fileio 0.1.0

Fluent file I/O crate for Rust: read/write/append lines easily, including write_line functionality
Documentation 
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use std::fs::{File, OpenOptions};
use std::io::{self, BufRead, BufReader, Write};

/// Fluent File I/O helper
pub struct FileIO {
    path: String,
}

impl FileIO {
    /// Create a new FileIO instance
    pub fn new(path: &str) -> Self {
        Self { path: path.to_string() }
    }

    /// Read entire file as a single String
    pub fn read_all(&self) -> io::Result<String> {
        std::fs::read_to_string(&self.path)
    }

    /// Read file line by line
    pub fn read_lines(&self) -> io::Result<Vec<String>> {
        let file = File::open(&self.path)?;
        let reader = BufReader::new(file);
        reader.lines().collect()
    }

    /// Append a line to the end of the file
    pub fn append(&self, content: &str) -> io::Result<()> {
        let mut file = OpenOptions::new()
            .append(true)
            .create(true)
            .open(&self.path)?;
        writeln!(file, "{}", content)?;
        Ok(())
    }

    /// Overwrite the entire file with new content
    pub fn write(&self, content: &str) -> io::Result<()> {
        let mut file = OpenOptions::new()
            .write(true)
            .truncate(true)
            .create(true)
            .open(&self.path)?;
        file.write_all(content.as_bytes())
    }

    /// Write or replace a specific line (line_number starts from 1)
    pub fn write_line(&self, line_number: usize, content: &str) -> io::Result<()> {
        if line_number == 0 {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "line_number must be >= 1",
            ));
        }
        let mut lines = self.read_lines().unwrap_or_default();

        // Ensure enough lines exist
        if line_number > lines.len() {
            lines.resize(line_number, String::new());
        }

        // Replace the specific line
        lines[line_number - 1] = content.to_string();

        // Overwrite the file
        self.write(&lines.join("\n"))
    }

    /// Insert a line at a specific line number (pushes following lines down)
    pub fn insert_line(&self, line_number: usize, content: &str) -> io::Result<()> {
        if line_number == 0 {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "line_number must be >= 1",
            ));
        }
        let mut lines = self.read_lines().unwrap_or_default();

        if line_number > lines.len() + 1 {
            lines.resize(line_number - 1, String::new());
        }

        lines.insert(line_number - 1, content.to_string());

        self.write(&lines.join("\n"))
    }
}

/// Helper function for convenience
pub fn file(path: &str) -> FileIO {
    FileIO::new(path)
}