namespace _espe.database
{
	
	/**
	 */
	enum enum_revision {
		r0 = 0,
		r1 = 1,
	}
	
	
	/**
	 */
	const _revision_order : Array<enum_revision> = [
		enum_revision.r0,
		enum_revision.r1,
	];
	
	
	/**
	 */
	export function get_implementation(
	) : lib_plankton.database.type_database
	{
		switch (_espe.conf.get().database.kind) {
			case "sqlite": {
				return lib_plankton.database.sqlite_database(
					{
						"path": _espe.conf.get().database.data["path"],
						"verbose": false,
					}
				);
				break;
			}
			default: {
				throw (new Error("database implementation not available: " + _espe.conf.get().database.kind));
			}
		}
	}
	
	
	/**
	 */
	function get_revision(
	) : Promise<enum_revision>
	{
		return (
			(
				get_implementation().query_select(
					{
						"source": "meta",
						"fields": ["revision"],
					}
				)
				.then<int>(
					(rows) => Promise.resolve<int>(rows[0]["revision"])
				)
				.catch<int>(
					() => Promise.resolve<int>(0)
				)
			)
			.then<enum_revision>(
				(revision_raw) => Promise.resolve<enum_revision>(revision_raw)
			)
		);
	}
	
	
	/**
	 */
	async function advance(
	) : Promise<boolean>
	{
		const implementation : lib_plankton.database.type_database = get_implementation();
		
		const revision_current : enum_revision = await get_revision();
		const index_current : int = _revision_order.indexOf(revision_current);
		const index_next : (null | int) = (
			(index_current < (_revision_order.length - 1))
			? (index_current + 1)
			: null
		);
		const revision_next : (null | enum_revision) = (
			(index_next !== null)
			? _revision_order[index_next]
			: null
		);
		if (revision_next !== null) {
			lib_plankton.log.notice(
				"database_advancement_necessary",
				{
					"revision_current": revision_current,
					"revision_next": revision_next,
				}
			);
			switch (revision_next) {
				case enum_revision.r1: {
					// structure
					{
						await implementation.query_create_table(
							{
								"name": "meta",
								"data_fields": [
									{
										"name": "revision",
										"type": lib_plankton.database.enum_type.integer,
										"nullable": false,
									},
								],
							}
						);
						await implementation.query_create_table(
							{
								"name": "members",
								"key_field": {
									"name": "id"
								},
								"data_fields": [
									{
										"name": "membership_number",
										"type": lib_plankton.database.enum_type.string_short,
										"nullable": false
									},
									{
										"name": "enabled",
										"type": lib_plankton.database.enum_type.boolean,
										"nullable": false
									},
									{
										"name": "name_login",
										"type": lib_plankton.database.enum_type.string_short,
										"nullable": true
									},
									{
										"name": "password_image",
										"type": lib_plankton.database.enum_type.string_medium,
										"nullable": true
									},
									{
										"name": "name_real_value",
										"type": lib_plankton.database.enum_type.string_medium,
										"nullable": false
									},
									{
										"name": "name_real_extension",
										"type": lib_plankton.database.enum_type.string_short,
										"nullable": true
									},
									{
										"name": "name_display",
										"type": lib_plankton.database.enum_type.string_medium,
										"nullable": true
									},
									{
										"name": "salutation",
										"type": lib_plankton.database.enum_type.string_short,
										"nullable": true
									},
									{
										"name": "email_address_private_value",
										"type": lib_plankton.database.enum_type.string_short,
										"nullable": true
									},
									{
										"name": "email_address_numberbased_use",
										"type": lib_plankton.database.enum_type.boolean,
										"nullable": false
									},
									{
										"name": "email_address_namebased_use",
										"type": lib_plankton.database.enum_type.boolean,
										"nullable": false
									},
									{
										"name": "email_redirect_to_private",
										"type": lib_plankton.database.enum_type.boolean,
										"nullable": false
									}
								],
								"constraints": [
									{
										"kind": "unique",
										"parameters": {
											"fields": ["membership_number"]
										}
									},
									{
										"kind": "unique",
										"parameters": {
											"fields": ["name_real_value","name_real_extension"]
										}
									},
									{
										"kind": "unique",
										"parameters": {
											"fields": ["name_login"]
										}
									}
								]
							}
						);
					}
					// data
					{
						await implementation.query_insert(
							{
								"table_name": "meta",
								"values": {
									"revision": revision_next,
								}
							}
						);
					}
					return Promise.resolve<boolean>(true);
					break;
				}
				default: {
					return Promise.reject<boolean>("unhandled advancement step");
					break;
				}
			}
		}
		else {
			lib_plankton.log.notice(
				"database_up_to_date",
				{
					"revision_current": revision_current,
				}
			);
			return Promise.resolve<boolean>(false);
		}
	}
	
	
	/**
	 */
	export async function advance_all(
	) : Promise<void>
	{
		while (true) {
			const modified : boolean = await advance();
			if (modified) {
				// do nothing
			}
			else {
				break;
			}
		}
	}
	
}