/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const SortableSet = require("./util/SortableSet");
const compareLocations = require("./compareLocations");

let debugId = 5000;

const getArray = set => Array.from(set);

const sortById = (a, b) => {
	if(a.id < b.id) return -1;
	if(b.id < a.id) return 1;
	return 0;
};

const sortOrigin = (a, b) => {
	const aIdent = a.module ? a.module.identifier() : "";
	const bIdent = b.module ? b.module.identifier() : "";
	if(aIdent < bIdent) return -1;
	if(aIdent > bIdent) return 1;
	return compareLocations(a.loc, b.loc);
};

class ChunkGroup {
	constructor(name) {
		this.groupDebugId = debugId++;
		this.name = name;
		this._children = new SortableSet(undefined, sortById);
		this._parents = new SortableSet(undefined, sortById);
		this._blocks = new SortableSet();
		this.chunks = [];
		this.origins = [];
	}

	/* istanbul ignore next */
	get debugId() {
		return Array.from(this.chunks, x => x.debugId).join("+");
	}

	get id() {
		return Array.from(this.chunks, x => x.id).join("+");
	}

	unshiftChunk(chunk) {
		const oldIdx = this.chunks.indexOf(chunk);
		if(oldIdx > 0) {
			this.chunks.splice(oldIdx, 1);
			this.chunks.unshift(chunk);
		} else if(oldIdx < 0) {
			this.chunks.unshift(chunk);
			return true;
		}
		return false;
	}

	insertChunk(chunk, before) {
		const oldIdx = this.chunks.indexOf(chunk);
		const idx = this.chunks.indexOf(before);
		if(idx < 0) {
			throw new Error("before chunk not found");
		}
		if(oldIdx >= 0 && oldIdx > idx) {
			this.chunks.splice(oldIdx, 1);
			this.chunks.splice(idx, 0, chunk);
		} else if(oldIdx < 0) {
			this.chunks.splice(idx, 0, chunk);
			return true;
		}
		return false;
	}

	pushChunk(chunk) {
		const oldIdx = this.chunks.indexOf(chunk);
		if(oldIdx >= 0) {
			return false;
		}
		this.chunks.push(chunk);
		return true;
	}

	replaceChunk(oldChunk, newChunk) {
		const oldIdx = this.chunks.indexOf(oldChunk);
		if(oldIdx < 0) return false;
		const newIdx = this.chunks.indexOf(newChunk);
		if(newIdx < 0) {
			this.chunks[oldIdx] = newChunk;
			return true;
		}
		if(newIdx < oldIdx) {
			this.chunks.splice(oldIdx, 1);
			return true;
		} else if(newIdx !== oldIdx) {
			this.chunks[oldIdx] = newChunk;
			this.chunks.splice(newIdx, 1);
			return true;
		}
	}

	removeChunk(chunk) {
		const idx = this.chunks.indexOf(chunk);
		if(idx >= 0) {
			this.chunks.splice(idx, 1);
			return true;
		}
		return false;
	}

	isInitial() {
		return false;
	}

	addChild(chunk) {
		if(this._children.has(chunk)) {
			return false;
		}
		this._children.add(chunk);
		return true;
	}

	getChildren() {
		return this._children.getFromCache(getArray);
	}

	getNumberOfChildren() {
		return this._children.size;
	}

	get childrenIterable() {
		return this._children;
	}

	removeChild(chunk) {
		if(!this._children.has(chunk)) {
			return false;
		}

		this._children.delete(chunk);
		chunk.removeParent(this);
		return true;
	}

	addParent(parentChunk) {
		if(!this._parents.has(parentChunk)) {
			this._parents.add(parentChunk);
			return true;
		}
		return false;
	}

	getParents() {
		return this._parents.getFromCache(getArray);
	}

	setParents(newParents) {
		this._parents.clear();
		for(const p of newParents)
			this._parents.add(p);
	}

	getNumberOfParents() {
		return this._parents.size;
	}

	hasParent(parent) {
		return this._parents.has(parent);
	}

	get parentsIterable() {
		return this._parents;
	}

	removeParent(chunk) {
		if(this._parents.delete(chunk)) {
			chunk.removeChunk(this);
			return true;
		}
		return false;
	}

	/**
	 * @return {Array} - an array containing the blocks
	 */
	getBlocks() {
		return this._blocks.getFromCache(getArray);
	}

	getNumberOfBlocks() {
		return this._blocks.size;
	}

	hasBlock(block) {
		return this._blocks.has(block);
	}

	get blocksIterable() {
		return this._blocks;
	}

	addBlock(block) {
		if(!this._blocks.has(block)) {
			this._blocks.add(block);
			return true;
		}
		return false;
	}

	addOrigin(module, loc, request) {
		this.origins.push({
			module,
			loc,
			request
		});
	}

	containsModule(module) {
		for(const chunk of this.chunks) {
			if(chunk.containsModule(module))
				return true;
		}
		return false;
	}

	remove(reason) {
		// cleanup parents
		for(const parentChunkGroup of this._parents) {
			// remove this chunk from its parents
			parentChunkGroup._children.delete(this);

			// cleanup "sub chunks"
			for(const chunkGroup of this._children) {
				/**
				 * remove this chunk as "intermediary" and connect
				 * it "sub chunks" and parents directly
				 */
				// add parent to each "sub chunk"
				chunkGroup.addParent(parentChunkGroup);
				// add "sub chunk" to parent
				parentChunkGroup.addChild(chunkGroup);
			}
		}

		/**
		 * we need to iterate again over the children
		 * to remove this from the childs parents.
		 * This can not be done in the above loop
		 * as it is not garuanteed that `this._parents` contains anything.
		 */
		for(const chunkGroup of this._children) {
			// remove this as parent of every "sub chunk"
			chunkGroup._parents.delete(this);
		}

		// cleanup blocks
		for(const block of this._blocks) {
			block.chunkGroup = null;
		}

		// remove chunks
		for(const chunk of this.chunks) {
			chunk.removeGroup(this);
		}
	}

	sortItems() {
		this.origins.sort(sortOrigin);
		this._parents.sort();
		this._children.sort();
	}

	checkConstraints() {
		const chunk = this;
		for(const child of chunk._children) {
			if(!child._parents.has(chunk))
				throw new Error(`checkConstraints: child missing parent ${chunk.debugId} -> ${child.debugId}`);
		}
		for(const parentChunk of chunk._parents) {
			if(!parentChunk._children.has(chunk))
				throw new Error(`checkConstraints: parent missing child ${parentChunk.debugId} <- ${chunk.debugId}`);
		}
	}
}

module.exports = ChunkGroup;