
+# 📍status-go API
 
-## Public methods in `./mobile/status.go`
+> [!NOTE]  
+> Unfortunately, for now there is no convenient docs like OpenAPI
 
-Only specific function signatures are currently supported:
+## 1️⃣ Public methods in `./mobile/status.go`
+
+### Description
+
+Any **public** functions in `./mobile/status.go` with the one of the following signatures:
    - `func(string) string` - 1 argument, 1 return 
    - `func() string` - 0 argument, 1 return
 
+### Address
+
+Endpoints address: `http://<address>/statusgo/<function-name>`.  
+
+Here, `statusgo` is the name of the package in `/mobile/status.go`. We might create more APIs next to it in the future.
+
+### Response
+
+Responses have JSON body with a single `error` field.  
+If `error` is empty, no error occurred.
+
+The structure of response is defined in [`APIResponse`](https://github.com/status-im/status-go/blob/91c6949cd25449d5459581a21f2c8b929290ced0/mobile/types.go#L9-L12):
+```go
+// APIResponse generic response from API.
+type APIResponse struct {
+    Error string `json:"error"`
+}
+```
+
+### Parameters
+
+Parameters are passed as request JSON body.  
+Specific parameters for each endpoint should be checked in the source code.
+
+### How to read the source code?
+
+As example, let's look at [`CreateAccountAndLogin`](https://github.com/status-im/status-go/blob/fc36a7e980fc8f73dd36d7e3db29675ddff1d5dc/mobile/status.go#L415-L417).
+```go
+func CreateAccountAndLogin(requestJSON string) string {
+	return callWithResponse(createAccountAndLogin, requestJSON)
+}
+```
+
+1. The function has 1 JSON string argument and 1 JSON string return value.
+2. The function wraps a private `createAccountAndLogin` with `callWithResponse`.  
+`callWithResponse` does some internal magic like logging the request and response.   
+So we should check [the private function](https://github.com/status-im/status-go/blob/fc36a7e980fc8f73dd36d7e3db29675ddff1d5dc/mobile/status.go#L419) for real arguments and return values:
+    ```go
+    func createAccountAndLogin(requestJSON string) string {
+        var request requests.CreateAccount
+        err := json.Unmarshal([]byte(requestJSON), &request)
+        // ...
+    }
+    ```
+3. We can see that the parameters are unmarshalled to [`requests.CreateAccount`](https://github.com/status-im/status-go/blob/f660be0daa7cc742a07f6a139ea5ac9966f3ebe0/protocol/requests/create_account.go#L35):
+    ```go
+    type CreateAccount struct {
+        RootDataDir   string `json:"rootDataDir"`
+        KdfIterations int    `json:"kdfIterations"`
+        // ...
+    ```
+4. We can also see that each the response is formed as [`makeJSONResponse(err)`](https://github.com/status-im/status-go/blob/fc36a7e980fc8f73dd36d7e3db29675ddff1d5dc/mobile/status.go#L422-L424):
+    ```go
+    if err != nil {
+        return makeJSONResponse(err)
+    }
+    ```
+   ... which wraps the error to [`APIResponse`](https://github.com/status-im/status-go/blob/91c6949cd25449d5459581a21f2c8b929290ced0/mobile/types.go#L9-L12):
+    ```go
+    // APIResponse generic response from API.
+    type APIResponse struct {
+        Error string `json:"error"`
+    }
+    ```
+
 ### Unsupported methods
 
-Attempt to call any other functions will return `501: Not Implemented` HTTP code.  
+Attempt to call any functions with unsupported signatures will return `501: Not Implemented` HTTP code.  
 For example, [`VerifyAccountPassword`](https://github.com/status-im/status-go/blob/669256095e16d953ca1af4954b90ca2ae65caa2f/mobile/status.go#L275-L277) has 3 arguments: 
 ```go
 func VerifyAccountPassword(keyStoreDir, address, password string) string {
@@ -38,16 +108,19 @@ For example, https://github.com/status-im/status-go/pull/5865 fixes some of thes
 
 Deprecated methods will have `Deprecation: true` HTTP header.
 
-## Signals in `./signal`
+## 2️⃣ Signals in `./signal`
 
-Each signal has [this structure](https://github.com/status-im/status-go/blob/c9b777a2186364b8f394ad65bdb18b128ceffa70/signal/signals.go#L30-L33):
+> [!NOTE]  
-```go
+> Unfortunately, there is no description of when any expected signals will appear.  
-// Envelope is a general signal sent upward from node to RN app
+> For now, you have to check the source code.
-type Envelope struct {
+
-    Type  string      `json:"type"`
+### Address
-    Event interface{} `json:"event"`
+
-}
+Signals are available at `ws://<address>/signals`.
-```
+
+Connect to it as the first thing when running `status-backend`.
+
+### Available signals
 
 List of possible events can be found in `./signal/event_*.go` files.
 
@@ -59,6 +132,18 @@ const (
 )
 ```
 
+### Signals structure
+
+Each signal has [this structure](https://github.com/status-im/status-go/blob/c9b777a2186364b8f394ad65bdb18b128ceffa70/signal/signals.go#L30-L33):
+```go
+// Envelope is a general signal sent upward from node to RN app
+type Envelope struct {
+    Type  string      `json:"type"`
+    Event interface{} `json:"event"`
+}
+```
+
+Here, `type` is the name of the event, e.g. `node.login`.     
 And the structure of this event is [defined in the same file](https://github.com/status-im/status-go/blob/6bcf5f1289f9160168574290cbd6f90dede3f8f6/signal/events_node.go#L36-L42):
 ```go
 // NodeLoginEvent returns the result of the login event
@@ -70,7 +155,6 @@ type NodeLoginEvent struct {
 }
 ```
 
-
 So the signal for `node.login` event will look like this (with corresponding data):
 ```json
 {
@@ -84,9 +168,33 @@ So the signal for `node.login` event will look like this (with corresponding dat
 }
 ```
 
-## Services in `./services/**/api.go`
+## 3️⃣ Services in `./services/**/api.go`
 
-Services are registered in go-ethereum JSON-RPC server. To call such method, send request to `statusgo/CallRPC` endpoint.
+Services are registered in the [go-ethereum JSON-RPC](https://geth.ethereum.org/docs/interacting-with-geth/rpc) server.   
+All `./services/**/api.go` are registered as services in geth. 
+
+Each method name has form `<namespace>_<method>`. In most cases namespace is the directory name, but it can be ensured in the `APIs` method of each service. For example, for [wallet service](https://github.com/status-im/status-go/blob/1d173734a608de2d71480d6ad39f4559f11a75e2/services/wallet/service.go#L288-L298):
+```go
+// APIs returns list of available RPC APIs.
+func (s *Service) APIs() []gethrpc.API {
+    return []gethrpc.API{
+        {
+            Namespace: "wallet",
+            Version:   "0.1.0",
+            Service:   NewAPI(s),
+            Public:    true,
+        },
+    }
+}
+```
+
+### Address
+
+These methods are available through `/statusgo/CallRPC` endpoint defined [here](https://github.com/status-im/status-go/blob/fc36a7e980fc8f73dd36d7e3db29675ddff1d5dc/mobile/status.go#L249-L260).
+
+This is the way desktop and mobile clients call these methods. You don't have to run a separate geth HTTP server for this.
+
+### Arguments
 
 For example:
 ```http request
@@ -105,12 +213,14 @@ POST http://localhost:12345/statusgo/CallRPC
 }
 ```
 
+Please reference to the source code for the list of methods and its arguments.
+
 ### Notes
 
 1. In this case, there's no limitation to the number of arguments, comparing to `mobile/status.go`, so ll method are supported.
 2. Deprecated methods won't have a corresponding `Deprecated: true`
 
-# Usage
+# 🏃‍♂️Usage
 
 Start the app with the address to listen to:
 ```shell
@@ -135,21 +245,35 @@ Access the exposed API with any HTTP client you prefer:
     - [Python](https://pypi.org/project/requests/)
     - [Go](https://pkg.go.dev/net/http)
 
-# Simple flows
+# 👌 Simple flows
 
 In most cases to start testing you'll need some boilerplate. Below are the simple call flows for common cases.
 
 ## Create account and login
 
-1. `InitializeApplication`
+1. Subscribe to `/signals`
-2. `CreateAccountAndLogin`
+2. Call  `/statusgo/InitializeApplication`
-3. `wakuext_startMessenger`
+3. Create an account
-4. `wallet_startWallet`
+   1. Call `/statusgo/CreateAccountAndLogin`
-5. `settings_getSettings` (temporary workaround, otherwise settings don't get saved into DB)
+   2. Wait for `node.login` signal 
+      - If `error` is empty, no error occurred
+      - If `error` is not empty, stop the operation
+4. Start required services 
+   1. Call  `/statusgo/CallRPC` with `{ "method": "wakuext_startMessenger", "params": [] }`
+   2. Call  `/statusgo/CallRPC` with `{ "method": "wallet_startWallet", "params": [] }`
+5. Apply temporary workarounds:
+   1. Call  `/statusgo/CallRPC` with `{ "method": "settings_getSettings", "params": [] }`  
+   _(otherwise settings don't get saved into DB)_
 
 ## Login into account
 
-1. `InitializeApplication`
+1. Subscribe to `/signals`
-2. `LoginAccount`
+2. Call  `/statusgo/InitializeApplication`
-3. `wakuext_startMessenger`
+3. Create an account
-4. `wallet_startWallet`
+   1. Call `/statusgo/LoginAccount`
+   2. Wait for `node.login` signal
+      - If `error` is empty, no error occurred
+      - If `error` is not empty, stop the operation
+4. Start required services
+   1. Call  `/statusgo/CallRPC` with `{ "method": "wakuext_startMessenger", "params": [] }`
+   2. Call  `/statusgo/CallRPC` with `{ "method": "wallet_startWallet", "params": [] }`