import Combine from "../Base/Combine"
import { Store, Stores } from "../../Logic/UIEventSource"
import Translations from "../i18n/Translations"
import { SubtleButton } from "../Base/SubtleButton"
import { VariableUiElement } from "../Base/VariableUIElement"
import Title from "../Base/Title"
import InputElementMap from "../Input/InputElementMap"
import BaseUIElement from "../BaseUIElement"
import FileSelectorButton from "../Input/FileSelectorButton"
import { FlowStep } from "./FlowStep"
import { parse } from "papaparse"
import { FixedUiElement } from "../Base/FixedUiElement"
import { TagUtils } from "../../Logic/Tags/TagUtils"
import { Feature, Point } from "geojson"

class FileSelector extends InputElementMap<FileList, { name: string; contents: Promise<string> }> {
    constructor(label: BaseUIElement) {
        super(
            new FileSelectorButton(label, { allowMultiple: false, acceptType: "*" }),
            (x0, x1) => {
                // Total hack: x1 is undefined is the backvalue - we effectively make this a one-way-story
                return x1 === undefined || x0 === x1
            },
            (filelist) => {
                if (filelist === undefined) {
                    return undefined
                }
                const file = filelist.item(0)
                return { name: file.name, contents: file.text() }
            },
            (_) => undefined
        )
    }
}

/**
 * The first step in the import flow: load a file and validate that it is a correct geojson or CSV file
 */
export class RequestFile extends Combine implements FlowStep<{ features: any[] }> {
    public readonly IsValid: Store<boolean>
    /**
     * The loaded GeoJSON
     */
    public readonly Value: Store<{ features: Feature<Point>[] }>

    constructor() {
        const t = Translations.t.importHelper.selectFile
        const csvSelector = new FileSelector(new SubtleButton(undefined, t.description))
        const loadedFiles = new VariableUiElement(
            csvSelector.GetValue().map((file) => {
                if (file === undefined) {
                    return t.noFilesLoaded.SetClass("alert")
                }
                return t.loadedFilesAre.Subs({ file: file.name }).SetClass("thanks")
            })
        )

        const text = Stores.flatten(
            csvSelector.GetValue().map((v) => {
                if (v === undefined) {
                    return undefined
                }
                return Stores.FromPromise(v.contents)
            })
        )

        const asGeoJson: Store<any | { error: string | BaseUIElement }> = text.map(
            (src: string) => {
                if (src === undefined) {
                    return undefined
                }
                try {
                    const parsed = JSON.parse(src)
                    if (parsed["type"] !== "FeatureCollection") {
                        return { error: t.errNotFeatureCollection }
                    }
                    if (parsed.features.some((f) => f.geometry.type != "Point")) {
                        return { error: t.errPointsOnly }
                    }
                    parsed.features.forEach((f) => {
                        const props = f.properties
                        for (const key in props) {
                            if (
                                props[key] === undefined ||
                                props[key] === null ||
                                props[key] === ""
                            ) {
                                delete props[key]
                            }
                            if (!TagUtils.isValidKey(key)) {
                                return { error: "Probably an invalid key: " + key }
                            }
                        }
                    })
                    return parsed
                } catch (e) {
                    // Loading as CSV
                    var lines: string[][] = <any>parse(src).data
                    const header = lines[0]
                    lines.splice(0, 1)
                    if (header.indexOf("lat") < 0 || header.indexOf("lon") < 0) {
                        return { error: t.errNoLatOrLon }
                    }

                    if (header.some((h) => h.trim() == "")) {
                        return { error: t.errNoName }
                    }

                    if (new Set(header).size !== header.length) {
                        return { error: t.errDuplicate }
                    }

                    const features = []
                    for (let i = 0; i < lines.length; i++) {
                        const attrs = lines[i]
                        if (attrs.length == 0 || (attrs.length == 1 && attrs[0] == "")) {
                            // empty line
                            continue
                        }
                        const properties = {}
                        for (let i = 0; i < header.length; i++) {
                            const v = attrs[i]
                            if (v === undefined || v === "") {
                                continue
                            }
                            properties[header[i]] = v
                        }
                        const coordinates = [Number(properties["lon"]), Number(properties["lat"])]
                        delete properties["lat"]
                        delete properties["lon"]
                        if (coordinates.some(isNaN)) {
                            return { error: "A coordinate could not be parsed for line " + (i + 2) }
                        }
                        const f = {
                            type: "Feature",
                            properties,
                            geometry: {
                                type: "Point",
                                coordinates,
                            },
                        }
                        features.push(f)
                    }

                    return {
                        type: "FeatureCollection",
                        features,
                    }
                }
            }
        )

        const errorIndicator = new VariableUiElement(
            asGeoJson.map((v) => {
                if (v === undefined) {
                    return undefined
                }
                if (v?.error === undefined) {
                    return undefined
                }
                let err: BaseUIElement
                if (typeof v.error === "string") {
                    err = new FixedUiElement(v.error)
                } else if (v.error.Clone !== undefined) {
                    err = v.error.Clone()
                } else {
                    err = v.error
                }
                return err.SetClass("alert")
            })
        )

        super([
            new Title(t.title, 1),
            t.fileFormatDescription,
            t.fileFormatDescriptionCsv,
            t.fileFormatDescriptionGeoJson,
            csvSelector,
            loadedFiles,
            errorIndicator,
        ])
        this.SetClass("flex flex-col wi")
        this.IsValid = asGeoJson.map(
            (geojson) => geojson !== undefined && geojson["error"] === undefined
        )
        this.Value = asGeoJson
    }
}