1 files changed, 100 insertions, 0 deletions
diff --git a/rust/theBook/chapter-12-command-line-project/minigrep/src/lib.rs b/rust/theBook/chapter-12-command-line-project/minigrep/src/lib.rs
new file mode 100644
index 0000000..60057db
--- /dev/null
+++ b/rust/theBook/chapter-12-command-line-project/minigrep/src/lib.rs
@@ -0,0 +1,100 @@
+use std::{error::Error, fs, env};
+
+pub struct Config {
+    pub query: String,
+    pub file_path: String,
+    pub ignore_case: bool,
+    pub case_option: bool,
+}
+
+impl Config {
+    pub fn build(args: &[String]) -> Result<Config, &'static str> {
+        if args.len() < 4 {
+            return Err("Not enough arguments");
+        }
+
+        let query = args[1].clone();
+        let file_path = args[2].clone(); // String
+        let ignore_case = env::var("IGNORE_CASE").is_ok();
+        let case_option = match args[3].as_str() {
+            "true" => true,
+            &_ => false
+        };
+    
+        Ok(Config {query, file_path, ignore_case, case_option})
+    }
+}
+
+// Box<dyn Error> means the function will return a type that implements the Error trait
+// But we don’t have to specify what particular type the return value will be
+// This gives us flexibility to return error values that may be of different types in different error cases
+pub fn run(config: Config) -> Result<(), Box<dyn Error>>{ // dyn dynamic
+    let contents = fs::read_to_string(config.file_path)?;
+
+    let result = if config.ignore_case {
+        search_case_insensitive(&config.query, &contents)
+    }   else if config.case_option {
+        search_case_insensitive(&config.query, &contents)
+    }   else {
+        search(&config.query, &contents)
+    };
+
+    for line in result {
+        println!("{line}");
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn case_sensitive() {
+        let query = "duct";
+        let content = "\
+Rust:
+safe, fast, productive.
+Pick three.
+Duck tape";
+
+        assert_eq!(vec!["safe, fast, productive."], search(query,content));
+    }
+
+    #[test]
+    fn case_insensitive() {
+        let query = "rUsT";
+        let content= "\
+Rust:
+safe, fast, productive.
+Pick three.
+Trust me.";
+
+        assert_eq!(vec!["Rust:", "Trust me."], search_case_insensitive(query, content));
+    }
+}
+
+pub fn search<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
+    let mut result = Vec::new();
+
+    for line in content.lines() {
+        if line.contains(query) {
+            result.push(line);
+        }
+    }
+    result
+}
+
+pub fn search_case_insensitive<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
+    let mut result = Vec::new();
+
+    let query = query.to_lowercase();
+
+    for line in content.lines() {
+        if line.to_lowercase().contains(&query) {
+            result.push(line);
+        }
+    }
+    result
+}