Component.js

import {
	add_render_callback,
	flush,
	flush_render_callbacks,
	schedule_update,
	dirty_components
} from './scheduler.js';
import { current_component, set_current_component } from './lifecycle.js';
import { blank_object, is_empty, is_function, run, run_all, noop } from './utils.js';
import {
	children,
	detach,
	start_hydrating,
	end_hydrating,
	get_custom_elements_slots,
	insert,
	element,
	attr
} from './dom.js';
import { transition_in } from './transitions.js';

/** @returns {void} */
export function bind(component, name, callback) {
	const index = component.$$.props[name];
	if (index !== undefined) {
		component.$$.bound[index] = callback;
		callback(component.$$.ctx[index]);
	}
}

/** @returns {void} */
export function create_component(block) {
	block && block.c();
}

/** @returns {void} */
export function claim_component(block, parent_nodes) {
	block && block.l(parent_nodes);
}

/** @returns {void} */
export function mount_component(component, target, anchor) {
	const { fragment, after_update } = component.$$;
	fragment && fragment.m(target, anchor);
	// onMount happens before the initial afterUpdate
	add_render_callback(() => {
		const new_on_destroy = component.$$.on_mount.map(run).filter(is_function);
		// if the component was destroyed immediately
		// it will update the `$$.on_destroy` reference to `null`.
		// the destructured on_destroy may still reference to the old array
		if (component.$$.on_destroy) {
			component.$$.on_destroy.push(...new_on_destroy);
		} else {
			// Edge case - component was destroyed immediately,
			// most likely as a result of a binding initialising
			run_all(new_on_destroy);
		}
		component.$$.on_mount = [];
	});
	after_update.forEach(add_render_callback);
}

/** @returns {void} */
export function destroy_component(component, detaching) {
	const $$ = component.$$;
	if ($$.fragment !== null) {
		flush_render_callbacks($$.after_update);
		run_all($$.on_destroy);
		$$.fragment && $$.fragment.d(detaching);
		// TODO null out other refs, including component.$$ (but need to
		// preserve final state?)
		$$.on_destroy = $$.fragment = null;
		$$.ctx = [];
	}
}

/** @returns {void} */
function make_dirty(component, i) {
	if (component.$$.dirty[0] === -1) {
		dirty_components.push(component);
		schedule_update();
		component.$$.dirty.fill(0);
	}
	component.$$.dirty[(i / 31) | 0] |= 1 << i % 31;
}

// TODO: Document the other params
/**
 * @param {SvelteComponent} component
 * @param {import('./public.js').ComponentConstructorOptions} options
 *
 * @param {import('./utils.js')['not_equal']} not_equal Used to compare props and state values.
 * @param {(target: Element | ShadowRoot) => void} [append_styles] Function that appends styles to the DOM when the component is first initialised.
 * This will be the `add_css` function from the compiled component.
 *
 * @returns {void}
 */
export function init(
	component,
	options,
	instance,
	create_fragment,
	not_equal,
	props,
	append_styles = null,
	dirty = [-1]
) {
	const parent_component = current_component;
	set_current_component(component);
	/** @type {import('./private.js').T$$} */
	const $$ = (component.$$ = {
		fragment: null,
		ctx: [],
		// state
		props,
		update: noop,
		not_equal,
		bound: blank_object(),
		// lifecycle
		on_mount: [],
		on_destroy: [],
		on_disconnect: [],
		before_update: [],
		after_update: [],
		context: new Map(options.context || (parent_component ? parent_component.$$.context : [])),
		// everything else
		callbacks: blank_object(),
		dirty,
		skip_bound: false,
		root: options.target || parent_component.$$.root
	});
	append_styles && append_styles($$.root);
	let ready = false;
	$$.ctx = instance
		? instance(component, options.props || {}, (i, ret, ...rest) => {
				const value = rest.length ? rest[0] : ret;
				if ($$.ctx && not_equal($$.ctx[i], ($$.ctx[i] = value))) {
					if (!$$.skip_bound && $$.bound[i]) $$.bound[i](value);
					if (ready) make_dirty(component, i);
				}
				return ret;
		  })
		: [];
	$$.update();
	ready = true;
	run_all($$.before_update);
	// `false` as a special case of no DOM component
	$$.fragment = create_fragment ? create_fragment($$.ctx) : false;
	if (options.target) {
		if (options.hydrate) {
			start_hydrating();
			// TODO: what is the correct type here?
			// @ts-expect-error
			const nodes = children(options.target);
			$$.fragment && $$.fragment.l(nodes);
			nodes.forEach(detach);
		} else {
			// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
			$$.fragment && $$.fragment.c();
		}
		if (options.intro) transition_in(component.$$.fragment);
		mount_component(component, options.target, options.anchor);
		end_hydrating();
		flush();
	}
	set_current_component(parent_component);
}

export let SvelteElement;

if (typeof HTMLElement === 'function') {
	SvelteElement = class extends HTMLElement {
		/** The Svelte component constructor */
		$$ctor;
		/** Slots */
		$$s;
		/** The Svelte component instance */
		$$c;
		/** Whether or not the custom element is connected */
		$$cn = false;
		/** Component props data */
		$$d = {};
		/** `true` if currently in the process of reflecting component props back to attributes */
		$$r = false;
		/** @type {Record<string, CustomElementPropDefinition>} Props definition (name, reflected, type etc) */
		$$p_d = {};
		/** @type {Record<string, Function[]>} Event listeners */
		$$l = {};
		/** @type {Map<Function, Function>} Event listener unsubscribe functions */
		$$l_u = new Map();

		constructor($$componentCtor, $$slots, use_shadow_dom) {
			super();
			this.$$ctor = $$componentCtor;
			this.$$s = $$slots;
			if (use_shadow_dom) {
				this.attachShadow({ mode: 'open' });
			}
		}

		addEventListener(type, listener, options) {
			// We can't determine upfront if the event is a custom event or not, so we have to
			// listen to both. If someone uses a custom event with the same name as a regular
			// browser event, this fires twice - we can't avoid that.
			this.$$l[type] = this.$$l[type] || [];
			this.$$l[type].push(listener);
			if (this.$$c) {
				const unsub = this.$$c.$on(type, listener);
				this.$$l_u.set(listener, unsub);
			}
			super.addEventListener(type, listener, options);
		}

		removeEventListener(type, listener, options) {
			super.removeEventListener(type, listener, options);
			if (this.$$c) {
				const unsub = this.$$l_u.get(listener);
				if (unsub) {
					unsub();
					this.$$l_u.delete(listener);
				}
			}
		}

		async connectedCallback() {
			this.$$cn = true;
			if (!this.$$c) {
				// We wait one tick to let possible child slot elements be created/mounted
				await Promise.resolve();
				if (!this.$$cn || this.$$c) {
					return;
				}
				function create_slot(name) {
					return () => {
						let node;
						const obj = {
							c: function create() {
								node = element('slot');
								if (name !== 'default') {
									attr(node, 'name', name);
								}
							},
							/**
							 * @param {HTMLElement} target
							 * @param {HTMLElement} [anchor]
							 */
							m: function mount(target, anchor) {
								insert(target, node, anchor);
							},
							d: function destroy(detaching) {
								if (detaching) {
									detach(node);
								}
							}
						};
						return obj;
					};
				}
				const $$slots = {};
				const existing_slots = get_custom_elements_slots(this);
				for (const name of this.$$s) {
					if (name in existing_slots) {
						$$slots[name] = [create_slot(name)];
					}
				}
				for (const attribute of this.attributes) {
					// this.$$data takes precedence over this.attributes
					const name = this.$$g_p(attribute.name);
					if (!(name in this.$$d)) {
						this.$$d[name] = get_custom_element_value(name, attribute.value, this.$$p_d, 'toProp');
					}
				}
				// Port over props that were set programmatically before ce was initialized
				for (const key in this.$$p_d) {
					if (!(key in this.$$d) && this[key] !== undefined) {
						this.$$d[key] = this[key]; // don't transform, these were set through JavaScript
						delete this[key]; // remove the property that shadows the getter/setter
					}
				}
				this.$$c = new this.$$ctor({
					target: this.shadowRoot || this,
					props: {
						...this.$$d,
						$$slots,
						$$scope: {
							ctx: []
						}
					}
				});

				// Reflect component props as attributes
				const reflect_attributes = () => {
					this.$$r = true;
					for (const key in this.$$p_d) {
						this.$$d[key] = this.$$c.$$.ctx[this.$$c.$$.props[key]];
						if (this.$$p_d[key].reflect) {
							const attribute_value = get_custom_element_value(
								key,
								this.$$d[key],
								this.$$p_d,
								'toAttribute'
							);
							if (attribute_value == null) {
								this.removeAttribute(this.$$p_d[key].attribute || key);
							} else {
								this.setAttribute(this.$$p_d[key].attribute || key, attribute_value);
							}
						}
					}
					this.$$r = false;
				};
				this.$$c.$$.after_update.push(reflect_attributes);
				reflect_attributes(); // once initially because after_update is added too late for first render

				for (const type in this.$$l) {
					for (const listener of this.$$l[type]) {
						const unsub = this.$$c.$on(type, listener);
						this.$$l_u.set(listener, unsub);
					}
				}
				this.$$l = {};
			}
		}

		// We don't need this when working within Svelte code, but for compatibility of people using this outside of Svelte
		// and setting attributes through setAttribute etc, this is helpful
		attributeChangedCallback(attr, _oldValue, newValue) {
			if (this.$$r) return;
			attr = this.$$g_p(attr);
			this.$$d[attr] = get_custom_element_value(attr, newValue, this.$$p_d, 'toProp');
			this.$$c?.$set({ [attr]: this.$$d[attr] });
		}

		disconnectedCallback() {
			this.$$cn = false;
			// In a microtask, because this could be a move within the DOM
			Promise.resolve().then(() => {
				if (!this.$$cn && this.$$c) {
					this.$$c.$destroy();
					this.$$c = undefined;
				}
			});
		}

		$$g_p(attribute_name) {
			return (
				Object.keys(this.$$p_d).find(
					(key) =>
						this.$$p_d[key].attribute === attribute_name ||
						(!this.$$p_d[key].attribute && key.toLowerCase() === attribute_name)
				) || attribute_name
			);
		}
	};
}

/**
 * @param {string} prop
 * @param {any} value
 * @param {Record<string, CustomElementPropDefinition>} props_definition
 * @param {'toAttribute' | 'toProp'} [transform]
 */
function get_custom_element_value(prop, value, props_definition, transform) {
	const type = props_definition[prop]?.type;
	value = type === 'Boolean' && typeof value !== 'boolean' ? value != null : value;
	if (!transform || !props_definition[prop]) {
		return value;
	} else if (transform === 'toAttribute') {
		switch (type) {
			case 'Object':
			case 'Array':
				return value == null ? null : JSON.stringify(value);
			case 'Boolean':
				return value ? '' : null;
			case 'Number':
				return value == null ? null : value;
			default:
				return value;
		}
	} else {
		switch (type) {
			case 'Object':
			case 'Array':
				return value && JSON.parse(value);
			case 'Boolean':
				return value; // conversion already handled above
			case 'Number':
				return value != null ? +value : value;
			default:
				return value;
		}
	}
}

/**
 * @internal
 *
 * Turn a Svelte component into a custom element.
 * @param {import('./public.js').ComponentType} Component  A Svelte component constructor
 * @param {Record<string, CustomElementPropDefinition>} props_definition  The props to observe
 * @param {string[]} slots  The slots to create
 * @param {string[]} accessors  Other accessors besides the ones for props the component has
 * @param {boolean} use_shadow_dom  Whether to use shadow DOM
 * @param {(ce: new () => HTMLElement) => new () => HTMLElement} [extend]
 */
export function create_custom_element(
	Component,
	props_definition,
	slots,
	accessors,
	use_shadow_dom,
	extend
) {
	let Class = class extends SvelteElement {
		constructor() {
			super(Component, slots, use_shadow_dom);
			this.$$p_d = props_definition;
		}
		static get observedAttributes() {
			return Object.keys(props_definition).map((key) =>
				(props_definition[key].attribute || key).toLowerCase()
			);
		}
	};
	Object.keys(props_definition).forEach((prop) => {
		Object.defineProperty(Class.prototype, prop, {
			get() {
				return this.$$c && prop in this.$$c ? this.$$c[prop] : this.$$d[prop];
			},
			set(value) {
				value = get_custom_element_value(prop, value, props_definition);
				this.$$d[prop] = value;
				this.$$c?.$set({ [prop]: value });
			}
		});
	});
	accessors.forEach((accessor) => {
		Object.defineProperty(Class.prototype, accessor, {
			get() {
				return this.$$c?.[accessor];
			}
		});
	});
	if (extend) {
		// @ts-expect-error - assigning here is fine
		Class = extend(Class);
	}
	Component.element = /** @type {any} */ (Class);
	return Class;
}

/**
 * Base class for Svelte components. Used when dev=false.
 *
 * @template {Record<string, any>} [Props=any]
 * @template {Record<string, any>} [Events=any]
 */
export class SvelteComponent {
	/**
	 * ### PRIVATE API
	 *
	 * Do not use, may change at any time
	 *
	 * @type {any}
	 */
	$$ = undefined;
	/**
	 * ### PRIVATE API
	 *
	 * Do not use, may change at any time
	 *
	 * @type {any}
	 */
	$$set = undefined;

	/** @returns {void} */
	$destroy() {
		destroy_component(this, 1);
		this.$destroy = noop;
	}

	/**
	 * @template {Extract<keyof Events, string>} K
	 * @param {K} type
	 * @param {((e: Events[K]) => void) | null | undefined} callback
	 * @returns {() => void}
	 */
	$on(type, callback) {
		if (!is_function(callback)) {
			return noop;
		}
		const callbacks = this.$$.callbacks[type] || (this.$$.callbacks[type] = []);
		callbacks.push(callback);
		return () => {
			const index = callbacks.indexOf(callback);
			if (index !== -1) callbacks.splice(index, 1);
		};
	}

	/**
	 * @param {Partial<Props>} props
	 * @returns {void}
	 */
	$set(props) {
		if (this.$$set && !is_empty(props)) {
			this.$$.skip_bound = true;
			this.$$set(props);
			this.$$.skip_bound = false;
		}
	}
}

/**
 * @typedef {Object} CustomElementPropDefinition
 * @property {string} [attribute]
 * @property {boolean} [reflect]
 * @property {'String'|'Boolean'|'Number'|'Array'|'Object'} [type]
 */