---
title: "Design Principles for lightr"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Design Principles for lightr}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r}
#| include: false
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

This vignette outlines the design decisions that have been taken during the development of the `{lightr}` R package, and provides some of the reasoning, and possible pros and cons of each decision.

This document is primarily intended to be read by those interested in understanding the code within the package and for potential package contributors.

## Scope

This package focuses on files produced by UV/VIS spectrophotometers.

## Architecture

This package has two-level of functions:

- low-level parsers to parse spectral data and metadata from a single file, for which the appropriate parser is known. Users have to create their own loops to parse multiple files, as described in `vignette("renormalise", package = "lightr")`.
- high-level parsers which automatically identify the relevant parser(s) (via the `dispatch_parser()` internal function) for a collection of files and consolidate all the data or metadata in a single rectangular data.frame.

```{comment}
#| echo: false
flowchart TD
    A(["lr_get_spec()"]) --> D["dispatch_parser"]
    B(["lr_get_metadata()"]) --> D
    C(["lr_convert_tocsv()"]) --> D
    D --> E["lr_parse_procspec"] & F["lr_parse_ttt"] & G["lr_parse_trt"] & H["lr_parse_jdx"] & I["lr_parse_trm"]
```

```{r}
#| fig-cap: Package architecture diagram
#| fig-alt: The high-level functions (lr_get_spec(), lr_get_metadata() and lr_convert_tocsv())
#|   feed individual files to the internal dispatch function (dispatch_parser()), which
#|   then passes each file to the relevant low-level parser.
knitr::include_graphics("architecture.svg")
```

## Naming conventions

- All exported functions start with the prefix `lr_`
- All low-level parsers are named as `lr_parse_<fileext>`
