# README

## Workflow

1. `01-prepare.sh`
   1. Install R interpreter
   2. Add required repos to resolve syslibs
   3. Install pak
   4. Install awscli for remote s3 sync
2. `02-build-binaries.sh`
   1. For every package, do
      1. Clone from GitHub CRAN mirror
      2. Install all system dependencies via `pak::local_install_dev_deps()`
      3. Checkout each available tag
      4. Build source package
      5. Build binary package
      6. Create Archive/ directory
      7. Move all versions besides the most recent one to Archive/ (for source and binary)
      8. Create `PACKAGES` metadata file using `cranlike` package
3. `03-upload.sh`
   1. Sync all binaries and sources to S3 bucket
4. `-4-create-archive-rds.sh`
   1. Create `Meta/archive.rds` file for each package so that `remotes::install_version()` can install archived versions
   2. Upload `Meta/archive.rds` to S3 bucket

## Support for archived versions

### `remotes::install_version()`

`remotes::install_version()` is searching for a `Meta/archive.rds` file in the `/src/contrib` directory.
This file must be a list of dataframes containing the information about the archived versions of the package.

Example:

```r

con <- gzcon(url(sprintf("%s/src/contrib/Meta/archive.rds",
                           c("CRAN" = "https://cloud.r-project.org")), "rb"))
foo = readRDS(con)
foo[[1]]
```

### `pak::pak(package@version)`

`pak` searches for `Archive/<package>` and is able to install all versions existing there.
Ensure to use a clean cache if other repos have been used before, i.e. call `pak::meta_clean(force = TRUE)` if in doubt or when testing.

## Lessons learned

- Newer R versions have issues compiling C code from older package Versions. Using an older R version to build the binaries is recommended.
- R 4.0.5 is used to build all binaries for R 4.x
- Binaries which cannot be built using R 4.0.5 often also require older system library or compiler versions and are out of scope for this project.