{-# LANGUAGE OverloadedStrings #-}
module CompileTests (tests) where

import Test.Tasty
import Test.Tasty.HUnit
import qualified Data.Aeson as A
import qualified Data.Aeson.Key as AK
import qualified Data.Aeson.KeyMap as AKM
import qualified Data.Vector as V
import qualified Data.ByteString.Lazy.Char8 as BL8

import FWL.AST
import FWL.Compile
import FWL.Util

tests :: TestTree
tests = testGroup "Compile"
  [ jsonStructureTests
  , chainTests
  , ruleExprTests
  , verdictTests
  , layerStrippingTests
  , continueTests
  , configTests
  ]

-- ─── Helpers ─────────────────────────────────────────────────────────────────

compileToValue :: String -> IO A.Value
compileToValue src = do
  p <- parseOk src
  case A.decode (compileToJson p) of
    Nothing -> assertFailure "Compiled output is not valid JSON" >> undefined
    Just v  -> return v

-- Navigate a Value by a list of string keys / numeric indices.
at :: [String] -> A.Value -> Maybe A.Value
at []     v                   = Just v
at (k:ks) (A.Object o)        =
  case AKM.lookup (AK.fromString k) o of
    Nothing -> Nothing
    Just v  -> at ks v
at (k:ks) (A.Array arr)       =
  case reads k of
    [(i,"")] | i < V.length arr -> at ks (arr V.! i)
    _                           -> Nothing
at _ _ = Nothing

nftArr :: A.Value -> IO [A.Value]
nftArr v =
  case at ["nftables"] v of
    Just (A.Array arr) -> return (V.toList arr)
    _                  -> assertFailure "Missing top-level 'nftables' array" >> undefined

withKey :: String -> [A.Value] -> [A.Value]
withKey k = filter (\v -> case at [k] v of Just _ -> True; _ -> False)

-- ─── JSON structure tests ────────────────────────────────────────────────────

jsonStructureTests :: TestTree
jsonStructureTests = testGroup "JSON structure"
  [ testCase "output is valid JSON" $ do
      _ <- compileToValue
        "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      return ()

  , testCase "top-level nftables array present" $ do
      v <- compileToValue "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      _ <- nftArr v
      return ()

  , testCase "metainfo is first element" $ do
      v <- compileToValue "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case arr of
        (first:_) -> case at ["metainfo"] first of
          Just _  -> return ()
          Nothing -> assertFailure "First element is not metainfo"
        [] -> assertFailure "Empty nftables array"

  , testCase "table object present" $ do
      v <- compileToValue "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      assertBool "Expected at least one table object"
        (not (null (withKey "table" arr)))

  , testCase "default table name is fwl" $ do
      v <- compileToValue "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case withKey "table" arr of
        (t:_) -> at ["table","name"] t @?= Just (A.String "fwl")
        []    -> assertFailure "No table object"

  , testCase "custom table name respected" $ do
      v <- compileToValue
        "config { table = \"custom\"; } \
        \policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case withKey "table" arr of
        (t:_) -> at ["table","name"] t @?= Just (A.String "custom")
        []    -> assertFailure "No table object"
  ]

-- ─── Chain declaration tests ─────────────────────────────────────────────────

chainTests :: TestTree
chainTests = testGroup "chain declarations"
  [ testCase "filter input chain has correct hook" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","hook"] c @?= Just (A.String "input")
        []    -> assertFailure "No chain"

  , testCase "filter chain type is filter" $ do
      v <- compileToValue
        "policy fwd : Frame \
        \  on { hook = Forward, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","type"] c @?= Just (A.String "filter")
        []    -> assertFailure "No chain"

  , testCase "NAT chain type is nat" $ do
      v <- compileToValue
        "policy nat_post : Frame \
        \  on { hook = Postrouting, table = NAT, priority = SrcNat } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","type"] c @?= Just (A.String "nat")
        []    -> assertFailure "No chain"

  , testCase "input chain default policy is drop" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","policy"] c @?= Just (A.String "drop")
        []    -> assertFailure "No chain"

  , testCase "output chain default policy is accept" $ do
      v <- compileToValue
        "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","policy"] c @?= Just (A.String "accept")
        []    -> assertFailure "No chain"

  , testCase "chain name matches policy name" $ do
      v <- compileToValue
        "policy my_input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      case withKey "chain" arr of
        (c:_) -> at ["chain","name"] c @?= Just (A.String "my_input")
        []    -> assertFailure "No chain"

  , testCase "two policies produce two chains" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; }; \
        \policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      length (withKey "chain" arr) @?= 2
  ]

-- ─── Rule expression tests ───────────────────────────────────────────────────

ruleExprs :: [A.Value] -> [A.Value]
ruleExprs arr =
  [ e | r  <- withKey "rule" arr
      , Just (A.Array es) <- [at ["rule","expr"] r]
      , e  <- V.toList es ]

ruleExprTests :: TestTree
ruleExprTests = testGroup "rule expressions"
  [ testCase "two arms produce two rules" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ if ct.state in { Established, Related } -> Allow; \
        \      | _ -> Drop; \
        \  };"
      arr <- nftArr v
      length (withKey "rule" arr) @?= 2

  , testCase "arm without guard produces one rule" $ do
      v <- compileToValue
        "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      length (withKey "rule" arr) @?= 1

  , testCase "rule expr array is present" $ do
      v <- compileToValue
        "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      case withKey "rule" arr of
        (r:_) -> case at ["rule","expr"] r of
          Just (A.Array _) -> return ()
          _                -> assertFailure "Missing or non-array 'expr'"
        [] -> assertFailure "No rule"

  , testCase "IPv4 ctor emits nfproto match" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | Frame(_, IPv4(ip, _)) -> Allow; \
        \      | _ -> Drop; \
        \  };"
      arr <- nftArr v
      let matches   = withKey "match" (ruleExprs arr)
          hasNfp    = any (\m ->
            at ["match","left","meta","key"] m == Just (A.String "nfproto"))
            matches
      assertBool "Expected nfproto match for IPv4 ctor" hasNfp

  , testCase "record field pat emits payload match" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | Frame(_, TCP(tcp { dport = :22 }, _)) -> Allow; \
        \      | _ -> Drop; \
        \  };"
      arr <- nftArr v
      let matches  = withKey "match" (ruleExprs arr)
          hasPort  = any (\m ->
            at ["match","right"] m == Just (A.String "22"))
            matches
      assertBool "Expected port 22 payload match" hasPort
  ]

-- ─── Verdict tests ───────────────────────────────────────────────────────────

allExprs :: [A.Value] -> [A.Value]
allExprs arr =
  concatMap (\r -> case at ["rule","expr"] r of
    Just (A.Array es) -> V.toList es; _ -> [])
  (withKey "rule" arr)

verdictTests :: TestTree
verdictTests = testGroup "verdicts"
  [ testCase "Allow compiles to accept" $ do
      v <- compileToValue
        "policy output : Frame \
        \  on { hook = Output, table = Filter, priority = Filter } \
        \  = { | _ -> Allow; };"
      arr <- nftArr v
      assertBool "Expected accept verdict"
        (not (null (withKey "accept" (allExprs arr))))

  , testCase "Drop compiles to drop" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      assertBool "Expected drop verdict"
        (not (null (withKey "drop" (allExprs arr))))

  , testCase "Masquerade compiles to masquerade" $ do
      v <- compileToValue
        "policy nat_post : Frame \
        \  on { hook = Postrouting, table = NAT, priority = SrcNat } \
        \  = { | _ -> Masquerade; };"
      arr <- nftArr v
      assertBool "Expected masquerade verdict"
        (not (null (withKey "masquerade" (allExprs arr))))

  , testCase "rule call compiles to jump" $ do
      v <- compileToValue
        "rule blockAll : Frame -> Action = \\f -> case f of { | _ -> Drop; }; \
        \policy fwd : Frame \
        \  on { hook = Forward, table = Filter, priority = Filter } \
        \  = { | frame -> blockAll(frame); };"
      arr <- nftArr v
      assertBool "Expected jump verdict for rule call"
        (not (null (withKey "jump" (allExprs arr))))
  ]

-- ─── Layer stripping tests ───────────────────────────────────────────────────

layerStrippingTests :: TestTree
layerStrippingTests = testGroup "layer stripping"
  [ testCase "Frame with and without Ether both emit nfproto match" $ do
      let withEther =
            "policy p1 : Frame \
            \  on { hook = Input, table = Filter, priority = Filter } \
            \  = { | Frame(_, Ether(_, IPv4(ip, _))) -> Allow; \
            \      | _ -> Drop; \
            \  };"
          withoutEther =
            "policy p1 : Frame \
            \  on { hook = Input, table = Filter, priority = Filter } \
            \  = { | Frame(_, IPv4(ip, _)) -> Allow; \
            \      | _ -> Drop; \
            \  };"
      v1 <- compileToValue withEther
      v2 <- compileToValue withoutEther
      arr1 <- nftArr v1
      arr2 <- nftArr v2
      let nfp arr = filter
            (\m -> at ["match","left","meta","key"] m == Just (A.String "nfproto"))
            (withKey "match" (ruleExprs arr))
      assertBool "Both should produce nfproto matches"
        (not (null (nfp arr1)) && not (null (nfp arr2)))
  ]

-- ─── Continue tests ───────────────────────────────────────────────────────────

continueTests :: TestTree
continueTests = testGroup "Continue"
  [ testCase "two terminal arms produce two rules" $ do
      v <- compileToValue
        "policy fwd : Frame \
        \  on { hook = Forward, table = Filter, priority = Filter } \
        \  = { | _ if ct.state in { Established } -> Allow; \
        \      | _ -> Drop; \
        \  };"
      arr <- nftArr v
      length (withKey "rule" arr) @?= 2

  , testCase "non-Continue arms still produce rules" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ if ct.state in { Established } -> Allow; \
        \      | _ -> Drop; \
        \  };"
      arr <- nftArr v
      assertBool "Should have rules for non-Continue arms"
        (not (null (withKey "rule" arr)))
  ]

-- ─── Config tests ─────────────────────────────────────────────────────────────

configTests :: TestTree
configTests = testGroup "config"
  [ testCase "all rule objects reference correct table" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      mapM_ (\r -> at ["rule","table"] r @?= Just (A.String "fwl"))
        (withKey "rule" arr)

  , testCase "chain objects reference correct table" $ do
      v <- compileToValue
        "policy input : Frame \
        \  on { hook = Input, table = Filter, priority = Filter } \
        \  = { | _ -> Drop; };"
      arr <- nftArr v
      mapM_ (\c -> at ["chain","table"] c @?= Just (A.String "fwl"))
        (withKey "chain" arr)
  ]