build.rs

use image::{ImageFormat, ImageReader};
use sha256::try_digest;
use std::error::Error;
use std::ffi::OsString;
use std::fs::{read_dir, rename, write};
use std::path::{Path, PathBuf};
use webp::Encoder;

#[allow(dead_code)]
fn encode_as_webp(path: &Path) -> Result<(), Box<dyn Error>> {
    let image = {
        let res = ImageReader::open(path)?.with_guessed_format()?;
        let format = res.format().ok_or("Failed to get format of file!")?;

        // skip these files
        if format == ImageFormat::WebP || format == ImageFormat::Ico {
            return Ok(());
        }

        res.decode()?
    };

    let encoded = Encoder::from_image(&image)?.encode(90.0);

    let new_path = {
        let mut res = path.parent().unwrap().to_owned();
        let mut filename = path.file_stem().unwrap().to_owned();
        filename.push(".webp");
        res.push(filename);
        res
    };

    println!("Writing WebP to {new_path:?}");

    write(new_path, &*encoded)?;

    Ok(())
}

#[allow(dead_code)]
fn add_hash_to_filename(path: &PathBuf) -> Result<(), Box<dyn Error>> {
    let hash = try_digest(path.clone())?;

    if let Some((_, current_hash)) = path.file_stem().unwrap().to_str().unwrap().split_once('-') {
        if current_hash == hash {
            return Ok(());
        }
    }

    let new_path = {
        let mut res = path.parent().unwrap().to_owned();
        let mut p = path.file_stem().unwrap().to_owned();
        p.push(format!("-{hash}."));
        p.push(path.extension().unwrap());
        res.push(p);
        res
    };

    println!("Renaming file to {new_path:?}");

    rename(path, new_path)?;

    Ok(())
}

#[allow(dead_code)]
fn remove_hash(path: &PathBuf) -> Result<(), Box<dyn Error>> {
    let Some((original_name, _)) = path.file_stem().unwrap().to_str().unwrap().split_once('-')
    else {
        return Ok(());
        // return Err("Hash not found in name!")?;
    };

    let new_path = {
        let mut res = path.parent().unwrap().to_owned();
        let mut f = OsString::new();
        f.push(format!("{original_name}."));
        f.push(path.extension().unwrap());
        res.push(f);
        res
    };

    println!("Renaming file to {new_path:?}");

    rename(path, new_path)?;

    Ok(())
}

fn main() -> Result<(), Box<dyn Error>> {
    println!("cargo:rerun-if-changed=migrations");
    println!("cargo:rerun-if-changed=assets");

    // pass the var RM_HASH to remove instead
    // can be set to anything
    let opt_rm = std::env::var_os("RM_HASH");
    let opt_encode = std::env::var_os("HASH");

    if opt_rm.is_none() && opt_encode.is_none() {
        return Ok(());
    }

    for entry in read_dir("./assets")?.filter_map(|entry| Some(entry.ok()?.path())) {
        match (opt_rm.clone(), opt_encode.clone()) {
            (Some(_), None) => {
                remove_hash(&entry)?;
            }
            (None, Some(_)) => {
                encode_as_webp(&entry)?;
                add_hash_to_filename(&entry)?;
            }
            _ => {}
        }
    }

    Ok(())
}