From 78153e8bf4b1a92a4f5a1305a5b1f5c975b2b201 Mon Sep 17 00:00:00 2001
From: Matthew Dillon <matthewrdillon@gmail.com>
Date: Tue, 7 Dec 2021 21:20:33 -0700
Subject: [PATCH] wip

---
 src/lib.rs    | 17 -----------------
 src/loader.rs | 39 ++++++++++++++++++++++++++++++++-------
 src/utils.rs  | 28 ++++++++++++++++++----------
 3 files changed, 50 insertions(+), 34 deletions(-)
 delete mode 100644 src/lib.rs

diff --git a/src/lib.rs b/src/lib.rs
deleted file mode 100644
index de5d775..0000000
--- a/src/lib.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-mod utils;
-
-// use wasm_bindgen::prelude::*;
-// 
-// #[cfg(feature = "wee_alloc")]
-// #[global_allocator]
-// static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
-// 
-// #[wasm_bindgen]
-// pub fn merge(files: js_sys::Array) -> wasm_bindgen::JsValue {
-//     utils::set_panic_hook();
-//     let files: Vec<String> = utils::translate_js_to_rust(files);
-//     let merged: gpx::Gpx = utils::join_gpx_files(files);
-//     let out_vec: Vec<u8> = utils::write_gpx_to_buffer(merged);
-// 
-//     JsValue::from_str(&String::from_utf8(out_vec).unwrap())
-// }
diff --git a/src/loader.rs b/src/loader.rs
index e81f614..6644c4b 100644
--- a/src/loader.rs
+++ b/src/loader.rs
@@ -9,7 +9,7 @@ use super::utils;
 
 pub enum Msg {
     FileLoaded(String, String),
-    Files(Vec<File>),
+    StartLoad(Vec<File>),
     FilesLoaded,
     Reset,
 }
@@ -18,6 +18,9 @@ pub struct Loader {
     readers: HashMap<String, FileReader>,
     files: Vec<String>,
     count: usize,
+    is_loading: bool,
+    // This field is to handle resetting the native HTML widget's state on error
+    field_value: &'static str,
 }
 
 impl Component for Loader {
@@ -29,6 +32,8 @@ impl Component for Loader {
             readers: HashMap::default(),
             files: vec![],
             count: 0,
+            is_loading: false,
+            field_value: "",
         }
     }
 
@@ -43,8 +48,15 @@ impl Component for Loader {
                 true
             }
 
-            Msg::Files(files) => {
+            Msg::StartLoad(files) => {
                 self.count = files.len();
+                if self.count < 2 {
+                    utils::alert("must load two or more files");
+                    ctx.link().send_message(Msg::Reset);
+                    return true;
+                }
+                self.is_loading = true;
+
                 for file in files.into_iter() {
                     let file_name = file.name();
                     let task = {
@@ -64,7 +76,14 @@ impl Component for Loader {
             }
 
             Msg::FilesLoaded => {
-                let merged = utils::merge(&self.files);
+                let merged = match utils::merge(&self.files) {
+                    Ok(result) => result,
+                    Err(err) => {
+                        utils::alert(&err.to_string());
+                        ctx.link().send_message(Msg::Reset);
+                        return true
+                    }
+                };
 
                 let window = web_sys::window().expect("no global `window` exists");
                 let document = window.document().expect("should have a document on window");
@@ -75,6 +94,8 @@ impl Component for Loader {
                 anchor_element.set_attribute("href", &url).unwrap();
                 anchor_element.set_attribute("download", "merged.gpx").unwrap();
 
+                self.is_loading = false;
+
                 let event = MouseEvent::new("click").unwrap();
                 anchor_element.dispatch_event(&event).unwrap();
 
@@ -85,6 +106,8 @@ impl Component for Loader {
                 self.readers = HashMap::default();
                 self.files = vec![];
                 self.count = 0;
+                self.is_loading = false;
+                self.field_value = "";
                 true
             }
         }
@@ -93,8 +116,10 @@ impl Component for Loader {
     fn view(&self, ctx: &Context<Self>) -> Html {
         let link = ctx.link();
         html! {
-            <>
-                <input type="file" multiple=true onchange={link.callback(move |e: Event| {
+            if self.is_loading {
+                <span>{"loading..."}</span>
+            } else {
+                <input type="file" value={self.field_value} multiple=true onchange={link.callback(move |e: Event| {
                     let mut result = Vec::new();
                     let input: HtmlInputElement = e.target_unchecked_into();
 
@@ -106,10 +131,10 @@ impl Component for Loader {
                             .map(File::from);
                         result.extend(files);
                     }
-                    Msg::Files(result)
+                    Msg::StartLoad(result)
                     })}
                 />
-            </>
+            }
         }
     }
 }
diff --git a/src/utils.rs b/src/utils.rs
index 6b402e1..4201c17 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,12 +1,14 @@
+use std::error::Error;
 use web_sys::Blob;
+use wasm_bindgen::prelude::*;
 
-fn join_gpx_files(files: &Vec<String>) -> gpx::Gpx {
+fn join_gpx_files(files: &Vec<String>) -> Result<gpx::Gpx, Box<dyn Error>> {
     let mut merged_gpx: gpx::Gpx = Default::default();
     let mut merged_track: gpx::Track = gpx::Track::new();
 
     for file in files.iter() {
         let buffer = std::io::BufReader::new(file.as_bytes());
-        let mut parsed_gpx: gpx::Gpx = gpx::read(buffer).expect("invalid gpx");
+        let mut parsed_gpx: gpx::Gpx = gpx::read(buffer)?;
 
         // consolidate all track segements into one single track.
         for track in parsed_gpx.tracks {
@@ -36,22 +38,28 @@ fn join_gpx_files(files: &Vec<String>) -> gpx::Gpx {
     merged_gpx.metadata = Some(metadata);
     merged_gpx.version = gpx::GpxVersion::Gpx11;
 
-    merged_gpx
+    Ok(merged_gpx)
 }
-fn write_gpx_to_buffer(gpx: gpx::Gpx) -> js_sys::Array {
+fn write_gpx_to_buffer(gpx: gpx::Gpx) -> Result<js_sys::Array, Box<dyn Error>> {
     let mut buffer = Vec::new();
-    gpx::write(&gpx, &mut buffer).unwrap();
+    gpx::write(&gpx, &mut buffer)?;
 
     let uint8arr = js_sys::Uint8Array::new(&unsafe { js_sys::Uint8Array::view(&buffer) }.into());
     let array = js_sys::Array::new();
     array.push(&uint8arr.buffer());
 
-    array
+    Ok(array)
 }
 
-pub fn merge(files: &Vec<String>) -> Blob {
-    let merged: gpx::Gpx = join_gpx_files(files);
-    let out_vec = write_gpx_to_buffer(merged);
+pub fn merge(files: &Vec<String>) -> Result<Blob, Box<dyn Error>> {
+    let merged: gpx::Gpx = join_gpx_files(files)?;
+    let out_vec = write_gpx_to_buffer(merged)?;
+    let result = Blob::new_with_u8_array_sequence(&out_vec).map_err(|e| e.as_string().unwrap() )?;
 
-    Blob::new_with_u8_array_sequence(&out_vec).unwrap()
+    Ok(result)
+}
+
+#[wasm_bindgen]
+extern {
+    pub fn alert(s: &str);
 }