libfw-client 0.2.0

//! libfw-client: WASM engine for browser file & folder transfers.
//!
//! This crate ships the *engine* that runs inside the browser: it performs
//! the HTTP transfer (via `fetch`), slices files into chunks, keeps memory
//! constant, retries with exponential backoff, and drives the task state
//! machine (`idle → downloading/uploading → paused → resumed →
//! completed/failed`).
#![recursion_limit = "512"]
//!
//! The [`LibfwClient`] WASM class is exported through `wasm-bindgen` and is
//! intended to be wrapped by the accompanying JS SDK (`sdk/`). The SDK owns
//! WASM instantiation, the File System Access API, IndexedDB persistence and
//! the `createWritable` byte sink — all data crosses the boundary through
//! the callbacks installed via [`LibfwClient::set_callbacks`].
//!
//! # Callbacks object
//!
//! ```js
//! engine.set_callbacks({
//!   onFileStart(path, size) {},
//!   onWriteChunk(path, offset, data) {},   // Uint8Array
//!   onFileCompleted(path) {},
//!   onProgress(done, total) {},
//!   loadState(direction, path) { return Promise.resolve(null); }, // IndexedDB
//!   saveState(direction, path, state) { return Promise.resolve(); },// IndexedDB
//!   getFileList() { return Promise.resolve([]); },       // uploads
//!   readFile(path, offset, length) { return Promise.resolve(new Uint8Array(0)); },
//!   log(msg) {},
//! });
//! ```

mod config;
mod download;
mod error;
mod js;
mod plan;
mod state;
mod upload;
mod ws;

pub use config::{backoff_ms, ClientConfig};
pub use error::LibfwError;
pub use plan::FileEntry;

use js_sys::Reflect;
use wasm_bindgen::prelude::*;

use crate::js::Callbacks;
use crate::state::{TaskControl, TaskState};

/// WASM engine facade. Construct via `new LibfwClient(options)`.
#[wasm_bindgen]
pub struct LibfwClient {
    config: ClientConfig,
    callbacks: Callbacks,
    control: TaskControl,
}

#[wasm_bindgen]
impl LibfwClient {
    /// Create an engine. `options` may include:
    /// `{ concurrency, uploadWindow, downloadWindow, downloadChunkSize,
    /// compress, chunkSize, maxRetries, baseRetryDelayMs, maxRetryDelayMs,
    /// timeoutMs }`.
    #[wasm_bindgen(constructor)]
    pub fn new(opts: JsValue) -> LibfwClient {
        let config = ClientConfig::from_js(&opts);
        LibfwClient {
            config,
            callbacks: Callbacks::new(),
            control: TaskControl::new(),
        }
    }

    /// Install the JS callbacks object (required before any transfer).
    pub fn set_callbacks(&self, callbacks: JsValue) {
        self.callbacks.set(callbacks);
    }

    /// Download every file under the virtual `dirPath` (empty = root).
    ///
    /// Resolves with the number of bytes written.
    pub fn download_folder(&self, base_url: &str, token: &str, dir_path: &str) -> js_sys::Promise {
        let base_url = base_url.to_string();
        let token = token.to_string();
        let dir_path = dir_path.to_string();
        let config = self.config.clone();
        let callbacks = self.callbacks.clone();
        let control = self.control.clone();

        wasm_bindgen_futures::future_to_promise(async move {
            control.reset();
            control.begin(TaskState::Downloading);
            match download::download_folder(
                &base_url,
                &token,
                &dir_path,
                &callbacks,
                &control,
                &config,
            )
            .await
            {
                Ok(total) => {
                    control.complete();
                    Ok(JsValue::from_f64(total as f64))
                }
                Err(e) => {
                    control.fail();
                    Err(e.to_js())
                }
            }
        })
    }

    /// Download a single file at `file_path` into the chosen local directory.
    ///
    /// Resolves with the number of bytes written.
    pub fn download_file(&self, base_url: &str, token: &str, file_path: &str) -> js_sys::Promise {
        let base_url = base_url.to_string();
        let token = token.to_string();
        let file_path = file_path.to_string();
        let config = self.config.clone();
        let callbacks = self.callbacks.clone();
        let control = self.control.clone();

        wasm_bindgen_futures::future_to_promise(async move {
            control.reset();
            control.begin(TaskState::Downloading);
            match download::download_single(
                &base_url,
                &token,
                &file_path,
                &callbacks,
                &control,
                &config,
            )
            .await
            {
                Ok(total) => {
                    control.complete();
                    Ok(JsValue::from_f64(total as f64))
                }
                Err(e) => {
                    control.fail();
                    Err(e.to_js())
                }
            }
        })
    }

    /// Upload the files reported by the JS `getFileList` callback.
    ///
    /// Resolves with the number of bytes uploaded.
    pub fn upload(&self, base_url: &str, token: &str) -> js_sys::Promise {
        let base_url = base_url.to_string();
        let token = token.to_string();
        let config = self.config.clone();
        let callbacks = self.callbacks.clone();
        let control = self.control.clone();

        wasm_bindgen_futures::future_to_promise(async move {
            control.reset();
            control.begin(TaskState::Uploading);
            match upload::upload(&base_url, &token, &callbacks, &control, &config).await {
                Ok(total) => {
                    control.complete();
                    Ok(JsValue::from_f64(total as f64))
                }
                Err(e) => {
                    control.fail();
                    Err(e.to_js())
                }
            }
        })
    }

    /// Pause the active transfer (state → `paused`).
    pub fn pause(&self) {
        self.control.pause();
    }

    /// Resume a paused transfer.
    pub fn resume(&self) {
        self.control.resume();
    }

    /// Cancel the active transfer (state → `failed`).
    pub fn cancel(&self) {
        self.control.cancel();
    }

    /// Current state: `idle | downloading | uploading | paused | completed |
    /// failed`.
    pub fn state(&self) -> String {
        self.control.state().as_str().to_string()
    }

    /// Progress in `[0, 1]`.
    pub fn progress(&self) -> f64 {
        self.control.progress()
    }

    /// Bytes transferred so far.
    pub fn done_bytes(&self) -> f64 {
        self.control.done_bytes() as f64
    }

    /// Total bytes to transfer.
    pub fn total_bytes(&self) -> f64 {
        self.control.total_bytes() as f64
    }

    /// Whether callbacks have been installed.
    pub fn has_callbacks(&self) -> bool {
        self.callbacks.is_set()
    }
}

/// Read an optional string field from a JS object (helper for the SDK).
#[wasm_bindgen]
pub fn js_option_string(obj: &JsValue, key: &str) -> Option<String> {
    Reflect::get(obj, &JsValue::from_str(key))
        .ok()
        .and_then(|v| v.as_string())
}

#[cfg(test)]
mod tests {
    #[test]
    #[cfg(target_arch = "wasm32")]
    fn engine_default_state_is_idle() {
        let engine = super::LibfwClient::new(wasm_bindgen::JsValue::NULL);
        assert_eq!(engine.state(), "idle");
        assert!(!engine.has_callbacks());
    }

    #[test]
    #[cfg(target_arch = "wasm32")]
    fn engine_options_parse() {
        let opts = js_sys::Object::new();
        js_sys::Reflect::set(&opts, &wasm_bindgen::JsValue::from_str("concurrency"), &wasm_bindgen::JsValue::from_f64(2.0))
            .unwrap();
        js_sys::Reflect::set(&opts, &wasm_bindgen::JsValue::from_str("compress"), &wasm_bindgen::JsValue::FALSE).unwrap();
        let engine = super::LibfwClient::new(opts.into());
        assert_eq!(engine.config.concurrency, 2);
        assert!(!engine.config.compress);
    }

    #[test]
    #[cfg(target_arch = "wasm32")]
    fn state_transitions_via_public_api() {
        use crate::state::TaskState;
        let engine = super::LibfwClient::new(wasm_bindgen::JsValue::NULL);
        engine.control.begin(TaskState::Downloading);
        engine.pause();
        assert_eq!(engine.state(), "paused");
        engine.resume();
        assert_eq!(engine.state(), "downloading");
        engine.cancel();
        assert_eq!(engine.state(), "failed");
    }
}