Pretty.hs

-- |
--
-- Module      : Snippet.Pretty
-- Copyright   : (c) 2026 Patrick Brisbin
-- License     : AGPL-3
-- Maintainer  : pbrisbin@gmail.com
-- Stability   : experimental
-- Portability : POSIX
module Snippet.Pretty
  ( Ann (..)
  , annToAnsi
  , prettySnippet
  , prettySnippetFill
  , snippetGutterWidth
  ) where

import Prelude

import Data.Foldable (toList)
import Data.List.NonEmpty (NonEmpty)
import Data.Maybe (fromMaybe)
import Prettyprinter hiding (line)
import Prettyprinter.Render.Terminal (AnsiStyle, Color (..), colorDull)
import Snippet.Line
import Snippet.Region
import Snippet.Snippet

data Ann
  = -- | Line numbers and left-hand bar
    AnnGutter
  | -- | Focused line content
    AnnFocused

annToAnsi :: Ann -> AnsiStyle
annToAnsi = \case
  AnnGutter -> colorDull Blue
  AnnFocused -> colorDull Green

-- | A 'Snippet's gutter fits the digits of its maximum (i.e. end) line number,
-- plus 1 character of whitespace.
snippetGutterWidth :: Snippet -> Int
snippetGutterWidth snippet = length (show @Int el) + 1
 where
  sl = snippet.region.startLine
  el = fromMaybe sl snippet.region.endLine

prettySnippet :: Snippet -> Doc Ann
prettySnippet snippet = prettySnippetFill w snippet
 where
  w = length (show @Int el) + 1
  sl = snippet.region.startLine
  el = fromMaybe sl snippet.region.endLine

-- | 'prettySnippet' but fill the left gutter to the given width
--
-- For example, if 'prettySnippet' gives:
--
-- @
--   |
-- 1 | ...
--   |
-- @
--
-- @'prettySnippetFill' 3@ gives:
--
-- @
--     |
--   1 | ...
--     |
-- @
--
-- This is useful if multiple snippets are being rendered together and their
-- line-numbers are different magnitudes. You can compute the width on the
-- outside and pass it in.
prettySnippetFill :: Int -> Snippet -> Doc Ann
prettySnippetFill w snippet =
  vsep
    [ indent w
        $ annotate AnnGutter "┌─"
          <+> pretty (snippet.uri)
          <> ":"
          <> pretty snippet.region.startLine
          <> ":"
          <> pretty snippet.region.startColumn
    , indent w $ annotate AnnGutter "│"
    , prettyLines w snippet.lines
    ]

prettyLines :: Int -> NonEmpty Line -> Doc Ann
prettyLines w = vsep . map (prettyLine w) . toList

prettyLine :: Int -> Line -> Doc Ann
prettyLine w line =
  -- TODO: this is a fill-right, I want fill-left
  annotate AnnGutter (fill w (maybe "" pretty line.number) <> "│")
    <+> pretty line.pre
    <> annotate AnnFocused (pretty line.focused)
    <> pretty line.post