import { Store, UIEventSource } from "../UIEventSource"
import { Or } from "../Tags/Or"
import { Overpass } from "../Osm/Overpass"
import FeatureSource from "../FeatureSource/FeatureSource"
import { Utils } from "../../Utils"
import { TagsFilter } from "../Tags/TagsFilter"
import SimpleMetaTagger from "../SimpleMetaTagger"
import LayoutConfig from "../../Models/ThemeConfig/LayoutConfig"
import RelationsTracker from "../Osm/RelationsTracker"
import { BBox } from "../BBox"
import Loc from "../../Models/Loc"
import LayerConfig from "../../Models/ThemeConfig/LayerConfig"
import Constants from "../../Models/Constants"
import TileFreshnessCalculator from "../FeatureSource/TileFreshnessCalculator"
import { Tiles } from "../../Models/TileRange"

export default class OverpassFeatureSource implements FeatureSource {
    public readonly name = "OverpassFeatureSource"

    /**
     * The last loaded features of the geojson
     */
    public readonly features: UIEventSource<{ feature: any; freshness: Date }[]> =
        new UIEventSource<any[]>(undefined)

    public readonly runningQuery: UIEventSource<boolean> = new UIEventSource<boolean>(false)
    public readonly timeout: UIEventSource<number> = new UIEventSource<number>(0)

    public readonly relationsTracker: RelationsTracker

    private readonly retries: UIEventSource<number> = new UIEventSource<number>(0)

    private readonly state: {
        readonly locationControl: Store<Loc>
        readonly layoutToUse: LayoutConfig
        readonly overpassUrl: Store<string[]>
        readonly overpassTimeout: Store<number>
        readonly currentBounds: Store<BBox>
    }
    private readonly _isActive: Store<boolean>
    /**
     * Callback to handle all the data
     */
    private readonly onBboxLoaded: (
        bbox: BBox,
        date: Date,
        layers: LayerConfig[],
        zoomlevel: number
    ) => void

    /**
     * Keeps track of how fresh the data is
     * @private
     */
    private readonly freshnesses: Map<string, TileFreshnessCalculator>

    constructor(
        state: {
            readonly locationControl: Store<Loc>
            readonly layoutToUse: LayoutConfig
            readonly overpassUrl: Store<string[]>
            readonly overpassTimeout: Store<number>
            readonly overpassMaxZoom: Store<number>
            readonly currentBounds: Store<BBox>
        },
        options: {
            padToTiles: Store<number>
            isActive?: Store<boolean>
            relationTracker: RelationsTracker
            onBboxLoaded?: (
                bbox: BBox,
                date: Date,
                layers: LayerConfig[],
                zoomlevel: number
            ) => void
            freshnesses?: Map<string, TileFreshnessCalculator>
        }
    ) {
        this.state = state
        this._isActive = options.isActive
        this.onBboxLoaded = options.onBboxLoaded
        this.relationsTracker = options.relationTracker
        this.freshnesses = options.freshnesses
        const self = this
        state.currentBounds.addCallback((_) => {
            self.update(options.padToTiles.data)
        })
    }

    private GetFilter(interpreterUrl: string, layersToDownload: LayerConfig[]): Overpass {
        let filters: TagsFilter[] = []
        let extraScripts: string[] = []
        for (const layer of layersToDownload) {
            if (layer.source.overpassScript !== undefined) {
                extraScripts.push(layer.source.overpassScript)
            } else {
                filters.push(layer.source.osmTags)
            }
        }
        filters = Utils.NoNull(filters)
        extraScripts = Utils.NoNull(extraScripts)
        if (filters.length + extraScripts.length === 0) {
            return undefined
        }
        return new Overpass(
            new Or(filters),
            extraScripts,
            interpreterUrl,
            this.state.overpassTimeout,
            this.relationsTracker
        )
    }

    private update(paddedZoomLevel: number) {
        if (!this._isActive.data) {
            return
        }
        const self = this
        this.updateAsync(paddedZoomLevel).then((bboxDate) => {
            if (bboxDate === undefined || self.onBboxLoaded === undefined) {
                return
            }
            const [bbox, date, layers] = bboxDate
            self.onBboxLoaded(bbox, date, layers, paddedZoomLevel)
        })
    }

    private async updateAsync(padToZoomLevel: number): Promise<[BBox, Date, LayerConfig[]]> {
        if (this.runningQuery.data) {
            console.log("Still running a query, not updating")
            return undefined
        }

        if (this.timeout.data > 0) {
            console.log("Still in timeout - not updating")
            return undefined
        }

        let data: any = undefined
        let date: Date = undefined
        let lastUsed = 0

        const layersToDownload = []
        const neededTiles = this.state.currentBounds.data
            .expandToTileBounds(padToZoomLevel)
            .containingTileRange(padToZoomLevel)
        for (const layer of this.state.layoutToUse.layers) {
            if (typeof layer === "string") {
                throw "A layer was not expanded!"
            }
            if (Constants.priviliged_layers.indexOf(layer.id) >= 0) {
                continue
            }
            if (this.state.locationControl.data.zoom < layer.minzoom) {
                continue
            }
            if (layer.doNotDownload) {
                continue
            }
            if (layer.source.geojsonSource !== undefined) {
                // Not our responsibility to download this layer!
                continue
            }
            const freshness = this.freshnesses?.get(layer.id)
            if (freshness !== undefined) {
                const oldestDataDate =
                    Math.min(
                        ...Tiles.MapRange(neededTiles, (x, y) => {
                            const date = freshness.freshnessFor(padToZoomLevel, x, y)
                            if (date === undefined) {
                                return 0
                            }
                            return date.getTime()
                        })
                    ) / 1000
                const now = new Date().getTime()
                const minRequiredAge = now / 1000 - layer.maxAgeOfCache
                if (oldestDataDate >= minRequiredAge) {
                    // still fresh enough - not updating
                    continue
                }
            }

            layersToDownload.push(layer)
        }

        if (layersToDownload.length == 0) {
            console.debug("Not updating - no layers needed")
            return
        }

        const self = this
        const overpassUrls = self.state.overpassUrl.data
        if (overpassUrls === undefined || overpassUrls.length === 0) {
            throw "Panic: overpassFeatureSource didn't receive any overpassUrls"
        }
        let bounds: BBox
        do {
            try {
                bounds = this.state.currentBounds.data
                    ?.pad(this.state.layoutToUse.widenFactor)
                    ?.expandToTileBounds(padToZoomLevel)

                if (bounds === undefined) {
                    return undefined
                }

                const overpass = this.GetFilter(overpassUrls[lastUsed], layersToDownload)

                if (overpass === undefined) {
                    return undefined
                }
                this.runningQuery.setData(true)
                ;[data, date] = await overpass.queryGeoJson(bounds)
            } catch (e) {
                self.retries.data++
                self.retries.ping()
                console.error(`QUERY FAILED due to`, e)

                await Utils.waitFor(1000)

                if (lastUsed + 1 < overpassUrls.length) {
                    lastUsed++
                    console.log("Trying next time with", overpassUrls[lastUsed])
                } else {
                    lastUsed = 0
                    self.timeout.setData(self.retries.data * 5)

                    while (self.timeout.data > 0) {
                        await Utils.waitFor(1000)
                        console.log(self.timeout.data)
                        self.timeout.data--
                        self.timeout.ping()
                    }
                }
            }
        } while (data === undefined && this._isActive.data)

        try {
            if (data === undefined) {
                return undefined
            }
            data.features.forEach((feature) =>
                SimpleMetaTagger.objectMetaInfo.applyMetaTagsOnFeature(
                    feature,
                    date,
                    undefined,
                    this.state
                )
            )
            self.features.setData(data.features.map((f) => ({ feature: f, freshness: date })))
            return [bounds, date, layersToDownload]
        } catch (e) {
            console.error("Got the overpass response, but could not process it: ", e, e.stack)
            return undefined
        } finally {
            self.retries.setData(0)
            self.runningQuery.setData(false)
        }
    }
}