csvpp 0.5.1

Compile csv++ source code to a target spreadsheet format
Documentation 
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use crate::{Compiler, Result};
use chrono::prelude::Local;
use log::info;
use std::fs;
use std::path;

const BACKUP_FORMATS: &[&str] = &[
    // filename.csv -> filename-2023-04-25.csv
    "%Y_%m_%d",
    // filename.csv -> filename-2023-04-25-1_00AM.csv
    "%Y_%m_%d-%I_%M%p",
    // filename.csv -> filename-2023-04-25-1_00_00AM.csv
    "%Y_%m_%d-%I_%M_%S%p",
    // filename.csv -> filename-2023-04-25-1_00_00_0000AM.csv
    "%Y_%m_%d-%I_%M_%S_%f%p",
];

/// Makes a copy of a file like foo.xlsx to foo-2023-04-25.xlsx
///
// NOTE:
// this operation is not atomic - to do so we'd need to create a tempfile, write to it
// then move it in place.  (but for this use case I don't think it matters)
pub(crate) fn backup_file<P: AsRef<path::Path>>(
    compiler: &Compiler,
    filename: P,
) -> Result<path::PathBuf> {
    let filename = filename.as_ref();

    info!("Backing up file: {}", filename.display());

    let filename_str = filename
        .to_str()
        .ok_or(compiler.output_error("Unable to format output filename"))?;

    let file_stem = filename
        .file_stem()
        .ok_or(compiler.output_error(format!("Unable to get base file for: {filename_str}")))?;

    let file_parent = filename.parent().ok_or(compiler.output_error(format!(
        "Unable to get parent base file for: {filename_str}",
    )))?;

    let file_extension = filename
        .extension()
        .ok_or(compiler.output_error(format!("Unable to get extension for: {filename_str}")))?;

    let now = Local::now();
    for time_format in BACKUP_FORMATS {
        let timestamp = now.format(time_format);

        let mut new_file = file_parent.to_path_buf();
        new_file.push(format!("{}-{timestamp}", file_stem.to_str().unwrap()));
        new_file.set_extension(file_extension);

        if new_file.exists() {
            continue;
        }

        if let Err(e) = fs::copy(filename, &new_file) {
            return Err(
                compiler.output_error(format!("Error making backup of {filename_str}: {e}",))
            );
        }

        return Ok(new_file);
    }

    Err(compiler.output_error(format!(
        "Unable to make backup of output file: {filename_str}",
    )))
}

#[cfg(test)]
mod tests {
    // use super::*;

    #[test]
    fn backup_file() {
        // TODO
    }
}