From d6d782b58463e08c3e2479e3fe762e6875b1d052 Mon Sep 17 00:00:00 2001
From: Ade Attwood <adrian.attwood@marketdojo.com>
Date: Thu, 27 Jun 2024 07:39:05 +0100
Subject: [PATCH] feat: setup configuration with default fallbacks

Summary:

Now the users configuration and the default configuration is separated. This
will make it easier to setup ivy with some defaults. Right now we only have the
backends configurable however, it looks like we will be making other components
of ivy configurable.

To use this you can now call `ivy.setup` with no parameters and you will get
the default config. You can also call it with a partial config and if the
option is not found in the users config it will fallback to the users config
value.

Test Plan:

Manual testing and with unit tests in CI
---
 lua/ivy/config.lua      | 33 +++++++++++++++++++++++++++++++++
 lua/ivy/config_spec.lua | 27 +++++++++++++++++++++++++++
 lua/ivy/init.lua        | 22 +++++++++++++---------
 lua/ivy/init_spec.lua   | 30 ++++++++++++++++++++++++++++++
 4 files changed, 103 insertions(+), 9 deletions(-)
 create mode 100644 lua/ivy/config.lua
 create mode 100644 lua/ivy/config_spec.lua
 create mode 100644 lua/ivy/init_spec.lua

diff --git a/lua/ivy/config.lua b/lua/ivy/config.lua
new file mode 100644
index 0000000..8ff1e6a
--- /dev/null
+++ b/lua/ivy/config.lua
@@ -0,0 +1,33 @@
+local config_mt = {}
+config_mt.__index = config_mt
+
+function config_mt:get_in(config, key_table)
+  local current_value = config
+  for _, key in ipairs(key_table) do
+    if current_value == nil then
+      return nil
+    end
+
+    current_value = current_value[key]
+  end
+
+  return current_value
+end
+
+function config_mt:get(key_table)
+  return self:get_in(self.user_config, key_table) or self:get_in(self.default_config, key_table)
+end
+
+local config = { user_config = {} }
+
+config.default_config = {
+  backends = {
+    "ivy.backends.buffers",
+    "ivy.backends.files",
+    "ivy.backends.lines",
+    "ivy.backends.rg",
+    "ivy.backends.lsp-workspace-symbols",
+  },
+}
+
+return setmetatable(config, config_mt)
diff --git a/lua/ivy/config_spec.lua b/lua/ivy/config_spec.lua
new file mode 100644
index 0000000..7ef8cd8
--- /dev/null
+++ b/lua/ivy/config_spec.lua
@@ -0,0 +1,27 @@
+local config = require "ivy.config"
+
+describe("config", function()
+  before_each(function()
+    config.user_config = {}
+  end)
+
+  it("gets the first item when there is only default values", function()
+    local first_backend = config:get { "backends", 1 }
+    assert.is_equal("ivy.backends.buffers", first_backend)
+  end)
+
+  it("returns nil if we access a key that is not a valid config item", function()
+    assert.is_nil(config:get { "not", "a", "thing" })
+  end)
+
+  it("returns the users overridden config value", function()
+    config.user_config = { backends = { "ivy.my.backend" } }
+    local first_backend = config:get { "backends", 1 }
+    assert.is_equal("ivy.my.backend", first_backend)
+  end)
+
+  it("returns a nested value", function()
+    config.user_config = { some = { nested = "value" } }
+    assert.is_equal(config:get { "some", "nested" }, "value")
+  end)
+end)
diff --git a/lua/ivy/init.lua b/lua/ivy/init.lua
index f62f6fc..58672ff 100644
--- a/lua/ivy/init.lua
+++ b/lua/ivy/init.lua
@@ -1,28 +1,32 @@
 local controller = require "ivy.controller"
+local config = require "ivy.config"
 local register_backend = require "ivy.register_backend"
 
--- Local variable to check if ivy has been setup, this is to prevent multiple
--- setups of ivy
-local has_setup = false
-
 local ivy = {}
 ivy.run = controller.run
 ivy.register_backend = register_backend
 
+-- Private variable to check if ivy has been setup, this is to prevent multiple
+-- setups of ivy. This is only exposed for testing purposes.
+---@private
+ivy.has_setup = false
+
 ---@class IvySetupOptions
 ---@field backends (IvyBackend | { ["1"]: string, ["2"]: IvyBackendOptions} | string)[]
 
----@param config IvySetupOptions
-function ivy.setup(config)
-  if has_setup then
+---@param user_config IvySetupOptions
+function ivy.setup(user_config)
+  if ivy.has_setup then
     return
   end
 
-  for _, backend in ipairs(config.backends) do
+  config.user_config = user_config or {}
+
+  for _, backend in ipairs(config:get { "backends" } or {}) do
     register_backend(backend)
   end
 
-  has_setup = true
+  ivy.has_setup = true
 end
 
 return ivy
diff --git a/lua/ivy/init_spec.lua b/lua/ivy/init_spec.lua
new file mode 100644
index 0000000..f8ea91b
--- /dev/null
+++ b/lua/ivy/init_spec.lua
@@ -0,0 +1,30 @@
+local ivy = require "ivy"
+local config = require "ivy.config"
+
+describe("ivy.setup", function()
+  before_each(function()
+    ivy.has_setup = false
+    config.user_config = {}
+  end)
+
+  it("sets the users config options", function()
+    ivy.setup { backends = { "ivy.backends.files" } }
+    assert.is_equal("ivy.backends.files", config:get { "backends", 1 })
+  end)
+
+  it("will not reconfigure if its called twice", function()
+    ivy.setup { backends = { "ivy.backends.files" } }
+    ivy.setup { backends = { "some.backend" } }
+    assert.is_equal("ivy.backends.files", config:get { "backends", 1 })
+  end)
+
+  it("does not crash if you don't pass in any params to the setup function", function()
+    ivy.setup()
+    assert.is_equal("ivy.backends.buffers", config:get { "backends", 1 })
+  end)
+
+  it("will fallback if the key is not set at all in the users config", function()
+    ivy.setup { some_key = "some_value" }
+    assert.is_equal("ivy.backends.buffers", config:get { "backends", 1 })
+  end)
+end)