namespace _zeitbild.repository.resource
{
	
	/**
	 */
	var _local_resource_event_chest : (
		null
		|
		lib_plankton.storage.type_chest<
			Array<any>,
			Record<string, any>,
			lib_plankton.database.type_description_create_table,
			lib_plankton.storage.sql_table_common.type_sql_table_common_search_term,
			Record<string, any>
		>
	) = null;
	
	
	/**
	 */
	var _local_resource_core_store : (
		null
		|
		lib_plankton.storage.type_store<
			int,
			Record<string, any>,
			{},
			lib_plankton.storage.type_sql_table_autokey_search_term,
			Record<string, any>
		>
	) = null;
	
	
	/**
	 */
	var _caldav_resource_store : (
		null
		|
		lib_plankton.storage.type_store<
			int,
			Record<string, any>,
			{},
			lib_plankton.storage.type_sql_table_autokey_search_term,
			Record<string, any>
		>
	) = null;
	
	
	/**
	 */
	var _resource_core_store : (
		null
		|
		lib_plankton.storage.type_store<
			_zeitbild.type_resource_id,
			Record<string, any>,
			{},
			lib_plankton.storage.type_sql_table_autokey_search_term,
			Record<string, any>
		>
	) = null;
	
	
	/**
	 */
	function get_local_resource_event_chest(
	) : lib_plankton.storage.type_chest<
		Array<any>,
		Record<string, any>,
		lib_plankton.database.type_description_create_table,
		lib_plankton.storage.sql_table_common.type_sql_table_common_search_term,
		Record<string, any>
	>
	{
		if (_local_resource_event_chest === null) {
			_local_resource_event_chest = lib_plankton.storage.sql_table_common.chest(
				{
					"database_implementation": _zeitbild.database.get_implementation(),
					"table_name": "local_resource_events",
					"key_names": ["local_resource_id","event_id"],
				}
			);
		}
		else {
			// do nothing
		}	
		return _local_resource_event_chest;
	}
	
	
	/**
	 */
	function get_local_resource_core_store(
	) : lib_plankton.storage.type_store<
		int,
		Record<string, any>,
		{},
		lib_plankton.storage.type_sql_table_autokey_search_term,
		Record<string, any>
	>
	{
		if (_local_resource_core_store === null) {
			_local_resource_core_store = lib_plankton.storage.sql_table_autokey_store(
				{
					"database_implementation": _zeitbild.database.get_implementation(),
					"table_name": "local_resources",
					"key_name": "id",
				}
			);
		}
		else {
			// do nothing
		}	
		return _local_resource_core_store;
	}
	
	
	/**
	 */
	function get_caldav_resource_store(
	) : lib_plankton.storage.type_store<
		int,
		Record<string, any>,
		{},
		lib_plankton.storage.type_sql_table_autokey_search_term,
		Record<string, any>
	>
	{
		if (_caldav_resource_store === null) {
			_caldav_resource_store = lib_plankton.storage.sql_table_autokey_store(
				{
					"database_implementation": _zeitbild.database.get_implementation(),
					"table_name": "caldav_resources",
					"key_name": "id",
				}
			);
		}
		else {
			// do nothing
		}	
		return _caldav_resource_store;
	}
	
	
	/**
	 */
	function get_resource_core_store(
	) : lib_plankton.storage.type_store<
		_zeitbild.type_resource_id,
		Record<string, any>,
		{},
		lib_plankton.storage.type_sql_table_autokey_search_term,
		Record<string, any>
	>
	{
		if (_resource_core_store === null) {
			_resource_core_store = lib_plankton.storage.sql_table_autokey_store(
				{
					"database_implementation": _zeitbild.database.get_implementation(),
					"table_name": "resources",
					"key_name": "id",
				}
			);
		}
		else {
			// do nothing
		}	
		return _resource_core_store;
	}
	
	
	/**
	 */
	/*
	function encode_resource_core(
		stuff : {
			object : _zeitbild.type_resource_object;
			sub_id : int;
		}
	) : Record<string, any>
	{
		return {
			"kind": stuff.object.kind,
			"sub_id": stuff.sub_id
		};
	}
	 */
	
	
	/**
	 * @todo data
	 */
	/*
	function decode_resource_core(
		row : Record<string, any>
	) : {
		object : _zeitbild.type_resource_object;
		sub_id : int;
	}
	{
		return {
			"object": {
				"kind": row["kind"],
				"data": null,
			},
			"sub_id": row["sub_id"],
		};
	}
	 */
	
	
	/**
	 */
	export async function read(
		resource_id : _zeitbild.type_resource_id
	) : Promise<_zeitbild.type_resource_object>
	{
		const dataset_core : Record<string, any> = await get_resource_core_store().read(resource_id);
		switch (dataset_core.kind) {
			case "local": {
				const dataset_extra_local_core : Record<string, any> = await get_local_resource_core_store().read(dataset_core.sub_id);
				const datasets_extra_local_event_ids : Array<Record<string, any>> = await get_local_resource_event_chest().search(
					{
						"expression": "(local_resource_id = $local_resource_id)",
						"arguments": {
							"local_resource_id": dataset_core.sub_id,
						}
					}
				);
				return Promise.resolve<_zeitbild.type_resource_object>(
					{
						"kind": "local",
						"data": {
							"event_ids": (
								datasets_extra_local_event_ids
								.map((hit) => hit.preview["event_id"])
							)
						}
					}
				);
			}
			case "caldav": {
				const dataset_extra_caldav : Record<string, any> = await get_caldav_resource_store().read(dataset_core.sub_id);
				return Promise.resolve<_zeitbild.type_resource_object>(
					{
						"kind": "caldav",
						"data": {
							"url": dataset_extra_caldav["url"],
							"read_only": dataset_extra_caldav["read_only"],
						}
					}
				);
				break;
			}
			default: {
				return Promise.reject<_zeitbild.type_resource_object>(
					new Error("invalid resource kind: " + dataset_core.kind)
				);
				break;
			}
		}
	}
	
	
	/**
	 */
	export async function create(
		resource_object : _zeitbild.type_resource_object
	) : Promise<_zeitbild.type_resource_id>
	{
		switch (resource_object.kind) {
			case "local": {
				const local_resource_id : int = await get_local_resource_core_store().create(
					{
						"_dummy": null,
					}
				);
				for await (const event_id of resource_object.data.event_ids) {
					await get_local_resource_event_chest().create(
						[local_resource_id, event_id]
					)
				}
				const resource_id : _zeitbild.type_resource_id = await get_resource_core_store().create(
					{
						"kind": "local",
						"sub_id": local_resource_id,
					}
				);
				return Promise.resolve<_zeitbild.type_resource_id>(resource_id);
				break;
			}
			case "caldav": {
				const caldav_resource_id : int = await get_caldav_resource_store().create(
					{
						"url": resource_object.data.url,
						"read_only": resource_object.data.read_only,
					}
				);
				const resource_id : _zeitbild.type_resource_id = await get_resource_core_store().create(
					{
						"kind": "caldav",
						"sub_id": caldav_resource_id,
					}
				);
				return Promise.resolve<_zeitbild.type_resource_id>(resource_id);
				break;
			}
			default: {
				throw (new Error("invalid resource kind: " + resource_object.kind));
				break;
			}
		}
	}
	
	
	/**
	 * @todo allow kind change?
	 */
	export async function update(
		resource_id : _zeitbild.type_resource_id,
		resource_object : _zeitbild.type_resource_object
	) : Promise<void>
	{
		const dataset_core : Record<string, any> = await get_resource_core_store().read(resource_id);
		if (dataset_core["kind"] !== resource_object.kind) {
			return Promise.reject(new Error("resource kind may not be altered"));
		}
		else {
			switch (resource_object.kind) {
				case "local": {
					// event_id list may not be altered directly
					/*
					const current_event_id_rows : {key : int; preview : Array<Record<string, any>>;} = await get_local_resource_event_chest().search(
						{
							"expression": "(local_resource_id = $local_resource_id)",
							"arguments": {
								"local_resource_id": dataset_core["sub_id"]
							}
						}
					);
					const contrast : {
						only_left : Array<{key : int; left : any;}>;
						both : Array<{key : int; left : any; right : any;}>;
						only_right : Array<{key : int; right : any;}>;
					} = lib_plankton.list.contrast<
						{key : Array<any>; preview : Record<string, any>;},
						_zeitbild.type_local_resource_event_id
					>(
						event_rows,
						(hit => hit.key),
						resource_object.data.event_ids,
						(x => x)
					);
					// TODO: single delete?
					for await (const entry of constrast.only_left) {
						await get_local_resource_event_store().delete(
							entry.key
						);
					}
					/*
					for await (const entry of contrast.both) {
						await get_local_resource_event_store().update(
							entry.left.key,
							encode_event(entry.right.object)
						);
					}
					for await (const entry of contrast.only_right) {
						const event_id : type_local_resource_event_id = await get_local_resource_event_store().create(
							encode_event(entry.right.object)
						);
					}
					 */
					break;
				}
				case "caldav": {
					await get_caldav_resource_store().update(
						dataset_core["sub_id"],
						{
							"url": resource_object.data.url,
							"read_only": resource_object.data.read_only,
						}
					);
					break;
				}
				default: {
					throw (new Error("invalid resource kind: " + resource_object.kind));
					break;
				}
			}
		}
	}
	
	
	/**
	 */
	export function local_resource_event_add(
		resource_id : _zeitbild.type_resource_id,
		event_id : _zeitbild.type_event_id
	) : Promise<void>
	{
		const dataset_core : Record<string, any> = await get_resource_core_store().read(resource_id);
		if (! (dataset_core.kind === "local")) {
			throw (new Error("not a local resource"));
		}
		else {
			return (
				get_local_resource_event_chest().write(
					[dataset_core["sub_id"], event_id],
					{}
				)
				.then(
					() => Promise.resolve(undefined)
				)
			);
		}
	}
	
	
	/**
	 */
	export function local_resource_event_delete(
		resource_id : _zeitbild.type_resource_id,
		event_id : _zeitbild.type_event_id
	) : Promise<void>
	{
		const dataset_core : Record<string, any> = await get_resource_core_store().read(resource_id);
		if (! (dataset_core.kind === "local")) {
			throw (new Error("not a local resource"));
		}
		else {
			return (
				get_local_resource_event_chest().delete(
					[dataset_core["sub_id"], event_id],
					{}
				)
				.then(
					() => Promise.resolve(undefined)
				)
			);
		}
	}
	
}