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use std::fmt::Display;
use std::fs;
use std::io::{Read, Write};
use std::path::Path;

/// A no-op struct that allows you to easily manipulate files.
pub struct File;

impl File {
    /// Read a file at `path` into a String.
    pub fn read<P: AsRef<Path>>(path: P) -> Result<String, String> {
        let mut file = fs::OpenOptions::new().read(true).open(&path);

        match &mut file {
            Ok(f) => {
                let mut contents = String::from("");
                match f.read_to_string(&mut contents) {
                    Ok(_) => Ok(contents),
                    Err(e) => Err(format!(
                        "Could not read from file '{}' because {}",
                        match path.as_ref().to_str() {
                            Some(s) => s,
                            None => "",
                        },
                        e.to_string()
                    )),
                }
            }
            Err(e) => Err(format!(
                "Could not open file '{}' because {}",
                match path.as_ref().to_str() {
                    Some(s) => s,
                    None => "",
                },
                e.to_string()
            )),
        }
    }

    /// Write a string to file.
    /// This truncates a file (sets its size to zero to clear its contents),
    /// and then writes `contents` to the file.
    pub fn write<P: AsRef<Path>, S: Display>(path: P, contents: S) -> Result<(), String> {
        let mut file = fs::OpenOptions::new()
            .create(true)
            .write(true)
            .truncate(true)
            .open(&path);

        match &mut file {
            Ok(f) => match writeln!(f, "{}", contents) {
                Ok(_) => Ok(()),
                Err(e) => Err(format!(
                    "Could not open file '{}' because {}",
                    match path.as_ref().to_str() {
                        Some(s) => s,
                        None => "",
                    },
                    e.to_string()
                )),
            },
            Err(e) => Err(format!(
                "Could not open file '{}' because {}",
                match path.as_ref().to_str() {
                    Some(s) => s,
                    None => "",
                },
                e.to_string()
            )),
        }
    }

    /// This does the same as write, but does not wipe the file,
    /// and appends `contents` to the end of the file.
    pub fn append<P: AsRef<Path>, S: Display>(path: P, contents: S) -> Result<(), String> {
        let mut file = fs::OpenOptions::new().append(true).write(true).open(&path);

        match &mut file {
            Ok(f) => match writeln!(f, "{}", contents) {
                Ok(_) => Ok(()),
                Err(e) => Err(format!(
                    "Could not open file '{}' because {}",
                    match path.as_ref().to_str() {
                        Some(s) => s,
                        None => "",
                    },
                    e.to_string()
                )),
            },
            Err(e) => Err(format!(
                "Could not open file '{}' because {}",
                match path.as_ref().to_str() {
                    Some(s) => s,
                    None => "",
                },
                e.to_string()
            )),
        }
    }
}