import { Injectable } from "@angular/core";
import { DocumentData } from "../symbols/DocumentData";
import { HttpClient } from "@angular/common/http";
import { take } from "rxjs/operators";

@Injectable({
	providedIn: "root"
})
export class DocumentFetchService {
	private language: string;

	constructor(private http: HttpClient) {
		this.language = document.body.parentElement.lang;
	}

	public async fetch(unsafeId: string): Promise<DocumentData> {
		const encodedId = this.encodeId(unsafeId);
		try {
			return await this.fetchWithLanguage(encodedId, this.language);
		} catch (e) {
			try {
				return await this.fetchWithLanguage(encodedId, "en");
			} catch (e) {
				return {
					found: false,
					id: encodedId,
					content: await this.fetchErrorContent(404)
				};
			}
		}
	}

	private async fetchWithLanguage(unsafeId: string, language: string): Promise<DocumentData> {
		const encodedId = this.encodeId(unsafeId);
		const response: string = await this.http.get("/documents/" + encodedId + "." + language + ".md", { responseType: "text" })
			.pipe(take(1)).toPromise();
		return {
			found: true,
			id: encodedId,
			content: await response
		};
	}

	public async fetchErrorContent(errorCode: number): Promise<string> {
		if (errorCode > 0 && errorCode <= 700) {
			try {
				const response: string = await this.http.get("/documents/" + errorCode + "." + this.language + ".md", { responseType: "text" })
					.pipe(take(1)).toPromise();
				return response;
			} catch (e) {
			}
		}
		return "Error " + errorCode + ".";
	}

	private encodeId(id: string): string {
		const encoded = id.split("/").map(encodeURIComponent).filter((part) => part.length > 0 && !/[^a-zA-Z0-9_-àùéèì]/.test(part)).join("/");
		if (encoded.length > 0) {
			return encoded;
		} else {
			return "index";
		}
	}
}