Stop tracking past learnsets-g6

`learnsets-g6` has always been versioned because in Gen 6, it contained
START move order.

For instance, Clefairy in BW2 has the following level-up moveset:

- START: Pound
- START: Growl
- L4: Encore
- L7: Sing
- L10: Double Slap

If you catch a wild level-10 Clefairy, its moveset will be: Growl,
Encore, Sing, Double Slap. A level-10 wild Clefairy will always have
Growl and never have Pound, because the order of its first two moves
matters.

PS's regular learnsets file doesn't take this into account, so we
tracked a `learnsets-g6` file that did, but also needed to keep in sync
with new game updates.

Well, these are no longer necessary. We've updated to Gen 7 and now
Gen 8, and we've never had START ordering for any of them. Anyone who
wants START ordering for Gen 6 can find it here:

https://github.com/Zarel/Pokemon-Gen-6-Learnsets

For this repo, though, `learnsets-g6` is still around (used only by
PSdex), but it can now be automatically built from `learnsets` without
losing anything, and so it can finally be `.gitignore`d.

.gitignore

@@ -5,7 +5,6 @@
 /index.html
 /preactalpha.html
 /data/*
-!/data/learnsets-g6.js
 node_modules/
 eslint-cache/
 .DS_Store

build-tools/build-learnsets

@@ -22,88 +22,35 @@ const Dex = require('../data/Pokemon-Showdown/.sim-dist/dex').Dex;
 const toID = Dex.getId;
 
 function updateLearnsets(callback) {
-	const reservedKeywords = ['return']; // `return` is the only ES3+ reserved keyword that (currently) raises conflicts
-	const numberRegExp = new RegExp('^[0-9]*');
-	const reservedRegExp = new RegExp('^(' + reservedKeywords.join('|') + '|\\d.*)$', 'g');
+	const numberRegExp = /^[0-9]*/;
+	const reservedRegExp = /^(return|\d.*)$/g; // `return` is the only ES3+ reserved keyword that (currently) raises conflicts
 	const alphabetize = (a, b) => a.localeCompare(b);
-	const getLsetGen = lset => lset.charAt(0);
 
-	const padNumString = str => str.padStart(3, '0');
-	const inLearnset = function (lset, learnset) {
-		const secondChar = lset.charAt(1);
-		if (secondChar !== 'L') return learnset.indexOf(lset) >= 0;
-
-		const firstFragment = lset.substr(0, 2);
-		const levelFragment = lset.substring(2, 5);
-		const paddedLevel = padNumString(levelFragment);
-		for (let i = 0, len = learnset.length; i < len; i++) {
-			if (learnset[i].substring(0, 2) !== firstFragment) continue;
-			// ignore PSdex starter moves sorting data
-			if (paddedLevel === padNumString(learnset[i].substring(2, 5))) return true;
-		}
-		return false;
-	};
 	const formatLset = function (lset) {
 		const secondChar = lset.charAt(1);
 		if (secondChar !== 'L') return lset;
 		const firstFragment = lset.substr(0, 2);
 		const levelFragment = lset.substr(2).match(numberRegExp)[0];
 		const sortFragment = lset.substr(2 + levelFragment.length);
-		return firstFragment + padNumString(levelFragment) + sortFragment;
+		return firstFragment + levelFragment.padStart(3, '0') + sortFragment;
 	};
 
 	const Pokedex = Dex.data.Pokedex;
 	const Learnsets = Dex.data.Learnsets;
 	const newLearnsetsG6 = {};
 
-	let oldLearnsetsG6;
-	try {
-		oldLearnsetsG6 = require(path.join(rootDir, 'data', 'learnsets-g6.js')).BattleLearnsets;
-	} catch (err) {
-		if (err.code !== 'MODULE_NOT_FOUND') return callback(err);
-		oldLearnsetsG6 = {};
-	}
-
 	for (const speciesid in Learnsets) {
-		if (!oldLearnsetsG6[speciesid] || !oldLearnsetsG6[speciesid].learnset) {
-			if (!Pokedex[speciesid] && speciesid !== 'rockruffdusk') console.log("ERROR: " + speciesid + " not found in Pokedex");
-			console.log("NEW ENTRY at learnsets-g6.js: " + speciesid + ".");
-			oldLearnsetsG6[speciesid] = {learnset: {}};
-		}
-	}
-	for (const speciesid in oldLearnsetsG6) {
-		if (!oldLearnsetsG6[speciesid] || !oldLearnsetsG6[speciesid].learnset) return callback(new TypeError("Invalid `learnsets-g6.js` entry for " + speciesid + "."));
-		if (!Learnsets[speciesid]) {
-			console.log("REMOVED ENTRY at learnsets-g6.js: " + (Pokedex[speciesid] ? Pokedex[speciesid].species : speciesid) + ".");
-			continue;
-		}
 		const newLearnset = {};
-		const oldLearnset = oldLearnsetsG6[speciesid].learnset;
 		const fullLearnset = Learnsets[speciesid].learnset;
-		if (!fullLearnset) return callback(new TypeError("Invalid data at `learnsets.js` for " + speciesid + "."));
-
-		// copy, but ignore moves removed in main file
-		for (const moveid in oldLearnset) {
-			if (!Array.isArray(oldLearnset[moveid])) return callback(new TypeError("Invalid data at `learnsets-g6.js` for " + speciesid + ":" + moveid + "."));
-			if (!fullLearnset[moveid]) continue;
-			newLearnset[moveid] = [];
-			for (let i = 0, len = oldLearnset[moveid].length; i < len; i++) {
-				if (!inLearnset(oldLearnset[moveid][i], fullLearnset[moveid])) continue;
-				newLearnset[moveid].push(oldLearnset[moveid][i]);
-			}
-		}
 
 		for (const moveid in fullLearnset) {
-			if (!Array.isArray(fullLearnset[moveid])) return callback(new TypeError("Invalid data at `learnsets.js` for " + speciesid + ":" + moveid + "."));
-
-			if (!newLearnset[moveid]) newLearnset[moveid] = [];
-			newLearnset[moveid] = newLearnset[moveid].map(formatLset);
-			for (let i = 0, len = fullLearnset[moveid].length; i < len; i++) {
-				if (getLsetGen(fullLearnset[moveid][i]) !== '8') continue;
-				if (inLearnset(fullLearnset[moveid][i], newLearnset[moveid])) continue;
-				newLearnset[moveid].push(formatLset(fullLearnset[moveid][i]));
-			}
-			newLearnset[moveid].sort(alphabetize);
+			newLearnset[moveid] = fullLearnset[moveid].filter(
+				learned => "87".includes(learned.charAt(0))
+			).map(
+				formatLset
+			).sort(
+				alphabetize
+			);
 		}
 
 		newLearnsetsG6[speciesid] = {learnset: newLearnset};
@@ -119,13 +66,13 @@ function updateLearnsets(callback) {
 		return a.num - b.num;
 	}).map(template => toID(template.species));
 
-	for (let i = 0, len = pokemonList.length; i < len; i++) {
-		const entry = newLearnsetsG6[pokemonList[i]];
+	for (const speciesid of pokemonList) {
+		const entry = newLearnsetsG6[speciesid];
 		if (!entry || !entry.learnset) continue;
-		const lsetSerialized = '{' + Object.keys(entry.learnset).sort(alphabetize).map(function (moveid) {
-			return moveid.replace(reservedRegExp, '"$1"') + ':' + JSON.stringify(entry.learnset[moveid]);
-		}).join(',') + '}';
-		buf.push(pokemonList[i] + ':{learnset:' + lsetSerialized + '}');
+		const lsetSerialized = '{' + Object.keys(entry.learnset).sort(alphabetize).map(
+			moveid => moveid.replace(reservedRegExp, '"$1"') + ':' + JSON.stringify(entry.learnset[moveid])
+		).join(',') + '}';
+		buf.push(speciesid + ':{learnset:' + lsetSerialized + '}');
 	}
 
 	const writeStream = fs.createWriteStream(path.join(rootDir, 'data', 'learnsets-g6.js')).on('error', callback);