extends VBoxContainer

const Style := preload("res://scripts/ui/ui_style.gd")

var main: Control
var exam_view: VBoxContainer
var mode_view: VBoxContainer
var exam_grid: GridContainer
var mode_grid: GridContainer
var question_bank_button: Button
var bank_status_label: Label
var bank_error_label: Label
var retry_button: Button
var current_stage := "exam"
var pending_question_bank_launch := false


func _ready() -> void:
	set_anchors_preset(Control.PRESET_FULL_RECT)
	add_theme_constant_override("separation", 18)
	resized.connect(_refresh_grid_columns)
	if not QuestionBankService.questions_changed.is_connected(_on_questions_changed):
		QuestionBankService.questions_changed.connect(_on_questions_changed)
	if not QuestionBankService.questions_load_failed.is_connected(_on_questions_load_failed):
		QuestionBankService.questions_load_failed.connect(_on_questions_load_failed)

	_build_exam_view()
	_build_mode_view()
	_show_stage("exam")


func on_show(payload: Variant = null) -> void:
	if str(payload) == "step3":
		_show_stage("step3")
	elif str(payload) == "exam":
		_show_stage("exam")
	_refresh_bank_state()


func on_hide() -> void:
	pending_question_bank_launch = false


func _build_exam_view() -> void:
	exam_view = VBoxContainer.new()
	exam_view.add_theme_constant_override("separation", 18)
	exam_view.size_flags_vertical = Control.SIZE_EXPAND_FILL
	add_child(exam_view)

	var eyebrow := Label.new()
	eyebrow.text = "CHOOSE YOUR EXAM"
	Style.set_label(eyebrow, 14, Style.CYAN)
	exam_view.add_child(eyebrow)

	var title := Label.new()
	title.text = "What are you preparing for?"
	Style.set_label(title, 34, Style.TEXT)
	exam_view.add_child(title)

	var subtitle := Label.new()
	subtitle.text = "Select a path to enter its study modes. More exams will be added as they are ready."
	subtitle.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
	Style.set_label(subtitle, 17, Style.MUTED)
	exam_view.add_child(subtitle)

	exam_grid = GridContainer.new()
	exam_grid.columns = 2
	exam_grid.add_theme_constant_override("h_separation", 16)
	exam_grid.add_theme_constant_override("v_separation", 16)
	exam_grid.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	exam_grid.size_flags_vertical = Control.SIZE_EXPAND_FILL
	exam_view.add_child(exam_grid)

	_add_exam_option("STEP 1", "Foundational sciences", false)
	_add_exam_option("STEP 2", "Clinical knowledge", false)
	_add_exam_option("STEP 3", "Advanced clinical management", true)
	_add_exam_option("CCS Cases", "Interactive case simulations", false)


func _build_mode_view() -> void:
	mode_view = VBoxContainer.new()
	mode_view.add_theme_constant_override("separation", 18)
	mode_view.size_flags_vertical = Control.SIZE_EXPAND_FILL
	add_child(mode_view)

	var back_button := Button.new()
	back_button.text = "<  All exams"
	back_button.alignment = HORIZONTAL_ALIGNMENT_LEFT
	back_button.custom_minimum_size = Vector2(150, 42)
	Style.style_chip(back_button, Style.CYAN)
	UISoundService.set_button_sound(back_button, "back")
	back_button.pressed.connect(func(): _show_stage("exam"))
	mode_view.add_child(back_button)

	var eyebrow := Label.new()
	eyebrow.text = "STEP 3"
	Style.set_label(eyebrow, 14, Style.LIME)
	mode_view.add_child(eyebrow)

	var title := Label.new()
	title.text = "Choose a study mode"
	Style.set_label(title, 34, Style.TEXT)
	mode_view.add_child(title)

	var subtitle := Label.new()
	subtitle.text = "Build clinical judgment through focused questions. Additional modes are in development."
	subtitle.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
	Style.set_label(subtitle, 17, Style.MUTED)
	mode_view.add_child(subtitle)

	mode_grid = GridContainer.new()
	mode_grid.columns = 2
	mode_grid.add_theme_constant_override("h_separation", 16)
	mode_grid.add_theme_constant_override("v_separation", 16)
	mode_grid.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	mode_view.add_child(mode_grid)

	question_bank_button = Button.new()
	question_bank_button.text = "Question Bank\nAdaptive core run  |  Available"
	question_bank_button.alignment = HORIZONTAL_ALIGNMENT_LEFT
	question_bank_button.custom_minimum_size = Vector2(360, 150)
	question_bank_button.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	question_bank_button.add_theme_font_size_override("font_size", 20)
	Style.style_primary_button(question_bank_button)
	question_bank_button.pressed.connect(_select_question_bank)
	mode_grid.add_child(question_bank_button)

	var dynamic_button := Button.new()
	dynamic_button.text = "Dynamic Questions\nAI-generated practice  |  Coming Soon"
	dynamic_button.alignment = HORIZONTAL_ALIGNMENT_LEFT
	dynamic_button.custom_minimum_size = Vector2(360, 150)
	dynamic_button.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	dynamic_button.add_theme_font_size_override("font_size", 20)
	dynamic_button.disabled = true
	mode_grid.add_child(dynamic_button)

	bank_status_label = Label.new()
	bank_status_label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
	Style.set_label(bank_status_label, 16, Style.CYAN)
	mode_view.add_child(bank_status_label)

	bank_error_label = Label.new()
	bank_error_label.autowrap_mode = TextServer.AUTOWRAP_WORD_SMART
	Style.set_label(bank_error_label, 15, Style.RED)
	mode_view.add_child(bank_error_label)

	retry_button = Button.new()
	retry_button.text = "Retry Question Bank"
	retry_button.custom_minimum_size = Vector2(220, 46)
	retry_button.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
	Style.style_chip(retry_button, Style.AMBER)
	retry_button.pressed.connect(_retry_question_bank)
	mode_view.add_child(retry_button)

	var spacer := Control.new()
	spacer.size_flags_vertical = Control.SIZE_EXPAND_FILL
	mode_view.add_child(spacer)


func _add_exam_option(option_name: String, description: String, available: bool) -> void:
	var button := Button.new()
	button.text = "%s\n%s  |  %s" % [option_name, description, "Available" if available else "Coming Soon"]
	button.alignment = HORIZONTAL_ALIGNMENT_LEFT
	button.custom_minimum_size = Vector2(360, 150)
	button.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	button.size_flags_vertical = Control.SIZE_EXPAND_FILL
	button.add_theme_font_size_override("font_size", 20)
	button.disabled = not available
	if available:
		Style.style_primary_button(button)
		button.pressed.connect(func(): _show_stage("step3"))
	exam_grid.add_child(button)


func _show_stage(stage_name: String) -> void:
	current_stage = stage_name
	pending_question_bank_launch = false
	if exam_view != null:
		exam_view.visible = stage_name == "exam"
	if mode_view != null:
		mode_view.visible = stage_name == "step3"
	_refresh_grid_columns()
	_refresh_bank_state()


func _select_question_bank() -> void:
	pending_question_bank_launch = true
	var excluded_ids: Array = ProfileService.get_profile().get("correct_question_ids", []).duplicate()
	QuestionBankService.load_next_random_question(excluded_ids)
	_refresh_bank_state()


func _retry_question_bank() -> void:
	pending_question_bank_launch = true
	QuestionBankService.retry_now()
	_refresh_bank_state()


func _on_questions_changed() -> void:
	_refresh_bank_state()
	if pending_question_bank_launch and visible and current_stage == "step3" and QuestionBankService.load_state == "ready":
		pending_question_bank_launch = false
		call_deferred("_start_question_bank")


func _on_questions_load_failed(_message: String) -> void:
	pending_question_bank_launch = false
	_refresh_bank_state()


func _refresh_bank_state() -> void:
	if question_bank_button == null:
		return
	var state := QuestionBankService.load_state
	question_bank_button.disabled = pending_question_bank_launch
	retry_button.visible = state == "failed" or state == "retrying"
	retry_button.disabled = state == "retrying"
	bank_error_label.text = QuestionBankService.last_error if state == "failed" or state == "retrying" else ""
	if pending_question_bank_launch or state == "loading":
		bank_status_label.text = "Preparing your question bank..."
	elif state == "retrying":
		bank_status_label.text = "Question bank unavailable. Retrying in %d seconds." % QuestionBankService.next_retry_seconds
	elif state == "ready":
		bank_status_label.text = "Question bank ready"
	elif state == "failed":
		bank_status_label.text = "The question bank could not be loaded."
	else:
		bank_status_label.text = "Question bank will load when selected."


func _start_question_bank() -> void:
	if not visible or current_stage != "step3" or not QuestionBankService.has_questions():
		return
	if BlockSessionService.start_core_run():
		UISoundService.play_sound("question")
		main.show_screen("player")
	else:
		bank_error_label.text = BlockSessionService.core_status_message


func _refresh_grid_columns() -> void:
	var column_count := 1 if size.x < 820.0 else 2
	if exam_grid != null:
		exam_grid.columns = column_count
	if mode_grid != null:
		mode_grid.columns = column_count