2 files changed, 103 insertions, 19 deletions

diff --git a/src/changes.rs b/src/changes.rs
index 5099364..986e9c4 100644
--- a/src/changes.rs
+++ b/src/changes.rs
@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 use rowan::NodeOrToken;
 use crate::pipeline::Change;
 
@@ -174,3 +176,46 @@ fn next_indentation(node: &rnix::SyntaxNode) -> Option<usize> {
         None
     }
 }
+
+/// give line & column of a position marker in the given string
+fn line_at_textpos(content: &str, pos: rowan::TextSize) -> Option<(usize, usize)> {
+    let pos: usize = pos.into();
+    content
+        .split("\n")
+        .scan(0usize, |acc,line| {
+            let start = *acc;
+            let end = line.len() + 1 + start;
+            *acc = end;
+            Some((start, end))
+        })
+        .enumerate()
+        .find(|(_, (_, end))| *end > pos)
+        .map(|(line, (start, _))| (line + 1, pos + 1 - start))
+}
+
+pub fn format_pos(path: &PathBuf, content: &str, pos1: rowan::TextSize) -> String {
+    let (line1, col1) = line_at_textpos(content, pos1).unwrap();
+    format!("{path:?}:{line1}:{col1}")
+}
+
+pub fn format_range(path: &PathBuf, content: &str, range: rowan::TextRange) -> String {
+    let (line1, col1) = line_at_textpos(content, range.start()).unwrap();
+    let (line2, col2) = line_at_textpos(content, range.end()).unwrap();
+    format!("{}:{line1}:{col1}-{line2}:{col2}", path.to_string_lossy())
+}
+
+pub fn format_range_json(path: &PathBuf, content: &str, range: rowan::TextRange) -> serde_json::Value {
+    let (line1, col1) = line_at_textpos(content, range.start()).unwrap();
+    let (line2, col2) = line_at_textpos(content, range.end()).unwrap();
+    serde_json::json!({
+        "file": path,
+        "start": {
+            "line": line1,
+            "column": col1
+        },
+        "end": {
+            "line": line2,
+            "column": col2
+        }
+    })
+}
diff --git a/src/main.rs b/src/main.rs
index 6e85257..bd448ce 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,7 +3,9 @@ use rowan::ast::AstNode;
 use clap::{arg, Parser};
 
 use queries::Query;
-use changes::apply_changes;
+use changes::{apply_changes, format_range};
+
+use crate::changes::format_range_json;
 
 #[allow(dead_code)]
 mod queries;
@@ -24,7 +26,11 @@ struct Args {
     #[arg(short, long)]
     debug: bool,
     #[arg(long)]
-    batchmode: bool
+    batchmode: bool,
+    #[arg(long)]
+    print_positions: bool,
+    #[arg(long)]
+    json: bool
 }
 
 fn main() {
@@ -38,31 +44,64 @@ fn main() {
     }
 
     if args.batchmode {
+        macro_rules! warn_arg {
+            ($arg: ident, $text:literal) => { if args.$arg {
+                eprintln!("Warning: option {} is ignored in batch mode.", $text);
+            }}
+        }
+
+        warn_arg!(json, "--json");
+        warn_arg!(print_positions, "--print-positions");
+
         batchmode::batchmode(args.path, query, args.debug);
     } else {
-        let (content, nexp) = match parse_nixfile(&args.path[0]) {
-            Err(e) => {
-                eprintln!("could not parse file: {e}");
-                exit(2);
-            },
-            Ok(exp) => exp
-        };
-
-        let (changes, results) = query.apply(&content, nexp.syntax().clone()).unwrap();
-
-        if args.debug {
-            println!("{changes:?}");
+        for path in &args.path {
+            handle_file(path, &args, &query)
         }
+    }
+}
+
+fn handle_file(path: &PathBuf, args: &Args, query: &Query) {
+    let (content, nexp) = match parse_nixfile(path) {
+        Err(e) => {
+            eprintln!("could not parse file: {e}");
+            exit(2);
+        },
+        Ok(exp) => exp
+    };
 
-        if changes.len() == 0 {
+    let (changes, results) = query.apply(&content, nexp.syntax().clone()).unwrap();
+
+    if args.debug {
+        println!("{changes:?}");
+    }
+
+    if changes.len() == 0 {
+        if args.print_positions {
+            if args.json {
+                let json = results
+                    .iter()
+                    .map(|result|
+                         format_range_json(path, &content, result.text_range()))
+                    .collect::<Vec<_>>();
+                println!("{}", serde_json::to_string(&json).unwrap());
+            } else {
+                for result in results {
+                    println!(
+                        "{}",
+                        format_range(path, &content, result.text_range())
+                    );
+                }
+            }
+        } else {
             for result in results {
                 println!("{result}");
             }
-        } else {
-            let changed = apply_changes(&content, changes, args.debug);
-
-            println!("{changed}");
         }
+    } else {
+        let changed = apply_changes(&content, changes, args.debug);
+
+        println!("{changed}");
     }
 }