Region.hs

-- |
--
-- Module      : Snippet.Region
-- Copyright   : (c) 2026 Patrick Brisbin
-- License     : AGPL-3
-- Maintainer  : pbrisbin@gmail.com
-- Stability   : experimental
-- Portability : POSIX
module Snippet.Region
  ( Region (..)
  , regionIsOneLine

    -- * Single-line helpers
  , lineRegion
  , lineRegionFrom
  , lineRegionFromTo
  ) where

import Prelude

import Data.Text (Text)
import GHC.Generics (Generic)

data Region = Region
  { startLine :: Int
  -- ^ The line number of the line containing the first character in the region.
  , endLine :: Maybe Int
  -- ^ The line number of the line containing the last character in the region.
  --
  -- If missing, defaults to 'startLine'.
  , startColumn :: Maybe Int
  -- ^ The column number of the first character of the region.
  --
  -- ^ If missing, defaults to @1@.
  , endColumn :: Maybe Int
  -- ^ The column number /one past/ the last character in the region.
  --
  -- If missing defaults to the position after the last character of the line,
  -- excluding newline.
  , message :: Maybe Text
  , subRegion :: Maybe Region
  }
  deriving stock (Eq, Generic, Show)

regionIsOneLine :: Region -> Bool
regionIsOneLine region = maybe True (== region.startLine) region.endLine

lineRegion :: Int -> Region
lineRegion startLine =
  Region
    { startLine
    , endLine = Nothing
    , startColumn = Nothing
    , endColumn = Nothing
    , message = Nothing
    , subRegion = Nothing
    }

lineRegionFrom :: Int -> Int -> Region
lineRegionFrom startLine sc =
  Region
    { startLine
    , endLine = Nothing
    , startColumn = Just sc
    , endColumn = Nothing
    , message = Nothing
    , subRegion = Nothing
    }

lineRegionFromTo :: Int -> Int -> Int -> Region
lineRegionFromTo startLine sc ec =
  Region
    { startLine
    , endLine = Nothing
    , startColumn = Just sc
    , endColumn = Just ec
    , message = Nothing
    , subRegion = Nothing
    }