/**
 * Localizer.js
 *
 * @author realor
 */

import { Bundle } from './Bundle.js'
import { BundleManager } from './BundleManager.js'

class I18N {
    static SEPARATOR = '|'

    _userLanguages = ['zh-CN']
    _requestedLanguages = null
    _supportedLanguages = new Set()
    defaultBundle = BundleManager.getBundle('base')

    constructor() {}

    static set(element, property, key, ...args) {
        if (element.i18n === undefined) {
            element.i18n = {}
        }
        element.i18n[property] = {
            key: key,
            args: args
        }
        element[property] = key
    }

    addSupportedLanguages(...languages) {
        for (let language of languages) {
            this._supportedLanguages.add(language)
        }
        this._requestedLanguages = null
    }

    get supportedLanguages() {
        return Array.from(this._supportedLanguages)
    }

    get userLanguages() {
        return this._userLanguages
    }

    set userLanguages(languages) {
        if (typeof languages === 'string') {
            this._userLanguages = [languages]
            this._requestedLanguages = null
        } else if (languages instanceof Array) {
            this._userLanguages = languages
            this._requestedLanguages = null
        }
    }

    get requestedLanguages() {
        if (this._requestedLanguages === null) {
            let set = new Set()
            this.userLanguages.forEach(language => {
                if (this._supportedLanguages.has(language)) {
                    set.add(language)
                }
                let parts = language.split('-')
                if (parts.length > 1) {
                    if (this._supportedLanguages.has(parts[0])) {
                        set.add(parts[0])
                    }
                }
            })
            set.add('') // default language
            this._requestedLanguages = Array.from(set)
        }
        return this._requestedLanguages
    }

    get(key, ...args) {
        if (typeof key !== 'string') return ''

        let bundle = null
        let index = key.indexOf(I18N.SEPARATOR)
        if (index === -1) {
            bundle = this.defaultBundle
        } else {
            bundle = BundleManager.getBundle(key.substring(0, index))
            key = key.substring(index + 1)
        }
        return bundle ? bundle.get(this.requestedLanguages, key, ...args) : key
    }

    updateTree(rootElement) {
        const promises = []
        const bundles = BundleManager.getBundles()
        bundles.forEach(bundle => {
            let promise = bundle.load(this.requestedLanguages)
            promises.push(promise)
        })

        Promise.allSettled(promises).finally(() => {
            const elements = rootElement.getElementsByTagName('*')
            for (let element of elements) {
                this.update(element)
            }
        })
    }

    update(element) {
        if (element.i18n) {
            for (let property in element.i18n) {
                let def = element.i18n[property]
                element[property] = this.get(def.key, ...def.args)
            }
        }
    }
}

export { I18N }