init.lua

-- =============================================================================
-- Starter Neovim Config
--
-- Drop this file at ~/.config/nvim/init.lua, or run install.sh.
-- Plugins auto-install on first launch. No manual steps needed.
--
-- Requires Neovim >= 0.12
-- =============================================================================

-- Common first tweaks (lines to edit when you're ready to personalize):
--   Line  72 — colorscheme:        swap 'tokyonight' for 'gruvbox' (or your own)
--   Line  65 — indent size:        change shiftwidth/tabstop from 2 to 4
--   Line  25 — plugins:            add or remove entries in vim.pack.add()
--
-- The fallback indent (2 spaces) is overridden per-file by guess-indent.nvim
-- which auto-detects the project's indentation. Adjust both values together.

-- 0 ─ Loader (faster startup) ────────────────────────────────────────────────
vim.loader.enable()

-- 1 ─ Leader keys ────────────────────────────────────────────────────────────
vim.g.mapleader = " "
vim.g.maplocalleader = " "

-- 2 ─ Plugins (auto-installed by Neovim's built-in vim.pack.add) ─────────────
vim.pack.add({
	{ src = "https://github.com/folke/tokyonight.nvim", name = "tokyonight.nvim" },
-- alternative theme — see colorscheme section below
-- { src = 'https://github.com/ellisonleao/gruvbox.nvim', name = 'gruvbox.nvim' },
	{ src = "https://github.com/folke/which-key.nvim", name = "which-key.nvim" },
	{ src = "https://github.com/folke/snacks.nvim", name = "snacks.nvim" },
	{ src = "https://github.com/williamboman/mason.nvim", name = "mason.nvim" },
	{ src = "https://github.com/williamboman/mason-lspconfig.nvim", name = "mason-lspconfig.nvim" },
	{ src = "https://github.com/neovim/nvim-lspconfig", name = "nvim-lspconfig" },
	{ src = "https://github.com/saghen/blink.cmp", name = "blink.cmp" },
	{ src = "https://github.com/saghen/blink.lib", name = "blink.lib" },
	{ src = "https://github.com/lewis6991/gitsigns.nvim", name = "gitsigns.nvim" },
	{ src = "https://github.com/NMAC427/guess-indent.nvim", name = "guess-indent.nvim" },
	{ src = "https://github.com/L3MON4D3/LuaSnip", name = "LuaSnip", version = vim.version.range("2.*") },
}, { confirm = false })

-- Build hook: LuaSnip needs 'make install_jsregexp' for advanced snippet transforms
vim.api.nvim_create_autocmd("PackChanged", {
	callback = function(ev)
		local name = ev.data.spec.name
		local kind = ev.data.kind
		if kind ~= "install" and kind ~= "update" then
			return
		end
		if name == "LuaSnip" and vim.fn.has("win32") ~= 1 and vim.fn.executable("make") == 1 then
			vim.system({ "make", "install_jsregexp" }, { cwd = ev.data.path }):wait()
		end
	end,
})

-- 3 ─ Which-key: keymap popup after pressing <Space> ─────────────────────────
require("which-key").setup({
	spec = {
		{ "<leader>s", group = "[S]earch" },
		{ "<leader>b", group = "[B]uffer" },
		{ "<leader>t", group = "[T]oggle" },
		{ "<leader>c", group = "[C]ode" },
		{ "<leader>f", group = "[F]ormat" },
		{ "<leader>r", group = "[R]ename" },
	},
})

-- 4 ─ Colorscheme ────────────────────────────────────────────────────────────
-- If icons look broken or missing, install a Nerd Font: https://www.nerdfonts.com/
-- Only one colorscheme at a time — the last uncommented line wins.
vim.cmd.colorscheme("tokyonight")
-- vim.cmd.colorscheme("gruvbox")

-- 5 ─ Options ────────────────────────────────────────────────────────────────
vim.opt.number = true -- line numbers
vim.opt.mouse = "a" -- allow mouse (helpful early on)
vim.opt.clipboard = "unnamedplus" -- sync with system clipboard
vim.opt.ignorecase = true -- case-insensitive search...
vim.opt.smartcase = true -- ...unless you type capitals
vim.opt.termguicolors = true -- 24-bit color support
vim.opt.expandtab = true -- spaces instead of tabs
vim.opt.shiftwidth = 2 -- fallback indent (guess-indent overrides per-file)
vim.opt.tabstop = 2
vim.opt.signcolumn = "yes" -- always show gutter
vim.opt.splitright = true -- vertical splits go right
vim.opt.splitbelow = true -- horizontal splits go below
vim.opt.cursorline = true -- highlight current line
vim.opt.scrolloff = 4 -- keep some context around cursor
vim.opt.confirm = true -- dialog on unsaved changes instead of error
vim.opt.inccommand = "split" -- live preview of :s substitutions
vim.opt.updatetime = 250 -- faster LSP diagnostics
vim.opt.timeoutlen = 300 -- faster which-key popup
vim.opt.showmode = false -- already shown in the statusline
vim.opt.breakindent = true -- wrapped lines keep their indentation
vim.opt.wrap = false -- no line wrapping in code

-- Persistent undo history — files accumulate in ~/.local/state/nvim/undo/
-- Clean up periodically:  rm -rf ~/.local/state/nvim/undo/
vim.opt.undofile = true
vim.opt.completeopt = "menu,menuone,noselect"
vim.opt.list = true -- show invisible characters
vim.opt.listchars = { tab = "» ", trail = "·", nbsp = "␣" }

-- Auto-detect indentation per file — overrides shiftwidth/tabstop above
require("guess-indent").setup({})

-- 6 ─ Escape Insert mode with jk ─────────────────────────────────────────────
vim.keymap.set("i", "jk", "<Esc>")

-- 7 ─ Yank highlight — flash yanked text briefly ─────────────────────────────
vim.api.nvim_create_autocmd("TextYankPost", {
	desc = "Flash yanked text",
	group = vim.api.nvim_create_augroup("starter-yank", { clear = true }),
	callback = function()
		vim.highlight.on_yank()
	end,
})

-- 8 ─ Essential keymaps (press <Space> and wait for which-key menu) ──────────

-- Search
vim.keymap.set("n", "<leader>sf", function()
	Snacks.picker.files()
end, { desc = "[S]earch [F]iles" })

vim.keymap.set("n", "<leader>sg", function()
	Snacks.picker.grep()
end, { desc = "[S]earch [G]rep" })

vim.keymap.set("n", "<leader>sh", function()
	Snacks.picker.help()
end, { desc = "[S]earch [H]elp" })

vim.keymap.set("n", "<leader>sk", function()
	Snacks.picker.keymaps()
end, { desc = "[S]earch [K]eymaps" })

vim.keymap.set("n", "<leader>s.", function()
	Snacks.picker.recent()
end, { desc = '[S]earch recent files ("." for repeat)' })

-- Buffers
vim.keymap.set("n", "<leader>bb", function()
	Snacks.picker.buffers()
end, { desc = "[B]uffer [B]rowse" })

-- Toggle
vim.keymap.set("n", "<leader>e", function()
	Snacks.explorer()
end, { desc = "[E]xplorer (file tree)" })

vim.keymap.set("n", "<leader>tt", function()
	Snacks.terminal()
end, { desc = "[T]erminal [T]oggle" })

-- Exit terminal mode (easier for beginners than <C-\><C-n>)
vim.keymap.set("t", "<Esc><Esc>", "<C-\\><C-n>", { desc = "Exit terminal mode" })

-- Config / Mason
vim.keymap.set("n", "<leader>cm", "<cmd>Mason<CR>", { desc = "[C]heck [M]ason (install LSPs)" })

-- Format
vim.keymap.set("n", "<leader>f", function()
	vim.lsp.buf.format({ async = true })
end, { desc = "[F]ormat buffer" })

-- File
vim.keymap.set("n", "<leader>w", "<cmd>write<CR>", { desc = "[W]rite (save)" })
vim.keymap.set("n", "<leader>q", "<cmd>close<CR>", { desc = "[Q]uit buffer" })

-- Clear search highlights with Escape
vim.keymap.set("n", "<Esc>", "<cmd>nohlsearch<CR>")

-- Split navigation — Ctrl + hjkl to move between windows
vim.keymap.set("n", "<C-h>", "<C-w><C-h>", { desc = "Focus left window" })
vim.keymap.set("n", "<C-l>", "<C-w><C-l>", { desc = "Focus right window" })
vim.keymap.set("n", "<C-j>", "<C-w><C-j>", { desc = "Focus lower window" })
vim.keymap.set("n", "<C-k>", "<C-w><C-k>", { desc = "Focus upper window" })

-- Better indent — keep selection in visual mode
vim.keymap.set("v", "<", "<gv")
vim.keymap.set("v", ">", ">gv")

-- 9 ─ Diagnostics: better error display ──────────────────────────────────────
vim.diagnostic.config({
	update_in_insert = false, -- less visual noise while typing
	severity_sort = true,
	float = {
		border = "rounded",
		source = "if_many",
	},
	virtual_text = true,
	jump = {
		on_jump = function(_, bufnr)
			vim.diagnostic.open_float({ bufnr = bufnr, scope = "cursor", focus = false })
		end,
	},
})

-- 10 ─ LSP: Language Server Protocol ─────────────────────────────────────────
--
-- Language servers power go-to-definition, hover docs, diagnostics, code
-- actions, and auto-completion. The flow:
--
--   Mason (install LS binaries via :Mason UI)
--     → mason-lspconfig (detects installed servers, calls vim.lsp.enable)
--       → Neovim built-in LSP client (vim.lsp.*)
--         → blink.cmp (surfaces LSP results as completion popup)
--
-- Run :checkhealth vim.lsp to see which servers are running and which
-- buffers they're attached to. (Neovim ≥0.12 removed :LspInfo; use
-- :checkhealth as the equivalent.)
--
-- The LspAttach autocmd below fires each time a server connects to a
-- buffer. It sets up keymaps (gd, gr, K, rename, code actions) and
-- document-highlighting on cursor hold.

-- Auto-attach keymaps and features when an LSP server connects to a buffer
vim.api.nvim_create_autocmd("LspAttach", {
	group = vim.api.nvim_create_augroup("starter-lsp-attach", { clear = true }),
	callback = function(event)
		local map = function(keys, func, desc)
			vim.keymap.set("n", keys, func, { buffer = event.buf, desc = "LSP: " .. desc })
		end

		map("gd", vim.lsp.buf.definition, "[G]oto [D]efinition")
		map("gr", vim.lsp.buf.references, "[G]oto [R]eferences")
		map("K", vim.lsp.buf.hover, "Hover Documentation")
		map("[d", vim.diagnostic.goto_prev, "Previous Diagnostic")
		map("]d", vim.diagnostic.goto_next, "Next Diagnostic")
		map("<leader>rn", vim.lsp.buf.rename, "[R]e[n]ame Symbol")
		map("<leader>ca", vim.lsp.buf.code_action, "[C]ode [A]ction")

		-- Highlight references on cursor hold
		local client = vim.lsp.get_client_by_id(event.data.client_id)
		if client and client.server_capabilities.documentHighlightProvider then
			vim.api.nvim_create_autocmd({ "CursorHold", "CursorHoldI" }, {
				buffer = event.buf,
				callback = vim.lsp.buf.document_highlight,
			})
			vim.api.nvim_create_autocmd({ "CursorMoved", "CursorMovedI" }, {
				buffer = event.buf,
				callback = vim.lsp.buf.clear_references,
			})
		end
	end,
})

-- Merge blink.cmp capabilities into all LSP server configs.
-- Without this, blink.cmp can't read completion, signature-help, or
-- snippet results from the LSP server.
vim.lsp.config("*", {
	capabilities = require("blink.cmp").get_lsp_capabilities(vim.lsp.protocol.make_client_capabilities()),
})

-- 11 ─ Mason: install and auto-configure language servers ────────────────────
--
-- Mason provides a UI (:Mason) to browse and install language servers,
-- formatters, linters, and debug adapters. It downloads binaries into
-- ~/.local/share/nvim/mason/ and manages them.
--
-- mason-lspconfig bridges Mason to Neovim's built-in LSP client. Whenever
-- you install a server through Mason, mason-lspconfig auto-enables it
-- (automatic_enable = true) so it starts the next time you open a matching
-- file. No per-server setup blocks needed.
--
-- To install a server, press <Space>cm to open the :Mason UI, press 2 for
-- LSP servers, search, and press i. Restart Neovim — the server attaches
-- automatically.
--
-- For per-server overrides (e.g. root_dir, extra settings), add a
-- vim.lsp.config("server_name", {...}) block BEFORE this setup call.
-- See docs/customizing.md.

require("mason").setup()

require("mason-lspconfig").setup({
	automatic_enable = true, -- auto-start every installed server (Neovim ≥0.11)
})

-- 12 ─ LuaSnip: snippet engine (powers the 'snippets' source in blink.cmp) ──
require("luasnip").setup({})

-- 13 ─ blink.cmp: auto-completion ────────────────────────────────────────────
--
-- blink.cmp replaces the older nvim-cmp. Sources (in priority order):
--   lsp       — language server results (the main source)
--   path      — filesystem paths
--   snippets  — LuaSnip snippets
--   buffer    — words already in the current buffer
--
-- Completion appears automatically as you type. Press <C-Space> to
-- manually open the menu. <C-y> accepts; <C-n>/<C-p> cycle through
-- suggestions; <Tab> jumps between snippet placeholders.
require("blink.cmp").setup({
	keymap = {
		preset = "none",
		["<C-Space>"] = { "show", "show_documentation", "hide_documentation" },
		["<C-y>"] = { "select_and_accept" },
		["<C-p>"] = { "select_prev", "fallback" },
		["<C-n>"] = { "select_next", "fallback" },
		["<C-b>"] = { "scroll_documentation_up", "fallback" },
		["<C-f>"] = { "scroll_documentation_down", "fallback" },
		["<Tab>"] = { "snippet_forward", "select_next", "fallback" },
		["<S-Tab>"] = { "snippet_backward", "select_prev", "fallback" },
	},
	fuzzy = { implementation = "lua" },
	sources = {
		default = { "lsp", "path", "snippets", "buffer" },
	},
	snippets = {
		preset = "luasnip",
	},
	completion = {
		menu = { border = "rounded" },
		documentation = { window = { border = "rounded" }, auto_show = true },
	},
	signature = { enabled = true },
})

-- 14 ─ Gitsigns: git change indicators in the gutter ─────────────────────────
require("gitsigns").setup()

-- 15 ─ Snacks: fuzzy finder, terminal, UI polish ─────────────────────────────
require("snacks").setup({
	explorer = { enabled = true },
	terminal = { enabled = true },
	picker = {
		matcher = {
			fuzzy = true,
			smartcase = true,
			filename_bonus = true,
		},
	},
})

-- 16 ─ Treesitter: better syntax highlighting (built into Neovim >= 0.12) ────
--
-- Neovim 0.12 ships parsers for C, Lua, Markdown, Vimscript, Vimdoc, and
-- Query files. Treesitter highlighting works automatically for those.
-- Install additional parsers via your OS package manager or tree-sitter CLI:
--   tree-sitter install python
--   tree-sitter install rust
--   tree-sitter install bash
--
-- The autocmd below tries to enable treesitter for every filetype and
-- silently skips languages without a parser installed.
vim.api.nvim_create_autocmd("FileType", {
	group = vim.api.nvim_create_augroup("starter-treesitter", { clear = true }),
	callback = function(args)
		local lang = vim.treesitter.language.get_lang(args.match)
		if not lang then
			return
		end

		local has_parser = vim.treesitter.language.add(lang)
		if not has_parser then
			return
		end

		pcall(vim.treesitter.start, args.buf, lang)
	end,
})