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diff --git a/chapter4/.DS_Store b/chapter4/.DS_Store
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diff --git a/chapter4/.gitignore b/chapter4/.gitignore
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index 0000000..96ef6c0
--- /dev/null
+++ b/chapter4/.gitignore
@@ -0,0 +1,2 @@
+/target
+Cargo.lock
diff --git a/chapter4/Cargo.toml b/chapter4/Cargo.toml
new file mode 100644
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+++ b/chapter4/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "imagecli"
+version = "0.1.0"
+authors = ["peshwar9"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+name = "imagix"
+path = "src/imagix/mod.rs"
+
+[[bin]]
+name = "imagecli"
+path = "src/imagecli.rs"
+
+[dependencies]
+image = "0.23.7"
+structopt = "0.3.15"
diff --git a/chapter4/src/imagecli.rs b/chapter4/src/imagecli.rs
new file mode 100644
index 0000000..3838897
--- /dev/null
+++ b/chapter4/src/imagecli.rs
@@ -0,0 +1,63 @@
+mod imagix;
+use ::imagix::error::ImagixError;
+use ::imagix::resize::{process_resize_request, Mode, SizeOption};
+use ::imagix::stats::get_stats;
+use std::path::PathBuf;
+use structopt::StructOpt;
+// Define commandline arguments in a struct
+
+#[derive(StructOpt, Debug)]
+#[structopt(
+    name = "resize",
+    about = "This is a tool for image resizing and stats",
+    help = "Specify subcommand resize or stats. For help, type imagecli resize --help or imagecli stats --help"
+)]
+enum Commandline {
+    #[structopt(help = "Specify size(small/medium/large) , mode(single/all) and srcfolder")]
+    Resize {
+        #[structopt(long)]
+        size: SizeOption,
+        #[structopt(long)]
+        mode: Mode,
+        #[structopt(long, parse(from_os_str))]
+        srcfolder: PathBuf,
+    },
+    #[structopt(help = "Specify srcfolder")]
+    Stats {
+        #[structopt(long, parse(from_os_str))]
+        srcfolder: PathBuf,
+    },
+}
+
+fn main() {
+    let args: Commandline = Commandline::from_args();
+    match args {
+        Commandline::Resize {
+            size,
+            mode,
+            srcfolder,
+        } => {
+            let mut src_folder = srcfolder;
+            match process_resize_request(size, mode, &mut src_folder) {
+                Ok(_) => println!("Image(s) resized successfully"),
+                Err(e) => match e {
+                    ImagixError::FileIOError(e) => println!("{}", e),
+                    ImagixError::UserInputError(e) => println!("{}", e),
+                    ImagixError::ImageResizingError(e) => println!("{}", e),
+                    _ => println!("Error in processing"),
+                },
+            };
+        }
+        Commandline::Stats { srcfolder } => match get_stats(srcfolder) {
+            Ok((count, size)) => println!(
+                "Found {:?} image files with aggregate size of {:?} MB",
+                count, size
+            ),
+            Err(e) => match e {
+                ImagixError::FileIOError(e) => println!("{}", e),
+                ImagixError::UserInputError(e) => println!("{}", e),
+                _ => println!("Error in processing"),
+            },
+        },
+    }
+}
diff --git a/chapter4/src/imagix/error.rs b/chapter4/src/imagix/error.rs
new file mode 100644
index 0000000..901c83d
--- /dev/null
+++ b/chapter4/src/imagix/error.rs
@@ -0,0 +1,39 @@
+use image::error;
+use std::convert::From;
+use std::{fmt, io};
+
+#[derive(Debug)]
+pub enum ImagixError {
+    FileIOError(String),
+    UserInputError(String),
+    ImageResizingError(String),
+    FormatError(String),
+}
+
+impl From<io::Error> for ImagixError {
+    fn from(error: io::Error) -> Self {
+        ImagixError::FileIOError("Error in File I/O".to_string())
+    }
+}
+
+impl From<error::ImageError> for ImagixError {
+    fn from(error: error::ImageError) -> Self {
+        ImagixError::ImageResizingError("Error in image processing".to_string())
+    }
+}
+
+impl From<io::ErrorKind> for ImagixError {
+    fn from(error: io::ErrorKind) -> Self {
+        ImagixError::UserInputError("Error in user input".to_string())
+    }
+}
+
+impl fmt::Display for ImagixError {
+    fn fmt(&self, out: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        write!(
+            out,
+            "{}",
+            ImagixError::FormatError("Error occurred".to_string())
+        )
+    }
+}
diff --git a/chapter4/src/imagix/mod.rs b/chapter4/src/imagix/mod.rs
new file mode 100644
index 0000000..2e0e46f
--- /dev/null
+++ b/chapter4/src/imagix/mod.rs
@@ -0,0 +1,3 @@
+pub mod error;
+pub mod resize;
+pub mod stats;
diff --git a/chapter4/src/imagix/resize.rs b/chapter4/src/imagix/resize.rs
new file mode 100644
index 0000000..6fc952a
--- /dev/null
+++ b/chapter4/src/imagix/resize.rs
@@ -0,0 +1,176 @@
+use image::ImageFormat;
+use std::path::PathBuf;
+use std::result::Result;
+use std::str::FromStr;
+use std::time::{Duration, Instant};
+use std::{fmt, fs, io};
+
+use super::error::ImagixError;
+
+struct Elapsed(Duration);
+
+impl Elapsed {
+    fn from(start: &Instant) -> Self {
+        Elapsed(start.elapsed())
+    }
+}
+#[derive(Debug)]
+pub enum SizeOption {
+    Small,
+    Medium,
+    Large,
+}
+impl fmt::Display for Elapsed {
+    fn fmt(&self, out: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        match (self.0.as_secs(), self.0.subsec_nanos()) {
+            (0, n) if n < 1000 => write!(out, "{} ns", n),
+            (0, n) if n < 1000_000 => write!(out, "{} µs", n / 1000),
+            (0, n) => write!(out, "{} ms", n / 1000_000),
+            (s, n) if s < 10 => write!(out, "{}.{:02} s", s, n / 10_000_000),
+            (s, _) => write!(out, "{} s", s),
+        }
+    }
+}
+impl FromStr for SizeOption {
+    type Err = ImagixError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "small" => Ok(SizeOption::Small),
+            "medium" => Ok(SizeOption::Medium),
+            "large" => Ok(SizeOption::Large),
+            _ => Err(ImagixError::UserInputError(
+                "Invalid input for size".to_string(),
+            )),
+            //default
+        }
+    }
+}
+
+impl FromStr for Mode {
+    type Err = ImagixError;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "single" => Ok(Mode::Single),
+            "all" => Ok(Mode::All),
+            _ => Err(ImagixError::UserInputError(
+                "Wrong value for mode".to_string(),
+            )),
+        }
+    }
+}
+#[derive(Debug, PartialEq)]
+pub enum Mode {
+    Single,
+    All,
+}
+
+pub fn process_resize_request(
+    size: SizeOption,
+    mode: Mode,
+    src_folder: &mut PathBuf,
+) -> Result<(), ImagixError> {
+    let size = match size {
+        SizeOption::Small => 200,
+        SizeOption::Medium => 400,
+        SizeOption::Large => 800,
+    };
+    let _ = match mode {
+        Mode::All => resize_all(size, src_folder)?,
+        Mode::Single => resize_single(size, src_folder)?,
+    };
+    Ok(())
+}
+
+fn resize_single(size: u32, src_folder: &mut PathBuf) -> Result<(), ImagixError> {
+    let mut src_folder = src_folder;
+    // Get file stem from src_folder
+    resize_image(size, &mut src_folder)?;
+    Ok(())
+}
+
+fn resize_all(size: u32, src_folder: &mut PathBuf) -> Result<(), ImagixError> {
+    if let Ok(entries) = get_image_files(src_folder.to_path_buf()) {
+        for mut entry in entries {
+            resize_image(size, &mut entry)?;
+        }
+    };
+    Ok(())
+}
+
+fn resize_image(size: u32, src_folder: &mut PathBuf) -> Result<(), ImagixError> {
+    // Construct destination file name th .png extension
+    let new_file_name = src_folder
+        .file_stem()
+        .unwrap()
+        .to_str()
+        .ok_or(std::io::ErrorKind::InvalidInput)
+        //       .map(|f| format!("{}-{:?}.png", f, size));
+        .map(|f| format!("{}.png", f));
+
+    // Construct path to destination folder i.e. create /tmp under source folder if not exists
+    let mut dest_folder = src_folder.clone();
+    dest_folder.pop();
+    dest_folder.push("tmp/");
+    if !dest_folder.exists() {
+        fs::create_dir(&dest_folder)?;
+    }
+    dest_folder.pop();
+    dest_folder.push("tmp/tmp.png");
+    dest_folder.set_file_name(new_file_name?.as_str());
+
+    // Open source image file, scale it to desired size and write output to destination-folder/destination-file
+    let timer = Instant::now();
+    let img = image::open(&src_folder)?;
+    let scaled = img.thumbnail(size, size);
+    let mut output = fs::File::create(&dest_folder)?;
+    scaled.write_to(&mut output, ImageFormat::Png)?;
+    println!(
+        "Thumbnailed file: {:?} to size {}x{} in {}. Output file in {:?}",
+        src_folder,
+        size,
+        size,
+        Elapsed::from(&timer),
+        dest_folder
+    );
+    Ok(())
+}
+
+pub fn get_image_files(src_folder: PathBuf) -> Result<Vec<PathBuf>, ImagixError> {
+    let entries = fs::read_dir(src_folder)
+        .map_err(|e| ImagixError::UserInputError("Invalid source folder".to_string()))?
+        .map(|res| res.map(|e| e.path()))
+        .collect::<Result<Vec<_>, io::Error>>()?
+        .into_iter()
+        .filter(|r| {
+            r.extension() == Some("JPG".as_ref())
+                || r.extension() == Some("jpg".as_ref())
+                || r.extension() == Some("PNG".as_ref())
+                || r.extension() == Some("png".as_ref())
+        })
+        .collect();
+    Ok(entries)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_single_image_resize() {
+        let mut path = PathBuf::from("/tmp/images/image1.jpg");
+        let destination_path = PathBuf::from("/tmp/images/tmp/image1.png");
+        match process_resize_request(SizeOption::Small, Mode::Single, &mut path) {
+            Ok(dest) => assert_eq!(true, destination_path.exists()),
+            Err(e) => println!("Error in single image: {:?}", e),
+        }
+        assert_eq!(true, destination_path.exists());
+    }
+    #[test]
+    fn test_multiple_image_resize() {
+        let mut path = PathBuf::from("/tmp/images/");
+        let _res = process_resize_request(SizeOption::Small, Mode::All, &mut path);
+        let destination_path1 = PathBuf::from("/tmp/images/tmp/image1.png");
+        let destination_path2 = PathBuf::from("/tmp/images/tmp/image2.png");
+        assert_eq!(true, destination_path1.exists());
+        assert_eq!(true, destination_path2.exists());
+    }
+}
diff --git a/chapter4/src/imagix/stats.rs b/chapter4/src/imagix/stats.rs
new file mode 100644
index 0000000..4184dd1
--- /dev/null
+++ b/chapter4/src/imagix/stats.rs
@@ -0,0 +1,24 @@
+use super::error::ImagixError;
+use super::resize::get_image_files;
+use std::path::PathBuf;
+
+pub fn get_stats(src_folder: PathBuf) -> Result<(usize, u64), ImagixError> {
+    let image_files = get_image_files(src_folder.to_path_buf())?;
+    let size = image_files
+        .iter()
+        .map(move |f| f.metadata().unwrap().len())
+        .sum::<u64>();
+    Ok((image_files.len(), size / 1000000))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_get_stats() {
+        let path = PathBuf::from("/tmp/images");
+        let (count, size) = get_stats(path).unwrap();
+        assert_eq!(count, 2);
+        assert_eq!(size, 8);
+    }
+}