defmodule CljElixir.REPLTest do
  use ExUnit.Case, async: true

  alias CljElixir.REPL

  describe "REPL.new" do
    test "creates initial state" do
      state = REPL.new()
      assert state.bindings == []
      assert state.history == []
      assert state.counter == 1
    end
  end

  describe "REPL.eval" do
    test "evaluates simple expression" do
      state = REPL.new()
      assert {:ok, "3", _} = REPL.eval("(+ 1 2)", state)
    end

    test "pr-str formats output" do
      state = REPL.new()
      {:ok, result, _} = REPL.eval("\"hello\"", state)
      assert result == "\"hello\""
    end

    test "nil result" do
      state = REPL.new()
      {:ok, result, _} = REPL.eval("nil", state)
      assert result == "nil"
    end

    test "map result" do
      state = REPL.new()
      {:ok, result, _} = REPL.eval("{:a 1 :b 2}", state)
      assert result =~ ":a"
      assert result =~ "1"
    end

    test "increments counter" do
      state = REPL.new()
      {:ok, _, state2} = REPL.eval("1", state)
      assert state2.counter == 2
      {:ok, _, state3} = REPL.eval("2", state2)
      assert state3.counter == 3
    end

    test "stores history" do
      state = REPL.new()
      {:ok, _, state2} = REPL.eval("(+ 1 2)", state)
      assert state2.history == ["(+ 1 2)"]
      {:ok, _, state3} = REPL.eval("(+ 3 4)", state2)
      assert state3.history == ["(+ 3 4)", "(+ 1 2)"]
    end

    test "error returns error tuple" do
      state = REPL.new()
      {:error, msg, _} = REPL.eval("(defmodule REPLErrTest (invalid-syntax", state)
      assert is_binary(msg)
      assert msg =~ "Error" or msg =~ "error"
    end

    test "defmodule persists across evals" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (defmodule REPLTestMod
          (defn hello [] :hi))
        """, state)

      {:ok, result, _} = REPL.eval("(REPLTestMod/hello)", state2)
      assert result == ":hi"
    end

    test "tuple result" do
      state = REPL.new()
      {:ok, result, _} = REPL.eval("#el[:ok 42]", state)
      assert result == "#el[:ok 42]"
    end

    test "list result" do
      state = REPL.new()
      {:ok, result, _} = REPL.eval("(list 1 2 3)", state)
      assert result == "(1 2 3)"
    end
  end

  describe "ns tracking" do
    test "ns sets current namespace" do
      state = REPL.new()
      assert REPL.current_ns(state) == "user"

      {:ok, _, state2} = REPL.eval("(ns ReplNsTest1)", state)
      assert state2.current_ns == "ReplNsTest1"
      assert REPL.current_ns(state2) == "ReplNsTest1"
    end

    test "ns with defn creates module" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTest2)
        (defn greet [name] (str "hello " name))
        """, state)

      assert state2.current_ns == "ReplNsTest2"
      {:ok, result, _} = REPL.eval("(ReplNsTest2/greet \"world\")", state2)
      assert result == "\"hello world\""
    end

    test "bare defn in active ns updates module" do
      state = REPL.new()

      # Set up initial module
      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTest3)
        (defn hello [] :hi)
        """, state)

      # Add a new function without ns
      {:ok, result, state3} = REPL.eval("(defn world [] :earth)", state2)
      assert result == "#'ReplNsTest3/world"

      # Both functions should work
      {:ok, r1, _} = REPL.eval("(ReplNsTest3/hello)", state3)
      assert r1 == ":hi"
      {:ok, r2, _} = REPL.eval("(ReplNsTest3/world)", state3)
      assert r2 == ":earth"
    end

    test "redefine function in active ns" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTest4)
        (defn greet [] "v1")
        """, state)

      {:ok, r1, _} = REPL.eval("(ReplNsTest4/greet)", state2)
      assert r1 == "\"v1\""

      # Redefine greet
      {:ok, _, state3} = REPL.eval("(defn greet [] \"v2\")", state2)

      {:ok, r2, _} = REPL.eval("(ReplNsTest4/greet)", state3)
      assert r2 == "\"v2\""
    end

    test "bare defn without ns evals plain" do
      state = REPL.new()
      # No namespace set — def outside module should fail
      {:error, _, _} = REPL.eval("(defn orphan [] :lost)", state)
    end

    test "expressions eval normally in ns context" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTest5)
        (defn add [a b] (+ a b))
        """, state)

      # Expression (no def) goes through plain eval
      {:ok, result, _} = REPL.eval("(ReplNsTest5/add 3 4)", state2)
      assert result == "7"
    end

    test "mixed defs and exprs in ns context" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTest6)
        (defn double [x] (* x 2))
        """, state)

      # Eval def + expression together
      {:ok, result, state3} =
        REPL.eval("""
        (defn triple [x] (* x 3))
        (ReplNsTest6/triple 5)
        """, state2)

      # Result should be the expression value
      assert result == "15"

      # Both functions should work
      {:ok, r1, _} = REPL.eval("(ReplNsTest6/double 4)", state3)
      assert r1 == "8"
    end

    test "switching namespace" do
      state = REPL.new()

      {:ok, _, state2} =
        REPL.eval("""
        (ns ReplNsTestA)
        (defn a-fn [] :from-a)
        """, state)

      {:ok, _, state3} =
        REPL.eval("""
        (ns ReplNsTestB)
        (defn b-fn [] :from-b)
        """, state2)

      assert state3.current_ns == "ReplNsTestB"

      # Both modules still work
      {:ok, r1, _} = REPL.eval("(ReplNsTestA/a-fn)", state3)
      assert r1 == ":from-a"
      {:ok, r2, _} = REPL.eval("(ReplNsTestB/b-fn)", state3)
      assert r2 == ":from-b"
    end
  end

  describe "REPL.balanced?" do
    test "balanced parens" do
      assert REPL.balanced?("(+ 1 2)")
      assert REPL.balanced?("(defn foo [x] (+ x 1))")
      assert REPL.balanced?("42")
      assert REPL.balanced?("")
    end

    test "unbalanced parens" do
      refute REPL.balanced?("(+ 1 2")
      refute REPL.balanced?("(defn foo [x]")
      refute REPL.balanced?("(let [x 1")
    end

    test "balanced with nested" do
      assert REPL.balanced?("(let [x (+ 1 2)] (* x x))")
    end

    test "string contents not counted" do
      assert REPL.balanced?("(str \"(hello)\")")
      assert REPL.balanced?("(str \"[not real]\")")
    end

    test "comment contents not counted" do
      assert REPL.balanced?("(+ 1 2) ; this has unbalanced (")
    end

    test "mixed delimiters" do
      assert REPL.balanced?("(let [{:keys [a b]} {:a 1 :b 2}] (+ a b))")
      refute REPL.balanced?("(let [{:keys [a b]} {:a 1 :b 2}] (+ a b)")
    end
  end
end