From 628b7b77372231bebae06aa092baccdf13e4cabb Mon Sep 17 00:00:00 2001
From: Stephen Waits <steve@waits.net>
Date: Sat, 11 Apr 2026 16:35:53 -0600
Subject: [PATCH] config: default options table with deep merge

---
 lua/tiny-debugger/config.lua | 68 +++++++++++++++++++++++++++++++++++-
 tests/test_config.lua        | 37 ++++++++++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_config.lua

diff --git a/lua/tiny-debugger/config.lua b/lua/tiny-debugger/config.lua
index 9ea5a51..cba3471 100644
--- a/lua/tiny-debugger/config.lua
+++ b/lua/tiny-debugger/config.lua
@@ -1,5 +1,71 @@
 local M = {}
 
-M.defaults = {}
+M.defaults = {
+  help_on_enter = true,
+  builtin_adapters = true,
+
+  keys = {
+    continue = "c",
+    step_over = "s",
+    step_into = "d",
+    step_out = "r",
+    run_to_cursor = "C",
+    breakpoint = "x",
+    cond_breakpoint = "X",
+    watch = "W",
+    hover = "K",
+    eval = "E",
+    terminate = "q",
+    restart = "R",
+    help = "?",
+  },
+
+  dapui = {
+    controls = { enabled = false },
+    layouts = {
+      {
+        position = "right",
+        size = 40,
+        elements = {
+          { id = "scopes", size = 0.50 },
+          { id = "watches", size = 0.25 },
+          { id = "stacks", size = 0.25 },
+        },
+      },
+      {
+        position = "bottom",
+        size = 12,
+        elements = {
+          { id = "repl", size = 0.50 },
+          { id = "console", size = 0.50 },
+        },
+      },
+    },
+  },
+
+  virtual_text = {
+    commented = true,
+    highlight_changed_variables = true,
+    only_first_definition = false,
+    all_frames = false,
+  },
+
+  adapters = {},
+}
+
+M.opts = vim.deepcopy(M.defaults)
+
+function M.merge(user_opts)
+  M.opts = vim.tbl_deep_extend("force", vim.deepcopy(M.defaults), user_opts or {})
+  -- preserve false values for disabled keys (tbl_deep_extend drops them)
+  if user_opts and user_opts.keys then
+    for k, v in pairs(user_opts.keys) do
+      if v == false then
+        M.opts.keys[k] = false
+      end
+    end
+  end
+  return M.opts
+end
 
 return M
diff --git a/tests/test_config.lua b/tests/test_config.lua
new file mode 100644
index 0000000..8efa5be
--- /dev/null
+++ b/tests/test_config.lua
@@ -0,0 +1,37 @@
+-- tests for config module
+local config = require("tiny-debugger.config")
+
+local function assert_eq(a, b, msg)
+  if a ~= b then
+    error(string.format("FAIL: %s — expected %s, got %s", msg, vim.inspect(b), vim.inspect(a)))
+  end
+end
+
+-- test 1: defaults unchanged after empty merge
+local opts = config.merge({})
+assert_eq(opts.keys.continue, "c", "default continue key")
+assert_eq(opts.help_on_enter, true, "default help_on_enter")
+assert_eq(opts.builtin_adapters, true, "default builtin_adapters")
+assert_eq(#opts.dapui.layouts, 2, "default layout count")
+
+-- test 2: partial key override
+opts = config.merge({ keys = { continue = "g" } })
+assert_eq(opts.keys.continue, "g", "overridden continue key")
+assert_eq(opts.keys.step_over, "s", "preserved step_over key")
+assert_eq(opts.keys.terminate, "q", "preserved terminate key")
+
+-- test 3: disable a key with false
+opts = config.merge({ keys = { continue = false } })
+assert_eq(opts.keys.continue, false, "disabled continue key")
+assert_eq(opts.keys.step_over, "s", "preserved step_over after disable")
+
+-- test 4: override help_on_enter
+opts = config.merge({ help_on_enter = false })
+assert_eq(opts.help_on_enter, false, "overridden help_on_enter")
+assert_eq(opts.keys.continue, "c", "keys preserved after help override")
+
+-- test 5: merge doesn't mutate defaults
+config.merge({ keys = { continue = "z" } })
+assert_eq(config.defaults.keys.continue, "c", "defaults not mutated")
+
+print("ALL CONFIG TESTS PASSED")