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168 | use extism_pdk::*;
use serde::{Serialize, Deserialize};
use thiserror::Error;
extern "C" {
fn hostPrintln(ptr: u64) -> u64;
}
pub fn println(text: String) {
let mut memory_text: Memory = extism_pdk::Memory::new(text.len());
memory_text.store(text);
unsafe { hostPrintln(memory_text.offset) };
}
extern "C" {
fn hostGetEnv(ptr: u64) -> u64;
}
pub fn get_env(name: String) -> String {
// copy the name of the environment variable to the shared memory
let mut variable_name: Memory = extism_pdk::Memory::new(name.len());
variable_name.store(name);
// call the host function
let offset: u64 = unsafe { hostGetEnv(variable_name.offset) };
// read the value of the result from the shared memory
let variable_value: Memory = extism_pdk::Memory::find(offset).unwrap();
// return the value
return variable_value.to_string().unwrap()
}
#[derive(Serialize, Deserialize, Debug)]
struct NatsConfig {
pub id: String,
pub url: String,
}
#[derive(Serialize, Deserialize, Debug)]
struct NatsMessage {
pub id: String,
pub subject: String,
pub data: String,
}
#[derive(Serialize, Deserialize, Debug)]
struct StringResult {
pub success: String,
pub failure: String,
}
#[derive(Error, Debug)]
pub enum NatsError {
#[error("Nats Connection issue")]
ConnectionFailure,
#[error("Store issue")]
MessageFailure,
#[error("Not found")]
NotFound,
}
extern "C" {
fn hostInitNatsConnection(offset: u64) -> u64;
}
pub fn init_nats_connection(nats_connection_id: String, nats_url: String) -> Result<String, Error> {
// Prepare the arguments for the host function
// with a JSON string:
// {
// "id": "id of the NATS connection",
// "url": "URL of the NATS server"
// }
let args = NatsConfig {
id: nats_connection_id,
url: nats_url,
};
let json_str: String = serde_json::to_string(&args).unwrap();
// Copy the string value to the shared memory
let mut memory_json_str: Memory = extism_pdk::Memory::new(json_str.len());
memory_json_str.store(json_str);
// Call host function with the offset of the arguments
let offset: u64 = unsafe { hostInitNatsConnection(memory_json_str.offset) };
// Get result from the shared memory
// The host function (hostInitNatsConnection) returns a JSON buffer:
// {
// "success": "id of the connection",
// "failure": "error message if error, else empty"
// }
let memory_result: Memory = extism_pdk::Memory::find(offset).unwrap();
let json_string:String = memory_result.to_string().unwrap();
let result: StringResult = serde_json::from_str(&json_string).unwrap();
if result.failure.is_empty() {
return Ok(result.success);
} else {
return Err(NatsError::ConnectionFailure.into());
}
}
extern "C" {
fn hostNatsPublish(offset: u64) -> u64;
}
pub fn nats_publish(nats_connection_id: String, subject: String, data: String) -> Result<String, Error> {
// Prepare the arguments for the host function
// with a JSON string:
// {
// "id": "id of the NATS client",
// "subject": "name",
// "data": "Bob Morane"
// }
let args = NatsMessage {
id: nats_connection_id,
subject: subject,
data: data,
};
let json_str: String = serde_json::to_string(&args).unwrap();
// Copy the string value to the shared memory
let mut memory_json_str: Memory = extism_pdk::Memory::new(json_str.len());
memory_json_str.store(json_str);
// Call host function with the offset of the arguments
let offset: u64 = unsafe { hostNatsPublish(memory_json_str.offset) };
// Get result from the shared memory
// The host function returns a JSON buffer:
// {
// "success": "OK",
// "failure": "error message if error, else empty"
// }
let memory_result: Memory = extism_pdk::Memory::find(offset).unwrap();
let json_string:String = memory_result.to_string().unwrap();
let result: StringResult = serde_json::from_str(&json_string).unwrap();
if result.failure.is_empty() {
return Ok(result.success);
} else {
return Err(NatsError::MessageFailure.into());
}
}
#[plugin_fn]
pub fn publish(input: String) -> FnResult<u64> {
let nats_url : String = get_env("NATS_URL".to_string());
let nats_connection : Result<String, Error> = init_nats_connection("natsconn01".to_string(), nats_url);
match nats_connection {
Ok(value) => println("🦀 nats connection: ".to_string() + &value),
Err(error) => println("😡 error: ".to_string() + &error.to_string()),
}
match nats_publish("natsconn01".to_string(), "news".to_string(), input.to_string()) {
Ok(value) => println("🦀 🙂 ".to_string() + &value),
Err(error) => println("😡 error: ".to_string() + &error.to_string()),
}
Ok(0)
}
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