defmodule CljElixir.Phase2Test do
  use ExUnit.Case, async: false

  # Helper to compile and evaluate CljElixir code
  # Uses vector_as_list: true until PersistentVector is implemented (Phase 3 WS-3)
  defp eval!(source) do
    case CljElixir.Compiler.eval_string(source, vector_as_list: true) do
      {:ok, result, _bindings} -> result
      {:error, errors} -> raise "CljElixir eval error: #{inspect(errors)}"
    end
  end

  # Protocols and core modules are compiled by the Mix compiler plugin
  # (compilers: [..., :clj_elixir] in mix.exs). No setup needed.

  # ==========================================================================
  # ILookup - get
  # ==========================================================================

  describe "get (ILookup)" do
    test "get from map with existing key" do
      assert eval!("(get {:a 1 :b 2} :a)") == 1
    end

    test "get from map with missing key returns nil" do
      assert eval!("(get {:a 1} :b)") == nil
    end

    test "get from map with missing key and default" do
      assert eval!("(get {:a 1} :b 42)") == 42
    end

    test "get from map with existing key ignores default" do
      assert eval!("(get {:a 1} :a 42)") == 1
    end
  end

  # ==========================================================================
  # IAssociative - assoc, contains?
  # ==========================================================================

  describe "assoc (IAssociative)" do
    test "assoc adds new key to map" do
      assert eval!("(assoc {:a 1} :b 2)") == %{a: 1, b: 2}
    end

    test "assoc updates existing key" do
      assert eval!("(assoc {:a 1} :a 2)") == %{a: 2}
    end

    test "assoc on empty map" do
      assert eval!("(assoc {} :a 1)") == %{a: 1}
    end
  end

  describe "contains? (IAssociative)" do
    test "contains? returns true for existing key" do
      assert eval!("(contains? {:a 1 :b 2} :a)") == true
    end

    test "contains? returns false for missing key" do
      assert eval!("(contains? {:a 1} :c)") == false
    end
  end

  # ==========================================================================
  # IMap - dissoc
  # ==========================================================================

  describe "dissoc (IMap)" do
    test "dissoc removes key from map" do
      assert eval!("(dissoc {:a 1 :b 2} :a)") == %{b: 2}
    end

    test "dissoc with missing key returns same map" do
      assert eval!("(dissoc {:a 1} :b)") == %{a: 1}
    end
  end

  # ==========================================================================
  # ICounted - count
  # ==========================================================================

  describe "count (ICounted)" do
    test "count of map" do
      assert eval!("(count {:a 1 :b 2 :c 3})") == 3
    end

    test "count of list" do
      assert eval!("(count (list 1 2 3))") == 3
    end

    test "count of empty map" do
      assert eval!("(count {})") == 0
    end

    test "count of tuple" do
      assert eval!("(count #el[1 2 3])") == 3
    end

    test "count of string" do
      assert eval!("(count \"hello\")") == 5
    end
  end

  # ==========================================================================
  # ISeq - first, rest
  # ==========================================================================

  describe "first/rest (ISeq)" do
    test "first of list" do
      assert eval!("(first (list 1 2 3))") == 1
    end

    test "rest of list" do
      assert eval!("(rest (list 1 2 3))") == [2, 3]
    end

    test "first of empty list" do
      assert eval!("(first (list))") == nil
    end

    test "rest of empty list" do
      assert eval!("(rest (list))") == []
    end
  end

  # ==========================================================================
  # ISeqable - seq
  # ==========================================================================

  describe "seq (ISeqable)" do
    test "seq of non-empty list returns the list" do
      assert eval!("(seq (list 1 2 3))") == [1, 2, 3]
    end

    test "seq of empty list returns nil" do
      assert eval!("(seq (list))") == nil
    end

    test "seq of map returns key-value pairs" do
      result = eval!("(seq {:a 1})")
      assert is_list(result)
      assert length(result) == 1
    end
  end

  # ==========================================================================
  # ICollection - conj
  # ==========================================================================

  describe "conj (ICollection)" do
    test "conj onto list prepends" do
      assert eval!("(conj (list 2 3) 1)") == [1, 2, 3]
    end

    test "conj onto map merges tuple entry" do
      result = eval!("(conj {:a 1} {:b 2})")
      assert result == %{a: 1, b: 2}
    end
  end

  # ==========================================================================
  # IIndexed - nth
  # ==========================================================================

  describe "nth (IIndexed)" do
    test "nth from tuple" do
      assert eval!("(nth #el[10 20 30] 1)") == 20
    end

    test "nth with default" do
      assert eval!("(nth #el[10 20] 5 :not-found)") == :"not-found"
    end
  end

  # ==========================================================================
  # IStack - peek, pop (via protocol on List)
  # ==========================================================================

  # Note: peek and pop are not in the builtin dispatch yet, they go through
  # the protocol directly - skip for now unless dispatch was added

  # ==========================================================================
  # Sequence wrapper functions
  # ==========================================================================

  describe "map (sequence function)" do
    test "map over list" do
      assert eval!("(map (fn [x] (inc x)) (list 1 2 3))") == [2, 3, 4]
    end
  end

  describe "filter" do
    test "filter list" do
      assert eval!("(filter (fn [x] (> x 2)) (list 1 2 3 4))") == [3, 4]
    end
  end

  describe "reduce" do
    test "reduce with initial value" do
      assert eval!("(reduce (fn [a b] (+ a b)) 0 (list 1 2 3))") == 6
    end

    test "reduce without initial value" do
      assert eval!("(reduce (fn [a b] (+ a b)) (list 1 2 3))") == 6
    end
  end

  describe "concat" do
    test "concat two lists" do
      assert eval!("(concat (list 1 2) (list 3 4))") == [1, 2, 3, 4]
    end
  end

  describe "take and drop" do
    test "take from list" do
      assert eval!("(take 2 (list 1 2 3 4))") == [1, 2]
    end

    test "drop from list" do
      assert eval!("(drop 2 (list 1 2 3 4))") == [3, 4]
    end
  end

  describe "sort" do
    test "sort list" do
      assert eval!("(sort (list 3 1 2))") == [1, 2, 3]
    end
  end

  describe "distinct" do
    test "distinct removes duplicates" do
      assert eval!("(distinct (list 1 2 1 3 2))") == [1, 2, 3]
    end
  end

  describe "frequencies" do
    test "frequencies counts occurrences" do
      assert eval!("(frequencies (list :a :b :a :c :b :a))") == %{a: 3, b: 2, c: 1}
    end
  end

  describe "partition" do
    test "partition into chunks" do
      assert eval!("(partition 2 (list 1 2 3 4))") == [[1, 2], [3, 4]]
    end
  end

  describe "mapcat" do
    test "mapcat flattens results" do
      assert eval!("(mapcat (fn [x] (list x x)) (list 1 2 3))") == [1, 1, 2, 2, 3, 3]
    end
  end

  # ==========================================================================
  # Map-specific functions
  # ==========================================================================

  describe "keys" do
    test "keys of map" do
      result = eval!("(keys {:a 1 :b 2})")
      assert Enum.sort(result) == [:a, :b]
    end
  end

  describe "vals" do
    test "vals of map" do
      result = eval!("(vals {:a 1 :b 2})")
      assert Enum.sort(result) == [1, 2]
    end
  end

  describe "merge" do
    test "merge two maps" do
      assert eval!("(merge {:a 1} {:b 2})") == %{a: 1, b: 2}
    end

    test "merge with overwrite" do
      assert eval!("(merge {:a 1} {:a 2})") == %{a: 2}
    end
  end

  describe "select-keys" do
    test "select-keys from map" do
      assert eval!("(select-keys {:a 1 :b 2 :c 3} (list :a :c))") == %{a: 1, c: 3}
    end
  end

  describe "into" do
    test "into map from list of tuples" do
      assert eval!("(into {} (list #el[:a 1] #el[:b 2]))") == %{a: 1, b: 2}
    end
  end

  # ==========================================================================
  # update
  # ==========================================================================

  describe "update" do
    test "update map value with function" do
      assert eval!("(update {:a 1} :a (fn [x] (inc x)))") == %{a: 2}
    end
  end

  # ==========================================================================
  # empty?
  # ==========================================================================

  describe "empty?" do
    test "empty? on empty map" do
      assert eval!("(empty? {})") == true
    end

    test "empty? on non-empty map" do
      assert eval!("(empty? {:a 1})") == false
    end
  end

  # ==========================================================================
  # Keyword-as-function through ILookup
  # ==========================================================================

  describe "keyword-as-function" do
    test "keyword as function on map" do
      assert eval!("(:name {:name \"Ada\"})") == "Ada"
    end

    test "keyword with default value" do
      assert eval!("(:age {:name \"Ada\"} 25)") == 25
    end
  end

  # ==========================================================================
  # Compound functions (get-in, assoc-in, update-in)
  # ==========================================================================

  describe "get-in" do
    test "get-in nested map" do
      assert eval!("(get-in {:a {:b {:c 42}}} (list :a :b :c))") == 42
    end

    test "get-in with missing key" do
      assert eval!("(get-in {:a {:b 1}} (list :a :c))") == nil
    end
  end

  describe "assoc-in" do
    test "assoc-in nested map" do
      assert eval!("(assoc-in {:a {:b 1}} (list :a :b) 2)") == %{a: %{b: 2}}
    end
  end

  describe "update-in" do
    test "update-in nested map" do
      assert eval!("(update-in {:a {:b 1}} (list :a :b) (fn [x] (inc x)))") == %{a: %{b: 2}}
    end
  end

  # ==========================================================================
  # reduce-kv
  # ==========================================================================

  describe "reduce-kv" do
    test "reduce-kv over map" do
      # Reduce a map collecting keys into a list
      result = eval!("(reduce-kv (fn [acc _k v] (+ acc v)) 0 {:a 1 :b 2 :c 3})")
      assert result == 6
    end
  end

  # ==========================================================================
  # FFI ? and ! preservation
  # ==========================================================================

  describe "FFI name munging fix" do
    test "Map/has-key? works correctly" do
      assert eval!("(Map/has-key? {:a 1} :a)") == true
    end

    test "Map/has-key? returns false for missing key" do
      assert eval!("(Map/has-key? {:a 1} :b)") == false
    end
  end

  # ==========================================================================
  # End-to-end integration
  # ==========================================================================

  describe "end-to-end integration" do
    test "realistic data transformation pipeline" do
      source = """
      (let [data (list {:name "Alice" :age 30}
                       {:name "Bob" :age 25}
                       {:name "Carol" :age 35})]
        (map (fn [p] (:name p)) (filter (fn [p] (> (get p :age) 28)) data)))
      """
      assert eval!(source) == ["Alice", "Carol"]
    end

    test "nested map operations" do
      source = """
      (let [m {:a 1 :b 2 :c 3}]
        (dissoc (assoc m :d 4) :b))
      """
      assert eval!(source) == %{a: 1, c: 3, d: 4}
    end

    test "count and empty? together" do
      source = """
      (let [m {:a 1}]
        (list (count m) (empty? m) (empty? {})))
      """
      assert eval!(source) == [1, false, true]
    end
  end
end