rudimentary file preview support

 - this currently has only been tested with text files
 - no line formatting is done yet
 - only prints the preview as a single line
 - folder previews can now be pushed onto a separate thread if needed

3 files changed, 155 insertions, 97 deletions

diff --git a/src/preview/preview_default.rs b/src/preview/preview_default.rs
index 9601800..691cf72 100644
--- a/src/preview/preview_default.rs
+++ b/src/preview/preview_default.rs
@@ -8,7 +8,7 @@ pub fn load_preview_path(context: &mut AppContext, backend: &mut TuiBackend, p:
     if p.is_dir() {
         preview_dir::load_preview(context, p);
     } else if p.is_file() {
-        preview_file::preview_path_with_script(context, backend, p);
+        preview_file::Background::preview_path_with_script(context, backend, p);
     }
 }
 
diff --git a/src/preview/preview_dir.rs b/src/preview/preview_dir.rs
index bf1d151..03ae189 100644
--- a/src/preview/preview_dir.rs
+++ b/src/preview/preview_dir.rs
@@ -4,45 +4,47 @@ use std::thread;
 
 use crate::context::AppContext;
 use crate::event::AppEvent;
+use crate::fs::JoshutoDirList;
 use crate::history::DirectoryHistory;
 
-pub fn load_preview(context: &mut AppContext, p: path::PathBuf) -> io::Result<path::PathBuf> {
-    // get preview
+pub fn load_preview(context: &mut AppContext, p: path::PathBuf) -> io::Result<()> {
     let options = context.config_ref().display_options_ref().clone();
     context
         .tab_context_mut()
         .curr_tab_mut()
         .history_mut()
         .create_or_soft_update(p.as_path(), &options)?;
-    Ok(p)
+    Ok(())
 }
 
-pub struct CursorDir {}
-
-impl CursorDir {
-    pub fn load(context: &mut AppContext) -> io::Result<()> {
-        let mut p: Option<path::PathBuf> = None;
-        if let Some(curr_list) = context.tab_context_ref().curr_tab_ref().curr_list_ref() {
-            if let Some(index) = curr_list.index {
-                let entry = &curr_list.contents[index];
-                p = Some(entry.file_path().to_path_buf())
+pub fn background_load_preview(
+    context: &mut AppContext,
+    p: path::PathBuf,
+) -> thread::JoinHandle<()> {
+    let need_to_load = match context
+        .tab_context_mut()
+        .curr_tab_mut()
+        .history_mut()
+        .get(p.as_path())
+    {
+        Some(entry) => entry.need_update(),
+        None => true,
+    };
+    if need_to_load {
+        let event_tx = context.events.event_tx.clone();
+        let options = context.config_ref().display_options_ref().clone();
+        let handle = thread::spawn(move || {
+            match JoshutoDirList::new(p, &options) {
+                Ok(dirlist) => {
+                    event_tx.send(AppEvent::PreviewDir(Ok(dirlist)));
+                }
+                Err(_) => {}
             }
-        }
-
-        let res = match p {
-            Some(p) if p.is_dir() => load_preview(context, p),
-            Some(p) => Err(io::Error::new(
-                io::ErrorKind::InvalidData,
-                "Not a directory".to_string(),
-            )),
-            None => Err(io::Error::new(
-                io::ErrorKind::NotFound,
-                "No such file or directory".to_string(),
-            )),
-        };
-        match res {
-            Ok(_) => Ok(()),
-            Err(e) => Err(e),
-        }
+            ()
+        });
+        handle
+    } else {
+        let handle = thread::spawn(|| ());
+        handle
     }
 }
diff --git a/src/preview/preview_file.rs b/src/preview/preview_file.rs
index 5aabb13..1a2e5f9 100644
--- a/src/preview/preview_file.rs
+++ b/src/preview/preview_file.rs
@@ -1,86 +1,142 @@
 use std::io;
 use std::path;
 use std::process::{Command, Output};
+use std::thread;
 
 use tui::layout::{Constraint, Direction, Layout, Rect};
 use tui::widgets::{Block, Borders};
 
 use crate::context::AppContext;
-use crate::ui::TuiBackend;
-
-pub fn preview_path_with_script(
-    context: &AppContext,
-    backend: &mut TuiBackend,
-    p: path::PathBuf,
-) -> io::Result<Output> {
-    let preview_options = context.config_ref().preview_options_ref();
-    let config = context.config_ref();
-
-    match preview_options.preview_script.as_ref() {
-        None => Err(io::Error::new(
-            io::ErrorKind::Other,
-            "No preview script specified",
-        )),
-        Some(script) => {
-            let area = backend.terminal.as_ref().unwrap().size().unwrap();
+use crate::event::AppEvent;
+use crate::ui::{self, TuiBackend};
 
-            let constraints: &[Constraint; 3] = &config.display_options_ref().default_layout;
-
-            let layout_rect = if config.display_options_ref().show_borders() {
-                let area = Rect {
-                    y: area.top() + 1,
-                    height: area.height - 2,
-                    ..area
-                };
-
-                let block = Block::default().borders(Borders::ALL);
-                let inner = block.inner(area);
-
-                let layout_rect = Layout::default()
-                    .direction(Direction::Horizontal)
-                    .constraints(constraints.as_ref())
-                    .split(inner);
-
-                let block = Block::default().borders(Borders::LEFT);
-                let inner3 = block.inner(layout_rect[2]);
-                inner3
-            } else {
-                let layout_rect = Layout::default()
-                    .direction(Direction::Horizontal)
-                    .vertical_margin(1)
-                    .constraints(constraints.as_ref())
-                    .split(area);
-                layout_rect[2]
-            };
-
-            let file_full_path = p.as_path();
-            let preview_width = layout_rect.width;
-            let preview_height = layout_rect.height;
-            let image_cache = 0;
-            let preview_image = if preview_options.preview_images { 1 } else { 0 };
+#[derive(Clone, Debug)]
+pub struct FilePreview {
+    pub _path: path::PathBuf,
+    pub status: std::process::ExitStatus,
+    pub output: String,
+}
+
+impl std::convert::From<(path::PathBuf, Output)> for FilePreview {
+    fn from((p, output): (path::PathBuf, Output)) -> Self {
+        let s = String::from_utf8_lossy(&output.stdout).to_string();
+        let status = output.status;
+        Self {
+            _path: p,
+            status,
+            output: s,
+        }
+    }
+}
+
+pub struct Foreground {}
+
+impl Foreground {
+    pub fn preview_path_with_script(
+        context: &AppContext,
+        backend: &mut TuiBackend,
+        p: path::PathBuf,
+    ) -> io::Result<Output> {
+        let preview_options = context.config_ref().preview_options_ref();
+        let config = context.config_ref();
+
+        match preview_options.preview_script.as_ref() {
+            None => Err(io::Error::new(
+                io::ErrorKind::Other,
+                "No preview script specified",
+            )),
+            Some(script) => {
+                let area = backend.terminal.as_ref().unwrap().size().unwrap();
+                let display_options = config.display_options_ref();
+                let constraints: &[Constraint; 3] = &display_options.default_layout;
+
+                let layout_rect = ui::build_layout(area, constraints, display_options)[2];
+
+                let file_full_path = p.as_path();
+                let preview_width = layout_rect.width;
+                let preview_height = layout_rect.height;
+                let image_cache = 0;
+                let preview_image = if preview_options.preview_images { 1 } else { 0 };
+
+                // spawn preview process
+                Command::new(script)
+                    .arg(file_full_path)
+                    .arg(preview_width.to_string())
+                    .arg(preview_height.to_string())
+                    .arg(image_cache.to_string())
+                    .arg(preview_image.to_string())
+                    .output()
+            }
+        }
+    }
+
+    pub fn preview_with_script(
+        context: &AppContext,
+        backend: &mut TuiBackend,
+    ) -> io::Result<Output> {
+        let curr_tab = context.tab_context_ref().curr_tab_ref();
+        let child_list = curr_tab.child_list_ref();
+
+        let preview_options = context.config_ref().preview_options_ref();
 
-            // spawn preview process
-            Command::new(script)
-                .arg(file_full_path)
-                .arg(preview_width.to_string())
-                .arg(preview_height.to_string())
-                .arg(image_cache.to_string())
-                .arg(preview_image.to_string())
-                .output()
+        let config = context.config_ref();
+
+        match child_list.and_then(|list| list.curr_entry_ref()) {
+            None => Err(io::Error::new(io::ErrorKind::Other, "No file to preview")),
+            Some(entry) => {
+                Self::preview_path_with_script(context, backend, entry.file_path().to_path_buf())
+            }
         }
     }
 }
 
-pub fn preview_with_script(context: &AppContext, backend: &mut TuiBackend) -> io::Result<Output> {
-    let curr_tab = context.tab_context_ref().curr_tab_ref();
-    let child_list = curr_tab.child_list_ref();
+pub struct Background {}
+
+impl Background {
+    pub fn preview_path_with_script(
+        context: &AppContext,
+        backend: &mut TuiBackend,
+        p: path::PathBuf,
+    ) {
+        if let Some(preview) = context.preview_context_ref().get_preview(p.as_path()) {
+            return;
+        }
+
+        let preview_options = context.config_ref().preview_options_ref();
+        let config = context.config_ref();
 
-    let preview_options = context.config_ref().preview_options_ref();
+        if let Some(script) = preview_options.preview_script.as_ref() {
+            let area = backend.terminal.as_ref().unwrap().size().unwrap();
+            let display_options = config.display_options_ref();
+            let constraints: &[Constraint; 3] = &display_options.default_layout;
+
+            let layout_rect = ui::build_layout(area, constraints, display_options)[2];
+
+            let preview_width = layout_rect.width;
+            let preview_height = layout_rect.height;
+            let image_cache = 0;
+            let preview_image = if preview_options.preview_images { 1 } else { 0 };
 
-    let config = context.config_ref();
+            let script = script.clone();
+            let event_tx = context.clone_event_tx();
+            let thread = thread::spawn(move || {
+                let file_full_path = p.as_path();
 
-    match child_list.and_then(|list| list.curr_entry_ref()) {
-        None => Err(io::Error::new(io::ErrorKind::Other, "No file to preview")),
-        Some(entry) => preview_path_with_script(context, backend, entry.file_path().to_path_buf()),
+                let res = Command::new(script)
+                    .arg(file_full_path)
+                    .arg(preview_width.to_string())
+                    .arg(preview_height.to_string())
+                    .arg(image_cache.to_string())
+                    .arg(preview_image.to_string())
+                    .output();
+                match res {
+                    Ok(output) => {
+                        let preview = FilePreview::from((p, output));
+                        event_tx.send(AppEvent::PreviewFile(preview));
+                    }
+                    Err(_) => {}
+                }
+            });
+        }
     }
 }