first impl of client lib for herodb

examples/clients/herodb.vsh

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+#!/usr/bin/env -S v -n -w -enable-globals run
+
+import incubaid.herolib.clients.herodb
+
+// Initialize the client
+mut client := herodb.new(herodb.Config{
+    url: 'http://localhost:3000'
+})!
+
+println('Connecting to HeroDB at ${client.server_url}...')
+
+// List instances
+instances := client.list_instances()!
+
+println('Found ${instances.len} instances:')
+
+for instance in instances {
+    println('----------------------------------------')
+    println('Index:       ${instance.index}')
+    println('Name:        ${instance.name}')
+    println('Created At:  ${instance.created_at}')
+    
+    // Parse backend info
+    backend := instance.get_backend_info() or {
+        println('Backend:     Unknown/Error (${err})')
+        continue
+    }
+    
+    println('Backend Type: ${backend.type_name}')
+    if backend.path != '' {
+        println('Backend Path: ${backend.path}')
+    }
+}
+println('----------------------------------------')

lib/clients/herodb/README.md

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+# HeroDB Client
+
+A V client library for interacting with the HeroDB JSON-RPC API.
+
+## Features
+
+- Connects to HeroDB's JSON-RPC server (default port 3000).
+- Lists running database instances.
+- Parses polymorphic backend types (InMemory, Redb, LanceDb).
+
+## Usage
+
+```v
+import incubaid.herolib.clients.herodb
+
+fn main() {
+    // Initialize the client
+    mut client := herodb.new(herodb.Config{
+        url: 'http://localhost:3000'
+    })!
+
+    // List instances
+    instances := client.list_instances()!
+
+    for instance in instances {
+        println('Index: ${instance.index}')
+        println('Name: ${instance.name}')
+        
+        // Parse backend info
+        backend := instance.get_backend_info()!
+        println('Backend: ${backend.type_name}')
+        if backend.path != '' {
+            println('Path: ${backend.path}')
+        }
+        println('---')
+    }
+}
+```
+
+## API Reference
+
+### `fn new(cfg Config) !HeroDB`
+
+Creates a new HeroDB client instance.
+
+### `fn (mut self HeroDB) list_instances() ![]InstanceMetadata`
+
+Retrieves a list of all currently loaded database instances.
+
+### `fn (m InstanceMetadata) get_backend_info() !BackendInfo`
+
+Helper method to parse the `backend_type` field from `InstanceMetadata` into a structured `BackendInfo` object.

lib/clients/herodb/herodb.v

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+module herodb
+
+import json
+import incubaid.herolib.core.httpconnection
+
+// JSON-RPC 2.0 Structures
+
+struct JsonRpcRequest {
+	jsonrpc string = '2.0'
+	method  string
+	params  []string
+	id      int
+}
+
+struct JsonRpcResponse[T] {
+	jsonrpc string
+	result  T
+	error   ?JsonRpcError
+	id      int
+}
+
+struct JsonRpcError {
+	code    int
+	message string
+	data    string
+}
+
+// HeroDB Specific Structures
+
+pub struct InstanceMetadata {
+pub:
+	index        int
+	name         string
+	// backend_type can be a string ("InMemory") or an object ({"Redb": "path"}).
+	// We use the `raw` attribute to capture the raw JSON and parse it manually.
+	backend_type string @[raw]
+	created_at   string
+}
+
+// Helper struct to represent the parsed backend info in a usable way
+pub struct BackendInfo {
+pub:
+	type_name string // "InMemory", "Redb", "LanceDb"
+	path      string // Empty for InMemory
+}
+
+pub struct HeroDB {
+pub:
+	server_url string
+pub mut:
+	conn ?&httpconnection.HTTPConnection
+}
+
+pub struct Config {
+pub:
+	url string = 'http://localhost:3000'
+}
+
+pub fn new(cfg Config) !HeroDB {
+	return HeroDB{
+		server_url: cfg.url
+	}
+}
+
+pub fn (mut self HeroDB) connection() !&httpconnection.HTTPConnection {
+	if mut conn := self.conn {
+		return conn
+	}
+
+	mut new_conn := httpconnection.new(
+		name:  'herodb'
+		url:   self.server_url
+		retry: 3
+	)!
+	self.conn = new_conn
+	return new_conn
+}
+
+fn (mut self HeroDB) rpc_call[T](method string) !T {
+	mut conn := self.connection()!
+
+	req := JsonRpcRequest{
+		method: method
+		id:     1
+		params: []
+	}
+
+	response := conn.post_json_generic[JsonRpcResponse[T]](
+		method:     .post
+		prefix:     ''
+		data:       json.encode(req)
+		dataformat: .json
+	)!
+
+	if err := response.error {
+		return error('RPC Error ${err.code}: ${err.message}')
+	}
+
+	return response.result
+}
+
+pub fn (mut self HeroDB) list_instances() ![]InstanceMetadata {
+	return self.rpc_call[[]InstanceMetadata]('db_listInstances')!
+}
+
+pub fn (m InstanceMetadata) get_backend_info() !BackendInfo {
+	if m.backend_type.len == 0 {
+		return error('empty backend_type')
+	}
+	if m.backend_type[0] == `"` {
+		// It's a string
+		val := json.decode(string, m.backend_type)!
+		return BackendInfo{
+			type_name: val
+		}
+	} else if m.backend_type[0] == `{` {
+		// It's an object
+		val := json.decode(map[string]string, m.backend_type)!
+		for k, v in val {
+			return BackendInfo{
+				type_name: k
+				path:      v
+			}
+		}
+	}
+	return error('unknown backend_type format: ${m.backend_type}')
+}