import { Map as ImmutableMap, List as ImmutableList, OrderedSet as ImmutableOrderedSet, fromJS } from "immutable";

import {
  COMPOSE_MOUNT,
  COMPOSE_UNMOUNT,
  COMPOSE_CHANGE,
  COMPOSE_CYCLE_ELEFRIEND,
  COMPOSE_REPLY,
  COMPOSE_REPLY_CANCEL,
  COMPOSE_DIRECT,
  COMPOSE_MENTION,
  COMPOSE_SUBMIT_REQUEST,
  COMPOSE_SUBMIT_SUCCESS,
  COMPOSE_SUBMIT_FAIL,
  COMPOSE_UPLOAD_REQUEST,
  COMPOSE_UPLOAD_SUCCESS,
  COMPOSE_UPLOAD_FAIL,
  COMPOSE_UPLOAD_UNDO,
  COMPOSE_UPLOAD_PROGRESS,
  COMPOSE_UPLOAD_PROCESSING,
  THUMBNAIL_UPLOAD_REQUEST,
  THUMBNAIL_UPLOAD_SUCCESS,
  THUMBNAIL_UPLOAD_FAIL,
  THUMBNAIL_UPLOAD_PROGRESS,
  COMPOSE_SUGGESTIONS_CLEAR,
  COMPOSE_SUGGESTIONS_READY,
  COMPOSE_SUGGESTION_SELECT,
  COMPOSE_SUGGESTION_IGNORE,
  COMPOSE_SUGGESTION_TAGS_UPDATE,
  COMPOSE_TAG_HISTORY_UPDATE,
  COMPOSE_ADVANCED_OPTIONS_CHANGE,
  COMPOSE_SENSITIVITY_CHANGE,
  COMPOSE_SPOILERNESS_CHANGE,
  COMPOSE_SPOILER_TEXT_CHANGE,
  COMPOSE_VISIBILITY_CHANGE,
  COMPOSE_LANGUAGE_CHANGE,
  COMPOSE_CONTENT_TYPE_CHANGE,
  COMPOSE_EMOJI_INSERT,
  COMPOSE_UPLOAD_CHANGE_REQUEST,
  COMPOSE_UPLOAD_CHANGE_SUCCESS,
  COMPOSE_UPLOAD_CHANGE_FAIL,
  COMPOSE_DOODLE_SET,
  COMPOSE_RESET,
  COMPOSE_POLL_ADD,
  COMPOSE_POLL_REMOVE,
  COMPOSE_POLL_OPTION_ADD,
  COMPOSE_POLL_OPTION_CHANGE,
  COMPOSE_POLL_OPTION_REMOVE,
  COMPOSE_POLL_SETTINGS_CHANGE,
  INIT_MEDIA_EDIT_MODAL,
  COMPOSE_CHANGE_MEDIA_DESCRIPTION,
  COMPOSE_CHANGE_MEDIA_FOCUS,
  COMPOSE_SET_STATUS,
} from "flavours/glitch/actions/compose";
import { REDRAFT } from "flavours/glitch/actions/statuses";
import { STORE_HYDRATE } from "flavours/glitch/actions/store";
import { TIMELINE_DELETE } from "flavours/glitch/actions/timelines";
import { me, defaultContentType } from "flavours/glitch/initial_state";
import { recoverHashtags } from "flavours/glitch/utils/hashtag";
import { unescapeHTML } from "flavours/glitch/utils/html";
import { overwrite } from "flavours/glitch/utils/js_helpers";
import { privacyPreference } from "flavours/glitch/utils/privacy_preference";

import { uuid } from "../uuid";

const totalElefriends = 3;

// ~4% chance you'll end up with an unexpected friend
// glitch-soc/mastodon repo created_at date: 2017-04-20T21:55:28Z
const glitchProbability = 1 - 0.0420215528;

const initialState = ImmutableMap({
  mounted: 0,
  advanced_options: ImmutableMap({
    do_not_federate: false,
    threaded_mode: false,
  }),
  sensitive: false,
  elefriend: Math.random() < glitchProbability ? Math.floor(Math.random() * totalElefriends) : totalElefriends,
  spoiler: false,
  spoiler_text: "",
  privacy: null,
  id: null,
  content_type: defaultContentType || "text/plain",
  text: "",
  focusDate: null,
  caretPosition: null,
  preselectDate: null,
  in_reply_to: null,
  is_submitting: false,
  is_uploading: false,
  is_changing_upload: false,
  progress: 0,
  isUploadingThumbnail: false,
  thumbnailProgress: 0,
  media_attachments: ImmutableList(),
  pending_media_attachments: 0,
  poll: null,
  suggestion_token: null,
  suggestions: ImmutableList(),
  default_advanced_options: ImmutableMap({
    do_not_federate: false,
    threaded_mode: null,  //  Do not reset
  }),
  default_privacy: "public",
  default_sensitive: false,
  default_language: "en",
  resetFileKey: Math.floor((Math.random() * 0x10000)),
  idempotencyKey: null,
  tagHistory: ImmutableList(),
  media_modal: ImmutableMap({
    id: null,
    description: "",
    focusX: 0,
    focusY: 0,
    dirty: false,
  }),
  doodle: ImmutableMap({
    fg: "rgb(  0,    0,    0)",
    bg: "rgb(255,  255,  255)",
    swapped: false,
    mode: "draw",
    size: "normal",
    weight: 2,
    opacity: 1,
    adaptiveStroke: true,
    smoothing: false,
  }),
});

const initialPoll = ImmutableMap({
  options: ImmutableList(["", ""]),
  expires_in: 24 * 3600,
  multiple: false,
});

function statusToTextMentions(state, status) {
  let set = ImmutableOrderedSet([]);

  if (status.getIn(["account", "id"]) !== me) {
    set = set.add(`@${status.getIn(["account", "acct"])} `);
  }

  return set.union(status.get("mentions").filterNot(mention => mention.get("id") === me).map(mention => `@${mention.get("acct")} `)).join("");
}

function apiStatusToTextMentions (state, status) {
  let set = ImmutableOrderedSet([]);

  if (status.account.id !== me) {
    set = set.add(`@${status.account.acct} `);
  }

  return set.union(status.mentions.filter(
    mention => mention.id !== me,
  ).map(
    mention => `@${mention.acct} `,
  )).join("");
}

function apiStatusToTextHashtags (state, status) {
  const text = unescapeHTML(status.content);
  return ImmutableOrderedSet([]).union(recoverHashtags(status.tags, text).map(
    (name) => `#${name} `,
  )).join("");
}

function clearAll(state) {
  return state.withMutations(map => {
    map.set("id", null);
    map.set("text", "");
    if (defaultContentType) {
      map.set("content_type", defaultContentType);
    }
    map.set("spoiler", false);
    map.set("spoiler_text", "");
    map.set("is_submitting", false);
    map.set("is_changing_upload", false);
    map.set("in_reply_to", null);
    map.update(
      "advanced_options",
      map => map.mergeWith(overwrite, state.get("default_advanced_options")),
    );
    map.set("privacy", state.get("default_privacy"));
    map.set("sensitive", state.get("default_sensitive"));
    map.set("language", state.get("default_language"));
    map.update("media_attachments", list => list.clear());
    map.set("poll", null);
    map.set("idempotencyKey", uuid());
  });
}

function continueThread (state, status) {
  return state.withMutations(function (map) {
    let text = apiStatusToTextMentions(state, status);
    text = text + apiStatusToTextHashtags(state, status);
    map.set("text", text);
    if (status.spoiler_text) {
      map.set("spoiler", true);
      map.set("spoiler_text", status.spoiler_text);
    } else {
      map.set("spoiler", false);
      map.set("spoiler_text", "");
    }
    map.set("is_submitting", false);
    map.set("in_reply_to", status.id);
    map.update(
      "advanced_options",
      map => map.merge(new ImmutableMap({ do_not_federate: status.local_only })),
    );
    map.set("privacy", status.visibility);
    map.set("sensitive", false);
    map.update("media_attachments", list => list.clear());
    map.set("poll", null);
    map.set("idempotencyKey", uuid());
    map.set("focusDate", new Date());
    map.set("caretPosition", null);
    map.set("preselectDate", new Date());
  });
}

function appendMedia(state, media, file) {
  const prevSize = state.get("media_attachments").size;

  return state.withMutations(map => {
    if (media.get("type") === "image") {
      media = media.set("file", file);
    }
    map.update("media_attachments", list => list.push(media.set("unattached", true)));
    map.set("is_uploading", false);
    map.set("is_processing", false);
    map.set("resetFileKey", Math.floor((Math.random() * 0x10000)));
    map.set("idempotencyKey", uuid());
    map.update("pending_media_attachments", n => n - 1);

    if (prevSize === 0 && (state.get("default_sensitive") || state.get("spoiler"))) {
      map.set("sensitive", true);
    }
  });
}

function removeMedia(state, mediaId) {
  const prevSize = state.get("media_attachments").size;

  return state.withMutations(map => {
    map.update("media_attachments", list => list.filterNot(item => item.get("id") === mediaId));
    map.set("idempotencyKey", uuid());

    if (prevSize === 1) {
      map.set("sensitive", false);
    }
  });
}

const insertSuggestion = (state, position, token, completion, path) => {
  return state.withMutations(map => {
    map.updateIn(path, oldText => `${oldText.slice(0, position)}${completion}${completion[0] === ":" ? "\u200B" : " "}${oldText.slice(position + token.length)}`);
    map.set("suggestion_token", null);
    map.set("suggestions", ImmutableList());
    if (path.length === 1 && path[0] === "text") {
      map.set("focusDate", new Date());
      map.set("caretPosition", position + completion.length + 1);
    }
    map.set("idempotencyKey", uuid());
  });
};

const ignoreSuggestion = (state, position, token, completion, path) => {
  return state.withMutations(map => {
    map.updateIn(path, oldText => `${oldText.slice(0, position + token.length)} ${oldText.slice(position + token.length)}`);
    map.set("suggestion_token", null);
    map.set("suggestions", ImmutableList());
    map.set("focusDate", new Date());
    map.set("caretPosition", position + token.length + 1);
    map.set("idempotencyKey", uuid());
  });
};

const sortHashtagsByUse = (state, tags) => {
  const personalHistory = state.get("tagHistory").map(tag => tag.toLowerCase());

  const tagsWithLowercase = tags.map(t => ({ ...t, lowerName: t.name.toLowerCase() }));
  const sorted = tagsWithLowercase.sort((a, b) => {
    const usedA = personalHistory.includes(a.lowerName);
    const usedB = personalHistory.includes(b.lowerName);

    if (usedA === usedB) {
      return 0;
    } else if (usedA && !usedB) {
      return -1;
    } else {
      return 1;
    }
  });
  sorted.forEach(tag => delete tag.lowerName);
  return sorted;
};

const insertEmoji = (state, position, emojiData) => {
  const emoji = emojiData.native;

  return state.withMutations(map => {
    map.update("text", oldText => `${oldText.slice(0, position)}${emoji}\u200B${oldText.slice(position)}`);
    map.set("focusDate", new Date());
    map.set("caretPosition", position + emoji.length + 1);
    map.set("idempotencyKey", uuid());
  });
};

const hydrate = (state, hydratedState) => {
  state = clearAll(state.merge(hydratedState));

  if (hydratedState.get("text")) {
    state = state.set("text", hydratedState.get("text")).set("focusDate", new Date());
  }

  return state;
};

const domParser = new DOMParser();

const expandMentions = status => {
  const fragment = domParser.parseFromString(status.get("content"), "text/html").documentElement;

  status.get("mentions").forEach(mention => {
    fragment.querySelector(`a[href="${mention.get("url")}"]`).textContent = `@${mention.get("acct")}`;
  });

  return fragment.innerHTML;
};

const expiresInFromExpiresAt = expires_at => {
  if (!expires_at) {
    return 24 * 3600;
  }
  const delta = (new Date(expires_at).getTime() - Date.now()) / 1000;
  return [300, 1800, 3600, 21600, 86400, 259200, 604800].find(expires_in => expires_in >= delta) || 24 * 3600;
};

const mergeLocalHashtagResults = (suggestions, prefix, tagHistory) => {
  prefix = prefix.toLowerCase();
  if (suggestions.length < 4) {
    const localTags = tagHistory.filter(tag => tag.toLowerCase().startsWith(prefix) && !suggestions.some(suggestion => suggestion.type === "hashtag" && suggestion.name.toLowerCase() === tag.toLowerCase()));
    return suggestions.concat(localTags.slice(0, 4 - suggestions.length).toJS().map(tag => ({ type: "hashtag", name: tag })));
  } else {
    return suggestions;
  }
};

const normalizeSuggestions = (state, { accounts, emojis, tags, token }) => {
  if (accounts) {
    return accounts.map(item => ({ id: item.id, type: "account" }));
  } else if (emojis) {
    return emojis.map(item => ({ ...item, type: "emoji" }));
  } else {
    return mergeLocalHashtagResults(sortHashtagsByUse(state, tags.map(item => ({ ...item, type: "hashtag" }))), token.slice(1), state.get("tagHistory"));
  }
};

const updateSuggestionTags = (state, token) => {
  const prefix = token.slice(1);

  const suggestions = state.get("suggestions").toJS();
  return state.merge({
    suggestions: ImmutableList(mergeLocalHashtagResults(suggestions, prefix, state.get("tagHistory"))),
    suggestion_token: token,
  });
};

export default function compose(state = initialState, action) {
  switch(action.type) {
    case STORE_HYDRATE:
      return hydrate(state, action.state.get("compose"));
    case COMPOSE_MOUNT:
      return state.set("mounted", state.get("mounted") + 1);
    case COMPOSE_UNMOUNT:
      return state.set("mounted", Math.max(state.get("mounted") - 1, 0));
    case COMPOSE_ADVANCED_OPTIONS_CHANGE:
      return state
        .set("advanced_options", state.get("advanced_options").set(action.option, !!overwrite(!state.getIn(["advanced_options", action.option]), action.value)))
        .set("idempotencyKey", uuid());
    case COMPOSE_SENSITIVITY_CHANGE:
      return state.withMutations(map => {
        if (!state.get("spoiler")) {
          map.set("sensitive", !state.get("sensitive"));
        }

        map.set("idempotencyKey", uuid());
      });
    case COMPOSE_SPOILERNESS_CHANGE:
      return state.withMutations(map => {
        map.set("spoiler", !state.get("spoiler"));
        map.set("idempotencyKey", uuid());

        if (!state.get("sensitive") && state.get("media_attachments").size >= 1) {
          map.set("sensitive", true);
        }
      });
    case COMPOSE_SPOILER_TEXT_CHANGE:
      return state
        .set("spoiler_text", action.text)
        .set("idempotencyKey", uuid());
    case COMPOSE_VISIBILITY_CHANGE:
      return state
        .set("privacy", action.value)
        .set("idempotencyKey", uuid());
    case COMPOSE_CONTENT_TYPE_CHANGE:
      return state
        .set("content_type", action.value)
        .set("idempotencyKey", uuid());
    case COMPOSE_CHANGE:
      return state
        .set("text", action.text)
        .set("idempotencyKey", uuid());
    case COMPOSE_CYCLE_ELEFRIEND:
      return state
        .set("elefriend", (state.get("elefriend") + 1) % totalElefriends);
    case COMPOSE_REPLY:
      return state.withMutations(map => {
        map.set("id", null);
        map.set("in_reply_to", action.status.get("id"));
        map.set("text", statusToTextMentions(state, action.status));
        map.set("privacy", privacyPreference(action.status.get("visibility"), state.get("default_privacy")));
        map.update(
          "advanced_options",
          map => map.merge(new ImmutableMap({ do_not_federate: !!action.status.get("local_only") })),
        );
        map.set("focusDate", new Date());
        map.set("caretPosition", null);
        map.set("preselectDate", new Date());
        map.set("idempotencyKey", uuid());

        map.update("media_attachments", list => list.filter(media => media.get("unattached")));

        if (action.status.get("language") && !action.status.has("translation")) {
          map.set("language", action.status.get("language"));
        } else {
          map.set("language", state.get("default_language"));
        }

        if (action.status.get("spoiler_text").length > 0) {
          let spoiler_text = action.status.get("spoiler_text");
          if (action.prependCWRe && !spoiler_text.match(/^re[: ]/i)) {
            spoiler_text = "re: ".concat(spoiler_text);
          }
          map.set("spoiler", true);
          map.set("spoiler_text", spoiler_text);
        } else {
          map.set("spoiler", false);
          map.set("spoiler_text", "");
        }
      });
    case COMPOSE_REPLY_CANCEL:
      state = state.setIn(["advanced_options", "threaded_mode"], false);
    // eslint-disable-next-line no-fallthrough -- fall-through to `COMPOSE_RESET` is intended
    case COMPOSE_RESET:
      return state.withMutations(map => {
        map.set("in_reply_to", null);
        if (defaultContentType) {
          map.set("content_type", defaultContentType);
        }
        map.set("text", "");
        map.set("spoiler", false);
        map.set("spoiler_text", "");
        map.set("privacy", state.get("default_privacy"));
        map.set("id", null);
        map.set("poll", null);
        map.set("language", state.get("default_language"));
        map.update(
          "advanced_options",
          map => map.mergeWith(overwrite, state.get("default_advanced_options")),
        );
        map.set("idempotencyKey", uuid());
      });
    case COMPOSE_SUBMIT_REQUEST:
      return state.set("is_submitting", true);
    case COMPOSE_UPLOAD_CHANGE_REQUEST:
      return state.set("is_changing_upload", true);
    case COMPOSE_SUBMIT_SUCCESS:
      return action.status && state.getIn(["advanced_options", "threaded_mode"]) ? continueThread(state, action.status) : clearAll(state);
    case COMPOSE_SUBMIT_FAIL:
      return state.set("is_submitting", false);
    case COMPOSE_UPLOAD_CHANGE_FAIL:
      return state.set("is_changing_upload", false);
    case COMPOSE_UPLOAD_REQUEST:
      return state.set("is_uploading", true).update("pending_media_attachments", n => n + 1);
    case COMPOSE_UPLOAD_PROCESSING:
      return state.set("is_processing", true);
    case COMPOSE_UPLOAD_SUCCESS:
      return appendMedia(state, fromJS(action.media), action.file);
    case COMPOSE_UPLOAD_FAIL:
      return state.set("is_uploading", false).set("is_processing", false).update("pending_media_attachments", n => n - 1);
    case COMPOSE_UPLOAD_UNDO:
      return removeMedia(state, action.media_id);
    case COMPOSE_UPLOAD_PROGRESS:
      return state.set("progress", Math.round((action.loaded / action.total) * 100));
    case THUMBNAIL_UPLOAD_REQUEST:
      return state.set("isUploadingThumbnail", true);
    case THUMBNAIL_UPLOAD_PROGRESS:
      return state.set("thumbnailProgress", Math.round((action.loaded / action.total) * 100));
    case THUMBNAIL_UPLOAD_FAIL:
      return state.set("isUploadingThumbnail", false);
    case THUMBNAIL_UPLOAD_SUCCESS:
      return state
        .set("isUploadingThumbnail", false)
        .update("media_attachments", list => list.map(item => {
          if (item.get("id") === action.media.id) {
            return fromJS(action.media);
          }

          return item;
        }));
    case INIT_MEDIA_EDIT_MODAL:
      const media =  state.get("media_attachments").find(item => item.get("id") === action.id);
      return state.set("media_modal", ImmutableMap({
        id: action.id,
        description: media.get("description") || "",
        focusX: media.getIn(["meta", "focus", "x"], 0),
        focusY: media.getIn(["meta", "focus", "y"], 0),
        dirty: false,
      }));
    case COMPOSE_CHANGE_MEDIA_DESCRIPTION:
      return state.setIn(["media_modal", "description"], action.description).setIn(["media_modal", "dirty"], true);
    case COMPOSE_CHANGE_MEDIA_FOCUS:
      return state.setIn(["media_modal", "focusX"], action.focusX).setIn(["media_modal", "focusY"], action.focusY).setIn(["media_modal", "dirty"], true);
    case COMPOSE_MENTION:
      return state.withMutations(map => {
        map.update("text", text => [text.trim(), `@${action.account.get("acct")} `].filter((str) => str.length !== 0).join(" "));
        map.set("focusDate", new Date());
        map.set("caretPosition", null);
        map.set("idempotencyKey", uuid());
      });
    case COMPOSE_DIRECT:
      return state.withMutations(map => {
        map.update("text", text => [text.trim(), `@${action.account.get("acct")} `].filter((str) => str.length !== 0).join(" "));
        map.set("privacy", "direct");
        map.set("focusDate", new Date());
        map.set("caretPosition", null);
        map.set("idempotencyKey", uuid());
      });
    case COMPOSE_SUGGESTIONS_CLEAR:
      return state.update("suggestions", ImmutableList(), list => list.clear()).set("suggestion_token", null);
    case COMPOSE_SUGGESTIONS_READY:
      return state.set("suggestions", ImmutableList(normalizeSuggestions(state, action))).set("suggestion_token", action.token);
    case COMPOSE_SUGGESTION_SELECT:
      return insertSuggestion(state, action.position, action.token, action.completion, action.path);
    case COMPOSE_SUGGESTION_IGNORE:
      return ignoreSuggestion(state, action.position, action.token, action.completion, action.path);
    case COMPOSE_SUGGESTION_TAGS_UPDATE:
      return updateSuggestionTags(state, action.token);
    case COMPOSE_TAG_HISTORY_UPDATE:
      return state.set("tagHistory", fromJS(action.tags));
    case TIMELINE_DELETE:
      if (action.id === state.get("in_reply_to")) {
        return state.set("in_reply_to", null);
      } else if (action.id === state.get("id")) {
        return state.set("id", null);
      } else {
        return state;
      }
    case COMPOSE_EMOJI_INSERT:
      return insertEmoji(state, action.position, action.emoji);
    case COMPOSE_UPLOAD_CHANGE_SUCCESS:
      return state
        .set("is_changing_upload", false)
        .setIn(["media_modal", "dirty"], false)
        .update("media_attachments", list => list.map(item => {
          if (item.get("id") === action.media.id) {
            return fromJS(action.media).set("unattached", !action.attached);
          }

          return item;
        }));
    case COMPOSE_DOODLE_SET:
      return state.mergeIn(["doodle"], action.options);
    case REDRAFT:
      const do_not_federate = !!action.status.get("local_only");
      let text = action.raw_text || unescapeHTML(expandMentions(action.status));
      return state.withMutations(map => {
        map.set("text", text);
        map.set("content_type", action.content_type || "text/plain");
        map.set("in_reply_to", action.status.get("in_reply_to_id"));
        map.set("privacy", action.status.get("visibility"));
        map.set("media_attachments", action.status.get("media_attachments").map((media) => media.set("unattached", true)));
        map.set("focusDate", new Date());
        map.set("caretPosition", null);
        map.set("idempotencyKey", uuid());
        map.set("sensitive", action.status.get("sensitive"));
        map.set("language", action.status.get("language"));
        map.update(
          "advanced_options",
          map => map.merge(new ImmutableMap({ do_not_federate })),
        );
        map.set("id", null);

        if (action.status.get("spoiler_text").length > 0) {
          map.set("spoiler", true);
          map.set("spoiler_text", action.status.get("spoiler_text"));

          if (map.get("media_attachments").size >= 1) {
            map.set("sensitive", true);
          }
        } else {
          map.set("spoiler", false);
          map.set("spoiler_text", "");
        }

        if (action.status.get("poll")) {
          map.set("poll", ImmutableMap({
            options: action.status.getIn(["poll", "options"]).map(x => x.get("title")),
            multiple: action.status.getIn(["poll", "multiple"]),
            expires_in: expiresInFromExpiresAt(action.status.getIn(["poll", "expires_at"])),
          }));
        }
      });
    case COMPOSE_SET_STATUS:
      return state.withMutations(map => {
        map.set("id", action.status.get("id"));
        map.set("text", action.text);
        map.set("content_type", action.content_type || "text/plain");
        map.set("in_reply_to", action.status.get("in_reply_to_id"));
        map.set("privacy", action.status.get("visibility"));
        map.set("media_attachments", action.status.get("media_attachments"));
        map.set("focusDate", new Date());
        map.set("caretPosition", null);
        map.set("idempotencyKey", uuid());
        map.set("sensitive", action.status.get("sensitive"));
        map.set("language", action.status.get("language"));

        if (action.spoiler_text.length > 0) {
          map.set("spoiler", true);
          map.set("spoiler_text", action.spoiler_text);
        } else {
          map.set("spoiler", false);
          map.set("spoiler_text", "");
        }

        if (action.status.get("poll")) {
          map.set("poll", ImmutableMap({
            options: action.status.getIn(["poll", "options"]).map(x => x.get("title")),
            multiple: action.status.getIn(["poll", "multiple"]),
            expires_in: expiresInFromExpiresAt(action.status.getIn(["poll", "expires_at"])),
          }));
        }
      });
    case COMPOSE_POLL_ADD:
      return state.set("poll", initialPoll);
    case COMPOSE_POLL_REMOVE:
      return state.set("poll", null);
    case COMPOSE_POLL_OPTION_ADD:
      return state.updateIn(["poll", "options"], options => options.push(action.title));
    case COMPOSE_POLL_OPTION_CHANGE:
      return state.setIn(["poll", "options", action.index], action.title);
    case COMPOSE_POLL_OPTION_REMOVE:
      return state.updateIn(["poll", "options"], options => options.delete(action.index));
    case COMPOSE_POLL_SETTINGS_CHANGE:
      return state.update("poll", poll => poll.set("expires_in", action.expiresIn).set("multiple", action.isMultiple));
    case COMPOSE_LANGUAGE_CHANGE:
      return state.set("language", action.language);
    default:
      return state;
  }
}