-- SPDX-FileCopyrightText: © 2022—2026 Vladimir Zorin <vladimir@deviant.guru>
-- SPDX-License-Identifier: LicenseRef-OWL-1.0-or-later
-- Licensed under OWL v1.0+. See LICENSE.

--[==[
Callback-based event emitter for the markdown parser. Invokes handlers
immediately as events occur, enabling true streaming rendering. Events
carry type, tag, optional text, and optional attrs fields.
]==]

-- Emit an event to the callback
local emit = function(self, event)
	if self.__state.callback then
		self.__state.callback(event)
	end
end

-- Emit a block start event
local emit_block_start = function(self, tag, attrs)
	self:emit({ type = "block_start", tag = tag, attrs = attrs })
end

-- Emit a block end event
local emit_block_end = function(self, tag)
	self:emit({ type = "block_end", tag = tag })
end

-- Emit a text event
local emit_text = function(self, text)
	if text and text ~= "" then
		self:emit({ type = "text", text = text })
	end
end

-- Emit an inline start event
local emit_inline_start = function(self, tag, attrs)
	self:emit({ type = "inline_start", tag = tag, attrs = attrs })
end

-- Emit an inline end event
local emit_inline_end = function(self, tag)
	self:emit({ type = "inline_end", tag = tag })
end

-- Emit a softbreak event
local emit_softbreak = function(self)
	self:emit({ type = "softbreak" })
end

-- Change the callback function
local set_callback = function(self, fn)
	self.__state.callback = fn
end

---! Create a new event emitter
---@ new(`on_event`{.func .opt}) -> `emitter`{.tbl}
local new = function(on_event)
	return {
		__state = {
			callback = on_event,
		},
		emit = emit,
		emit_block_start = emit_block_start,
		emit_block_end = emit_block_end,
		emit_inline_start = emit_inline_start,
		emit_inline_end = emit_inline_end,
		emit_text = emit_text,
		emit_softbreak = emit_softbreak,
		set_callback = set_callback,
	}
end

return { new = new }