/*
 This file is part of TALER
 (C) 2015 GNUnet e.V.

 TALER is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 TALER is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */


/**
 * Script that is injected into (all!) pages to allow them
 * to interact with the GNU Taler wallet via DOM Events.
 *
 * @author Florian Dold
 */


/// <reference path="../lib/decl/chrome/chrome.d.ts" />
/// <reference path="../lib/decl/urijs/URIjs.d.ts" />

"use strict";

// Make sure we don't pollute the namespace too much.
namespace TalerNotify {
  const PROTOCOL_VERSION = 1;

  if (!taler) {
    console.error("Taler wallet lib not included, HTTP 402 payments not" +
                  " supported");
  }

  function subst(url: string, H_contract: string) {
    url = url.replace("${H_contract}", H_contract);
    url = url.replace("${$}", "$");
    return url;
  }

  interface Handler {
    type: string;
    listener: (e: CustomEvent) => void|Promise<void>;
  }
  const handlers: Handler[] = [];

  function hashContract(contract: string): Promise<string> {
    let walletHashContractMsg = {
      type: "hash-contract",
      detail: {contract}
    };
    return new Promise((resolve, reject) => {
      chrome.runtime.sendMessage(walletHashContractMsg, (resp: any) => {
        if (!resp.hash) {
          console.log("error", resp);
          reject(Error("hashing failed"));
        }
        resolve(resp.hash);
      });
    });
  }

  function checkRepurchase(contract: string): Promise<any> {
    const walletMsg = {
      type: "check-repurchase",
      detail: {
        contract: contract
      },
    };
    return new Promise((resolve, reject) => {
      chrome.runtime.sendMessage(walletMsg, (resp: any) => {
        resolve(resp);
      });
    });
  }

  function putHistory(historyEntry: any): Promise<void> {
    const walletMsg = {
      type: "put-history-entry",
      detail: {
        historyEntry,
      },
    };
    return new Promise((resolve, reject) => {
      chrome.runtime.sendMessage(walletMsg, (resp: any) => {
        resolve();
      });
    });
  }

  function init() {
    chrome.runtime.sendMessage({type: "ping"}, (resp) => {
      if (chrome.runtime.lastError) {
        console.log("extension not yet ready");
        window.setTimeout(init, 200);
        return;
      }
      registerHandlers();
      // Hack to know when the extension is unloaded
      let port = chrome.runtime.connect();

      port.onDisconnect.addListener(() => {
        console.log("chrome runtime disconnected, removing handlers");
        for (let handler of handlers) {
          document.removeEventListener(handler.type, handler.listener);
        }
      });

      if (resp && resp.type === "fetch") {
        console.log("it's fetch");
        taler.internalOfferContractFrom(resp.contractUrl);
        document.documentElement.style.visibility = "hidden";

      } else if (resp && resp.type === "execute") {
        console.log("it's execute");
        document.documentElement.style.visibility = "hidden";
        taler.internalExecutePayment(resp.contractHash,
                                     resp.payUrl,
                                     resp.offerUrl);
      }
    });
  }

  console.log("loading Taler content script");
  init();

  interface HandlerFn {
    (detail: any, sendResponse: (msg: any) => void): void;
  }

  function registerHandlers() {
    /**
     * Add a handler for a DOM event, which automatically
     * handles adding sequence numbers to responses.
     */
    function addHandler(type: string, handler: HandlerFn) {
      let handlerWrap = (e: CustomEvent) => {
        if (e.type != type) {
          throw Error(`invariant violated`);
        }
        let callId: number|undefined = undefined;
        if (e.detail && e.detail.callId != undefined) {
          callId = e.detail.callId;
        }
        let responder = (msg?: any) => {
          let fullMsg = Object.assign({}, msg, {callId});
          let evt = new CustomEvent(type + "-result", {detail: fullMsg});
          document.dispatchEvent(evt);
        };
        handler(e.detail, responder);
      };
      document.addEventListener(type, handlerWrap);
      handlers.push({type, listener: handlerWrap});
    }


    addHandler("taler-query-id", (msg: any, sendResponse: any) => {
      // FIXME: maybe include this info in taoer-probe?
      sendResponse({id: chrome.runtime.id})
    });

    addHandler("taler-probe", (msg: any, sendResponse: any) => {
      sendResponse();
    });

    addHandler("taler-create-reserve", (msg: any) => {
      let params = {
        amount: JSON.stringify(msg.amount),
        callback_url: URI(msg.callback_url)
          .absoluteTo(document.location.href),
        bank_url: document.location.href,
        wt_types: JSON.stringify(msg.wt_types),
      };
      let uri = URI(chrome.extension.getURL("pages/confirm-create-reserve.html"));
      let redirectUrl = uri.query(params).href();
      window.location.href = redirectUrl;
    });

    addHandler("taler-confirm-reserve", (msg: any, sendResponse: any) => {
      let walletMsg = {
        type: "confirm-reserve",
        detail: {
          reservePub: msg.reserve_pub
        }
      };
      chrome.runtime.sendMessage(walletMsg, (resp) => {
        sendResponse();
      });
    });


    addHandler("taler-confirm-contract", async(msg: any) => {
      if (!msg.contract_wrapper) {
        console.error("contract wrapper missing");
        return;
      }

      const offer = msg.contract_wrapper;

      if (!offer.contract) {
        console.error("contract field missing");
        return;
      }

      if (!offer.H_contract) {
        console.error("H_contract field missing");
        return;
      }

      let walletHashContractMsg = {
        type: "hash-contract",
        detail: {contract: offer.contract}
      };

      let contractHash = await hashContract(offer.contract);

      if (contractHash != offer.H_contract) {
        console.error("merchant-supplied contract hash is wrong");
        return;
      }

      let resp = await checkRepurchase(offer.contract);

      if (resp.error) {
        console.error("wallet backend error", resp);
        return;
      }

      if (resp.isRepurchase) {
        console.log("doing repurchase");
        console.assert(resp.existingFulfillmentUrl);
        console.assert(resp.existingContractHash);
        window.location.href = subst(resp.existingFulfillmentUrl,
                                     resp.existingContractHash);

      } else {

        let merchantName = "(unknown)";
        try {
          merchantName = offer.contract.merchant.name;
        } catch (e) {
          // bad contract / name not included
        }

        let historyEntry = {
          timestamp: (new Date).getTime(),
          subjectId: `contract-${contractHash}`,
          type: "offer-contract",
          detail: {
            contractHash,
            merchantName,
          }
        };
        await putHistory(historyEntry);

        const uri = URI(chrome.extension.getURL(
          "pages/confirm-contract.html"));
        const params = {
          offer: JSON.stringify(offer),
          merchantPageUrl: document.location.href,
        };
        const target = uri.query(params).href();
        if (msg.replace_navigation === true) {
          document.location.replace(target);
        } else {
          document.location.href = target;
        }
      }
    });

    addHandler("taler-payment-failed", (msg: any, sendResponse: any) => {
      const walletMsg = {
        type: "payment-failed",
        detail: {},
      };
      chrome.runtime.sendMessage(walletMsg, (resp) => {
        sendResponse();
      })
    });

    addHandler("taler-payment-succeeded", (msg: any, sendResponse: any) => {
      sendResponse();
    });

    addHandler("taler-get-payment", (msg: any, sendResponse: any) => {
      const walletMsg = {
        type: "execute-payment",
        detail: {
          H_contract: msg.H_contract,
        },
      };

      chrome.runtime.sendMessage(walletMsg, (resp) => {
        if (resp.rateLimitExceeded) {
          console.error("rate limit exceeded, check for redirect loops");
        }

        if (!resp.success) {
          if (msg.offering_url) {
            window.location.href = msg.offering_url;
          } else {
            console.error("execute-payment failed", resp);
          }
          return;
        }
        let contract = resp.contract;
        if (!contract) {
          throw Error("contract missing");
        }

        // We have the details for then payment, the merchant page
        // is responsible to give it to the merchant.
        sendResponse({
                       H_contract: msg.H_contract,
                       contract: resp.contract,
                       payment: resp.payReq,
                     });
      });
    });
  }
}