const registeredTiles = new Map()
const pendingTiles = new Map()
/** Implements a baseTexture cache. The last textures are kept for reuse  */
let keepTextures = 0
const keptTextures = []

/** The current Tile implementation simply uses PIXI.Sprites.
 *
 * BTW: PIXI.extras.TilingSprite is not appropriate. It should be used for
 * repeating patterns.
 **/
export default class Tile extends PIXI.Sprite {
    constructor(texture, url) {
        super(texture)
        this.url = url
        this.register(url)
    }

    /**
     * Static method to enable keeping of base textures
     *
     * @static
     * @param {*} value
     * @memberof Tile
     */
    static enableKeepTextures(value = 1000) {
        keepTextures = value
    }

    /**
     * Marks the given url as pending. Pending tiles should not be destroyed
     *
     * @static
     * @param {*} url
     * @memberof Tile
     */
    static schedule(url) {
        let count = 0
        if (pendingTiles.has(url)) {
            count = pendingTiles.get(url)
        }
        pendingTiles.set(url, count + 1)
        // console.log("Tile.scheduled", url, pendingTiles.size)
    }

    /**
     * Returns true iff the url is pending
     *
     * @static
     * @param {*} url
     * @returns
     * @memberof Tile
     */
    static isPending(url) {
        return pendingTiles.has(url) && pendingTiles.get(url) > 0
    }

    static isObsolete(url) {
        if (registeredTiles.has(url) && registeredTiles.get(url) > 0) {
            return false
        }
        return true
    }

    /**
     * Removes the given url from pending urls.
     *
     * @static
     * @param {*} url
     * @memberof Tile
     */
    static unschedule(url) {
        if (pendingTiles.has(url)) {
            let count = pendingTiles.get(url)
            if (count > 1) {
                pendingTiles.set(url, count - 1)
            }
            else {
                pendingTiles.clear(url)
            }
        }
        // console.log("Tile.unscheduled", url, pendingTiles.size)
    }

    /**
     * Loads a tile from image using the PIXI.Texture.fromImage method.
     *
     * @static
     * @param {*} imageId
     * @param {*} crossorigin
     * @param {*} scaleMode
     * @returns
     * @memberof Tile
     */
    static fromImage(imageId, crossorigin, scaleMode) {
        return new Tile(PIXI.Texture.fromImage(imageId, crossorigin, scaleMode), imageId)
    }

    /**
     * Registers the tile in the global reference counter for textures
     *
     * @param {*} url
     * @param {boolean} [debug=false]
     * @memberof Tile
     */
    register(url, debug = false) {
        Tile.unschedule(url)
        if (registeredTiles.has(url)) {
            let tiles = registeredTiles.get(url)
            tiles.add(this)
            if (debug) console.log("Tile.register", url, tiles.size)
        }
        else {
            registeredTiles.set(url, new Set([this]))
            if (debug) console.log("Tile.register", url, 1)
        }
    }

    /**
     * Unregisters the rile in the global reference counter for textures
     *
     * @returns {number} The number of how often a texture is used.
     * @memberof Tile
     */
    unregister() {
        let tiles = registeredTiles.get(this.url)
        tiles.delete(this)
        if (tiles.size == 0) {
            registeredTiles.delete(this.url)
            return 0
        }
        return tiles.size
    }

    /**
     * Destroys this sprite and optionally its texture and children
     *
     * @param {*} options  Part of the PIXI API, but ignored in the implementation
     * @memberof Tile
     */
    destroy(options, debug = true) {
        let count = this.unregister()

        if (keepTextures > 0) {
            keptTextures.push({ url: this.url, texture: this.texture})

            let opts = { children: true, texture: false, baseTexture: false }
            if (debug) console.log("Tile.destroy", registeredTiles.size, opts)
            super.destroy(opts)

            while(keptTextures.length > keepTextures) {
                let {url, texture} = keptTextures.shift() 
                if (Tile.isObsolete(url)) {
                    texture.destroy(true) // Destroy base as well
                    if (debug) console.log("Destroying texture and baseTexture", url)
                }
            }
        }
        else {
            // No longer registered and not pending
            if (count <= 0 && !Tile.isPending(this.url)) {
                let opts = { children: true, texture: true, baseTexture: true }
                super.destroy(opts)
                if (debug) console.log("Tile.destroy", registeredTiles.size, opts)
            }
            else {
                let opts = { children: true, texture: false, baseTexture: false }
                if (debug) console.log("Tile.destroy", registeredTiles.size, opts)
                super.destroy(opts)
            }
            if (this.parent != null) {
                // UO: Emit warning and remove
                console.warn("Destroying tile with parent. Hiding instead")
                this.visible = false
            }
        }
    }

    /**
     * Returns an available texture that can be reused
     *
     * @param {*} url
     * @returns
     * @memberof Tile
     */
    static textureAvailable(url) {
        if (registeredTiles.has(url)) {
            let tiles = registeredTiles.get(url)
            for (let tile of tiles.values()) {
                //console.log("Reusing cached texture", tile.parent)
                return tile.texture
            }
        }
        return null
    }

    /**
     * Texture received too late. We do not need it.
     * @param {*} url 
     * @param {*} texture 
     */
    static lateTexture(url, texture) {
        let destroyBase = !registeredTiles.has(url)
        texture.destroy(destroyBase)
    }

    static printInfos() {
        let references = new Map()
        let multiples = 0
        for (let [url, tiles] of registeredTiles.entries()) {
            let count = tiles.size
            references.set(url, count)
            if (count > 1) {
                multiples += 1
            }
        }
        console.log({ multiples, references })
    }
}