module DependencyInjection where

import CheapskateRenderer (HTML, MarkDown, htmlToText, markDownToHtml, textToMarkDown)

--import CMarkGFMRenderer (HTML, MarkDown, textToMarkDown, markDownToHtml, htmlToText)

import Control.Category ((>>>)) -- f >>> g = g . f

import qualified Data.Text as T

-- | a table of contents consists of a heading and a list of entries

data TableOfContents = Section Heading [TocEntry]

-- | a ToC entry can be a heading or a sub-table of contents

data TocEntry = Head Heading | Sub TableOfContents

-- | a heading can be just a title string or an url with a title and the actual link

data Heading = Title String | Url String String

-- | render a ToC entry as a Markdown String with the proper indentation

teToMd :: Int -> TocEntry -> String

teToMd depth (Head head) = headToMd depth head

teToMd depth (Sub toc) = tocToMd depth toc

-- | render a heading as a Markdown String with the proper indentation

headToMd :: Int -> Heading -> String

headToMd depth (Title str) = indent depth ++ "* " ++ str ++ "\n"

headToMd depth (Url title url) = indent depth ++ "* [" ++ title ++ "](" ++ url ++ ")\n"

-- | convert a ToC to Markdown String. The parameter depth is used for proper indentation.

tocToMd :: Int -> TableOfContents -> String

tocToMd depth (Section heading entries) = headToMd depth heading ++ concatMap (teToMd (depth+2)) entries

-- | produce a String of length n, consisting only of blanks

indent :: Int -> String

indent n = replicate n ' '

-- | render a ToC as a Text (consisting of properly indented Markdown)

tocToMDText :: TableOfContents -> T.Text

tocToMDText = T.pack . tocToMd 0

-- | render a ToC as a Text with html markup.

-- we specify this function as a chain of parse and rendering functions that must be provided externally

tocToHtmlText :: (TableOfContents -> T.Text) -- 1. a renderer function from ToC to Text with markdown markups

-> (T.Text -> MarkDown) -- 2. a parser function from Text to a MarkDown document

-> (MarkDown -> HTML) -- 3. a renderer function from MarkDown to an HTML document

-> (HTML -> T.Text) -- 4. a renderer function from HTML to Text

-> TableOfContents -- the actual ToC to be rendered

-> T.Text -- the Text output (containing html markup)

tocToHtmlText tocToMdText textToMd mdToHtml htmlToText =

tocToMdText >>> -- 1. render a ToC as a Text (consisting of properly indented Markdown)

textToMd >>> -- 2. parse text with Markdown to a MarkDown data structure

mdToHtml >>> -- 3. convert the MarkDown data to an HTML data structure

htmlToText -- 4. render the HTML data to a Text with hmtl markup

-- | a default implementation of a ToC to html Text renderer.

-- this function is constructed by partially applying `tocToHtmlText`

-- to four functions matching the signature of `tocToHtmlText`.

defaultTocToHtmlText :: TableOfContents -> T.Text

defaultTocToHtmlText =

tocToHtmlText

tocToMDText -- the ToC to markdown Text renderer as defined above

textToMarkDown -- a MarkDown parser, externally provided via import

markDownToHtml -- a MarkDown to HTML renderer, externally provided via import

htmlToText -- a HTML to Text with html markup, externally provided via import

demoDI = do

let toc = Section (Title "Chapter 1")

[ Sub $ Section (Title "Section a")

[Head $ Title "First Heading",

Head $ Url "Second Heading" "http://the.url"]

, Sub $ Section (Url "Section b" "http://the.section.b.url")

[ Sub $ Section (Title "UnderSection b1")

[Head $ Title "First", Head $ Title "Second"]]]

putStrLn $ T.unpack $ tocToMDText toc

putStrLn $ T.unpack $ defaultTocToHtmlText toc