5 files changed, 205 insertions, 92 deletions

diff --git a/bin/src/config.rs b/bin/src/config.rs
index e0f5cbd..25c2a7f 100644
--- a/bin/src/config.rs
+++ b/bin/src/config.rs
@@ -42,13 +42,28 @@ pub struct Check {
     /// Supported values: stderr, errfmt, json (on feature flag only)
     #[clap(short = 'o', long, default_value_t, parse(try_from_str))]
     pub format: OutFormat,
+
+    /// Enable "streaming" mode, accept file on stdin, output diagnostics on stdout
+    #[clap(short, long = "stdin")]
+    pub streaming: bool,
 }
 
 impl Check {
     pub fn vfs(&self) -> Result<ReadOnlyVfs, ConfigErr> {
-        let ignore = dirs::build_ignore_set(&self.ignore, &self.target, self.unrestricted)?;
-        let files = dirs::walk_nix_files(ignore, &self.target)?;
-        vfs(files.collect::<Vec<_>>())
+        if self.streaming {
+            use std::io::{self, BufRead};
+            let src = io::stdin()
+                .lock()
+                .lines()
+                .map(|l| l.unwrap())
+                .collect::<Vec<String>>()
+                .join("\n");
+            Ok(ReadOnlyVfs::singleton("<stdin>", src.as_bytes()))
+        } else {
+            let ignore = dirs::build_ignore_set(&self.ignore, &self.target, self.unrestricted)?;
+            let files = dirs::walk_nix_files(ignore, &self.target)?;
+            vfs(files.collect::<Vec<_>>())
+        }
     }
 }
 
@@ -69,13 +84,46 @@ pub struct Fix {
     /// Do not fix files in place, display a diff instead
     #[clap(short, long = "dry-run")]
     pub diff_only: bool,
+
+    /// Enable "streaming" mode, accept file on stdin, output diagnostics on stdout
+    #[clap(short, long = "stdin")]
+    pub streaming: bool,
+}
+
+pub enum FixOut {
+    Diff,
+    Stream,
+    Write,
 }
 
 impl Fix {
     pub fn vfs(&self) -> Result<ReadOnlyVfs, ConfigErr> {
-        let ignore = dirs::build_ignore_set(&self.ignore, &self.target, self.unrestricted)?;
-        let files = dirs::walk_nix_files(ignore, &self.target)?;
-        vfs(files.collect::<Vec<_>>())
+        if self.streaming {
+            use std::io::{self, BufRead};
+            let src = io::stdin()
+                .lock()
+                .lines()
+                .map(|l| l.unwrap())
+                .collect::<Vec<String>>()
+                .join("\n");
+            Ok(ReadOnlyVfs::singleton("<stdin>", src.as_bytes()))
+        } else {
+            let ignore = dirs::build_ignore_set(&self.ignore, &self.target, self.unrestricted)?;
+            let files = dirs::walk_nix_files(ignore, &self.target)?;
+            vfs(files.collect::<Vec<_>>())
+        }
+    }
+
+    // i need this ugly helper because clap's data model
+    // does not reflect what i have in mind
+    pub fn out(&self) -> FixOut {
+        if self.diff_only {
+            FixOut::Diff
+        } else if self.streaming {
+            FixOut::Stream
+        } else {
+            FixOut::Write
+        }
     }
 }
 
@@ -92,6 +140,38 @@ pub struct Single {
     /// Do not fix files in place, display a diff instead
     #[clap(short, long = "dry-run")]
     pub diff_only: bool,
+
+    /// Enable "streaming" mode, accept file on stdin, output diagnostics on stdout
+    #[clap(short, long = "stdin")]
+    pub streaming: bool,
+}
+
+impl Single {
+    pub fn vfs(&self) -> Result<ReadOnlyVfs, ConfigErr> {
+        if self.streaming {
+            use std::io::{self, BufRead};
+            let src = io::stdin()
+                .lock()
+                .lines()
+                .map(|l| l.unwrap())
+                .collect::<Vec<String>>()
+                .join("\n");
+            Ok(ReadOnlyVfs::singleton("<stdin>", src.as_bytes()))
+        } else {
+            let src = std::fs::read_to_string(self.target.as_ref().unwrap())
+                .map_err(ConfigErr::InvalidPath)?;
+            Ok(ReadOnlyVfs::singleton("<stdin>", src.as_bytes()))
+        }
+    }
+    pub fn out(&self) -> FixOut {
+        if self.diff_only {
+            FixOut::Diff
+        } else if self.streaming {
+            FixOut::Stream
+        } else {
+            FixOut::Write
+        }
+    }
 }
 
 #[derive(Clap, Debug)]
diff --git a/bin/src/explain.rs b/bin/src/explain.rs
index 6aefa7e..de171aa 100644
--- a/bin/src/explain.rs
+++ b/bin/src/explain.rs
@@ -13,3 +13,14 @@ pub fn explain(code: u32) -> Result<&'static str, ExplainErr> {
             .ok_or(ExplainErr::LintNotFound(code)),
     }
 }
+
+pub mod main {
+
+    use crate::{config::Explain as ExplainConfig, err::StatixErr};
+
+    pub fn main(explain_config: ExplainConfig) -> Result<(), StatixErr> {
+        let explanation = super::explain(explain_config.target)?;
+        println!("{}", explanation);
+        Ok(())
+    }
+}
diff --git a/bin/src/fix.rs b/bin/src/fix.rs
index c378c13..e4ea94d 100644
--- a/bin/src/fix.rs
+++ b/bin/src/fix.rs
@@ -3,10 +3,10 @@ use std::borrow::Cow;
 use rnix::TextRange;
 
 mod all;
-pub use all::all;
+use all::all;
 
 mod single;
-pub use single::single;
+use single::single;
 
 type Source<'a> = Cow<'a, str>;
 
@@ -30,3 +30,87 @@ impl<'a> FixResult<'a> {
         }
     }
 }
+
+pub mod main {
+    use std::borrow::Cow;
+
+    use crate::{
+        config::{Fix as FixConfig, FixOut, Single as SingleConfig},
+        err::{FixErr, StatixErr},
+    };
+
+    use similar::TextDiff;
+
+    pub fn all(fix_config: FixConfig) -> Result<(), StatixErr> {
+        let vfs = fix_config.vfs()?;
+        for entry in vfs.iter() {
+            match (fix_config.out(), super::all(entry.contents)) {
+                (FixOut::Diff, fix_result) => {
+                    let src = fix_result
+                        .map(|r| r.src)
+                        .unwrap_or(Cow::Borrowed(entry.contents));
+                    let text_diff = TextDiff::from_lines(entry.contents, &src);
+                    let old_file = format!("{}", entry.file_path.display());
+                    let new_file = format!("{} [fixed]", entry.file_path.display());
+                    println!(
+                        "{}",
+                        text_diff
+                            .unified_diff()
+                            .context_radius(4)
+                            .header(&old_file, &new_file)
+                    );
+                }
+                (FixOut::Stream, fix_result) => {
+                    let src = fix_result
+                        .map(|r| r.src)
+                        .unwrap_or(Cow::Borrowed(entry.contents));
+                    println!("{}", &src)
+                }
+                (FixOut::Write, Some(fix_result)) => {
+                    let path = entry.file_path;
+                    std::fs::write(path, &*fix_result.src).map_err(FixErr::InvalidPath)?;
+                }
+                _ => (),
+            };
+        }
+        Ok(())
+    }
+
+    pub fn single(single_config: SingleConfig) -> Result<(), StatixErr> {
+        let vfs = single_config.vfs()?;
+        let entry = vfs.iter().next().unwrap();
+        let path = entry.file_path.display().to_string();
+        let original_src = entry.contents;
+        let (line, col) = single_config.position;
+
+        match (single_config.out(), super::single(line, col, original_src)) {
+            (FixOut::Diff, single_result) => {
+                let fixed_src = single_result
+                    .map(|r| r.src)
+                    .unwrap_or(Cow::Borrowed(original_src));
+                let text_diff = TextDiff::from_lines(original_src, &fixed_src);
+                let old_file = &path;
+                let new_file = format!("{} [fixed]", &path);
+                println!(
+                    "{}",
+                    text_diff
+                        .unified_diff()
+                        .context_radius(4)
+                        .header(&old_file, &new_file)
+                );
+            }
+            (FixOut::Stream, single_result) => {
+                let src = single_result
+                    .map(|r| r.src)
+                    .unwrap_or(Cow::Borrowed(original_src));
+                println!("{}", &src)
+            }
+            (FixOut::Write, Ok(single_result)) => {
+                let path = entry.file_path;
+                std::fs::write(path, &*single_result.src).map_err(FixErr::InvalidPath)?;
+            }
+            (_, Err(e)) => return Err(e.into()),
+        };
+        Ok(())
+    }
+}
diff --git a/bin/src/lint.rs b/bin/src/lint.rs
index b5856c1..da9ee22 100644
--- a/bin/src/lint.rs
+++ b/bin/src/lint.rs
@@ -13,10 +13,7 @@ pub fn lint(vfs_entry: VfsEntry) -> LintResult {
     let source = vfs_entry.contents;
     let parsed = rnix::parse(source);
 
-    let error_reports = parsed
-        .errors()
-        .into_iter()
-        .map(Report::from_parse_err);
+    let error_reports = parsed.errors().into_iter().map(Report::from_parse_err);
 
     let reports = parsed
         .node()
@@ -36,3 +33,19 @@ pub fn lint(vfs_entry: VfsEntry) -> LintResult {
 
     LintResult { file_id, reports }
 }
+
+pub mod main {
+    use std::io;
+
+    use super::lint;
+    use crate::{config::Check as CheckConfig, err::StatixErr, traits::WriteDiagnostic};
+
+    pub fn main(check_config: CheckConfig) -> Result<(), StatixErr> {
+        let vfs = check_config.vfs()?;
+        let mut stderr = io::stderr();
+        vfs.iter().map(lint).for_each(|r| {
+            stderr.write(&r, &vfs, check_config.format).unwrap();
+        });
+        Ok(())
+    }
+}
diff --git a/bin/src/main.rs b/bin/src/main.rs
index 3adf42e..fabc509 100644
--- a/bin/src/main.rs
+++ b/bin/src/main.rs
@@ -6,94 +6,19 @@ mod fix;
 mod lint;
 mod traits;
 
-use std::io::{self, BufRead};
-
-use crate::{
-    err::{FixErr, SingleFixErr, StatixErr},
-    traits::WriteDiagnostic,
-};
+use crate::err::StatixErr;
 
 use clap::Clap;
 use config::{Opts, SubCommand};
-use similar::TextDiff;
 
 fn _main() -> Result<(), StatixErr> {
     let opts = Opts::parse();
     match opts.cmd {
-        SubCommand::Check(check_config) => {
-            let vfs = check_config.vfs()?;
-            let mut stderr = io::stderr();
-            vfs.iter().map(lint::lint).for_each(|r| {
-                stderr.write(&r, &vfs, check_config.format).unwrap();
-            });
-        }
-        SubCommand::Fix(fix_config) => {
-            let vfs = fix_config.vfs()?;
-            for entry in vfs.iter() {
-                if let Some(fix_result) = fix::all(entry.contents) {
-                    if fix_config.diff_only {
-                        let text_diff = TextDiff::from_lines(entry.contents, &fix_result.src);
-                        let old_file = format!("{}", entry.file_path.display());
-                        let new_file = format!("{} [fixed]", entry.file_path.display());
-                        println!(
-                            "{}",
-                            text_diff
-                                .unified_diff()
-                                .context_radius(4)
-                                .header(&old_file, &new_file)
-                        );
-                    } else {
-                        let path = entry.file_path;
-                        std::fs::write(path, &*fix_result.src).map_err(FixErr::InvalidPath)?;
-                    }
-                }
-            }
-        }
-        // FIXME: this block nasty, configure in/out streams in `impl Single` maybe
-        SubCommand::Single(single_config) => {
-            let src = if let Some(path) = &single_config.target {
-                std::fs::read_to_string(&path).map_err(SingleFixErr::InvalidPath)?
-            } else {
-                io::stdin()
-                    .lock()
-                    .lines()
-                    .map(|l| l.unwrap())
-                    .collect::<Vec<String>>()
-                    .join("\n")
-            };
-
-            let path_id = if let Some(path) = &single_config.target {
-                path.display().to_string()
-            } else {
-                "<unknown>".to_owned()
-            };
-
-            let (line, col) = single_config.position;
-            let single_fix_result = fix::single(line, col, &src)?;
-            if single_config.diff_only {
-                let text_diff = TextDiff::from_lines(src.as_str(), &single_fix_result.src);
-                let old_file = path_id.to_string();
-                let new_file = format!("{} [fixed]", path_id);
-                println!(
-                    "{}",
-                    text_diff
-                        .unified_diff()
-                        .context_radius(4)
-                        .header(&old_file, &new_file)
-                );
-            } else if let Some(path) = single_config.target {
-                std::fs::write(&path, &*single_fix_result.src)
-                    .map_err(SingleFixErr::InvalidPath)?;
-            } else {
-                print!("{}", &*single_fix_result.src)
-            }
-        }
-        SubCommand::Explain(explain_config) => {
-            let explanation = explain::explain(explain_config.target)?;
-            println!("{}", explanation)
-        }
+        SubCommand::Check(config) => lint::main::main(config),
+        SubCommand::Fix(config) => fix::main::all(config),
+        SubCommand::Single(config) => fix::main::single(config),
+        SubCommand::Explain(config) => explain::main::main(config),
     }
-    Ok(())
 }
 
 fn main() {