// Oak Video Editor - Non-Linear Video Editor
// Copyright (C) 2026 Oak Team
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//! M12 P2: the real node-graph surface.
//!
//! Builds the gpui node-graph data (`RealNode` / `RealPort` / `RealEdge`)
//! from the CURRENT SEQUENCE's graph (M14 R3: the direct oaknode graph walk
//! — the app links the module rlibs and reads the project graph itself):
//!
//! - the sequence node becomes the output card (rightmost);
//! - every clip block becomes a card titled with its label (or "Clip");
//! - effects (everything else in the sequence graph) sit between;
//! - footage nodes (the media) feed the clip's `tex_in` from the left;
//! - declared inputs become input ports (id string as the label); every
//!   node exposes one "out" output port (the module declares no outputs;
//!   edges are enumerated from `Graph::output_connections`);
//! - REAL edges connect the source node's main output to the target
//!   node's input port; a synthesized "clip → output" wire per clip
//!   connects the clip's main output to the sequence's `tex_in` (the
//!   module's place-block flow never wires blocks to the sequence node —
//!   the C++ reaches it through track nodes, which do not exist here);
//! - positions come from the sequence node's context position map, with a
//!   deterministic role-grid fallback layout (footage | effects | clips |
//!   output) when a node has no entry yet — the first drag persists
//!   through the undoable position setter.
//!
//! Identity mapping: `NodeId` = the module node identity (stable across
//! frames). `PortId` packs `(node identity, kind, index)` — input port
//! `(id << 4) | (index << 1)`, output port `(id << 4) | 1`. Identities
//! are arena slots (low index bits, zero generation for most nodes), so
//! the shifts are injective.
//!
//! Structural timeline plumbing (track lists, tracks, gaps, transitions)
//! is NOT displayed: those nodes carry no graph edges in the module world
//! and would only add empty cards; the displayed graph is the media chain
//! clip → effects → output the C++ node editor centers on.

use std::collections::HashMap;

use gpui::node_graph::{
	EdgeData, EdgeId, NodeData, NodeId, PortData, PortId, PortDataType, PortKind,
};
use gpui::{hsla, point, px, Hsla, Pixels, Point, SharedString};

use oaknode::id::NodeId as DomainNodeId;

use crate::oakui::graphops::{self, ProjectRef};

/// The sequence node type id (the graph's output card).
const TYPE_ID_SEQUENCE: &str = "org.olivevideoeditor.Olive.sequence";
/// Clip block type id (the graph's clip cards).
const TYPE_ID_CLIP_BLOCK: &str = "org.olivevideoeditor.Olive.clipblock";
/// Footage node type id (the graph's media cards).
const TYPE_ID_FOOTAGE: &str = "org.olivevideoeditor.Olive.footage";
/// Structural timeline nodes never shown in the node editor.
const TYPE_ID_TRACK: &str = "org.olivevideoeditor.Olive.track";
const TYPE_ID_TRACK_LIST: &str = "org.olivevideoeditor.Olive.tracklist";
const TYPE_ID_GAP_BLOCK: &str = "org.olivevideoeditor.Olive.gapblock";
const TYPE_ID_TRANSITION_BLOCK: &str = "org.olivevideoeditor.Olive.transitionblock";

/// The "video" wire type used by the real graph (the module exposes no
/// per-input type names; all node ports are treated as video).
fn video_type() -> PortDataType {
	PortDataType::new("video", hsla(0.55, 0.75, 0.6, 1.0))
}

/// The "output" wire type for the module's implicit outputs.
fn out_type() -> PortDataType {
	PortDataType::new("video", hsla(0.08, 0.7, 0.55, 1.0))
}

/// Pack a node identity + kind + index into a global `PortId`.
fn port_id(node: u64, kind: PortKind, index: u32) -> PortId {
	match kind {
		PortKind::Input => PortId((node << 4) | ((index as u64) << 1)),
		PortKind::Output => PortId((node << 4) | 1),
	}
}

/// Unpack a `PortId` into `(node identity, kind, index)`.
fn unpack_port(id: PortId) -> (u64, PortKind, u32) {
	let raw = id.0;
	let node = raw >> 4;
	if raw & 1 == 1 {
		(node, PortKind::Output, 0)
	} else {
		(node, PortKind::Input, ((raw >> 1) & 0x7) as u32)
	}
}

/// A stable REAL edge id from `(from node, to node, input id)` (FNV-1a,
/// high bit masked so it can never collide with the synthesized-wire tag
/// [`is_output_wire`] reserves).
fn real_edge_id(from: u64, to: u64, input_id: &str) -> EdgeId {
	let mut h: u64 = 0xcbf29ce484222325;
	for &b in [from.to_le_bytes(), to.to_le_bytes()].concat().iter() {
		h ^= b as u64;
		h = h.wrapping_mul(0x100000001b3);
	}
	for &b in input_id.as_bytes() {
		h ^= b as u64;
		h = h.wrapping_mul(0x100000001b3);
	}
	EdgeId(h & 0x7fff_ffff_ffff_ffff)
}

/// The synthesized "clip → output" wire's id: tagged with the high bit so
/// the app can tell structural wires apart from real edges (whose ids are
/// masked below the tag — see [`real_edge_id`]).
fn output_wire_id(clip: u64) -> EdgeId {
	EdgeId(0x8000_0000_0000_0000 | real_edge_id(clip, clip, "out").0)
}

/// Whether `id` is a synthesized structural wire (never a real edge).
pub fn is_output_wire(id: EdgeId) -> bool {
	id.0 & 0x8000_0000_0000_0000 != 0
}

/// A node card in the real graph.
#[derive(Debug, Clone)]
pub struct RealNode {
	/// The module node identity.
	pub id: NodeId,
	/// Card title.
	pub title: SharedString,
	/// Graph-space position.
	pub position: Point<Pixels>,
	/// Input ports (top to bottom).
	pub inputs: Vec<RealPort>,
	/// The single implicit output port.
	pub outputs: Vec<RealPort>,
	/// Category accent.
	pub header_color: Option<Hsla>,
	/// Collapsed state.
	pub collapsed: bool,
	/// Enabled state.
	pub enabled: bool,
}

impl NodeData for RealNode {
	type Port = RealPort;

	fn id(&self) -> NodeId {
		self.id
	}

	fn title(&self) -> SharedString {
		self.title.clone()
	}

	fn position(&self) -> Point<Pixels> {
		self.position
	}

	fn inputs(&self) -> Vec<Self::Port> {
		self.inputs.clone()
	}

	fn outputs(&self) -> Vec<Self::Port> {
		self.outputs.clone()
	}

	fn header_color(&self) -> Option<Hsla> {
		self.header_color
	}

	fn is_collapsed(&self) -> bool {
		self.collapsed
	}

	fn is_enabled(&self) -> bool {
		self.enabled
	}
}

/// A port on a real node.
#[derive(Debug, Clone)]
pub struct RealPort {
	/// Global port id.
	pub id: PortId,
	/// Direction.
	pub kind: PortKind,
	/// Port label.
	pub label: SharedString,
	/// Wire type.
	pub data_type: PortDataType,
	/// Whether an edge is attached.
	pub connected: bool,
}

impl PortData for RealPort {
	fn id(&self) -> PortId {
		self.id
	}

	fn kind(&self) -> PortKind {
		self.kind
	}

	fn label(&self) -> SharedString {
		self.label.clone()
	}

	fn data_type(&self) -> PortDataType {
		self.data_type.clone()
	}

	fn is_connected(&self) -> bool {
		self.connected
	}
}

/// A wire between two real nodes.
#[derive(Debug, Clone)]
pub struct RealEdge {
	/// Stable edge id.
	pub id: EdgeId,
	/// Source node.
	pub from_node: NodeId,
	/// Source output port.
	pub from_port: PortId,
	/// Target node.
	pub to_node: NodeId,
	/// Target input port.
	pub to_port: PortId,
}

impl EdgeData for RealEdge {
	fn id(&self) -> EdgeId {
		self.id
	}

	fn from_node(&self) -> NodeId {
		self.from_node
	}

	fn from_port(&self) -> PortId {
		self.from_port
	}

	fn to_node(&self) -> NodeId {
		self.to_node
	}

	fn to_port(&self) -> PortId {
		self.to_port
	}
}

/// Deterministic header accents per node identity.
fn node_color(ident: u64) -> Hsla {
	let hues = [0.55f32, 0.6, 0.08, 0.3, 0.78, 0.45, 0.9, 0.15];
	hsla(hues[(ident as usize) % hues.len()], 0.5, 0.35, 1.0)
}

/// Whether a sequence-graph node should be shown in the node editor: the
/// media chain (sequence output, clip blocks, footage, effects) only;
/// structural timeline plumbing (tracks, track lists, gaps, transitions)
/// is hidden.
fn is_displayed(type_id: &str) -> bool {
	!matches!(
		type_id,
		TYPE_ID_TRACK | TYPE_ID_TRACK_LIST | TYPE_ID_GAP_BLOCK | TYPE_ID_TRANSITION_BLOCK
	)
}

/// A displayed node: its domain id plus its type id.
struct TypedNode {
	/// The node's domain id.
	id: DomainNodeId,
	/// The node's identity.
	ident: u64,
	/// The node's type id.
	type_id: String,
}

/// The displayable nodes of the sequence's graph, in identity order (the
/// sequence node itself exactly once).
fn graph_nodes(g: &oaknode::graph::Graph, seq: DomainNodeId) -> Vec<TypedNode> {
	let mut out: Vec<TypedNode> = g
		.node_ids()
		.into_iter()
		.filter_map(|id| {
			let type_id = graphops::node_type_id(g, id);
			if !is_displayed(&type_id) {
				return None;
			}
			Some(TypedNode {
				id,
				ident: id.identity(),
				type_id,
			})
		})
		.filter(|n| n.id != seq)
		.collect();
	// The sequence node itself: exactly one output card.
	out.push(TypedNode {
		id: seq,
		ident: seq.identity(),
		type_id: TYPE_ID_SEQUENCE.into(),
	});
	out.sort_by_key(|n| n.ident);
	out
}

/// The context position of `node` in the sequence's map, or the (0,0)
/// sentinel the fallback layout replaces.
fn context_position(
	g: &oaknode::graph::Graph,
	seq: DomainNodeId,
	node: DomainNodeId,
) -> Point<Pixels> {
	let placed = g.get(node).and_then(|e| {
		e.core
			.context_positions
			.iter()
			.find(|(c, _, _)| *c == seq)
			.map(|(_, pos, _)| *pos)
	});
	match placed {
		Some((x, y)) if x != 0.0 || y != 0.0 => point(px(x as f32), px(y as f32)),
		_ => point(px(0.0), px(0.0)),
	}
}

/// Build the (nodes, edges) snapshot of the sequence's node graph.
pub fn build_graph(project: &ProjectRef, seq: DomainNodeId) -> (Vec<RealNode>, Vec<RealEdge>) {
	let g = graphops::lock(project);
	let g = &g.graph;
	let mut nodes = Vec::new();
	let mut edges = Vec::new();
	if !g.is_valid(seq) {
		return (nodes, edges);
	}
	let seq_ident = seq.identity();
	let seq_label = graphops::node_label(g, seq);
	let seq_name = g
		.get(seq)
		.map(|e| e.behavior.name().to_string())
		.unwrap_or_default();

	let all = graph_nodes(g, seq);

	// Build every card's ports first (inputs, the implicit output), so
	// real edges can resolve their target port index by matching the
	// input id against the already-built cards.
	let mut built: Vec<(TypedNode, RealNode)> = Vec::new();
	for typed in all {
		let ident = typed.ident;
		let title = if typed.type_id == TYPE_ID_SEQUENCE {
			if seq_label.is_empty() {
				seq_name.clone()
			} else {
				seq_label.clone()
			}
		} else {
			let label = graphops::node_label(g, typed.id);
			let name = g
				.get(typed.id)
				.map(|e| e.behavior.name().to_string())
				.unwrap_or_default();
			if label.is_empty() {
				name
			} else {
				label
			}
		};

		// Inputs.
		let input_ids: Vec<String> = g
			.get(typed.id)
			.map(|e| e.core.inputs.iter().map(|i| i.id.clone()).collect())
			.unwrap_or_default();
		let mut inputs = Vec::with_capacity(input_ids.len());
		for (idx, id_str) in input_ids.iter().enumerate() {
			if id_str.is_empty() {
				continue;
			}
			inputs.push(RealPort {
				id: port_id(ident, PortKind::Input, idx as u32),
				kind: PortKind::Input,
				label: id_str.clone().into(),
				data_type: video_type(),
				connected: g.is_input_connected(typed.id, id_str, -1),
			});
		}

		// The single implicit output.
		let out_count = g.output_connections(typed.id).len();
		let outputs = vec![RealPort {
			id: port_id(ident, PortKind::Output, 0),
			kind: PortKind::Output,
			label: SharedString::new_static("out"),
			data_type: out_type(),
			connected: out_count > 0,
		}];

		let position = context_position(g, seq, typed.id);
		built.push((
			typed,
			RealNode {
				id: NodeId(ident),
				title: title.into(),
				position,
				inputs,
				outputs,
				header_color: Some(node_color(ident)),
				collapsed: false,
				enabled: true,
			},
		));
	}

	// Outgoing REAL edges: every source node's output connections, with
	// the target port resolved to the index of the input whose id matches
	// (the module stores edges by input id; the index may differ from 0 —
	// e.g. a clip's `tex_in` sits after `enabled_in`).
	let mut node_edges: Vec<(u64, Vec<RealEdge>)> = Vec::new();
	for (typed, _) in &built {
		let mut edges_of = Vec::new();
		for (to, conn_id, _element) in g.output_connections(typed.id) {
			if !g.is_valid(to) || conn_id.is_empty() {
				continue;
			}
			let to_ident = to.identity();
			let to_index = built
				.iter()
				.find(|(t, _)| t.ident == to_ident)
				.and_then(|(_, n)| n.inputs.iter().position(|p| p.label.as_ref() == conn_id))
				.unwrap_or(0) as u32;
			edges_of.push(RealEdge {
				id: real_edge_id(typed.ident, to_ident, &conn_id),
				from_node: NodeId(typed.ident),
				from_port: port_id(typed.ident, PortKind::Output, 0),
				to_node: NodeId(to_ident),
				to_port: port_id(to_ident, PortKind::Input, to_index),
			});
		}
		node_edges.push((typed.ident, edges_of));
	}

	// Fallback layout: nodes without a persisted context position get a
	// deterministic role grid — footage | effects | clips | output as
	// columns, a per-role row counter as the row (the same grid the
	// C++-era node editor lays chains out on). Nodes the user has
	// already dragged keep their persisted position. `fallback_base`
	// mirrors this grid so the first drag moves from the displayed
	// position rather than the origin.
	let mut row_at_role: HashMap<u32, u32> = HashMap::new();
	for (typed, node) in built.iter_mut() {
		if node.position != point(px(0.0), px(0.0)) {
			continue;
		}
		let role = role_of(&typed.type_id, typed.ident == seq_ident);
		let row = row_at_role.entry(role).or_insert(0);
		let x = 40.0 + (role as f32) * 260.0;
		let y = 40.0 + (*row as f32) * 180.0;
		*row += 1;
		node.position = point(px(x), px(y));
	}

	// Assemble: every built card + its real edges, plus the synthesized
	// "clip → output" wires (each clip's main output into the sequence's
	// `tex_in`, its first declared input).
	let clip_input = port_id(seq_ident, PortKind::Input, 0);
	for (typed, node) in built {
		if typed.type_id == TYPE_ID_CLIP_BLOCK {
			edges.push(RealEdge {
				id: output_wire_id(typed.ident),
				from_node: node.id,
				from_port: port_id(typed.ident, PortKind::Output, 0),
				to_node: NodeId(seq_ident),
				to_port: clip_input,
			});
		}
		if let Some((_, real)) = node_edges.iter().find(|(id, _)| *id == typed.ident) {
			edges.extend(real.iter().cloned());
		}
		nodes.push(node);
	}
	(nodes, edges)
}

/// The role column of a displayed node (footage | effects | clips |
/// output); drives the fallback grid's x position.
fn role_of(type_id: &str, is_output: bool) -> u32 {
	if is_output {
		3
	} else if type_id == TYPE_ID_FOOTAGE {
		0
	} else if type_id == TYPE_ID_CLIP_BLOCK {
		2
	} else {
		1 // effects
	}
}

/// The provisional position the builder assigns to an unplaced node: the
/// role column and the per-role row among the OTHER unplaced nodes in
/// sorted display order (mirrors the fallback grid in `build_graph`).
/// `apply_edit` uses it so the first drag release writes
/// `(displayed base + delta)` instead of `(origin + delta)`.
fn fallback_base(g: &oaknode::graph::Graph, seq: DomainNodeId, ident: u64) -> (f64, f64) {
	let seq_ident = seq.identity();
	let all = graph_nodes(g, seq);
	let target = all
		.iter()
		.find(|n| n.ident == ident)
		.expect("the moved node is part of the displayed graph");
	let target_role = role_of(&target.type_id, ident == seq_ident);
	let mut row: u32 = 0;
	for n in &all {
		if n.ident == ident {
			break;
		}
		if role_of(&n.type_id, n.ident == seq_ident) != target_role {
			continue;
		}
		// Placed nodes do not consume a row.
		let placed = g
			.get(n.id)
			.and_then(|e| {
				e.core
					.context_positions
					.iter()
					.find(|(c, _, _)| *c == seq)
					.map(|(_, pos, _)| *pos)
			})
			.map(|(x, y)| x != 0.0 || y != 0.0)
			.unwrap_or(false);
		if !placed {
			row += 1;
		}
	}
	(
		40.0 + f64::from(target_role * 260),
		40.0 + f64::from(row * 180),
	)
}

/// Resolve a domain node id from a widget identity, validating it against
/// the graph.
fn find_node(g: &oaknode::graph::Graph, ident: u64) -> Result<DomainNodeId, String> {
	let Some(id) = graphops::id_of(ident) else {
		return Err(format!("node {ident} not found"));
	};
	if !g.is_valid(id) {
		return Err(format!("node {ident} not found"));
	}
	Ok(id)
}

// ---------------------------------------------------------------------------
// Connection rules and edit application
// ---------------------------------------------------------------------------

/// Whether connecting output port `from` to input port `to` is valid in
/// the graph: output → input, distinct nodes, and the target input must
/// exist and be free. The sequence node's inputs are connectable like any
/// other (its `tex_in` starts unconnected; a user wire replaces the
/// synthesized one once the graph grows real edges).
pub fn can_connect(project: &ProjectRef, from: PortId, to: PortId) -> bool {
	let (from_node, from_kind, _) = unpack_port(from);
	let (to_node, to_kind, to_index) = unpack_port(to);
	if from_kind != PortKind::Output || to_kind != PortKind::Input {
		return false;
	}
	if from_node == to_node {
		return false;
	}
	let guard = graphops::lock(project);
	let g = &guard.graph;
	let Ok(node) = find_node(g, to_node) else {
		return false;
	};
	let Some(entry) = g.get(node) else {
		return false;
	};
	let Some(id_str) = entry.core.inputs.get(to_index as usize).map(|i| i.id.clone()) else {
		return false;
	};
	if id_str.is_empty() {
		return false;
	}
	!g.is_input_connected(node, &id_str, -1)
}

/// Apply a node-graph edit to the sequence's graph (undoable through the
/// global undo stack).
pub fn apply_edit(
	project: &ProjectRef,
	seq: DomainNodeId,
	edit: &gpui::node_graph::NodeGraphEvent,
) -> Result<(), String> {
	use gpui::node_graph::NodeGraphEvent;
	match edit {
		NodeGraphEvent::ConnectionRequested { from, to } => {
			let (from_node, from_kind, _) = unpack_port(*from);
			let (to_node, to_kind, to_index) = unpack_port(*to);
			if from_kind != PortKind::Output || to_kind != PortKind::Input {
				return Err("connection endpoints must be output → input".into());
			}
			let (src, dst, id_str) = {
				let guard = graphops::lock(project);
				let g = &guard.graph;
				let src = find_node(g, from_node)?;
				let dst = find_node(g, to_node)?;
				let id_str = g
					.get(dst)
					.and_then(|e| e.core.inputs.get(to_index as usize))
					.map(|i| i.id.clone())
					.filter(|s| !s.is_empty());
				let Some(id_str) = id_str else {
					return Err("target input missing".into());
				};
				(src, dst, id_str)
			};
			let cmd = graphops::connect_command(project, src, dst, &id_str)?;
			graphops::push_command(cmd, "Connect Nodes")
		}
		NodeGraphEvent::DisconnectionRequested { edge } => {
			if is_output_wire(*edge) {
				// The synthesized clip → output wire is structural; the
				// graph has no such edge to remove.
				return Ok(());
			}
			let (dst, conn_id) = {
				let guard = graphops::lock(project);
				let g = &guard.graph;
				let mut found = None;
				'outer: for (typed_from, to, conn_id, _) in g.output_connections_all() {
					if real_edge_id(typed_from.identity(), to.identity(), &conn_id).0 == edge.0 {
						found = Some((to, conn_id));
						break 'outer;
					}
				}
				found.ok_or_else(|| format!("edge {} not found", edge.0))?
			};
			let cmd = graphops::disconnect_command(project, dst, &conn_id)?;
			graphops::push_command(cmd, "Disconnect Nodes")
		}
		NodeGraphEvent::NodeMoveRequested { nodes, delta } => {
			for node in nodes {
				let (id, base) = {
					let guard = graphops::lock(project);
					let g = &guard.graph;
					let id = find_node(g, node.0)?;
					let placed = g
						.get(id)
						.and_then(|e| {
							e.core
								.context_positions
								.iter()
								.find(|(c, _, _)| *c == seq)
								.map(|(_, pos, _)| *pos)
						})
						.filter(|(x, y)| *x != 0.0 || *y != 0.0);
					let base = match placed {
						Some(pos) => pos,
						None => fallback_base(g, seq, node.0),
					};
					(id, base)
				};
				let cmd = graphops::set_context_position_command(
					project,
					id,
					seq,
					base.0 + f64::from(delta.x.as_f32()),
					base.1 + f64::from(delta.y.as_f32()),
				)?;
				graphops::push_command(cmd, "Set Position")?;
			}
			Ok(())
		}
		NodeGraphEvent::DeleteRequested { nodes, .. } => {
			for node in nodes {
				// The output node is the graph's context; never deleted.
				if node.0 == seq.identity() {
					continue;
				}
				let id = {
					let guard = graphops::lock(project);
					find_node(&guard.graph, node.0)?
				};
				graphops::remove_node(project, id)?;
			}
			Ok(())
		}
		_ => Ok(()),
	}
}