---
title: "Hook Testing"
author: '@jemus42'
date: "5/16/2020"
output: github_document
---

```{r setup, include=TRUE}
knitr::knit_hooks$set(source = function(x, options) {

  # The original source in a fenced code block
  source_orig <- paste(c("```r", x, "```\n"), collapse = "\n")

  fold_option <- options[["code_fold"]]

  # If option not set or explicitly FALSE, return regular code chunk
  if (is.null(fold_option) | isFALSE(fold_option)) {
   return(source_orig) 
  } 
  
  summary_text <- ifelse(
    is.character(fold_option), # If the option is text,
    fold_option,               # use it as <summary>Label</summary>,
    "Click to expand"          # otherwise here's a default
  )
  
  # Output details tag
  glue::glue(
    "<details>
      <summary>{summary_text}</summary>
      {source_orig}
    </details>"
  )
})

```

### Regular output as usual, `code_fold` not set

```{r testing-hook-hide}
library(dplyr, warn.conflicts = FALSE)
iris %>%
  filter(Sepal.Width > 3) %>%
  head(5)
```

### Hidden source, custom summary, `code_fold="I heard you like flowers"`

```{r testing-hook-show, code_fold="I heard you like flowers"}
iris %>%
  filter(Sepal.Width > 3) %>%
  head(5)
```

### Hidden source, default summary, `code_fold=TRUE`

```{r testing-hook-show-default, code_fold=TRUE}
iris %>%
  filter(Sepal.Width > 3) %>%
  head(5)
```

### Source shown, `code_fold=FALSE`

```{r testing-hook-show-disabled, code_fold=FALSE}
iris %>%
  filter(Sepal.Width > 3) %>%
  head(5)
```