pokemon-showdown/data/mods/mixandmega/scripts.ts

export const Scripts: ModdedBattleScriptsData = {
	init() {
		for (const i in this.data.Items) {
			if (!this.data.Items[i].megaStone) continue;
			this.modData('Items', i).onTakeItem = false;
			const id = this.toID(this.data.Items[i].megaStone);
			this.modData('FormatsData', id).isNonstandard = null;
		}
	},
	actions: {
		canMegaEvo(pokemon) {
			if (pokemon.species.isMega) return null;

			const item = pokemon.getItem();
			if (item.megaStone) {
				if (item.megaStone === pokemon.baseSpecies.name) return null;
				return item.megaStone;
			} else {
				return null;
			}
		},
		runMegaEvo(pokemon) {
			if (pokemon.species.isMega) return false;

			// @ts-ignore
			const species: Species = this.getMixedSpecies(pokemon.m.originalSpecies, pokemon.canMegaEvo);

			// Pokémon affected by Sky Drop cannot Mega Evolve. Enforce it here for now.
			for (const foeActive of pokemon.foes()) {
				if (foeActive.volatiles['skydrop']?.source === pokemon) {
					return false;
				}
			}

			// Do we have a proper sprite for it?
			if (this.dex.species.get(pokemon.canMegaEvo!).baseSpecies === pokemon.m.originalSpecies) {
				pokemon.formeChange(species, pokemon.getItem(), true);
			} else {
				const oSpecies = this.dex.species.get(pokemon.m.originalSpecies);
				// @ts-ignore
				const oMegaSpecies = this.dex.species.get(species.originalMega);
				pokemon.formeChange(species, pokemon.getItem(), true);
				this.battle.add('-start', pokemon, oMegaSpecies.requiredItem, '[silent]');
				if (oSpecies.types.length !== pokemon.species.types.length || oSpecies.types[1] !== pokemon.species.types[1]) {
					this.battle.add('-start', pokemon, 'typechange', pokemon.species.types.join('/'), '[silent]');
				}
			}

			pokemon.canMegaEvo = null;
			return true;
		},
		getMixedSpecies(originalForme, megaForme) {
			const originalSpecies = this.dex.species.get(originalForme);
			const megaSpecies = this.dex.species.get(megaForme);
			if (originalSpecies.baseSpecies === megaSpecies.baseSpecies) return megaSpecies;
			// @ts-ignore
			const deltas = this.getMegaDeltas(megaSpecies);
			// @ts-ignore
			const species = this.doGetMixedSpecies(originalSpecies, deltas);
			return species;
		},
		getMegaDeltas(megaSpecies) {
			const baseSpecies = this.dex.species.get(megaSpecies.baseSpecies);
			const deltas: {
				ability: string,
				baseStats: SparseStatsTable,
				weighthg: number,
				originalMega: string,
				requiredItem: string | undefined,
				type?: string,
				isMega?: boolean,
			} = {
				ability: megaSpecies.abilities['0'],
				baseStats: {},
				weighthg: megaSpecies.weighthg - baseSpecies.weighthg,
				originalMega: megaSpecies.name,
				requiredItem: megaSpecies.requiredItem,
			};
			let statId: StatID;
			for (statId in megaSpecies.baseStats) {
				deltas.baseStats[statId] = megaSpecies.baseStats[statId] - baseSpecies.baseStats[statId];
			}
			if (megaSpecies.types.length > baseSpecies.types.length) {
				deltas.type = megaSpecies.types[1];
			} else if (megaSpecies.types.length < baseSpecies.types.length) {
				deltas.type = 'mono';
			} else if (megaSpecies.types[1] !== baseSpecies.types[1]) {
				deltas.type = megaSpecies.types[1];
			}
			if (megaSpecies.isMega) deltas.isMega = true;
			return deltas;
		},
		doGetMixedSpecies(speciesOrForme, deltas) {
			if (!deltas) throw new TypeError("Must specify deltas!");
			const species = this.dex.deepClone(this.dex.species.get(speciesOrForme));
			species.abilities = {'0': deltas.ability};
			if (species.types[0] === deltas.type) {
				species.types = [deltas.type];
			} else if (deltas.type === 'mono') {
				species.types = [species.types[0]];
			} else if (deltas.type) {
				species.types = [species.types[0], deltas.type];
			}
			const baseStats = species.baseStats;
			for (const statName in baseStats) {
				baseStats[statName] = this.battle.clampIntRange(baseStats[statName] + deltas.baseStats[statName], 1, 255);
			}
			species.weighthg = Math.max(1, species.weighthg + deltas.weighthg);
			species.originalMega = deltas.originalMega;
			species.requiredItem = deltas.requiredItem;
			if (deltas.isMega) species.isMega = true;
			return species;
		},
	},
};