extends VBoxContainer

const Style := preload("res://scripts/ui/ui_style.gd")
const BLOCK_SIZES := [20, 19, 19, 20, 19, 19, 20, 19, 19, 20, 19, 19]

var main: Control
var simulation := {}
var questions: Array = []
var responses := {}
var filtered_indices: Array[int] = []
var review_position := 0
var active_filter := "all"
var progress_label: Label
var content: VBoxContainer
var previous_button: Button
var next_button: Button
var empty_label: Label
var media_requests: Array[HTTPRequest] = []
var image_overlay: Control
var image_texture: TextureRect
var return_screen := "selection"


func _ready() -> void:
	set_anchors_preset(Control.PRESET_FULL_RECT)
	add_theme_constant_override("separation", 10)
	var toolbar := HBoxContainer.new()
	toolbar.add_theme_constant_override("separation", 8)
	add_child(toolbar)
	var back := Button.new()
	back.text = "< Results"
	Style.style_chip(back, Style.CYAN)
	back.pressed.connect(func(): main.show_screen("simulation_results", {"simulation": simulation, "return_screen": return_screen}))
	toolbar.add_child(back)
	progress_label = Label.new()
	progress_label.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	progress_label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	Style.set_label(progress_label, 17, Style.TEXT)
	toolbar.add_child(progress_label)
	var filters := GridContainer.new()
	filters.columns = 4
	filters.add_theme_constant_override("h_separation", 8)
	filters.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	add_child(filters)
	var group := ButtonGroup.new()
	for definition in [["All", "all"], ["Incorrect", "incorrect"], ["Unanswered", "unanswered"], ["Flagged", "flagged"]]:
		var button := Button.new()
		button.text = definition[0]
		button.toggle_mode = true
		button.button_group = group
		button.button_pressed = definition[1] == "all"
		Style.style_chip(button, Style.CYAN)
		button.pressed.connect(_set_filter.bind(definition[1]))
		button.size_flags_horizontal = Control.SIZE_EXPAND_FILL
		filters.add_child(button)

	var scroll := ScrollContainer.new()
	scroll.size_flags_vertical = Control.SIZE_EXPAND_FILL
	scroll.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	add_child(scroll)
	content = VBoxContainer.new()
	content.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	content.add_theme_constant_override("separation", 10)
	scroll.add_child(content)
	empty_label = Label.new()
	empty_label.visible = false
	empty_label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	Style.set_label(empty_label, 19, Style.MUTED)
	content.add_child(empty_label)

	var navigation := HBoxContainer.new()
	navigation.add_theme_constant_override("separation", 10)
	add_child(navigation)
	previous_button = Button.new()
	previous_button.text = "< Previous"
	previous_button.custom_minimum_size = Vector2(180, 48)
	Style.style_chip(previous_button, Style.CYAN)
	previous_button.pressed.connect(_move.bind(-1))
	navigation.add_child(previous_button)
	var spacer := Control.new()
	spacer.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	navigation.add_child(spacer)
	next_button = Button.new()
	next_button.text = "Next >"
	next_button.custom_minimum_size = Vector2(180, 48)
	Style.style_primary_button(next_button)
	next_button.pressed.connect(_move.bind(1))
	navigation.add_child(next_button)
	_build_image_overlay()


func on_show(payload: Variant = null) -> void:
	if typeof(payload) == TYPE_DICTIONARY:
		var wrapper: Dictionary = payload
		simulation = wrapper.get("simulation", wrapper)
		return_screen = str(wrapper.get("return_screen", "selection"))
	questions = simulation.get("reviewQuestions", [])
	responses.clear()
	for response in simulation.get("responses", []):
		responses[str(response.get("questionExternalId", ""))] = response
	active_filter = "all"
	review_position = 0
	_apply_filter()


func on_hide() -> void:
	_clear_media_requests()
	image_overlay.visible = false


func _unhandled_key_input(event: InputEvent) -> void:
	if not visible or not event.pressed or event.echo:
		return
	if event.keycode == KEY_LEFT:
		_move(-1)
		get_viewport().set_input_as_handled()
	elif event.keycode == KEY_RIGHT:
		_move(1)
		get_viewport().set_input_as_handled()
	elif event.keycode == KEY_ESCAPE and image_overlay.visible:
		image_overlay.visible = false
		get_viewport().set_input_as_handled()


func _set_filter(filter_name: String) -> void:
	active_filter = filter_name
	review_position = 0
	_apply_filter()


func _apply_filter() -> void:
	filtered_indices.clear()
	for index in range(questions.size()):
		var question: Dictionary = questions[index]
		var response: Dictionary = responses.get(str(question.get("externalId", "")), {})
		var selected := str(response.get("choiceId", ""))
		var correct := str(question.get("correctChoiceId", ""))
		if _matches_filter(active_filter, selected, correct, bool(response.get("flagged", false))):
			filtered_indices.append(index)
	_render_question()


func _move(direction: int) -> void:
	var target := review_position + direction
	if target < 0 or target >= filtered_indices.size():
		return
	review_position = target
	_render_question()


func _render_question() -> void:
	_clear_content()
	_clear_media_requests()
	if filtered_indices.is_empty():
		empty_label = Label.new()
		empty_label.text = "No questions match this filter."
		empty_label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
		Style.set_label(empty_label, 19, Style.MUTED)
		content.add_child(empty_label)
		progress_label.text = "0 questions"
		previous_button.disabled = true
		next_button.disabled = true
		return
	var question_index := filtered_indices[review_position]
	var question: Dictionary = questions[question_index]
	var response: Dictionary = responses.get(str(question.get("externalId", "")), {})
	var selected := str(response.get("choiceId", ""))
	var correct := str(question.get("correctChoiceId", ""))
	progress_label.text = "Question %d of %d  |  Block %d  |  %s" % [review_position + 1, filtered_indices.size(), _block_for_index(question_index) + 1, "Correct" if selected == correct else "Unanswered" if selected == "" else "Incorrect"]
	previous_button.disabled = review_position == 0
	next_button.disabled = review_position + 1 >= filtered_indices.size()
	_add_text(str(question.get("stem", "")), 18, Style.TEXT)
	_add_media(question.get("media", []))
	_add_labs(question.get("labs", []))
	_add_text(str(question.get("leadIn", "")), 21, Style.TEXT)
	var explanations: Dictionary = question.get("choiceExplanations", {})
	for raw_choice in question.get("choices", []):
		var choice: Dictionary = raw_choice
		var choice_id := str(choice.get("id", ""))
		var panel := PanelContainer.new()
		var border := Style.LIME if choice_id == correct else Style.RED if choice_id == selected else Style.BORDER
		var background := Color("1f7a3a") if choice_id == correct else Color("8f1d2c") if choice_id == selected else Style.SURFACE
		panel.add_theme_stylebox_override("panel", Style.panel_box(background, border))
		content.add_child(panel)
		var choice_content := VBoxContainer.new()
		panel.add_child(choice_content)
		var suffix := "  [Correct answer]" if choice_id == correct else "  [Your answer]" if choice_id == selected else ""
		var answer := Label.new()
		answer.text = "%s. %s%s" % [choice_id, str(choice.get("text", "")), suffix]
		answer.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
		Style.set_label(answer, 17, Style.TEXT)
		choice_content.add_child(answer)
		var explanation := str(explanations.get(choice_id, ""))
		if not explanation.is_empty():
			var detail := Label.new()
			detail.text = explanation
			detail.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
			Style.set_label(detail, 15, Style.TEXT)
			choice_content.add_child(detail)
	_add_heading("Explanation")
	_add_text(str(question.get("explanation", "")), 17, Style.TEXT)
	_add_references(question.get("references", []))


func _add_heading(value: String) -> void:
	var label := Label.new()
	label.text = value
	Style.set_label(label, 20, Style.CYAN)
	content.add_child(label)


func _add_text(value: String, size_value: int, color: Color) -> void:
	var label := Label.new()
	label.text = value
	label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
	Style.set_label(label, size_value, color)
	content.add_child(label)


func _add_labs(labs: Array) -> void:
	if labs.is_empty():
		return
	_add_heading("Laboratory studies")
	for raw_lab in labs:
		var lab: Dictionary = raw_lab
		_add_text("%s: %s" % [str(lab.get("name", lab.get("test", ""))), str(lab.get("value", ""))], 15, Style.TEXT)


func _add_references(references: Array) -> void:
	if references.is_empty():
		return
	_add_heading("References")
	for raw_reference in references:
		var reference: Dictionary = raw_reference
		var url := str(reference.get("url", ""))
		if not url.begins_with("https://"):
			continue
		var link := LinkButton.new()
		link.text = str(reference.get("title", url))
		link.tooltip_text = url
		link.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
		link.text_overrun_behavior = TextServer.OVERRUN_TRIM_ELLIPSIS
		link.add_theme_color_override("font_color", Style.CYAN)
		link.pressed.connect(func(target_url: String = url): OS.shell_open(target_url))
		content.add_child(link)


func _add_media(media: Array) -> void:
	for raw_url in media:
		var url := _resolve_media_url(str(raw_url))
		if url.is_empty():
			continue
		var preview := TextureRect.new()
		preview.custom_minimum_size = Vector2(0, 260)
		preview.expand_mode = TextureRect.EXPAND_IGNORE_SIZE
		preview.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_CENTERED
		preview.mouse_default_cursor_shape = Control.CURSOR_POINTING_HAND
		content.add_child(preview)
		var request := HTTPRequest.new()
		request.request_completed.connect(func(result: int, code: int, _headers: PackedStringArray, body: PackedByteArray): _on_media_loaded(result, code, body, preview))
		media_requests.append(request)
		add_child(request)
		request.request(url)


func _on_media_loaded(result: int, code: int, body: PackedByteArray, preview: TextureRect) -> void:
	if result != HTTPRequest.RESULT_SUCCESS or code < 200 or code >= 300 or not is_instance_valid(preview):
		return
	var image := Image.new()
	var error := image.load_png_from_buffer(body)
	if error != OK: error = image.load_jpg_from_buffer(body)
	if error != OK: error = image.load_webp_from_buffer(body)
	if error != OK: return
	preview.texture = ImageTexture.create_from_image(image)
	preview.gui_input.connect(func(event: InputEvent):
		if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.pressed:
			image_texture.texture = preview.texture
			image_overlay.visible = true
	)


func _build_image_overlay() -> void:
	image_overlay = Control.new()
	image_overlay.visible = false
	image_overlay.top_level = true
	image_overlay.mouse_filter = Control.MOUSE_FILTER_STOP
	image_overlay.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
	add_child(image_overlay)
	var background := ColorRect.new()
	background.color = Color(Style.BACKGROUND, 0.97)
	background.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
	image_overlay.add_child(background)
	image_texture = TextureRect.new()
	image_texture.set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
	image_texture.offset_left = 24
	image_texture.offset_top = 72
	image_texture.offset_right = -24
	image_texture.offset_bottom = -24
	image_texture.expand_mode = TextureRect.EXPAND_IGNORE_SIZE
	image_texture.stretch_mode = TextureRect.STRETCH_KEEP_ASPECT_CENTERED
	image_overlay.add_child(image_texture)
	var close := Button.new()
	close.text = "X"
	close.position = Vector2(16, 16)
	close.custom_minimum_size = Vector2(44, 44)
	Style.style_chip(close, Style.CYAN)
	close.pressed.connect(func(): image_overlay.visible = false)
	image_overlay.add_child(close)


func _resolve_media_url(value: String) -> String:
	if value.begins_with("http://") or value.begins_with("https://"):
		return value
	var path := value if value.begins_with("/") else "/%s" % value
	var base := QuestionBankService.question_api_base_url
	var scheme_end := base.find("://")
	var path_start := base.find("/", scheme_end + 3)
	return "%s%s" % [base if path_start < 0 else base.substr(0, path_start), path]


func _clear_content() -> void:
	for child in content.get_children():
		child.queue_free()


func _clear_media_requests() -> void:
	for request in media_requests:
		if is_instance_valid(request): request.queue_free()
	media_requests.clear()


func _block_for_index(index: int) -> int:
	var consumed := 0
	for block in range(BLOCK_SIZES.size()):
		if index < consumed + BLOCK_SIZES[block]: return block
		consumed += BLOCK_SIZES[block]
	return BLOCK_SIZES.size() - 1


static func _matches_filter(filter_name: String, selected: String, correct: String, flagged: bool) -> bool:
	match filter_name:
		"incorrect": return selected != "" and selected != correct
		"unanswered": return selected == ""
		"flagged": return flagged
		_: return true