MapComplete/Logic/ImageProviders/ImageProvider.ts

import { Store, UIEventSource } from "../UIEventSource"
import BaseUIElement from "../../UI/BaseUIElement"
import { LicenseInfo } from "./LicenseInfo"
import { Utils } from "../../Utils"

export interface ProvidedImage {
    url: string
    key: string
    provider: ImageProvider
}

export default abstract class ImageProvider {
    public abstract readonly defaultKeyPrefixes: string[]

    public abstract SourceIcon(backlinkSource?: string): BaseUIElement

    /**
     * Given a properies object, maps it onto _all_ the available pictures for this imageProvider
     */
    public GetRelevantUrls(
        allTags: Store<any>,
        options?: {
            prefixes?: string[]
        }
    ): UIEventSource<ProvidedImage[]> {
        const prefixes = options?.prefixes ?? this.defaultKeyPrefixes
        if (prefixes === undefined) {
            throw "No `defaultKeyPrefixes` defined by this image provider"
        }
        const relevantUrls = new UIEventSource<
            { url: string; key: string; provider: ImageProvider }[]
        >([])
        const seenValues = new Set<string>()
        allTags.addCallbackAndRunD((tags) => {
            for (const key in tags) {
                if (!prefixes.some((prefix) => key.startsWith(prefix))) {
                    continue
                }
                const values = Utils.NoEmpty(tags[key]?.split(";")?.map((v) => v.trim()) ?? [])
                for (const value of values) {
                    if (seenValues.has(value)) {
                        continue
                    }
                    seenValues.add(value)
                    this.ExtractUrls(key, value).then((promises) => {
                        for (const promise of promises ?? []) {
                            if (promise === undefined) {
                                continue
                            }
                            promise.then((providedImage) => {
                                if (providedImage === undefined) {
                                    return
                                }
                                relevantUrls.data.push(providedImage)
                                relevantUrls.ping()
                            })
                        }
                    })
                }
            }
        })
        return relevantUrls
    }

    public abstract ExtractUrls(key: string, value: string): Promise<Promise<ProvidedImage>[]>

    public abstract DownloadAttribution(url: string): Promise<LicenseInfo>
}