local api = vim.api
local helper = require("signup.helper")

local M = {}

local SignatureHelp = {}
SignatureHelp.__index = SignatureHelp

function SignatureHelp.new()
	local instance = setmetatable({
		_display_sig_win = function() end, -- function to open signatures window
		_display_doc_win = function() end, -- function to open documentation window
		sig_content = nil, -- current signature buffer content
		sig_winnr = nil,
		sig_bufnr = nil,
		sig_win_height = nil,
		sig_win_showing = false,
		ns = nil,
		markid = nil,
		timer = nil,
		current_signatures = nil,
		enabled = false,
		current_signature_idx = nil,

		doc_winnr = nil,
		doc_bufnr = nil,
		doc_win_showing = false,
		doc_win_focused = false,
		config = nil,

		active_winnr = vim.api.nvim_get_current_win(),
	}, SignatureHelp)

	instance._default_config = {
		silent = false,
		icons = {
			parameter = "",
			method = "󰡱 ",
			documentation = "󱪙 ",
		},
		colors = {
			parameter = "#86e1fc",
			method = "#c099ff",
			documentation = "#4fd6be",
			default_value = "#a80888",
		},
		active_parameter_colors = {
			bg = "#86e1fc",
			fg = "#1a1a1a",
		},
		hi_parameter = "LspSignatureActiveParameter",
		win_opts = {
			border = "rounded",
			winblend = 10,
			zindex = 200,
			max_height = 20,
			max_width = 80,
			anchor_bias = "below", -- below|above|auto
			offset_y = 0,
			offset_x = 0,
		},

		trigger_chars = { "(", "," },
		auto_close = true,
		preview_parameters = true,
		debounce_time = 100,
		render_style = {
			separator = true,
			compact = true,
			align_icons = true,
		},
	}

	return instance
end

function SignatureHelp:hide_sig_win()
	if self.sig_win_showing then
		helper.close_float_window(self.sig_winnr)
	end
	helper.delete_buffer(self.sig_bufnr)
	helper.delete_buffer(self.doc_bufnr)

	self:hide_doc_win()

	self.sig_winnr = nil
	self.sig_bufnr = nil
	self.doc_bufnr = nil -- we want to nil this here and not when we hide the doc win in case we want to reopen the doc win
	self.current_signatures = nil
	self.sig_win_showing = false
end

function SignatureHelp:hide_doc_win()
	if self.doc_win_showing then
		helper.close_float_window(self.doc_winnr)
		self.doc_winnr = nil
		self.doc_win_showing = false
	end
end

function SignatureHelp:extract_default_value(param_info)
	-- Check if parameter has documentation that might contain default value
	if not param_info.documentation then
		return nil
	end

	local doc = type(param_info.documentation) == "string" and param_info.documentation
		or param_info.documentation.value

	-- Look for common default value patterns
	local patterns = {
		"default:%s*([^%s]+)",
		"defaults%s+to%s+([^%s]+)",
		"%(default:%s*([^%)]+)%)",
	}

	for _, pattern in ipairs(patterns) do
		local default = doc:match(pattern)
		if default then
			return default
		end
	end

	return nil
end

function SignatureHelp:set_active_parameter_highlights(param_str, lines)
	if not self.sig_bufnr or not api.nvim_buf_is_valid(self.sig_bufnr) then
		return
	end

	self.ns = api.nvim_create_namespace("lsp_signature_hi_parameter")
	local hi = self.config.hi_parameter

	local s, e, line_num
	for l, line in ipairs(lines) do
		local ss, ee, _ = string.find(line, param_str, 1, true)
		if ss ~= nil then
			line_num = l - 1
			s = ss
			e = ee
		end
	end

	if s and e and s > 0 then
		self.markid = api.nvim_buf_set_extmark(
			self.sig_bufnr,
			self.ns,
			line_num,
			s,
			{ id = self.markid, end_line = line_num, end_col = e, hl_group = hi, strict = false }
		)
	end
end

function SignatureHelp:display_sig_win(result)
	if not result or not result.signatures or #result.signatures == 0 then
		self:hide_sig_win()
		if self.doc_win_showing then
			self:hide_doc_win()
		end
		return
	end

	if not self.sig_win_showing then
		local ft = vim.bo.ft
		self._display_sig_win, self._display_doc_win = helper.create_float_windows(result, ft, self.config.win_opts)
		self.sig_bufnr, self.sig_winnr, self.sig_content = self._display_sig_win()

		local param_str = helper.get_parameter_label(result)
		self:set_active_parameter_highlights(param_str, self.sig_content)
		self.sig_win_showing = true
	end
	local param_str = helper.get_parameter_label(result)
	self:set_active_parameter_highlights(param_str, self.sig_content)
end

function SignatureHelp:display_doc_win()
	if self.doc_win_showing then
		return
	else
		self.doc_bufnr, self.doc_winnr = self._display_doc_win()
		self.doc_win_showing = true
		self.doc_win_focused = true
		vim.api.nvim_set_current_win(self.doc_winnr)

		exit_docs = function()
			vim.api.nvim_set_current_win(self.active_winnr)
			vim.fn.feedkeys("i", "t") --put us back into insert mode
			self.doc_win_focused = false
		end

		if self.doc_bufnr ~= nil then
			vim.keymap.set(
				"n",
				"q",
				exit_docs,
				{ silent = true, noremap = true, nowait = true, buffer = self.doc_bufnr }
			)
			vim.keymap.set(
				"n",
				"<esc>",
				exit_docs,
				{ silent = true, noremap = true, nowait = true, buffer = self.doc_bufnr }
			)
		end
	end
end

function SignatureHelp:trigger()
	if not self.enabled then
		return
	end

	local params = vim.lsp.util.make_position_params()
	vim.lsp.buf_request(0, "textDocument/signatureHelp", params, function(err, result, _, _)
		if err then
			if not self.config.silent then
				vim.notify("Error in LSP Signature Help: " .. vim.inspect(err), vim.log.levels.ERROR)
			end
			self:hide_sig_win()
			self:hide_doc_win()
			return
		end

		if result and result.signatures and #result.signatures > 0 then
			self.current_signatures = result.signatures

			self:display_sig_win(result)
		else
			self:hide_sig_win()
			self:hide_doc_win()
			-- Only notify if not silent and if there was actually no signature help
			if not self.config.silent and result then
				vim.notify("No signature help available", vim.log.levels.INFO)
			end
		end
	end)
end

function SignatureHelp:check_capability()
	local clients = vim.lsp.get_clients()
	for _, client in ipairs(clients) do
		if client.server_capabilities.signatureHelpProvider then
			self.enabled = true
			return
		end
	end
	self.enabled = false
end

function SignatureHelp:setup_autocmds()
	local group = api.nvim_create_augroup("LspSignatureHelp", { clear = true })

	local function debounced_trigger()
		if self.timer then
			vim.fn.timer_stop(self.timer)
		end
		self.timer = vim.fn.timer_start(self.debounce_time, function()
			self:trigger()
		end)
	end

	api.nvim_create_autocmd({ "InsertEnter", "CursorMovedI" }, {
		group = group,
		callback = function()
			debounced_trigger()
		end,
	})

	-- make sure signature help windows get closed if we switch out of the doc window
	-- instead of exiting it using the exit keymaps
	api.nvim_create_autocmd({ "WinEnter" }, {
		group = group,
		callback = function()
			vim.defer_fn(function()
				if self.active_winnr == vim.api.nvim_get_current_win() and vim.api.nvim_get_mode().mode == "n" then
					self:hide_sig_win()
					self:hide_doc_win()
				end
			end, 30)
		end,
	})

	api.nvim_create_autocmd({ "CursorMoved" }, {
		group = group,
		callback = function()
			if self.normal_mode_active then
				debounced_trigger()
			end
		end,
	})

	api.nvim_create_autocmd({ "InsertLeave" }, {
		group = group,
		callback = function()
			if self.doc_win_focused == false then
				self:hide_sig_win()
				self:hide_doc_win()
				self.normal_mode_active = false
			end
		end,
	})

	api.nvim_create_autocmd("LspAttach", {
		group = group,
		callback = function()
			vim.defer_fn(function()
				self:check_capability()
			end, 100)
		end,
	})
end

-- Add navigation between multiple signatures
function SignatureHelp:next_signature()
	if not self.current_signatures then
		return
	end
	self.current_signature_idx = (self.current_signature_idx or 0) + 1
	if self.current_signature_idx > #self.current_signatures then
		self.current_signature_idx = 1
	end
	self:display_sig_win({
		signatures = self.current_signatures,
		activeParameter = self.current_active_parameter,
		activeSignature = self.current_signature_idx - 1,
	})
end

function SignatureHelp:prev_signature()
	if not self.current_signatures then
		return
	end
	self.current_signature_idx = (self.current_signature_idx or 1) - 1
	if self.current_signature_idx < 1 then
		self.current_signature_idx = #self.current_signatures
	end
	self:display_sig_win({
		signatures = self.current_signatures,
		activeParameter = self.current_active_parameter,
		activeSignature = self.current_signature_idx - 1,
	})
end

function SignatureHelp:toggle_docs()
	if self.doc_win_showing then
		self:hide_doc_win()
	elseif self.sig_win_showing then
		self:display_doc_win()
	end
end

function M.setup(opts)
	-- Ensure setup is called only once
	if M._initialized then
		return M._instance
	end

	opts = opts or {}
	local signature_help = SignatureHelp.new()

	-- Deep merge user config with defaults
	signature_help.config = vim.tbl_deep_extend("force", signature_help._default_config, opts)

	-- Setup highlights with user config
	local function setup_highlights()
		local colors = signature_help.config.colors
		local highlights = {
			SignatureHelpBorder = { link = "FloatBorder" },
			SignatureHelpMethod = { fg = colors.method },
			SignatureHelpParameter = { fg = colors.parameter },
			SignatureHelpDocumentation = { fg = colors.documentation },
			SignatureHelpDefaultValue = { fg = colors.default_value, italic = true },
			LspSignatureActiveParameter = {
				fg = signature_help.config.active_parameter_colors.fg,
				bg = signature_help.config.active_parameter_colors.bg,
			},
		}

		for group, hl_opts in pairs(highlights) do
			vim.api.nvim_set_hl(0, group, hl_opts)
		end
	end

	-- Setup highlights and ensure they persist across colorscheme changes
	setup_highlights()
	vim.api.nvim_create_autocmd("ColorScheme", {
		group = vim.api.nvim_create_augroup("LspSignatureColors", { clear = true }),
		callback = setup_highlights,
	})

	-- Setup autocmds
	signature_help:setup_autocmds()

	-- Store instance for potential reuse
	M._initialized = true
	M._instance = signature_help

	-- Add API methods for external use
	M.toggle_docs = function()
		signature_help:toggle_docs()
	end

	return signature_help
end

-- Add version and metadata for lazy.nvim compatibility
M.version = "1.0.0"
M.dependencies = {
	"nvim-treesitter/nvim-treesitter",
}

return M