Restructure export code and arg handling

src/export/text.rs

@@ -0,0 +1,94 @@
+use std::fs::File;
+use std::io::{BufWriter, Write};
+
+use time::format_description::FormatItem;
+use time::macros::format_description;
+use unicode_width::UnicodeWidthStr;
+
+use crate::euph::api::Snowflake;
+use crate::euph::SmallMessage;
+use crate::store::{MsgStore, Tree};
+use crate::vault::Vault;
+
+const TIME_FORMAT: &[FormatItem<'_>] =
+    format_description!("[year]-[month]-[day] [hour]:[minute]:[second]");
+const TIME_EMPTY: &str = "                   ";
+
+pub async fn export_to_file(
+    vault: &Vault,
+    room: String,
+    file: &mut BufWriter<File>,
+) -> anyhow::Result<()> {
+    let vault = vault.euph(room);
+
+    let mut exported_trees = 0;
+    let mut exported_msgs = 0;
+    let mut tree_id = vault.first_tree_id().await;
+    while let Some(some_tree_id) = tree_id {
+        let tree = vault.tree(&some_tree_id).await;
+        write_tree(file, &tree, some_tree_id, 0)?;
+        tree_id = vault.next_tree_id(&some_tree_id).await;
+
+        exported_trees += 1;
+        exported_msgs += tree.len();
+
+        if exported_trees % 10000 == 0 {
+            println!("  {exported_trees} trees, {exported_msgs} messages")
+        }
+    }
+    println!("  {exported_trees} trees, {exported_msgs} messages in total");
+
+    Ok(())
+}
+
+fn write_tree(
+    file: &mut BufWriter<File>,
+    tree: &Tree<SmallMessage>,
+    id: Snowflake,
+    indent: usize,
+) -> anyhow::Result<()> {
+    let indent_string = "| ".repeat(indent);
+
+    if let Some(msg) = tree.msg(&id) {
+        write_msg(file, &indent_string, msg)?;
+    } else {
+        write_placeholder(file, &indent_string)?;
+    }
+
+    if let Some(children) = tree.children(&id) {
+        for child in children {
+            write_tree(file, tree, *child, indent + 1)?;
+        }
+    }
+
+    Ok(())
+}
+
+fn write_msg(
+    file: &mut BufWriter<File>,
+    indent_string: &str,
+    msg: &SmallMessage,
+) -> anyhow::Result<()> {
+    let nick = &msg.nick;
+    let nick_empty = " ".repeat(nick.width());
+
+    for (i, line) in msg.content.lines().enumerate() {
+        if i == 0 {
+            let time = msg
+                .time
+                .0
+                .format(TIME_FORMAT)
+                .expect("time can be formatted");
+            writeln!(file, "{time} {indent_string}[{nick}] {line}")?;
+        } else {
+            writeln!(file, "{TIME_EMPTY} {indent_string}| {nick_empty} {line}")?;
+        }
+    }
+
+    Ok(())
+}
+
+fn write_placeholder(file: &mut BufWriter<File>, indent_string: &str) -> anyhow::Result<()> {
+    writeln!(file, "{TIME_EMPTY} {indent_string}[...]")?;
+    Ok(())
+}