{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE NumericUnderscores #-}

-- | The construction side: circle-sweep bulk load against the arrival-order
-- session kernel, persistent single insertion, constraint recovery and Ruppert
-- refinement. Each reports the library's own work counters alongside the time,
-- because the claim being measured is about work done rather than seconds.
module Moonlight.Triangulation.BuildBench (benchmarks) where

import BenchSupport (randomPoints, requireRight, timedValue)
import Control.DeepSeq (force)
import Control.Exception (evaluate)
import Control.Monad (forM_, unless)
import Data.List (sort)
import Data.Primitive.PrimArray (indexPrimArray, sizeofPrimArray)
import qualified Data.Vector as V
import Moonlight.Triangulation
import Moonlight.Triangulation.BulkLoad (empty, insert)
import Moonlight.Triangulation.Cdt (constraintBatchStats, recoverConstraints)
-- The facade withholds this constructor. The benchmark indexes the builder's
-- own input mapping, so every handle it forges is one the builder issued, and
-- it owns that obligation explicitly by naming the module that grants it.
import Moonlight.Triangulation.Handles.HandleDefs (VertexId (VertexId))
import Moonlight.Triangulation.Session (insertVertex, withLocalSession, withSession)
import Moonlight.Triangulation.Types
  ( InsertionResult (insertionTriangulation)
  , refinementStats
  , statEdgeFlips
  , statLocationWalkSteps
  , statRefinementFaceChecks
  , statRefinementQueuePops
  )

benchmarks :: IO ()
benchmarks = do
  putStrLn "moonlight-triangulation native construction benchmark"
  forM_ [1_000, 10_000, 50_000] benchmarkConstruction
  forM_ [1_000, 10_000, 50_000, 100_000, 1_000_000] benchmarkSingletonInsertionCrossover
  benchmarkConstraints 8_000 800
  benchmarkRefinement 2_500

benchmarkConstruction :: Int -> IO ()
benchmarkConstruction count = do
  let points = V.fromList (randomPoints 0x9e3779b97f4a7c15 count)
  swept <- timedValue ("circle-sweep/" <> show count) $ requireRight (delaunay unitElementDefaults points)
  (_, sessioned, _) <- timedValue ("session/" <> show count) $
    requireRight
      ( withSession (empty unitElementDefaults) (V.length points) $
          V.mapM_ insertVertex points
      )
  evaluate (force (canonicalEdges (buildTriangulation swept) == canonicalEdges sessioned)) >>= \equal ->
    if equal then pure () else fail "circle-sweep and session construction disagree"

benchmarkSingletonInsertionCrossover :: Int -> IO ()
benchmarkSingletonInsertionCrossover count = do
  let points = V.fromList (randomPoints 0xd1b54a32d192ed03 count)
  built <- requireRight (delaunay unitElementDefaults points)
  let query = Point 0.000_123_456_7 (-0.000_765_432_1)
      base = buildTriangulation built
  scheduled <- timedValue ("singleton-scheduled-public-insert/" <> show count) $ requireRight (insert base query)
  (_, local, _) <- timedValue ("singleton-local-session-insert/" <> show count) $
    requireRight (withLocalSession base 1 (insertVertex query))
  let scheduledMesh = insertionTriangulation scheduled
  unless (null (validateTriangulation scheduledMesh)) $
    fail ("scheduled singleton insertion produced an invalid triangulation at " <> show count <> " sites")
  unless (null (validateTriangulation local)) $
    fail ("local singleton insertion produced an invalid triangulation at " <> show count <> " sites")
  scheduledCanonical <- requireRight (canonicalize scheduledMesh)
  localCanonical <- requireRight (canonicalize local)
  equal <- evaluate (force (scheduledCanonical == localCanonical))
  unless equal $
    fail ("scheduled and local singleton insertion disagree semantically at " <> show count <> " sites")
  putStrLn ("singleton-insertion-crossover/" <> show count <> "-semantic-witness: ok")

benchmarkConstraints :: Int -> Int -> IO ()
benchmarkConstraints pointCount constraintCount = do
  built <- requireRight (delaunay unitElementDefaults (V.fromList (randomPoints 0x94d049bb133111eb pointCount)))
  let cdt = fromDelaunay (buildTriangulation built)
      inputMapping = buildInputVertices built
      requestIndices =
        V.fromList
          ( take constraintCount
              [ (a, b)
              | index <- [0 ..]
              , let a = index `mod` pointCount
                    b = (index * 6151 + pointCount `quot` 2) `mod` pointCount
              , a /= b
              ]
          )
  pairs <-
    V.mapM
      (\(fromIndex, toIndex) ->
        let len = sizeofPrimArray inputMapping
            mFrom = if fromIndex >= 0 && fromIndex < len then Just (VertexId (indexPrimArray inputMapping fromIndex)) else Nothing
            mTo = if toIndex >= 0 && toIndex < len then Just (VertexId (indexPrimArray inputMapping toIndex)) else Nothing
        in case (mFrom, mTo) of
          (Just from, Just to) -> pure (from, to)
          _ -> fail "constraint benchmark endpoint is out of range"
      )
      requestIndices
  batch <- timedValue "cdt/recovery" (requireRight (recoverConstraints cdt pairs))
  putStrLn ("cdt/recovery-stats: " <> show (constraintBatchStats batch))

-- Ruppert refinement on a constrained square. The Steiner budget is the
-- variable of interest: both the encroachment search and the outer-region
-- classification are per-insertion costs, so their growth shows as a widening
-- gap between the two budgets rather than in either figure alone.
benchmarkRefinement :: Int -> IO ()
benchmarkRefinement steinerBudget = do
  cdtBuild <- requireRight $ constrainedDelaunay
    unitElementDefaults
    (V.fromList [Point 0 0, Point 64 0, Point 64 64, Point 0 64, Point 20 20, Point 44 44] :: V.Vector (Point))
    (V.fromList [(0, 1), (1, 2), (2, 3), (3, 0), (4, 5)])
  let cdt :: ConstrainedDelaunayTriangulation (Point)
      cdt = buildTriangulation cdtBuild
      parameters :: Int -> RefinementParameters
      parameters budget = defaultRefinementParameters
        { refineMaxAdditionalVertices = Just budget
        , refineMaxArea = Just 0.5
        , refineMaxRadiusEdgeRatio = Just 1.0
        , refineExcludeOuterFaces = True
        , refineKeepConstraintEdges = False
        }
  forM_ [steinerBudget `quot` 4, steinerBudget] $ \budget -> do
    refined <- timedValue ("refine/steiner-" <> show budget) (requireRight (refine id (parameters budget) cdt))
    let stats = refinementStats refined
    putStrLn ("refine-added/" <> show budget <> ": " <> show (refinementAddedVertices refined))
    putStrLn
      ( "refine-work/"
          <> show budget
          <> ": location-steps="
          <> show (statLocationWalkSteps stats)
          <> ", face-checks="
          <> show (statRefinementFaceChecks stats)
          <> ", queue-pops="
          <> show (statRefinementQueuePops stats)
          <> ", flips="
          <> show (statEdgeFlips stats)
      )

canonicalEdges :: Triangulation mode vertex directed undirected face -> [(Point, Point)]
canonicalEdges triangulation =
  sort
    [ ordered (vertexPoint triangulation (origin triangulation edge)) (vertexPoint triangulation (destination triangulation edge))
    | undirected <- undirectedEdges triangulation
    , let edge = normalizedDirected undirected
    ]
 where
  ordered :: Ord value => value -> value -> (value, value)
  ordered left right = if left <= right then (left, right) else (right, left)