1 files changed, 31 insertions, 8 deletions

diff --git a/src/main.rs b/src/main.rs
index 833c846..fe0ba04 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,6 @@
 use std::fmt;
 use std::fs::{read_to_string, write};
-use std::io::{Error as IoError, Result as IoResult};
+use std::io::{self, Error as IoError, IsTerminal, Read, Result as IoResult, Write};
 use std::path::PathBuf;
 use std::str::FromStr;
 use wmap_renderer::{Configuration, StageType, render_to_png, render_to_svg};
@@ -71,14 +71,17 @@ fn stage_from_str(s: &str) -> Option<StageType> {
 }
 
 struct Arguments {
-    input: PathBuf,
+    input: Option<PathBuf>,
     output: PathBuf,
+    write_to_stdout: bool,
     stage: StageType,
     image_type: ImageType,
 }
 
 fn print_help() {
-    println!("Usage: wmap [-t|--type IMAGE_TYPE] [-s|--stage STAGE] [-o|--output OUTPUT_FILE] INPUT_FILE");
+    println!(
+        "Usage: wmap [-t|--type IMAGE_TYPE] [-s|--stage STAGE] [-o|--output OUTPUT_FILE] INPUT_FILE"
+    );
 }
 
 fn parse_arguments() -> Result<Arguments, lexopt::Error> {
@@ -86,6 +89,7 @@ fn parse_arguments() -> Result<Arguments, lexopt::Error> {
 
     let mut input = None;
     let mut output: String = String::new();
+    let mut write_to_stdout: bool = false;
     let mut stage = StageType::Activities;
     let mut image_type = ImageType::Png;
 
@@ -117,9 +121,17 @@ fn parse_arguments() -> Result<Arguments, lexopt::Error> {
             _ => return Err(argument.unexpected()),
         }
     }
-    let input = PathBuf::from(input.ok_or("missing argument INPUT_FILE")?);
+    let input = input.map(PathBuf::from);
     let output = if output.is_empty() {
-        input.with_extension(image_type.to_string())
+        if io::stdout().is_terminal() {
+            match &input {
+                Some(path) => path.with_extension(image_type.to_string()),
+                None => PathBuf::from(format!("./map.{image_type}")),
+            }
+        } else {
+            write_to_stdout = true;
+            PathBuf::new()
+        }
     } else {
         PathBuf::from(output)
     };
@@ -127,6 +139,7 @@ fn parse_arguments() -> Result<Arguments, lexopt::Error> {
     Ok(Arguments {
         input,
         output,
+        write_to_stdout,
         stage,
         image_type,
     })
@@ -135,8 +148,14 @@ fn parse_arguments() -> Result<Arguments, lexopt::Error> {
 fn run() -> IoResult<()> {
     let arguments = parse_arguments().map_err(|_| IoError::other("Unable to parse arguments"))?;
 
-    arguments.input.try_exists()?;
-    let source = read_to_string(arguments.input)?;
+    let source = if let Some(input_path) = arguments.input {
+        input_path.try_exists()?;
+        read_to_string(input_path)?
+    } else {
+        let mut buffer = String::new();
+        io::stdin().read_to_string(&mut buffer)?;
+        buffer
+    };
     let map = wmap_parser::parse(&source);
     let configuration = Configuration::default();
 
@@ -147,7 +166,11 @@ fn run() -> IoResult<()> {
             .map_err(|_| IoError::other("Unable to render SVG"))?
             .into_bytes(),
     };
-    write(arguments.output, image_data)?;
+    if arguments.write_to_stdout {
+        io::stdout().write_all(&image_data)?;
+    } else {
+        write(arguments.output, image_data)?;
+    }
     Ok(())
 }