feat(cast): call json flag (#8618)

* add call json flag

* update json param to option

* address comments

crates/cast/bin/cmd/call.rs

@@ -62,6 +62,10 @@ pub struct CallArgs {
     #[arg(long, short)]
     block: Option<BlockId>,
 
+    /// Print the decoded output as JSON.
+    #[arg(long, short, help_heading = "Display options")]
+    json: bool,
+
     #[command(subcommand)]
     command: Option<CallSubcommands>,
 
@@ -112,6 +116,7 @@ impl CallArgs {
             decode_internal,
             labels,
             data,
+            json,
         } = self;
 
         if let Some(data) = data {
@@ -190,7 +195,7 @@ impl CallArgs {
             return Ok(());
         }
 
-        println!("{}", Cast::new(provider).call(&tx, func.as_ref(), block).await?);
+        println!("{}", Cast::new(provider).call(&tx, func.as_ref(), block, json).await?);
 
         Ok(())
     }

crates/cast/src/lib.rs

@@ -118,7 +118,7 @@ where
     /// let tx = TransactionRequest::default().to(to).input(bytes.into());
     /// let tx = WithOtherFields::new(tx);
     /// let cast = Cast::new(alloy_provider);
-    /// let data = cast.call(&tx, None, None).await?;
+    /// let data = cast.call(&tx, None, None, false).await?;
     /// println!("{}", data);
     /// # Ok(())
     /// # }
@@ -128,6 +128,7 @@ where
         req: &WithOtherFields<TransactionRequest>,
         func: Option<&Function>,
         block: Option<BlockId>,
+        json: bool,
     ) -> Result<String> {
         let res = self.provider.call(req).block(block.unwrap_or_default()).await?;
 
@@ -168,6 +169,9 @@ where
         // handle case when return type is not specified
         Ok(if decoded.is_empty() {
             format!("{res}\n")
+        } else if json {
+            let tokens = decoded.iter().map(format_token_raw).collect::<Vec<_>>();
+            serde_json::to_string_pretty(&tokens).unwrap()
         } else {
             // seth compatible user-friendly return type conversions
             decoded.iter().map(format_token).collect::<Vec<_>>().join("\n")