use crate::document::DocumentMessageHandler;
use crate::input::{keyboard::Key, keyboard::MouseMotion, InputPreprocessor};
use crate::message_prelude::*;
use crate::misc::{HintData, HintGroup, HintInfo, KeysGroup};
use crate::tool::{tools::resize::Resize, DocumentToolData, Fsm, ToolActionHandlerData};
use glam::DAffine2;
use graphene::{layers::style, Operation};
use serde::{Deserialize, Serialize};

#[derive(Default)]
pub struct Ellipse {
	fsm_state: EllipseToolFsmState,
	data: EllipseToolData,
}

#[impl_message(Message, ToolMessage, Ellipse)]
#[derive(PartialEq, Clone, Debug, Hash, Serialize, Deserialize)]
pub enum EllipseMessage {
	DragStart,
	DragStop,
	Resize { center: Key, lock_ratio: Key },
	Abort,
}

impl<'a> MessageHandler<ToolMessage, ToolActionHandlerData<'a>> for Ellipse {
	fn process_action(&mut self, action: ToolMessage, data: ToolActionHandlerData<'a>, responses: &mut VecDeque<Message>) {
		if action == ToolMessage::UpdateHints {
			self.fsm_state.update_hints(responses);
			return;
		}

		let new_state = self.fsm_state.transition(action, data.0, data.1, &mut self.data, data.2, responses);

		if self.fsm_state != new_state {
			self.fsm_state = new_state;
			self.fsm_state.update_hints(responses);
		}
	}

	fn actions(&self) -> ActionList {
		use EllipseToolFsmState::*;
		match self.fsm_state {
			Ready => actions!(EllipseMessageDiscriminant; DragStart),
			Drawing => actions!(EllipseMessageDiscriminant; DragStop, Abort, Resize),
		}
	}
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum EllipseToolFsmState {
	Ready,
	Drawing,
}

impl Default for EllipseToolFsmState {
	fn default() -> Self {
		EllipseToolFsmState::Ready
	}
}

#[derive(Clone, Debug, Default)]
struct EllipseToolData {
	data: Resize,
}

impl Fsm for EllipseToolFsmState {
	type ToolData = EllipseToolData;

	fn transition(
		self,
		event: ToolMessage,
		document: &DocumentMessageHandler,
		tool_data: &DocumentToolData,
		data: &mut Self::ToolData,
		input: &InputPreprocessor,
		responses: &mut VecDeque<Message>,
	) -> Self {
		let mut shape_data = &mut data.data;
		use EllipseMessage::*;
		use EllipseToolFsmState::*;
		if let ToolMessage::Ellipse(event) = event {
			match (self, event) {
				(Ready, DragStart) => {
					shape_data.start(document, input.mouse.position);
					responses.push_back(DocumentMessage::StartTransaction.into());
					shape_data.path = Some(vec![generate_uuid()]);
					responses.push_back(DocumentMessage::DeselectAllLayers.into());

					responses.push_back(
						Operation::AddEllipse {
							path: shape_data.path.clone().unwrap(),
							insert_index: -1,
							transform: DAffine2::ZERO.to_cols_array(),
							style: style::PathStyle::new(None, Some(style::Fill::new(tool_data.primary_color))),
						}
						.into(),
					);

					Drawing
				}
				(state, Resize { center, lock_ratio }) => {
					if let Some(message) = shape_data.calculate_transform(document, center, lock_ratio, input) {
						responses.push_back(message);
					}

					state
				}
				(Drawing, DragStop) => {
					// TODO: introduce comparison threshold when operating with canvas coordinates (https://github.com/GraphiteEditor/Graphite/issues/100)
					match shape_data.drag_start == input.mouse.position {
						true => responses.push_back(DocumentMessage::AbortTransaction.into()),
						false => responses.push_back(DocumentMessage::CommitTransaction.into()),
					}

					shape_data.cleanup();
					Ready
				}
				(Drawing, Abort) => {
					responses.push_back(DocumentMessage::AbortTransaction.into());
					shape_data.cleanup();

					Ready
				}
				_ => self,
			}
		} else {
			self
		}
	}

	fn update_hints(&self, responses: &mut VecDeque<Message>) {
		let hint_data = match self {
			EllipseToolFsmState::Ready => HintData(vec![HintGroup(vec![
				HintInfo {
					key_groups: vec![],
					mouse: Some(MouseMotion::LmbDrag),
					label: String::from("Draw Ellipse"),
					plus: false,
				},
				HintInfo {
					key_groups: vec![KeysGroup(vec![Key::KeyShift])],
					mouse: None,
					label: String::from("Constrain Circular"),
					plus: true,
				},
				HintInfo {
					key_groups: vec![KeysGroup(vec![Key::KeyAlt])],
					mouse: None,
					label: String::from("From Center"),
					plus: true,
				},
			])]),
			EllipseToolFsmState::Drawing => HintData(vec![HintGroup(vec![
				HintInfo {
					key_groups: vec![KeysGroup(vec![Key::KeyShift])],
					mouse: None,
					label: String::from("Constrain Circular"),
					plus: false,
				},
				HintInfo {
					key_groups: vec![KeysGroup(vec![Key::KeyAlt])],
					mouse: None,
					label: String::from("From Center"),
					plus: false,
				},
			])]),
		};

		responses.push_back(FrontendMessage::UpdateInputHints { hint_data }.into());
	}
}