/*
 * Slopbot scrape backend: discord.js messages to the core message shape.
 *
 * The mapping is duck-typed so tests run without a bot token. The live shape was
 * checked against the discord.js 14 typings; a live check is still owed at C8.
 */

import type { FetchPage, ScrapeBackend } from "../src/engine.js";
import type { CoreAttachment, CoreEmbed, CoreMessage, CoreSticker, MediaMessage } from "../src/types.js";

/** Discord message flag for a voice message. */
const VOICE_MESSAGE_FLAG = 1 << 13;

/** The minimal fetcher the backend needs. The real one wraps a discord.js client. */
export interface SlopbotFetcher {
    fetchMessages(channelId: string, options: { limit: number; before?: string }): Promise<unknown[]>;
}

/** discord.js Collections are iterable and have `.values()`; tests use Maps and arrays. */
function collectionValues(value: any): any[] {
    if (!value) return [];
    if (Array.isArray(value)) return value;
    if (typeof value.values === "function") return [...value.values()];
    return [];
}

function mapAttachments(message: any): CoreAttachment[] {
    return collectionValues(message?.attachments).map((attachment: any) => ({
        id: attachment?.id ?? null,
        filename: attachment?.name ?? attachment?.filename ?? "",
        url: attachment?.url ?? null,
        contentType: attachment?.contentType ?? attachment?.content_type ?? null,
        size: attachment?.size ?? null,
        width: attachment?.width ?? null,
        height: attachment?.height ?? null,
        durationSecs: attachment?.duration ?? attachment?.durationSecs ?? attachment?.duration_secs ?? null
    }));
}

/** Dimensions of the first embed part that has them: video, image, then thumbnail. */
function embedDataSize(data: any) {
    for (const part of [data?.video, data?.image, data?.thumbnail]) {
        if (part && Number.isFinite(part.width) && Number.isFinite(part.height)) {
            return { width: part.width, height: part.height };
        }
    }
    return { width: null, height: null };
}

function mapEmbeds(message: any): CoreEmbed[] {
    const assetUrl = (value: any) => value?.url ?? (typeof value === "string" ? value : null);

    return collectionValues(message?.embeds).map((embed: any) => {
        const data = embed?.data ?? embed ?? {};
        const size = embedDataSize(data);
        return {
            type: data.type ?? null,
            url: data.url ?? null,
            title: data.title ?? null,
            provider: data.provider?.name ?? null,
            videoUrl: assetUrl(data.video),
            imageUrl: assetUrl(data.image),
            thumbnailUrl: assetUrl(data.thumbnail),
            width: size.width,
            height: size.height
        };
    });
}

function mapStickers(message: any): CoreSticker[] {
    return collectionValues(message?.stickers).map((sticker: any) => ({
        id: sticker?.id ?? null,
        name: sticker?.name ?? null,
        formatType: sticker?.format ?? null
    }));
}

function isVoiceMessage(message: any): boolean {
    const flags = message?.flags;
    if (typeof flags?.has === "function") return flags.has(VOICE_MESSAGE_FLAG);
    return Boolean(Number(flags ?? 0) & VOICE_MESSAGE_FLAG);
}

function createdAt(message: any): string | null {
    if (message?.createdAt instanceof Date) return message.createdAt.toISOString();
    if (typeof message?.timestamp === "string") return message.timestamp;
    return null;
}

function mapSnapshot(snapshot: any): MediaMessage & { content: string; timestamp: string | null } {
    const source = snapshot?.message ?? snapshot;

    return {
        content: source?.content ?? "",
        timestamp: createdAt(source),
        attachments: mapAttachments(source),
        embeds: mapEmbeds(source),
        stickerItems: mapStickers(source),
        voiceMessage: isVoiceMessage(source)
    };
}

/** Map one discord.js message to the core message shape. */
export function mapSlopbotMessage(message: any): CoreMessage {
    const reference = message?.reference;
    const edited = message?.editedAt ?? message?.editedTimestamp ?? null;

    return {
        id: String(message?.id ?? ""),
        author: {
            id: String(message?.author?.id ?? ""),
            username: message?.author?.username ?? "",
            avatar: message?.author?.avatar ?? null
        },
        content: message?.content ?? "",
        timestamp: createdAt(message) ?? "",
        editedAt: edited instanceof Date ? edited.toISOString() : null,
        replyTo: reference?.messageId
            ? { id: String(reference.messageId), authorId: null, authorName: null }
            : null,
        attachments: mapAttachments(message),
        embeds: mapEmbeds(message),
        stickerItems: mapStickers(message),
        forwarded: collectionValues(message?.messageSnapshots).map(mapSnapshot),
        voiceMessage: isVoiceMessage(message)
    };
}

export class SlopbotBackend implements ScrapeBackend {
    readonly name = "slopbot" as const;

    constructor(private readonly fetcher: SlopbotFetcher) {}

    async fetchPage(channelId: string, before: string | null, limit: number): Promise<FetchPage> {
        const messages = await this.fetcher.fetchMessages(channelId, {
            limit,
            ...(before ? { before } : {})
        });

        const mapped = messages.map(mapSlopbotMessage).filter(message => message.id.length > 0);
        mapped.sort((a, b) => (BigInt(a.id) < BigInt(b.id) ? -1 : 1));
        return { messages: mapped };
    }
}