const CommentItem = require( './CommentItem.js' );
const HeadingItem = require( './HeadingItem.js' );
const ThreadItem = require( './ThreadItem.js' );

/**
 * Groups thread items (headings and comments) generated by parsing a discussion page.
 *
 * @class ThreadItemSet
 */
function ThreadItemSet() {
	this.threadItems = [];
	this.commentItems = [];
	this.threadItemsByName = {};
	this.threadItemsById = {};
	this.threads = [];
}

OO.initClass( ThreadItemSet );

/**
 * Create a new ThreadItemSet from a JSON serialization
 *
 * @param {Array} threads Hash object
 * @param {HTMLElement} rootNode
 * @param {mw.dt.Parser} parser
 * @return {ThreadItemSet}
 */
ThreadItemSet.static.newFromJSON = function ( threads, rootNode, parser ) {
	const result = new ThreadItemSet();

	function infuse( itemHash, parent ) {
		const item = ThreadItem.static.newFromJSON( itemHash, rootNode );

		result.addThreadItem( item );

		item.replies = itemHash.replies.map( ( replyHash ) => infuse( replyHash, item ) );
		item.parent = parent;

		return item;
	}

	threads.forEach( ( itemHash ) => {
		infuse( itemHash, null );
	} );

	// Calculate names (currently not stored in the metadata) - can't be done
	// in the above loop because we have to wait until we have all the
	// replies.
	parser.computeIdsAndNames( result );

	return result;
};

/**
 * @param {ThreadItem} item
 */
ThreadItemSet.prototype.addThreadItem = function ( item ) {
	this.threadItems.push( item );
	if ( item instanceof CommentItem ) {
		this.commentItems.push( item );
	}
	if ( item instanceof HeadingItem ) {
		this.threads.push( item );
	}
};

/**
 * @return {boolean}
 */
ThreadItemSet.prototype.isEmpty = function () {
	return this.threadItems.length === 0;
};

/**
 * @param {ThreadItem} item
 */
ThreadItemSet.prototype.updateIdAndNameMaps = function ( item ) {
	if ( !this.threadItemsByName[ item.name ] ) {
		this.threadItemsByName[ item.name ] = [];
	}
	this.threadItemsByName[ item.name ].push( item );

	this.threadItemsById[ item.id ] = item;
};

/**
 * Get all discussion comments (and headings) within a DOM subtree.
 *
 * This returns a flat list, use #getThreads to get a tree structure starting at section headings.
 *
 * For example, for a MediaWiki discussion like this (we're dealing with HTML DOM here, the wikitext
 * syntax is just for illustration):
 *
 *     == A ==
 *     B. ~~~~
 *     : C.
 *     : C. ~~~~
 *     :: D. ~~~~
 *     ::: E. ~~~~
 *     ::: F. ~~~~
 *     : G. ~~~~
 *     H. ~~~~
 *     : I. ~~~~
 *
 * This function would return a structure like:
 *
 *     [
 *       HeadingItem( { level: 0, range: (h2: A)        } ),
 *       CommentItem( { level: 1, range: (p: B)         } ),
 *       CommentItem( { level: 2, range: (li: C, li: C) } ),
 *       CommentItem( { level: 3, range: (li: D)        } ),
 *       CommentItem( { level: 4, range: (li: E)        } ),
 *       CommentItem( { level: 4, range: (li: F)        } ),
 *       CommentItem( { level: 2, range: (li: G)        } ),
 *       CommentItem( { level: 1, range: (p: H)         } ),
 *       CommentItem( { level: 2, range: (li: I)        } )
 *     ]
 *
 * @return {ThreadItem[]} Thread items
 */
ThreadItemSet.prototype.getThreadItems = function () {
	return this.threadItems;
};

/**
 * Same as getFlatThreadItems, but only returns the CommentItems
 *
 * @return {CommentItem[]} Comment items
 */
ThreadItemSet.prototype.getCommentItems = function () {
	return this.commentItems;
};

/**
 * Find ThreadItems by their name
 *
 * This will usually return a single-element array, but it may return multiple comments if they're
 * indistinguishable by name. In that case, use their IDs to disambiguate.
 *
 * @param {string} name Name
 * @return {ThreadItem[]} Thread items, empty array if not found
 */
ThreadItemSet.prototype.findCommentsByName = function ( name ) {
	return this.threadItemsByName[ name ] || [];
};

/**
 * Find a ThreadItem by its ID
 *
 * @param {string} id ID
 * @return {ThreadItem|null} Thread item, null if not found
 */
ThreadItemSet.prototype.findCommentById = function ( id ) {
	return this.threadItemsById[ id ] || null;
};

/**
 * Group discussion comments into threads and associate replies to original messages.
 *
 * Each thread must begin with a heading. Original messages in the thread are treated as replies to
 * its heading. Other replies are associated based on the order and indentation level.
 *
 * Note that the objects in `comments` are extended in-place with the additional data.
 *
 * For example, for a MediaWiki discussion like this (we're dealing with HTML DOM here, the wikitext
 * syntax is just for illustration):
 *
 *     == A ==
 *     B. ~~~~
 *     : C.
 *     : C. ~~~~
 *     :: D. ~~~~
 *     ::: E. ~~~~
 *     ::: F. ~~~~
 *     : G. ~~~~
 *     H. ~~~~
 *     : I. ~~~~
 *
 * This function would return a structure like:
 *
 *     [
 *       HeadingItem( { level: 0, range: (h2: A), replies: [
 *         CommentItem( { level: 1, range: (p: B), replies: [
 *           CommentItem( { level: 2, range: (li: C, li: C), replies: [
 *             CommentItem( { level: 3, range: (li: D), replies: [
 *               CommentItem( { level: 4, range: (li: E), replies: [] } ),
 *               CommentItem( { level: 4, range: (li: F), replies: [] } ),
 *             ] } ),
 *           ] } ),
 *           CommentItem( { level: 2, range: (li: G), replies: [] } ),
 *         ] } ),
 *         CommentItem( { level: 1, range: (p: H), replies: [
 *           CommentItem( { level: 2, range: (li: I), replies: [] } ),
 *         ] } ),
 *       ] } )
 *     ]
 *
 * @return {HeadingItem[]} Tree structure of comments, top-level items are the headings.
 */
ThreadItemSet.prototype.getThreads = function () {
	return this.threads;
};

module.exports = ThreadItemSet;