tried to add a feature that would keep a streak

src/main.rs

@@ -1,9 +1,13 @@
-use chrono::{Datelike, Local};
+use chrono::{Datelike, Local, Duration};
 use clap::{Parser, Subcommand};
 use std::env;
 use std::process::Command;
 use std::fs::File;
 use std::io::Write;
+use std::fs::read_to_string;
+
+use serde::{Deserialize, Serialize};
+use serde_yaml;
 
 #[derive(Parser)]
 #[command(author, version, about = "A simple CLI tool example", long_about = None)]
@@ -28,15 +32,108 @@ enum Commands {
     },
 }
 
-fn main() {
-    let args = Args::parse();
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+struct DailyPostMetadata {
+    streak: u32,
+}
 
+fn get_daily_filepath() -> Result<String, String> {
     let DAILY_FILEPATH = match env::var("VIMTODAY_DAILY_FILEPATH") {
         Ok(val) => val,
         Err(_e) => String::from("oops")
     };
+
+    return Ok(DAILY_FILEPATH);
+}
+
+fn get_yesterday_filepath() -> Result<String, String> {
+    let today = Local::now();
+    let yesterday = today - Duration::days(1);
+    let daily_filepath = get_daily_filepath().unwrap();
+
+    let today_date_str = format!("{}-{:02}-{:02}", yesterday.year(), yesterday.month(), yesterday.day());
+    let file_name = format!("{}.md", &today_date_str);
+    let folder_name = format!("{}/{}", &daily_filepath, yesterday.year());
+    let mut directory_iterator = std::fs::read_dir(&folder_name).unwrap();
+
+    let file_exists = directory_iterator.any(|filename| *filename.unwrap().file_name() == *file_name);
+
+    if file_exists {
+        return Ok(file_name);
+    } else {
+        return Err("File don't exist".to_string());
+    }
+}
+
+fn read_daily_post_metadata(filepath: &str)-> Result<DailyPostMetadata, &str> {
+    let mut reading_yaml: bool = false;
+    let mut yaml_lines: Vec<String> = Vec::new();
+
+    for line in read_to_string(filepath).unwrap().lines() {
+        let line_str = line.to_string();
+        if line_str == "---" && reading_yaml == false {
+            reading_yaml = true;
+            yaml_lines.push(line_str);
+        } else if line_str == "---" && reading_yaml == true {
+            yaml_lines.push(line_str);
+            break;
+        } else if reading_yaml == true {
+            yaml_lines.push(line_str);
+        }
+    }
+
+    let combined_yaml = yaml_lines.join("\\n");
+    let metadata = serde_yaml::from_str(&combined_yaml.to_string());
+    return match metadata {
+        Ok(metadata) => Ok(metadata),
+        Err(_e) => Err("No metadata found")
+    };
+}
+
+fn update_streak(daily_filepath: &str, file: &mut File) {
+    // Get filepath from yesterday. If does not exist, return 0.
+    let mut streak: u32 = 0;
+    let yesterday_filepath = get_yesterday_filepath();
+
+    if let Err(e) = yesterday_filepath {
+        let today_metadata = DailyPostMetadata {
+            streak: 1,
+        };
+
+        let stringified_yaml = serde_yaml::to_string(&today_metadata).unwrap();
+        file.write_all(stringified_yaml.as_bytes()).expect("Unable to write YAML metadata");
+        return ();
+    }
+
+    let filepath = yesterday_filepath.unwrap();
+    let metadata: Result<DailyPostMetadata, &str> = read_daily_post_metadata(&filepath);
+
+    // Get metadata from yesterday's post. If metadata does not exist, return 1.
+    if let Err(e) = metadata {
+        let today_metadata = DailyPostMetadata {
+            streak: 2,
+        };
+
+        let stringified_yaml = serde_yaml::to_string(&today_metadata).unwrap();
+        file.write_all(stringified_yaml.as_bytes()).expect("Unable to write YAML metadata");
+        return ();
+    }
+
+    let prev_metadata: DailyPostMetadata = metadata.unwrap();
+    let today_metadata = DailyPostMetadata {
+        streak:  prev_metadata.streak + 1,
+    };
+
+    let stringified_yaml = serde_yaml::to_string(&today_metadata).unwrap();
+    file.write_all(stringified_yaml.as_bytes()).expect("Unable to write YAML metadata");
+}
+
+fn main() {
+    let args = Args::parse();
+
     let today = Local::now();
     let today_date_str = format!("{}-{:02}-{:02}", today.year(), today.month(), today.day());
+    let DAILY_FILEPATH = get_daily_filepath().unwrap();
     
     let file_path = format!("{}/{}/{}.md", &DAILY_FILEPATH, today.year(), &today_date_str);
     // Check if file is there already
@@ -50,6 +147,9 @@ fn main() {
         // Create a new file
         let mut file = File::create(&file_path).unwrap();
 
+        // Write YAML
+        let curent_streak = update_streak(&DAILY_FILEPATH, &mut file);
+
         // Write date at the start
         let date_header = format!("#{}", &today_date_str);
         writeln!(&mut file, "{}", &date_header);