// SPDX-FileCopyrightText: 2021 Johannes Loher
//
// SPDX-License-Identifier: MIT

import { DS4Actor } from "./actor/actor";
import { mathEvaluator } from "./expression-evaluation/evaluator";
import { getGame } from "./helpers";

import type { DS4Item } from "./item/item";

declare global {
    interface DocumentClassConfig {
        ActiveEffect: typeof DS4ActiveEffect;
    }
}

type PromisedType<T> = T extends Promise<infer U> ? U : T;

export class DS4ActiveEffect extends ActiveEffect {
    /**
     * A fallback icon that can be used if no icon is defined for the effect.
     */
    static FALLBACK_ICON = "icons/svg/aura.svg";

    /**
     * A cached reference to the source document to avoid recurring database lookups
     */
    protected source: PromisedType<ReturnType<typeof fromUuid>> | undefined = undefined;

    /**
     * Whether or not this effect is currently surpressed.
     */
    get isSurpressed(): boolean {
        const originatingItem = this.originatingItem;
        if (!originatingItem) {
            return false;
        }
        return originatingItem.isNonEquippedEuipable();
    }

    /**
     * The item which this effect originates from if it has been transferred from an item to an actor.
     */
    get originatingItem(): DS4Item | undefined {
        if (!(this.parent instanceof DS4Actor)) {
            return;
        }
        const itemIdRegex = /Item\.([a-zA-Z0-9]+)/;
        const itemId = this.data.origin?.match(itemIdRegex)?.[1];
        if (!itemId) {
            return;
        }
        return this.parent.items.get(itemId);
    }

    /**
     * The number of times this effect should be applied.
     */
    get factor(): number {
        return this.originatingItem?.activeEffectFactor ?? 1;
    }

    override apply(actor: DS4Actor, change: foundry.data.ActiveEffectData["changes"][number]): unknown {
        change.value = Roll.replaceFormulaData(change.value, actor.data);
        try {
            change.value = DS4ActiveEffect.safeEval(change.value).toString();
        } catch (e) {
            logger.warn(e);
            // this is a valid case, e.g., if the effect change simply is a string
        }
        return super.apply(actor, change);
    }

    /**
     * Gets the current source name based on the cached source object.
     */
    async getCurrentSourceName(): Promise<string> {
        const game = getGame();
        const origin = await this.getSource();
        if (origin === null) return game.i18n.localize("None");
        return origin.name ?? game.i18n.localize("Unknown");
    }

    /**
     * Gets the source document for this effect. Uses the cached {@link DS4ActiveEffect#source} if it has already been
     * set.
     */
    protected async getSource(): ReturnType<typeof fromUuid> {
        if (this.source === undefined) {
            this.source = this.data.origin !== undefined ? await fromUuid(this.data.origin) : null;
        }
        return this.source;
    }

    /**
     * Create a new {@link DS4ActiveEffect} using default data.
     *
     * @param parent The parent {@link DS4Actor} or {@link DS4Item} of the effect.
     * @returns A promise that resolved to the created effect or udifined of the creation was prevented.
     */
    static async createDefault(parent: DS4Actor | DS4Item): Promise<DS4ActiveEffect | undefined> {
        const createData = {
            label: getGame().i18n.localize(`DS4.NewEffectLabel`),
            icon: this.FALLBACK_ICON,
        };

        return this.create(createData, { parent, pack: parent.pack ?? undefined });
    }

    static safeEval(expression: string): number | `${number | boolean}` {
        const result = mathEvaluator.evaluate(expression);
        if (!Number.isNumeric(result)) {
            throw new Error(`mathEvaluator.evaluate produced a non-numeric result from expression "${expression}"`);
        }
        return result as number | `${number | boolean}`;
    }
}