"use strict";

const matchValue = require("match-value");

const operations = require("../../operations");
const internalOperations = require("../../internal-operations");
const NoChange = require("../util/no-change");
const ConsumeNode = require("../util/consume-node");

/*
Translate index modifiers on a single field into a top-level (non-composite) index element
{ type: "index"|"removeIndex", indexType, isComposite: true|false, field|fields}
*/

// MARKER: Filter out ConsumeNode from result (doublecheck that their presence doesn't signify a bug!), figure out autogeneration for index names, improve error for localColumn to explicitly say "don't provide a column name" (via partial match followed by error, eg. forbidden + wrapError)

function handleCollection(node, { registerStateHandler, defer }) {
	let createNode = matchValue.literal(node.type, {
		createCollectionCommand: operations.createCollection,
		changeCollectionCommand: operations.changeCollection
	});

	let indexNodes = [];

	registerStateHandler("encounteredLocalIndex", (item) => {
		// FIXME: Make named index
		// FIXME: Default name generation for indexes
		indexNodes.push(item);
	});

	return defer(() => {
		if (indexNodes.length > 0) {
			let indexesObject = operations.indexes(indexNodes.map(({ node, key }) => {
				// FIXME: Why is it allowed to call operations.index with the same arguments? That should be disallowed.
				return internalOperations._index({
					indexType: node.indexType,
					field: operations.field(key),
					clauses: node.clauses
				});
			}));

			return createNode(node.name, node.operations.concat([ indexesObject ]));
		} else {
			return NoChange;
		}
	});
}

module.exports = {
	name: "move-out-indexes",
	category: [ "normalization" ],
	visitors: {
		localIndex: (node, { setState, findNearestStep }) => {
			let { key } = findNearestStep("$object");
			setState("encounteredLocalIndex", { node, key });

			return ConsumeNode;
		},
		createCollectionCommand: handleCollection,
		changeCollectionCommand: handleCollection


		// MARKER: Move indexes from column definitions to table index definition, with auto-generated name; may need some way to select "only within node of type X" (where X = fields)
		//		IDEA: propertyPath and typePath arguments, for the visitor to determine whether it is appearing in the correct place (otherwise NoChange)
		
	}
};