Add new `--style` called `header-filesize` and display it by default (#1988)

Also rename `header` to `header-filename`.

Related to #1701

111 files changed, 302 insertions, 42 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 97bc6e7b..ae734641 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Features
 
+- New style component `header-filesize` to show size of the displayed file in the header. See #1988 (@mdibaiee)
+
 ## Bugfixes
 
 ## Other
diff --git a/Cargo.lock b/Cargo.lock
index 4d8fecb1..4c17fd90 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -82,6 +82,7 @@ dependencies = [
  "atty",
  "bincode",
  "bugreport",
+ "bytesize",
  "clap",
  "clircle",
  "console",
@@ -170,6 +171,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "439989e6b8c38d1b6570a384ef1e49c8848128f5a97f3914baef02920842712f"
 
 [[package]]
+name = "bytesize"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c58ec36aac5066d5ca17df51b3e70279f5670a72102f5752cb7e7c856adfc70"
+
+[[package]]
 name = "cc"
 version = "1.0.72"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index 639e9d96..99a65642 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -65,6 +65,7 @@ dirs-next = { version = "2.0.0", optional = true }
 grep-cli = { version = "0.1.6", optional = true }
 regex = { version = "1.0", optional = true }
 walkdir = { version = "2.0", optional = true }
+bytesize = { version = "1.1.0" }
 
 [dependencies.git2]
 version = "0.13"
diff --git a/src/bin/bat/clap_app.rs b/src/bin/bat/clap_app.rs
index e0460f74..0a1a81cf 100644
--- a/src/bin/bat/clap_app.rs
+++ b/src/bin/bat/clap_app.rs
@@ -396,11 +396,19 @@ pub fn build_app(interactive_output: bool) -> ClapApp<'static, 'static> {
                 .validator(|val| {
                     let mut invalid_vals = val.split(',').filter(|style| {
                         !&[
-                            "auto", "full", "plain", "header", "grid", "rule", "numbers", "snip",
+                            "auto",
+                            "full",
+                            "plain",
+                            "header",
+                            "header-filename",
+                            "header-filesize",
+                            "grid",
+                            "rule",
+                            "numbers",
+                            "snip",
                             #[cfg(feature = "git")]
-                                "changes",
-                        ]
-                            .contains(style)
+                            "changes",
+                        ].contains(style)
                     });
 
                     if let Some(invalid) = invalid_vals.next() {
@@ -426,7 +434,9 @@ pub fn build_app(interactive_output: bool) -> ClapApp<'static, 'static> {
                      * auto: same as 'full', unless the output is piped.\n  \
                      * plain: disables all available components.\n  \
                      * changes: show Git modification markers.\n  \
-                     * header: show filenames before the content.\n  \
+                     * header: alias for 'header-filename'.\n  \
+                     * header-filename: show filenames before the content.\n  \
+                     * header-filesize: show file sizes before the content.\n  \
                      * grid: vertical/horizontal lines to separate side bar\n          \
                        and the header from the content.\n  \
                      * rule: horizontal lines to delimit files.\n  \
diff --git a/src/input.rs b/src/input.rs
index ffaca0ae..3c295822 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -1,4 +1,5 @@
 use std::convert::TryFrom;
+use std::fs;
 use std::fs::File;
 use std::io::{self, BufRead, BufReader, Read};
 use std::path::{Path, PathBuf};
@@ -87,6 +88,7 @@ impl<'a> InputKind<'a> {
 #[derive(Clone, Default)]
 pub(crate) struct InputMetadata {
     pub(crate) user_provided_name: Option<PathBuf>,
+    pub(crate) size: Option<u64>,
 }
 
 pub struct Input<'a> {
@@ -130,9 +132,14 @@ impl<'a> Input<'a> {
 
     fn _ordinary_file(path: &Path) -> Self {
         let kind = InputKind::OrdinaryFile(path.to_path_buf());
+        let metadata = InputMetadata {
+            size: fs::metadata(path).map(|m| m.len()).ok(),
+            ..InputMetadata::default()
+        };
+
         Input {
             descr