feat: picker provider resolver

Author: kawre

Diff for: README.md

@@ -278,11 +278,13 @@ injector = { ---@type table<lc.lang, lc.inject>
 
 ### picker
 
-Supported picker providers are `telescope` and `fzf-lua`
+Supported picker providers are `telescope` and `fzf-lua`.
+When provider is `nil`, [leetcode.nvim] will first try to use `fzf-lua`,
+if not found it will fallback to `telescope`.
 
 ```lua
 ---@type lc.picker
-picker = { provider = "telescope" },
+picker = { provider = nil },
 ```
 
 ### hooks

Diff for: lua/leetcode/config/template.lua

@@ -38,7 +38,7 @@
 
 ---@alias lc.storage table<"cache"|"home", string>
 
----@alias lc.picker { provider: "fzf-lua" | "telescope" }
+---@alias lc.picker { provider?: "fzf-lua" | "telescope" }
 
 ---@class lc.UserConfig
 local M = {
@@ -104,7 +104,7 @@ local M = {
     },
 
     ---@type lc.picker
-    picker = { provider = "telescope" },
+    picker = { provider = nil },
 
     hooks = {
         ---@type fun()[]

Diff for: lua/leetcode/picker/init.lua

@@ -1,14 +1,31 @@
 local log = require("leetcode.logger")
 local config = require("leetcode.config")
 
----@type string
-local provider = config.user.picker.provider
-assert(pcall(require, provider), ("specified picker provider not found: `%s`"):format(provider))
-provider = provider == "fzf-lua" and "fzf" or provider
----@cast provider "fzf" | "telescope"
+---@return "fzf" | "telescope"
+local function resolve_provider()
+    ---@type string
+    local provider = config.user.picker.provider
+
+    if provider == nil then
+        local fzf_ok = pcall(require, "fzf-lua")
+        if fzf_ok then
+            return "fzf"
+        end
+        local telescope_ok = pcall(require, "telescope")
+        if telescope_ok then
+            return "telescope"
+        end
+        error("no supported picker provider found")
+    else
+        local provider_ok = pcall(require, provider)
+        assert(provider_ok, ("specified picker provider not found: `%s`"):format(provider))
+        return provider == "fzf-lua" and "fzf" or provider
+    end
+end
 
 ---@class leet.Picker
 local P = {}
+P.provider = resolve_provider()
 
 function P.hl_to_ansi(hl_group)
     local color = vim.api.nvim_get_hl(0, { name = hl_group })
@@ -46,7 +63,7 @@ function P.normalize(items)
 end
 
 function P.pick(path, ...)
-    local rpath = table.concat({ "leetcode.picker", path, provider }, ".")
+    local rpath = table.concat({ "leetcode.picker", path, P.provider }, ".")
     return require(rpath)(...)
 end