import { action } from "mobx";

import { TokenStore } from "@client/state/TokenStore";
import ApiError from "@common/ApiError";
import { ErrorCode } from "@common/ErrorCode";
import { TokenGrantPasswordRequest, TokenGrantRefreshRequest, TokenGrantResponse } from "@common/httpApi";
import log from "@common/logger";
import { DefaultEvents, TypedEventEmitter } from "@common/TypedEventEmitter";

export { ApiError };

interface HttpApiEvents extends DefaultEvents {
    tokenGranted(response: TokenGrantResponse): void;
    error(err: ApiError): void;
    tokenError(err: ApiError): void;
}

export default class HttpApi extends TypedEventEmitter<HttpApiEvents> {
    baseUrl: string;

    tokenStore: TokenStore;

    private get authorizationHeader(): {} | { "Authorization": string } {
        if (!this.tokenStore.accessToken) {
            return {};
        }
        return { Authorization: `Bearer ${this.tokenStore.accessToken.token}` };
    }

    constructor(baseUrl: string = `${location.protocol}//${location.hostname}:${location.port}/api`) {
        super();
        while (baseUrl.charAt(baseUrl.length - 1) === "/") {
            baseUrl = baseUrl.substring(0, baseUrl.length - 1);
        }
        this.baseUrl = baseUrl;

        this.tokenStore = new TokenStore();

        this.on("error", (err: ApiError) => {
            if (err.code === ErrorCode.BadToken) {
                this.emit("tokenError", err);
            }
        });

        this.on("tokenGranted", this.onTokenGranted);
    }

    async makeRequest(url: string, options?: RequestInit, body?: any): Promise<any> {
        try {
            options = options || {};
            options = {
                headers: {
                    "Content-Type": "application/json",
                    ...this.authorizationHeader,
                    ...options.headers || {},
                },
                body: JSON.stringify(body),
                ...options,
            };
            let response: Response;
            try {
                response = await fetch(this.baseUrl + url, options);
            } catch (err) {
                throw new ApiError("Http request error", ErrorCode.Internal, err);
            }
            let responseBody: any;
            try {
                responseBody = await response.json() || {};
            } catch (e) {
                throw new ApiError("Invalid JSON response", ErrorCode.Internal, e);
            }
            if (!response.ok) {
                throw new ApiError(responseBody.message || response.statusText, responseBody.code, responseBody.data);
            }
            return responseBody;
        } catch (err) {
            this.emit("error", err);
            throw err;
        }
    }

    async grantPassword(username: string, password: string) {
        const request: TokenGrantPasswordRequest = {
            grant_type: "password", username, password,
        };
        const response: TokenGrantResponse = await this.makeRequest("/token/grant", {
            method: "POST",
        }, request);
        this.emit("tokenGranted", response);
    }

    async grantRefresh() {
        const { refreshToken } = this.tokenStore;
        if (!refreshToken.isValid) {
            throw new ApiError("can not grant refresh with invalid refresh_token");
        }
        const request: TokenGrantRefreshRequest = {
            grant_type: "refresh", refresh_token: refreshToken.token!,
        };
        const response: TokenGrantResponse = await this.makeRequest("/token/grant", {
            method: "POST",
        }, request);
        this.emit("tokenGranted", response);
    }

    @action.bound
    private onTokenGranted(response: TokenGrantResponse) {
        this.tokenStore.accessToken.token = response.access_token;
        this.tokenStore.refreshToken.token = response.refresh_token;
        this.tokenStore.saveLocalStorage();
        const { accessToken, refreshToken } = this.tokenStore;
        log.debug({
            accessToken: accessToken.claims, refreshToken: refreshToken.claims,
        }, "got new tokens");
    }
}