import type { CursorState } from '@inkfinite/core';
import { shapeBoundsForState } from '@inkfinite/core/geometry';
import { type Box2, Box2 as Box2Ops, type Vec2, Vec2 as Vec2Ops } from '@inkfinite/core/geometry';
import type { EditorState, ToolId } from '@inkfinite/core';
import { getSelectedShapes } from '@inkfinite/core';

export type SelectionSummary = { count: number; kind?: string; bounds?: { w: number; h: number } };

export type SnapSummary = { enabled: boolean; gridSize?: number; angleStepDeg?: number };

export type PersistenceStatus = {
	backend: 'indexeddb' | 'filesystem';
	state: 'saved' | 'saving' | 'error';
	lastSavedAt?: number;
	pendingWrites?: number;
	errorMsg?: string;
};

export type StatusBarVM = {
	cursorWorld: Vec2;
	cursorScreen?: Vec2;
	toolId: ToolId;
	mode: 'idle' | 'dragging' | 'panning' | 'text-edit' | string;
	selection: SelectionSummary;
	snap: SnapSummary;
	persistence: PersistenceStatus;
};

/**
 * Convert the current camera zoom factor into a human-friendly percentage.
 */
export function getZoomPct(state: EditorState): number {
	const pct = state.camera.zoom * 100;
	if (!Number.isFinite(pct)) {
		return 100;
	}
	return Math.round(pct);
}

/**
 * Get the active tool identifier from UI state.
 */
export function getToolId(state: EditorState): ToolId {
	return state.ui.toolId;
}

/**
 * Summarize the current selection for display.
 */
export function getSelectionSummary(state: EditorState): SelectionSummary {
	const shapes = getSelectedShapes(state);
	const count = shapes.length;

	if (count === 0) {
		return { count: 0 };
	}

	const combinedBounds = combineBounds(shapes.map((shape) => shapeBoundsForState(state, shape)));

	const kind =
		count === 1
			? shapes[0].type
			: shapes.every((shape) => shape.type === shapes[0].type)
				? shapes[0].type
				: 'mixed';

	return {
		count,
		kind,
		bounds: combinedBounds
			? { w: Box2Ops.width(combinedBounds), h: Box2Ops.height(combinedBounds) }
			: undefined
	};
}

const SNAP_DEFAULT: SnapSummary = { enabled: false };

/**
 * Provide safe defaults for snap/grid summary until features are enabled.
 */
export function getSnapSummary(_: EditorState): SnapSummary {
	return { ...SNAP_DEFAULT };
}

/**
 * Compose the full StatusBar view model from editor/cursor/persistence state.
 */
export function buildStatusBarVM(
	editorState: EditorState,
	cursorState: CursorState,
	persistence: PersistenceStatus,
	mode: StatusBarVM['mode'] = 'idle'
): StatusBarVM {
	return {
		cursorWorld: Vec2Ops.clone(cursorState.cursorWorld),
		cursorScreen: cursorState.cursorScreen
			? Vec2Ops.clone(cursorState.cursorScreen)
			: undefined,
		toolId: getToolId(editorState),
		mode,
		selection: getSelectionSummary(editorState),
		snap: getSnapSummary(editorState),
		persistence: { ...persistence }
	};
}

function combineBounds(boxes: Box2[]): Box2 | null {
	if (boxes.length === 0) {
		return null;
	}
	let combined = Box2Ops.clone(boxes[0]);
	for (let index = 1; index < boxes.length; index++) {
		const box = boxes[index];
		combined = {
			min: {
				x: Math.min(combined.min.x, box.min.x),
				y: Math.min(combined.min.y, box.min.y)
			},
			max: { x: Math.max(combined.max.x, box.max.x), y: Math.max(combined.max.y, box.max.y) }
		};
	}
	return combined;
}