Added prompt for when zola build output-dir mentions an existing directory. (#1558)

* Next version

* Added ask prompt for output-dir flag

Added `ask_bool` prompt for `--output-dir` for when the output directory
targeted already exists in the file system.

[Issue: #1378]

* Updated the documentation for #1378

* Added missing "sure" in prompt text

* Added timeout to prompt + dirname

* Fixed complication errors

Co-authored-by: Vincent Prouillet <balthek@gmail.com>

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Changelog
 
+
 ## 0.15.0
 
 

Cargo.toml

@@ -28,7 +28,7 @@ termcolor = "1.0.4"
 url = "2"
 # Below is for the serve cmd
 hyper = { version = "0.14.1", default-features = false, features = ["runtime", "server", "http2", "http1"] }
-tokio = { version = "1.0.1", default-features = false, features = ["rt", "fs"] }
+tokio = { version = "1.0.1", default-features = false, features = ["rt", "fs", "time"] }
 percent-encoding = "2"
 notify = "4"
 ws = "0.9"

docs/content/documentation/getting-started/cli-usage.md

@@ -46,7 +46,7 @@ $ zola build --base-url $DEPLOY_URL
 This is useful for example when you want to deploy previews of a site to a dynamic URL, such as Netlify
 deploy previews.
 
-You can override the default output directory `public` by passing another value to the `output-dir` flag (if this directory already exists, it is deleted).
+You can override the default output directory `public` by passing another value to the `output-dir` flag (if this directory already exists, the user will be prompted whether to replace the folder).
 
 ```bash
 $ zola build --output-dir $DOCUMENT_ROOT

src/cmd/build.rs

@@ -1,9 +1,12 @@
 use std::path::Path;
 
-use errors::Result;
+use errors::{Error, Result};
 use site::Site;
 
 use crate::console;
+use crate::prompt::ask_bool_timeout;
+
+const BUILD_PROMPT_TIMEOUT_MILLIS: u64 = 10_000;
 
 pub fn build(
     root_dir: &Path,
@@ -14,6 +17,27 @@ pub fn build(
 ) -> Result<()> {
     let mut site = Site::new(root_dir, config_file)?;
     if let Some(output_dir) = output_dir {
+        // Check whether output directory exists or not
+        // This way we don't replace already existing files.
+        if output_dir.exists() {
+            console::warn(&format!("The directory '{}' already exists. Building to this directory will delete files contained within this directory.", output_dir.display()));
+
+            // Prompt the user to ask whether they want to continue.
+            let clear_dir = tokio::runtime::Runtime::new()
+                .expect("Tokio runtime failed to instantiate")
+                .block_on(ask_bool_timeout(
+                    "Are you sure you want to continue?",
+                    false,
+                    std::time::Duration::from_millis(BUILD_PROMPT_TIMEOUT_MILLIS),
+                ))?;
+
+            if !clear_dir {
+                return Err(Error::msg(
+                    "Cancelled build process because output directory already exists.",
+                ));
+            }
+        }
+
         site.set_output_path(output_dir);
     }
     if let Some(b) = base_url {

src/prompt.rs

@@ -1,8 +1,10 @@
 use std::io::{self, BufRead, Write};
+use std::time::Duration;
 
 use url::Url;
 
 use errors::Result;
+use crate::console;
 
 /// Wait for user input and return what they typed
 fn read_line() -> Result<String> {
@@ -32,6 +34,24 @@ pub fn ask_bool(question: &str, default: bool) -> Result<bool> {
     }
 }
 
+/// Ask a yes/no question to the user with a timeout
+pub async fn ask_bool_timeout(question: &str, default: bool, timeout: Duration) -> Result<bool> {
+    let (tx, rx) = tokio::sync::oneshot::channel();
+
+    let q = question.to_string();
+    std::thread::spawn(move || {
+        tx.send(ask_bool(&q, default)).unwrap();
+    });
+
+    match tokio::time::timeout(timeout, rx).await {
+        Err(_) => {
+            console::warn("\nWaited too long for response.");
+            Ok(default)
+        }
+        Ok(val) => val.expect("Tokio failed to properly execute"),
+    }
+}
+
 /// Ask a question to the user where they can write a URL
 pub fn ask_url(question: &str, default: &str) -> Result<String> {
     print!("{} ({}): ", question, default);