-- lua/theme.lua
-- Reads Noctalia's generated Alacritty theme (~/.config/alacritty/themes/noctalia.toml)
-- and applies matching highlight groups in Neovim, including Treesitter captures.
-- Monotone palette: only keywords, functions, parameters, strings, and comments
-- carry a distinct color. Everything else (variables, types, constants,
-- punctuation, operators, tags, numbers, booleans) sits in foreground or gray.
local M = {}

local THEME_PATH = vim.fn.expand("~/.config/alacritty/themes/noctalia.toml")

local function parse_alacritty_colors(path)
	local f = io.open(path, "r")
	if not f then return nil end

	local colors = { primary = {}, normal = {}, bright = {} }
	local section

	for line in f:lines() do
		local sec = line:match("^%[colors%.(%a+)%]")
		if sec then
			-- only track top-level sections we care about (primary, normal, bright);
			-- nested ones like [colors.search.matches] won't match %a+ and are skipped
			section = colors[sec] and sec or nil
		elseif section then
			local key, val = line:match("^(%a+)%s*=%s*['\"](#%x+)['\"]")
			if key and val then
				colors[section][key] = val
			end
		end
	end

	f:close()
	return colors
end

function M.load()
	local c = parse_alacritty_colors(THEME_PATH)
	if not c or not c.primary.background or not c.primary.foreground then
		vim.notify("noctalia theme not found or unparsable: " .. THEME_PATH, vim.log.levels.WARN)
		return
	end

	local bg, fg = c.primary.background, c.primary.foreground
	local n, b = c.normal, c.bright
	local hl = vim.api.nvim_set_hl

	local gray_dim = "#5a5a5a"  -- comments, punctuation, gutter — de-emphasized
	local gray_mid = "#7a7a7a"  -- line numbers

	-- The five accent colors — everything else stays monotone
	local c_keyword   = n.magenta
	local c_function  = n.blue
	local c_parameter = b.white  -- subtly brighter than fg, not a hue, keeps "args" scannable
	local c_string    = n.green
	local c_comment   = "#968466"

	-- Base UI
	hl(0, "Normal", { fg = fg, bg = bg })
	hl(0, "NormalFloat", { fg = fg, bg = bg })
	hl(0, "CursorLine", { bg = n.black })
	hl(0, "Visual", { bg = n.black, fg = fg })
	hl(0, "Pmenu", { fg = fg, bg = n.black })
	hl(0, "PmenuSel", { fg = bg, bg = b.white })
	hl(0, "LineNr", { fg = gray_mid })
	hl(0, "CursorLineNr", { fg = b.white, bold = true })
	hl(0, "SignColumn", { bg = bg })
	hl(0, "VertSplit", { fg = n.black })
	hl(0, "WinSeparator", { fg = n.black })
	hl(0, "StatusLine", { fg = fg, bg = n.black })
	hl(0, "StatusLineNC", { fg = gray_mid, bg = n.black })
	hl(0, "Search", { fg = "#161616", bg = gray_mid })
	hl(0, "IncSearch", { fg = "#161616", bg = b.white })

	-- Treesitter capture groups — the five accented categories
	hl(0, "@comment", { fg = c_comment, italic = true })

	hl(0, "@keyword", { fg = c_keyword })
	hl(0, "@keyword.function", { fg = c_keyword })
	hl(0, "@keyword.return", { fg = c_keyword })
	hl(0, "@conditional", { fg = c_keyword })
	hl(0, "@repeat", { fg = c_keyword })

	hl(0, "@function", { fg = c_function })
	hl(0, "@function.builtin", { fg = c_function })
	hl(0, "@function.call", { fg = c_function })
	hl(0, "@method", { fg = c_function })
	hl(0, "@method.call", { fg = c_function })

	hl(0, "@parameter", { fg = c_parameter, italic = true })

	hl(0, "@string", { fg = c_string })
	hl(0, "@string.escape", { fg = c_string, bold = true })

	-- Everything else — monotone, falls back to fg or gray
	hl(0, "@variable", { fg = fg })
	hl(0, "@variable.builtin", { fg = fg })
	hl(0, "@type", { fg = fg })
	hl(0, "@type.builtin", { fg = fg })
	hl(0, "@constructor", { fg = fg })
	hl(0, "@constant", { fg = fg })
	hl(0, "@constant.builtin", { fg = fg })
	hl(0, "@property", { fg = fg })
	hl(0, "@field", { fg = fg })
	hl(0, "@number", { fg = fg })
	hl(0, "@boolean", { fg = fg })
	hl(0, "@tag", { fg = fg })
	hl(0, "@tag.attribute", { fg = fg })
	hl(0, "@operator", { fg = gray_mid })
	hl(0, "@punctuation.delimiter", { fg = gray_dim })
	hl(0, "@punctuation.bracket", { fg = gray_dim })

	-- Legacy / non-Treesitter syntax groups (classic :syntax highlighting —
	-- used by filetypes with no Treesitter parser, or plugins that still
	-- rely on regex-based syntax files). Mirrors the same monotone scheme.
	hl(0, "Comment", { fg = c_comment, italic = true })

	hl(0, "Statement", { fg = c_keyword })
	hl(0, "Keyword", { fg = c_keyword })
	hl(0, "Conditional", { fg = c_keyword })
	hl(0, "Repeat", { fg = c_keyword })
	hl(0, "Label", { fg = c_keyword })
	hl(0, "Exception", { fg = c_keyword })

	hl(0, "Function", { fg = c_function })

	hl(0, "String", { fg = c_string })
	hl(0, "Character", { fg = c_string })

	-- Everything else — monotone, no separate hue
	hl(0, "Identifier", { fg = fg })
	hl(0, "Constant", { fg = fg })
	hl(0, "Number", { fg = fg })
	hl(0, "Boolean", { fg = fg })
	hl(0, "Float", { fg = fg })
	hl(0, "Type", { fg = fg })
	hl(0, "StorageClass", { fg = fg })
	hl(0, "Structure", { fg = fg })
	hl(0, "Typedef", { fg = fg })
	hl(0, "PreProc", { fg = fg })
	hl(0, "Include", { fg = fg })
	hl(0, "Define", { fg = fg })
	hl(0, "Macro", { fg = fg })
	hl(0, "PreCondit", { fg = fg })
	hl(0, "Special", { fg = fg })
	hl(0, "SpecialChar", { fg = fg })
	hl(0, "SpecialComment", { fg = c_comment, italic = true })
	hl(0, "Tag", { fg = fg })
	hl(0, "Debug", { fg = fg })
	hl(0, "Underlined", { fg = fg, underline = true })
	hl(0, "Ignore", { fg = gray_dim })

	hl(0, "Operator", { fg = gray_mid })
	hl(0, "Delimiter", { fg = gray_dim })

	-- Kept distinct: these are signals, not syntax decoration
	hl(0, "Todo", { fg = n.yellow, bold = true })
	hl(0, "Error", { fg = n.red, bold = true })

	-- Diagnostics stay colored — functional signal, not syntax decoration
	hl(0, "DiagnosticError", { fg = n.red })
	hl(0, "DiagnosticWarn", { fg = n.yellow })
	hl(0, "DiagnosticInfo", { fg = n.blue })
	hl(0, "DiagnosticHint", { fg = n.cyan })
end

-- Reapply automatically whenever Noctalia regenerates the Alacritty theme
-- (e.g. on a theme switch), without needing to restart Neovim.
function M.watch()
	local w = vim.uv.new_fs_event()
	if not w then return end
	w:start(THEME_PATH, {}, vim.schedule_wrap(function()
		M.load()
	end))
end

return M