refactor read options

src/bin/hq.rs

@@ -5,87 +5,124 @@ use std::{
 };
 
 use clap::{Parser, Subcommand};
-use hq_rs::{parse_filter, query, write};
 
 #[derive(Parser)]
 #[command(version, about)]
 struct Args {
-    #[clap(short, long, value_name = "FILE", help = "HCL file to read from")]
-    file: Option<String>,
-
+    // the `Read` options are duplicated here because when no command is given
+    // then the `read` command is the default and its options come from the root
     #[arg(value_name = "filter", help = "HCL filter expression")]
     filter: Option<String>,
 
+    #[clap(short, long, value_name = "FILE", help = "HCL file to read from")]
+    file: Option<String>,
+
     #[command(subcommand)]
     command: Option<Command>,
 }
 
 #[derive(Subcommand)]
 enum Command {
     #[command(about = "Read value from HCL (default)")]
-    Read,
+    Read {
+        #[arg(value_name = "filter", help = "HCL filter expression")]
+        filter: Option<String>,
+
+        #[clap(short, long, value_name = "FILE", help = "HCL file to read from")]
+        file: Option<String>,
+    },
     #[command(about = "Write value into HCL")]
     Write {
+        #[arg(value_name = "filter", help = "HCL filter expression")]
+        filter: Option<String>,
+
+        #[clap(short, long, value_name = "FILE", help = "HCL file to read from")]
+        file: Option<String>,
+
         #[arg(required = true, help = "Value to write into HCL")]
         value: String,
     },
 }
 
-impl Default for Command {
-    fn default() -> Self {
-        Self::Read
-    }
-}
-
 fn main() -> Result<(), Box<dyn Error>> {
     let args = Args::parse();
 
-    // Read the HCL from either a file or stdin
-    let buf = if let Some(file_path) = args.file {
-        fs::read_to_string(file_path)?
-    } else {
-        let mut stdin = io::stdin();
-        let mut buf = String::new();
-        stdin.read_to_string(&mut buf)?;
-        buf
-    };
-
     match args.command {
-        None | Some(Command::Read) => {
-            let body: hcl::Body = hcl::from_str(&buf)?;
-
-            if let Some(filter) = args.filter {
-                let mut fields = parse_filter(&filter)?;
-                let query_results = query(&mut fields, &body);
-                for query_result in query_results {
-                    let s = query_result.to_string()?;
-                    print!("{s}");
-                    io::stdout().flush()?;
-                    if !s.ends_with('\n') {
-                        println!();
-                    }
-                }
-            } else {
-                println!("HCL from stdin contained:");
-                println!(" * {} top-level attribute(s)", body.attributes().count());
-                println!(" * {} top-level block(s)", body.blocks().count());
-            }
+        None => {
+            read(args.filter, args.file)?;
+        }
+        Some(Command::Read { filter, file }) => {
+            read(filter, file)?;
         }
-        Some(Command::Write { value }) => {
-            let mut body: hcl_edit::structure::Body = buf.parse()?;
+        Some(Command::Write {
+            filter,
+            file,
+            value,
+        }) => {
+            write(filter, file, value)?;
+        }
+    }
 
-            let expr: hcl_edit::expr::Expression = value.parse()?;
-            if let Some(filter) = args.filter {
-                let fields = parse_filter(&filter)?;
-                write(fields, &mut body, &expr)?;
-                print!("{body}");
-                io::stdout().flush()?;
-            } else {
-                print!("{expr}");
+    Ok(())
+}
+
+fn read_stdin() -> Result<String, Box<dyn Error>> {
+    let mut stdin = io::stdin();
+    let mut buf = String::new();
+    stdin.read_to_string(&mut buf)?;
+    Ok(buf)
+}
+
+fn read(filter: Option<String>, file: Option<String>) -> Result<(), Box<dyn Error>> {
+    let contents = match file {
+        Some(file) => fs::read_to_string(file)?,
+        None => read_stdin()?,
+    };
+    let body: hcl::Body = hcl::from_str(&contents)?;
+    match filter {
+        Some(filter) => {
+            let mut fields = hq_rs::parse_filter(&filter)?;
+            let query_results = hq_rs::query(&mut fields, &body);
+            for query_result in query_results {
+                let s = query_result.to_string()?;
+                print!("{s}");
                 io::stdout().flush()?;
+                if !s.ends_with('\n') {
+                    println!();
+                }
             }
         }
+        None => {
+            println!("HCL from stdin contained:");
+            println!(" * {} top-level attribute(s)", body.attributes().count());
+            println!(" * {} top-level block(s)", body.blocks().count());
+        }
     }
+    Ok(())
+}
 
+fn write(
+    filter: Option<String>,
+    file: Option<String>,
+    value: String,
+) -> Result<(), Box<dyn Error>> {
+    let contents = match file {
+        Some(file) => fs::read_to_string(file)?,
+        None => read_stdin()?,
+    };
+    let mut body: hcl_edit::structure::Body = contents.parse()?;
+    let expr: hcl_edit::expr::Expression = value.parse()?;
+    match filter {
+        Some(filter) => {
+            let fields = hq_rs::parse_filter(&filter)?;
+            hq_rs::write(fields, &mut body, &expr)?;
+            print!("{body}");
+            io::stdout().flush()?;
+        }
+        None => {
+            print!("{expr}");
+            io::stdout().flush()?;
+        }
+    }
     Ok(())
 }