Rust : 生成日历管理markdown文件的小工具

需求：
拟生成以下markdown管理小工具，这也是我日常工作日程表。
可以输入任意时间段，运行后就可以生成以上的markdown文件。

一、toml

[package]
name = "rust-workfile"
version = "0.1.0"
edition = "2021"

[dependencies]
chrono ="0.4.38"

二、main.rs
// 假设 从2025-01-01到2016-01-01

use std::fs::OpenOptions;
use std::collections::HashMap;
use std::io::Write;
use chrono::prelude::*;
fn main() {
    let file_name = "./workfile_2025.md" ;
    let start_date= "2025-01-01";
    let end_date  = "2026-01-01";
    write_markdown_file(file_name,start_date,end_date);
}
fn write_markdown_file(file_name: &str,start_date:&str, end_date:&str){
    let mut _file = OpenOptions::new().read(true).write(true).create(true).open(file_name).unwrap();
    let mut buffer = String::new();
    buffer.push_str("# workfile \n\n");
    let start_date: NaiveDate = NaiveDate::parse_from_str(start_date, "%Y-%m-%d").unwrap();
    let end_date : NaiveDate = NaiveDate::parse_from_str(end_date, "%Y-%m-%d").unwrap();
    let delta_days = end_date.signed_duration_since(start_date).num_days();
    let weeks_num = (delta_days as f32 / 7.0 ).ceil() as usize;
    let start_week = start_date.week(Weekday::Mon);
    let first_day = start_week.first_day();
    let first_days = first_day.iter_weeks().take(weeks_num).collect::<Vec<NaiveDate>>();
    let mut month_map :HashMap<String,bool> = HashMap::new();
    for first_date in first_days{

        let format_year_month = format!("## {} \n\n",first_date.format("%Y年%m月"));
        if !month_map.contains_key(&format_year_month) {
            buffer.push_str(&format_year_month); 
            month_map.insert(format_year_month,true);
           
        }
        let week_dates :Vec<NaiveDate> = first_date.iter_days().take(5).collect();
        //### [2024_12_2-2024-12_6]
        let format_week_start_end = format!("### [{}-{}] \n\n",week_dates[0].format("%Y_%m_%d"),week_dates[4].format("%Y_%m_%d"));       
        buffer.push_str(&format_week_start_end);
        // #### 周一[2024_12_2]：
        for week_date  in week_dates{
            let str_week_day = get_weekday_string(&week_date);
            let format_date = format!("#### {}[{}]\n\n",str_week_day,week_date.format("%Y_%m_%d"));
            buffer.push_str(&format_date);
        }

    }
    _file
        .write(&buffer.as_bytes())
        .expect("write failed!");
    println!("文件已经生成！");
}
fn get_weekday_string(date :&NaiveDate) ->&str{
    let weekday = date.weekday();
    let weekday_str = match weekday{
        Weekday::Mon => "周一",
        Weekday::Tue => "周二",
        Weekday::Wed => "周三",
        Weekday::Thu => "周四",
        Weekday::Fri => "周五",
        Weekday::Sat => "周六",
        Weekday::Sun => "周日", 
         _ => "Unknown",
    };
    weekday_str
}