1 files changed, 132 insertions, 0 deletions
diff --git a/src/TextViewport/Render/RenderState.hs b/src/TextViewport/Render/RenderState.hs
new file mode 100644
index 0000000..26e92e1
--- /dev/null
+++ b/src/TextViewport/Render/RenderState.hs
@@ -0,0 +1,132 @@
+module TextViewport.Render.RenderState where
+
+import Data.Sequence (Seq)
+import Data.Sequence qualified as Seq
+import TextViewport.Buffer.Item
+import TextViewport.Buffer.Buffer (Buffer(Buffer))
+import TextViewport.Buffer.Buffer qualified as Buffer
+import TextViewport.Render.RenderBuffer (renderBuffer)
+import TextViewport.Render.RenderCache (RenderCache(..), emptyRenderCacheFor, resizeCache)
+import TextViewport.Render.RenderedBuffer (RenderedBuffer(RenderedBuffer))
+import TextViewport.Render.RenderedBuffer qualified as RenderedBuffer
+
+data RenderState = RenderState
+  { rsBuffer    :: Buffer             -- original items
+  , rsCache     :: RenderCache        -- per-item cached renders
+  , rsRendered  :: RenderedBuffer     -- fully segmented + hyphenated lines
+  , rsWidth     :: Int                -- segmenting width
+  , rsLineCount :: Int                
+  } deriving (Eq, Show)
+
+mkRenderState :: Int -> Buffer -> RenderState
+mkRenderState width buf =
+  let (cache1, rendered) = renderBuffer width buf (emptyRenderCacheFor buf)
+  in RenderState
+       { rsBuffer    = buf
+       , rsCache     = cache1
+       , rsRendered  = rendered
+       , rsWidth     = width
+       , rsLineCount = length (RenderedBuffer.flatten rendered)
+       }
+
+-- RenderState has to be rebuilt whenever the buffer or the width changes.
+updateRenderState :: Int -> Buffer -> RenderState -> RenderState
+updateRenderState width buf rs =
+  let (cache1, rendered) = renderBuffer width buf (rsCache rs)
+  in rs
+      { rsBuffer    = buf
+      , rsCache     = cache1
+      , rsRendered  = rendered
+      , rsWidth     = width
+      , rsLineCount = length (RenderedBuffer.flatten rendered)
+      }
+
+modifyItemRS :: Int -> (Item -> Item) -> RenderState -> RenderState
+modifyItemRS ix f st =
+  let buf'    = Buffer.modifyItem ix f (rsBuffer st)
+      cache'  = resizeCache buf' (rsCache st)
+      (cache1, rendered1) = renderBuffer (rsWidth st) buf' cache'
+  in st { rsBuffer    = buf'
+        , rsCache     = cache1
+        , rsRendered  = rendered1
+        , rsLineCount = length (RenderedBuffer.flatten rendered1)
+        }
+
+insertItem :: Int -> Item -> RenderState -> RenderState
+insertItem i newItem st =
+  let Buffer items = rsBuffer st
+      items'       = Seq.insertAt i newItem items
+      buf'         = Buffer items'
+      cache'       = resizeCache buf' (rsCache st)
+      (cache1, rendered1) = renderBuffer (rsWidth st) buf' cache'
+  in st { rsBuffer = buf'
+        , rsCache = cache1
+        , rsRendered = rendered1
+        , rsLineCount = length (RenderedBuffer.flatten rendered1)
+        }
+
+deleteItem :: Int -> RenderState -> RenderState
+deleteItem i st =
+  let Buffer items = rsBuffer st
+      items'       = Seq.deleteAt i items
+      buf'         = Buffer items'
+      cache'       = resizeCache buf' (rsCache st)
+      (cache1, rendered1) = renderBuffer (rsWidth st) buf' cache'
+  in st { rsBuffer = buf'
+        , rsCache = cache1
+        , rsRendered = rendered1
+        , rsLineCount = length (RenderedBuffer.flatten rendered1)
+        }
+
+replaceItem :: Int -> Item -> RenderState -> RenderState
+replaceItem i newItem st =
+  let Buffer items = rsBuffer st
+      items'       = Seq.update i newItem items
+      buf'         = Buffer items'
+      cache'       = resizeCache buf' (rsCache st)
+      (cache1, rendered1) = renderBuffer (rsWidth st) buf' cache'
+  in st { rsBuffer = buf'
+        , rsCache = cache1
+        , rsRendered = rendered1
+        , rsLineCount = length (RenderedBuffer.flatten rendered1)
+        }
+
+appendItem :: Item -> RenderState -> RenderState
+appendItem newItem st =
+  insertItem (Seq.length (let Buffer xs = rsBuffer st in xs)) newItem st
+
+clearBuffer :: RenderState -> RenderState
+clearBuffer st =
+  let buf' = Buffer Seq.empty
+      cache' = RenderCache Seq.empty
+  in st { rsBuffer = buf'
+        , rsCache = cache'
+        , rsRendered = RenderedBuffer Seq.empty
+        , rsLineCount = 0
+        }
+
+fromList :: Int -> [Item] -> RenderState
+fromList width xs =
+  let buf     = Buffer (Seq.fromList xs)
+      cache0  = RenderCache (Seq.replicate (length xs) Nothing)
+      (cache1, rendered) = renderBuffer width buf cache0
+  in RenderState
+       { rsBuffer    = buf
+       , rsCache     = cache1
+       , rsRendered  = rendered
+       , rsWidth     = width
+       , rsLineCount = length (RenderedBuffer.flatten rendered)
+       }
+
+fromSeq :: Int -> Seq Item -> RenderState
+fromSeq width items =
+  let buf     = Buffer items
+      cache0  = RenderCache (Seq.replicate (Seq.length items) Nothing)
+      (cache1, rendered) = renderBuffer width buf cache0
+  in RenderState
+       { rsBuffer    = buf
+       , rsCache     = cache1
+       , rsRendered  = rendered
+       , rsWidth     = width
+       , rsLineCount = length (RenderedBuffer.flatten rendered)
+       }