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

4 files changed, 50 insertions, 8 deletions

diff --git a/src/context/app_context.rs b/src/context/app_context.rs
index e03079a..5c206e5 100644
--- a/src/context/app_context.rs
+++ b/src/context/app_context.rs
@@ -2,16 +2,16 @@ use std::collections::VecDeque;
 use std::sync::mpsc;
 
 use crate::config;
-use crate::context::{LocalStateContext, TabContext, WorkerContext};
+use crate::context::{LocalStateContext, PreviewContext, TabContext, WorkerContext};
 use crate::event::{AppEvent, Events};
 use crate::util::search::SearchPattern;
 
 pub struct AppContext {
     pub exit: bool,
-    // app config
-    config: config::AppConfig,
     // event loop querying
     pub events: Events,
+    // app config
+    config: config::AppConfig,
     // context related to tabs
     tab_context: TabContext,
     // context related to local file state
@@ -22,6 +22,8 @@ pub struct AppContext {
     message_queue: VecDeque<String>,
     // context related to io workers
     worker_context: WorkerContext,
+    // context related to previews
+    preview_context: PreviewContext,
 }
 
 impl AppContext {
@@ -36,6 +38,7 @@ impl AppContext {
             search_context: None,
             message_queue: VecDeque::with_capacity(4),
             worker_context: WorkerContext::new(event_tx),
+            preview_context: PreviewContext::new(),
             config,
         }
     }
@@ -47,6 +50,9 @@ impl AppContext {
     pub fn flush_event(&self) {
         self.events.flush();
     }
+    pub fn clone_event_tx(&self) -> mpsc::Sender<AppEvent> {
+        self.events.event_tx.clone()
+    }
 
     pub fn config_ref(&self) -> &config::AppConfig {
         &self.config
@@ -87,6 +93,13 @@ impl AppContext {
         self.search_context = Some(pattern);
     }
 
+    pub fn preview_context_ref(&self) -> &PreviewContext {
+        &self.preview_context
+    }
+    pub fn preview_context_mut(&mut self) -> &mut PreviewContext {
+        &mut self.preview_context
+    }
+
     pub fn worker_context_ref(&self) -> &WorkerContext {
         &self.worker_context
     }
diff --git a/src/context/mod.rs b/src/context/mod.rs
index a1b8ed9..0a5f6c2 100644
--- a/src/context/mod.rs
+++ b/src/context/mod.rs
@@ -1,9 +1,11 @@
 mod app_context;
 mod local_state;
+mod preview_context;
 mod tab_context;
 mod worker_context;
 
 pub use self::app_context::AppContext;
 pub use self::local_state::LocalStateContext;
+pub use self::preview_context::PreviewContext;
 pub use self::tab_context::TabContext;
 pub use self::worker_context::WorkerContext;
diff --git a/src/context/preview_context.rs b/src/context/preview_context.rs
new file mode 100644
index 0000000..d344323
--- /dev/null
+++ b/src/context/preview_context.rs
@@ -0,0 +1,27 @@
+use std::collections::HashMap;
+use std::io;
+use std::path;
+use std::process;
+
+use crate::event::AppEvent;
+use crate::preview::preview_file::FilePreview;
+
+pub struct PreviewContext {
+    pub previews: HashMap<path::PathBuf, FilePreview>,
+}
+
+impl PreviewContext {
+    pub fn new() -> Self {
+        Self {
+            previews: HashMap::new(),
+        }
+    }
+
+    pub fn get_preview(&self, p: &path::Path) -> Option<&FilePreview> {
+        self.previews.get(p)
+    }
+
+    pub fn insert_preview(&mut self, p: path::PathBuf, file_preview: FilePreview) {
+        self.previews.insert(p, file_preview);
+    }
+}
diff --git a/src/context/worker_context.rs b/src/context/worker_context.rs
index bd0802c..10b464b 100644
--- a/src/context/worker_context.rs
+++ b/src/context/worker_context.rs
@@ -7,23 +7,23 @@ use crate::event::AppEvent;
 use crate::io::{IoWorkerObserver, IoWorkerProgress, IoWorkerThread};
 
 pub struct WorkerContext {
+    // to send info
+    event_tx: mpsc::Sender<AppEvent>,
     // queue of IO workers
     worker_queue: VecDeque<IoWorkerThread>,
     // current worker
     worker: Option<IoWorkerObserver>,
-    // to send info
-    event_tx: mpsc::Sender<AppEvent>,
 }
 
 impl WorkerContext {
     pub fn new(event_tx: mpsc::Sender<AppEvent>) -> Self {
         Self {
+            event_tx,
             worker_queue: VecDeque::new(),
             worker: None,
-            event_tx,
         }
     }
-    pub fn get_event_tx(&self) -> mpsc::Sender<AppEvent> {
+    pub fn clone_event_tx(&self) -> mpsc::Sender<AppEvent> {
         self.event_tx.clone()
     }
     // worker related
@@ -61,7 +61,7 @@ impl WorkerContext {
     }
 
     pub fn start_next_job(&mut self) {
-        let tx = self.get_event_tx();
+        let tx = self.clone_event_tx();
 
         if let Some(worker) = self.worker_queue.pop_front() {
             let src = worker.paths[0].parent().unwrap().to_path_buf();