Add option to export to stdout

CHANGELOG.md

@@ -17,6 +17,7 @@ Procedure when bumping the version number:
 ### Added
 - `--verbose` flag
 - `json-stream` room export format
+- Option to export to stdout
 
 ### Changed
 - Respect colon-delimited emoji when calculating nick hue

src/export.rs

@@ -4,9 +4,9 @@ mod json;
 mod text;
 
 use std::fs::File;
-use std::io::{BufWriter, Write};
+use std::io::{self, BufWriter, Write};
 
-use crate::vault::EuphVault;
+use crate::vault::{EuphRoomVault, EuphVault};
 
 #[derive(Debug, Clone, Copy, clap::ValueEnum)]
 pub enum Format {
@@ -57,12 +57,28 @@ pub struct Args {
     /// If the value ends with a `/`, it is assumed to point to a directory and
     /// `%r.%e` will be appended.
     ///
+    /// If the value is a literal `-`, the export will be written to stdout. To
+    /// write to a file named `-`, you can use `./-`.
+    ///
     /// Must be a valid utf-8 encoded string.
     #[arg(long, short, default_value_t = Into::into("%r.%e"))]
     #[arg(verbatim_doc_comment)]
     out: String,
 }
 
+async fn export_room<W: Write>(
+    vault: &EuphRoomVault,
+    out: &mut W,
+    format: Format,
+) -> anyhow::Result<()> {
+    match format {
+        Format::Text => text::export(vault, out).await?,
+        Format::Json => json::export(vault, out).await?,
+        Format::JsonStream => json::export_stream(vault, out).await?,
+    }
+    Ok(())
+}
+
 pub async fn export(vault: &EuphVault, mut args: Args) -> anyhow::Result<()> {
     if args.out.ends_with('/') {
         args.out.push_str("%r.%e");
@@ -79,21 +95,24 @@ pub async fn export(vault: &EuphVault, mut args: Args) -> anyhow::Result<()> {
     };
 
     if rooms.is_empty() {
-        println!("No rooms to export");
+        eprintln!("No rooms to export");
     }
 
     for room in rooms {
-        let out = format_out(&args.out, &room, args.format);
-        println!("Exporting &{room} as {} to {out}", args.format.name());
-
-        let vault = vault.room(room);
-        let mut file = BufWriter::new(File::create(out)?);
-        match args.format {
-            Format::Text => text::export_to_file(&vault, &mut file).await?,
-            Format::Json => json::export_to_file(&vault, &mut file).await?,
-            Format::JsonStream => json::export_stream_to_file(&vault, &mut file).await?,
+        if args.out == "-" {
+            eprintln!("Exporting &{room} as {} to stdout", args.format.name());
+            let vault = vault.room(room);
+            let mut stdout = BufWriter::new(io::stdout());
+            export_room(&vault, &mut stdout, args.format).await?;
+            stdout.flush()?;
+        } else {
+            let out = format_out(&args.out, &room, args.format);
+            eprintln!("Exporting &{room} as {} to {out}", args.format.name());
+            let vault = vault.room(room);
+            let mut file = BufWriter::new(File::create(out)?);
+            export_room(&vault, &mut file, args.format).await?;
+            file.flush()?;
         }
-        file.flush()?;
     }
 
     Ok(())

src/export/json.rs

@@ -1,14 +1,10 @@
-use std::fs::File;
-use std::io::{BufWriter, Write};
+use std::io::Write;
 
 use crate::vault::EuphRoomVault;
 
 const CHUNK_SIZE: usize = 10000;
 
-pub async fn export_to_file(
-    vault: &EuphRoomVault,
-    file: &mut BufWriter<File>,
-) -> anyhow::Result<()> {
+pub async fn export<W: Write>(vault: &EuphRoomVault, file: &mut W) -> anyhow::Result<()> {
     write!(file, "[")?;
 
     let mut total = 0;
@@ -39,14 +35,10 @@ pub async fn export_to_file(
     write!(file, "\n]")?;
 
     println!("  {total} messages in total");
-
     Ok(())
 }
 
-pub async fn export_stream_to_file(
-    vault: &EuphRoomVault,
-    file: &mut BufWriter<File>,
-) -> anyhow::Result<()> {
+pub async fn export_stream<W: Write>(vault: &EuphRoomVault, file: &mut W) -> anyhow::Result<()> {
     let mut total = 0;
     let mut offset = 0;
     loop {
@@ -69,6 +61,5 @@ pub async fn export_stream_to_file(
     }
 
     println!("  {total} messages in total");
-
     Ok(())
 }

src/export/text.rs

@@ -1,5 +1,4 @@
-use std::fs::File;
-use std::io::{BufWriter, Write};
+use std::io::Write;
 
 use euphoxide::api::MessageId;
 use time::format_description::FormatItem;
@@ -14,16 +13,13 @@ const TIME_FORMAT: &[FormatItem<'_>] =
     format_description!("[year]-[month]-[day] [hour]:[minute]:[second]");
 const TIME_EMPTY: &str = "                   ";
 
-pub async fn export_to_file(
-    vault: &EuphRoomVault,
-    file: &mut BufWriter<File>,
-) -> anyhow::Result<()> {
+pub async fn export<W: Write>(vault: &EuphRoomVault, out: &mut W) -> anyhow::Result<()> {
     let mut exported_trees = 0;
     let mut exported_msgs = 0;
     let mut root_id = vault.first_root_id().await;
     while let Some(some_root_id) = root_id {
         let tree = vault.tree(some_root_id).await;
-        write_tree(file, &tree, some_root_id, 0)?;
+        write_tree(out, &tree, some_root_id, 0)?;
         root_id = vault.next_root_id(some_root_id).await;
 
         exported_trees += 1;
@@ -38,8 +34,8 @@ pub async fn export_to_file(
     Ok(())
 }
 
-fn write_tree(
-    file: &mut BufWriter<File>,
+fn write_tree<W: Write>(
+    out: &mut W,
     tree: &Tree<SmallMessage>,
     id: MessageId,
     indent: usize,
@@ -47,22 +43,22 @@ fn write_tree(
     let indent_string = "| ".repeat(indent);
 
     if let Some(msg) = tree.msg(&id) {
-        write_msg(file, &indent_string, msg)?;
+        write_msg(out, &indent_string, msg)?;
     } else {
-        write_placeholder(file, &indent_string)?;
+        write_placeholder(out, &indent_string)?;
     }
 
     if let Some(children) = tree.children(&id) {
         for child in children {
-            write_tree(file, tree, *child, indent + 1)?;
+            write_tree(out, tree, *child, indent + 1)?;
         }
     }
 
     Ok(())
 }
 
-fn write_msg(
-    file: &mut BufWriter<File>,
+fn write_msg<W: Write>(
+    file: &mut W,
     indent_string: &str,
     msg: &SmallMessage,
 ) -> anyhow::Result<()> {
@@ -85,7 +81,7 @@ fn write_msg(
     Ok(())
 }
 
-fn write_placeholder(file: &mut BufWriter<File>, indent_string: &str) -> anyhow::Result<()> {
+fn write_placeholder<W: Write>(file: &mut W, indent_string: &str) -> anyhow::Result<()> {
     writeln!(file, "{TIME_EMPTY} {indent_string}[...]")?;
     Ok(())
 }