develop_debug 0.2.0

use std::fs;
fn main() {
    println!("cargo:rerun-if-changed=Cargo.toml");
    println!("cargo:rerun-if-changed=T.README.md");
    println!("cargo:rerun-if-changed=/src/lib.rs");
    // Use the file that corresponds to the compilation option
    if cfg!(debug_assertions) {
        // println!("cargo:warning=The crate 'develop_debug' is running in debug mode");
        println!("cargo:rustc-env=develop_debug=true");
        let enable = fs::copy("./src/mode/debug_mode.rs", "./src/copy_mode.rs");
        if let Err(err) = enable {
            println!("cargo:warning=Failed to copy file 'debug_mode.rs'. {}", err);
        }
    } else {
        println!("cargo:rustc-env=develop_debug=false");
        // println!("cargo:warning=The crate 'develop_debug' is running in release mode");
        let ignore = fs::copy("./src/mode/release_mode.rs", "./src/copy_mode.rs");
        if let Err(err) = ignore {
            println!(
                "cargo:warning=Failed to copy file 'release_mode.rs'. {}",
                err
            );
        }
    }
    // If the version changes, change the version in the file `copy_mode.rs`.
    let copy = fs::read_to_string("./src/copy_mode.rs");
    if let Ok(s) = copy {
        let update_ver = s.replace(
            "version = \"...\"",
            &format!("version = \"{}\"", env!("CARGO_PKG_VERSION")),
        );
        if let Err(err) = fs::write("./src/copy_mode.rs", update_ver) {
            println!(
                "cargo:warning=Failed to update version in './src/copy_mode.rs'. {}",
                err
            );
        }
    }
    // If the version changes, change the version in the file `README.md`.
    let tr = fs::read_to_string("./T.README.md");
    if let Ok(s) = tr {
        let t = s.replace("{ver}", env!("CARGO_PKG_VERSION"));
        let how = fs::read_to_string("./tests/how_to_use.rs");
        if let Ok(h) = how {
            let readme = t.replace("{how_to_use}", &h);
            if let Err(err) = fs::write("./README.md", readme) {
                println!("cargo:warning=Failed to write './README.md'. {}", err);
            }
        }
    }
}