import { I18nService as I18nServiceAbstraction } from '../abstractions/i18n.service';

export class I18nService implements I18nServiceAbstraction {
    locale: string;
    // First locale is the default (English)
    supportedTranslationLocales: string[] = ['en'];
    translationLocale: string;
    collator: Intl.Collator;

    protected inited: boolean;
    protected defaultMessages: any = {};
    protected localeMessages: any = {};

    constructor(protected systemLanguage: string, protected localesDirectory: string,
        protected getLocalesJson: (formattedLocale: string) => Promise<any>) {
        this.systemLanguage = systemLanguage.replace('_', '-');
    }

    async init(locale?: string) {
        if (this.inited) {
            throw new Error('i18n already initialized.');
        }
        if (this.supportedTranslationLocales == null || this.supportedTranslationLocales.length === 0) {
            throw new Error('supportedTranslationLocales not set.');
        }

        this.inited = true;
        this.locale = this.translationLocale = locale != null ? locale : this.systemLanguage;

        try {
            this.collator = new Intl.Collator(this.locale);
        } catch {
            this.collator = null;
        }

        if (this.supportedTranslationLocales.indexOf(this.translationLocale) === -1) {
            this.translationLocale = this.translationLocale.slice(0, 2);

            if (this.supportedTranslationLocales.indexOf(this.translationLocale) === -1) {
                this.translationLocale = this.supportedTranslationLocales[0];
            }
        }

        if (this.localesDirectory != null) {
            await this.loadMessages(this.translationLocale, this.localeMessages);
            if (this.translationLocale !== this.supportedTranslationLocales[0]) {
                await this.loadMessages(this.supportedTranslationLocales[0], this.defaultMessages);
            }
        }
    }

    t(id: string, p1?: string, p2?: string, p3?: string): string {
        return this.translate(id, p1, p2, p3);
    }

    translate(id: string, p1?: string, p2?: string, p3?: string): string {
        let result: string;
        if (this.localeMessages.hasOwnProperty(id) && this.localeMessages[id]) {
            result = this.localeMessages[id];
        } else if (this.defaultMessages.hasOwnProperty(id) && this.defaultMessages[id]) {
            result = this.defaultMessages[id];
        } else {
            result = '';
        }

        if (result !== '') {
            if (p1 != null) {
                result = result.split('__$1__').join(p1);
            }
            if (p2 != null) {
                result = result.split('__$2__').join(p2);
            }
            if (p3 != null) {
                result = result.split('__$3__').join(p3);
            }
        }

        return result;
    }

    private async loadMessages(locale: string, messagesObj: any): Promise<any> {
        const formattedLocale = locale.replace('-', '_');
        const locales = await this.getLocalesJson(formattedLocale);
        for (const prop in locales) {
            if (!locales.hasOwnProperty(prop)) {
                continue;
            }
            messagesObj[prop] = locales[prop].message;

            if (locales[prop].placeholders) {
                for (const placeProp in locales[prop].placeholders) {
                    if (!locales[prop].placeholders.hasOwnProperty(placeProp) ||
                        !locales[prop].placeholders[placeProp].content) {
                        continue;
                    }

                    const replaceToken = '\\$' + placeProp.toUpperCase() + '\\$';
                    let replaceContent = locales[prop].placeholders[placeProp].content;
                    if (replaceContent === '$1' || replaceContent === '$2' || replaceContent === '$3') {
                        replaceContent = '__' + replaceContent + '__';
                    }
                    messagesObj[prop] = messagesObj[prop].replace(new RegExp(replaceToken, 'g'), replaceContent);
                }
            }
        }
    }

}