/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

/* global browser, module, onMessageFromTab */

class AboutCompatBroker {
  constructor(bindings) {
    this._injections = bindings.injections;
    this._uaOverrides = bindings.uaOverrides;
    this._shims = bindings.shims;

    if (!this._injections && !this._uaOverrides && !this._shims) {
      throw new Error("No interventions; about:compat broker is not needed");
    }

    this.portsToAboutCompatTabs = this.buildPorts();
    this._injections?.bindAboutCompatBroker(this);
    this._uaOverrides?.bindAboutCompatBroker(this);
    this._shims?.bindAboutCompatBroker(this);
  }

  buildPorts() {
    const ports = new Set();

    browser.runtime.onConnect.addListener(port => {
      ports.add(port);
      port.onDisconnect.addListener(function() {
        ports.delete(port);
      });
    });

    async function broadcast(message) {
      for (const port of ports) {
        port.postMessage(message);
      }
    }

    return { broadcast };
  }

  filterOverrides(overrides) {
    return overrides
      .filter(override => override.availableOnPlatform)
      .map(override => {
        const { id, active, bug, domain, hidden } = override;
        return { id, active, bug, domain, hidden };
      });
  }

  getInterventionById(id) {
    for (const [type, things] of Object.entries({
      overrides: this._uaOverrides?.getAvailableOverrides() || [],
      interventions: this._injections?.getAvailableInjections() || [],
      shims: this._shims?.getAvailableShims() || [],
    })) {
      for (const what of things) {
        if (what.id === id) {
          return { type, what };
        }
      }
    }
    return {};
  }

  bootup() {
    onMessageFromTab(msg => {
      switch (msg.command || msg) {
        case "toggle": {
          const id = msg.id;
          const { type, what } = this.getInterventionById(id);
          if (!what) {
            return Promise.reject(
              `No such override or intervention to toggle: ${id}`
            );
          }
          const active = type === "shims" ? !what.disabledReason : what.active;
          this.portsToAboutCompatTabs
            .broadcast({ toggling: id, active })
            .then(async () => {
              switch (type) {
                case "interventions": {
                  if (active) {
                    await this._injections?.disableInjection(what);
                  } else {
                    await this._injections?.enableInjection(what);
                  }
                  break;
                }
                case "overrides": {
                  if (active) {
                    await this._uaOverrides?.disableOverride(what);
                  } else {
                    await this._uaOverrides?.enableOverride(what);
                  }
                  break;
                }
                case "shims": {
                  if (active) {
                    await this._shims?.disableShimForSession(id);
                  } else {
                    await this._shims?.enableShimForSession(id);
                  }
                  // no need to broadcast the "toggled" signal for shims, as
                  // they send a shimsUpdated message themselves instead
                  return;
                }
              }
              this.portsToAboutCompatTabs.broadcast({
                toggled: id,
                active: !active,
              });
            });
          break;
        }
        case "getAllInterventions": {
          return Promise.resolve({
            overrides:
              (this._uaOverrides?.isEnabled() &&
                this.filterOverrides(
                  this._uaOverrides?.getAvailableOverrides()
                )) ||
              false,
            interventions:
              (this._injections?.isEnabled() &&
                this.filterOverrides(
                  this._injections?.getAvailableInjections()
                )) ||
              false,
            shims: this._shims?.getAvailableShims() || false,
          });
        }
      }
      return undefined;
    });
  }
}

module.exports = AboutCompatBroker;