import React, {PropTypes} from 'react';
import PermalinkButton from 'coral-plugin-permalinks/PermalinkButton';

import AuthorName from 'coral-plugin-author-name/AuthorName';

import TagLabel from 'coral-plugin-tag-label/TagLabel';
import Content from 'coral-plugin-commentcontent/CommentContent';
import PubDate from 'coral-plugin-pubdate/PubDate';
import {ReplyBox, ReplyButton} from 'coral-plugin-replies';
import FlagComment from 'coral-plugin-flags/FlagComment';
import {TransitionGroup} from 'react-transition-group';
import cn from 'classnames';

import {
  BestButton,
  IfUserCanModifyBest,
  BEST_TAG,
  commentIsBest,
  BestIndicator
} from 'coral-plugin-best/BestButton';
import Slot from 'coral-framework/components/Slot';
import LoadMore from './LoadMore';
import IgnoredCommentTombstone from './IgnoredCommentTombstone';
import {TopRightMenu} from './TopRightMenu';
import {EditableCommentContent} from './EditableCommentContent';
import {getActionSummary, iPerformedThisAction} from 'coral-framework/utils';
import {getEditableUntilDate} from './util';
import styles from './Comment.css';

const isStaff = (tags) => !tags.every((t) => t.name !== 'STAFF');
const hasComment = (nodes, id) => nodes.some((node) => node.id === id);

// resetCursors will return the id cursors of the first and second newest comment in
// the current reply list. The cursors are used to dertermine which
// comments to show. The spare cursor functions as a backup in case one
// of the comments gets deleted.
function resetCursors(state, props) {
  const replies = props.comment.replies;
  if (replies && replies.nodes.length) {
    const idCursors = [replies.nodes[replies.nodes.length - 1].id];
    if (replies.nodes.length >= 2) {
      idCursors.push(replies.nodes[replies.nodes.length - 2].id);
    }
    return {idCursors};
  }
  return {idCursors: []};
}

// invalidateCursor is called whenever a comment is removed which is referenced
// by one of the 2 id cursors. It returns a new set of id cursors calculated
// using the help of the backup cursor.
function invalidateCursor(invalidated, state, props) {
  const alt = invalidated === 1 ? 0 : 1;
  const replies = props.comment.replies;
  const idCursors = [];
  if (state.idCursors[alt]) {
    idCursors.push(state.idCursors[alt]);
    const index = replies.nodes.findIndex((node) => node.id === idCursors[0]);
    const prevInLine = replies.nodes[index - 1];
    if (prevInLine) {
      idCursors.push(prevInLine.id);
    }
  }
  return {idCursors};
}

// hold actions links (e.g. Reply) along the comment footer
const ActionButton = ({children}) => {
  return (
    <span className="comment__action-button comment__action-button--nowrap">
      {children}
    </span>
  );
};

class Comment extends React.Component {

  constructor(props) {
    super(props);

    // timeout to keep track of Comment edit window expiration
    this.editWindowExpiryTimeout = null;
    this.onClickEdit = this.onClickEdit.bind(this);
    this.stopEditing = this.stopEditing.bind(this);
    this.state = {

      // Whether the comment should be editable (e.g. after a commenter clicking the 'Edit' button on their own comment)
      isEditing: false,
      replyBoxVisible: false,
      animateEnter: false,
      ...resetCursors({}, props),
    };
  }

  componentWillReceiveProps(next) {
    const {comment: {replies: prevReplies}} = this.props;
    const {comment: {replies: nextReplies}} = next;
    if (
        prevReplies && nextReplies &&
        nextReplies.nodes.length < prevReplies.nodes.length
    ) {

      // Invalidate first cursor if referenced comment was removed.
      if (this.state.idCursors[0] && !hasComment(nextReplies.nodes, this.state.idCursors[0])) {
        this.setState(invalidateCursor(0, this.state, next));
      }

      // Invalidate second cursor if referenced comment was removed.
      if (this.state.idCursors[1] && !hasComment(nextReplies.nodes, this.state.idCursors[1])) {
        this.setState(invalidateCursor(1, this.state, next));
      }
    }
  }

  componentWillEnter(callback) {
    callback();
    const userId = this.props.currentUser ? this.props.currentUser.id : null;
    if (this.props.comment.id.indexOf('pending') >= 0) {
      return;
    }
    if (userId && this.props.comment.user.id === userId) {

      // This comment was just added by currentUser.
      if (Date.now() - Number(new Date(this.props.comment.created_at)) < 30 * 1000) {
        return;
      }
    }
    this.setState({animateEnter: true});
  }

  static propTypes = {
    reactKey: PropTypes.string.isRequired,

    // id of currently opened ReplyBox. tracked in Stream.js
    activeReplyBox: PropTypes.string.isRequired,
    disableReply: PropTypes.bool,
    setActiveReplyBox: PropTypes.func.isRequired,
    showSignInDialog: PropTypes.func.isRequired,
    postFlag: PropTypes.func.isRequired,
    deleteAction: PropTypes.func.isRequired,
    parentId: PropTypes.string,
    highlighted: PropTypes.string,
    addNotification: PropTypes.func.isRequired,
    postComment: PropTypes.func.isRequired,
    depth: PropTypes.number.isRequired,
    liveUpdates: PropTypes.bool.isRequired,
    asset: PropTypes.shape({
      id: PropTypes.string,
      title: PropTypes.string,
      url: PropTypes.string
    }).isRequired,
    currentUser: PropTypes.shape({
      id: PropTypes.string.isRequired
    }),
    charCountEnable: PropTypes.bool.isRequired,
    maxCharCount: PropTypes.number,
    comment: PropTypes.shape({
      depth: PropTypes.number,
      action_summaries: PropTypes.array.isRequired,
      body: PropTypes.string.isRequired,
      id: PropTypes.string.isRequired,
      tags: PropTypes.arrayOf(
        PropTypes.shape({
          name: PropTypes.string
        })
      ),
      replies: PropTypes.object,
      user: PropTypes.shape({
        id: PropTypes.string.isRequired,
        name: PropTypes.string.isRequired
      }).isRequired,
      editing: PropTypes.shape({
        edited: PropTypes.bool,

        // ISO8601
        editableUntil: PropTypes.string,
      })
    }).isRequired,

    // given a comment, return whether it should be rendered as ignored
    commentIsIgnored: React.PropTypes.func,

    // dispatch action to add a tag to a comment
    addCommentTag: React.PropTypes.func,

    // dispatch action to remove a tag from a comment
    removeCommentTag: React.PropTypes.func,

    // dispatch action to ignore another user
    ignoreUser: React.PropTypes.func,

    // edit a comment, passed (id, asset_id, { body })
    editComment: React.PropTypes.func,
  }

  onClickEdit (e) {
    e.preventDefault();
    this.setState({isEditing: true});
  }

  stopEditing () {
    if (this._isMounted) {
      this.setState({isEditing: false});
    }
  }

  hasIgnoredReplies() {
    return this.props.comment.replies &&
      this.props.comment.replies.nodes.some((reply) => this.props.commentIsIgnored(reply));
  }

  loadNewReplies = () => {
    const {replies, replyCount, id} = this.props.comment;
    if (replyCount > replies.nodes.length) {
      this.props.loadMore(id).then(() => {
        this.setState(resetCursors(this.state, this.props));
      });
      return;
    }
    this.setState(resetCursors);
  };

  // getVisibileReplies returns a list containing comments
  // which were authored by current user or comes before the `idCursor`.
  getVisibileReplies() {
    const {comment: {replies}, currentUser, liveUpdates} = this.props;
    const idCursor = this.state.idCursors[0];
    const userId = currentUser ? currentUser.id : null;

    if (!replies) {
      return [];
    }

    if (liveUpdates) {
      return replies.nodes;
    }

    const view = [];
    let pastCursor = false;
    replies.nodes.forEach((comment) => {
      if (idCursor && !pastCursor || comment.user.id === userId) {
        view.push(comment);
      }
      if (comment.id === idCursor) {
        pastCursor = true;
      }
    });
    return view;
  }

  componentDidMount() {
    this._isMounted = true;
    if (this.editWindowExpiryTimeout) {
      this.editWindowExpiryTimeout = clearTimeout(this.editWindowExpiryTimeout);
    }

    // if still in the edit window, set a timeout to re-render once it expires
    const msLeftToEdit = editWindowRemainingMs(this.props.comment);
    if (msLeftToEdit > 0) {
      this.editWindowExpiryTimeout = setTimeout(() => {

        // re-render
        this.setState(this.state);
      }, msLeftToEdit);
    }
  }
  componentWillUnmount() {
    if (this.editWindowExpiryTimeout) {
      this.editWindowExpiryTimeout = clearTimeout(this.editWindowExpiryTimeout);
    }
    this._isMounted = false;
  }
  render () {
    const {
      comment,
      parentId,
      currentUser,
      asset,
      depth,
      postComment,
      addNotification,
      showSignInDialog,
      highlighted,
      postFlag,
      postDontAgree,
      setActiveReplyBox,
      activeReplyBox,
      deleteAction,
      addCommentTag,
      removeCommentTag,
      ignoreUser,
      liveUpdates,
      disableReply,
      commentIsIgnored,
      maxCharCount,
      charCountEnable
    } = this.props;

    const view = this.getVisibileReplies();

    const hasMoreComments = comment.replies && (comment.replies.hasNextPage || comment.replies.nodes.length > view.length);
    const replyCount = this.hasIgnoredReplies() ? '' : comment.replyCount;
    const flagSummary = getActionSummary('FlagActionSummary', comment);
    const dontAgreeSummary = getActionSummary(
      'DontAgreeActionSummary',
      comment
    );
    let myFlag = null;
    if (iPerformedThisAction('FlagActionSummary', comment)) {
      myFlag = flagSummary.find((s) => s.current_user);
    } else if (iPerformedThisAction('DontAgreeActionSummary', comment)) {
      myFlag = dontAgreeSummary.find((s) => s.current_user);
    }

    let commentClass = parentId
      ? `reply ${styles.Reply}`
      : `comment ${styles.Comment}`;
    commentClass += comment.id.indexOf('pending') >= 0 ? ` ${styles.pendingComment}` : '';

    // call a function, and if it errors, call addNotification('error', ...) (e.g. to show user a snackbar)
    const notifyOnError = (fn, errorToMessage) =>
      async function(...args) {
        if (typeof errorToMessage !== 'function') {
          errorToMessage = (error) => error.message;
        }
        try {
          return await fn(...args);
        } catch (error) {
          addNotification('error', errorToMessage(error));
          throw error;
        }
      };

    const addBestTag = notifyOnError(
      () =>
        addCommentTag({
          id: comment.id,
          tag: BEST_TAG
        }),
      () => 'Failed to tag comment as best'
    );

    const removeBestTag = notifyOnError(
      () =>
        removeCommentTag({
          id: comment.id,
          tag: BEST_TAG
        }),
      () => 'Failed to remove best comment tag'
    );

    return (
      <div
        className={cn(commentClass, 'talk-stream-comment-wrapper', {[styles.enter]: this.state.animateEnter})}
        id={`c_${comment.id}`}
        style={{marginLeft: depth * 30}}
      >
        <hr aria-hidden={true} />
        <div
          className={highlighted === comment.id ? 'highlighted-comment' : ''}
        >
          <AuthorName author={comment.user} className={'talk-stream-comment-user-name'} />
          {isStaff(comment.tags) ? <TagLabel>Staff</TagLabel> : null}

          {commentIsBest(comment)
            ? <TagLabel><BestIndicator /></TagLabel>
            : null }

          <span className={`${styles.bylineSecondary} talk-stream-comment-user-byline`} >
            <PubDate created_at={comment.created_at} className={'talk-stream-comment-published-date'} />
            {
              (comment.editing && comment.editing.edited)
              ? <span>&nbsp;<span className={styles.editedMarker}>(Edited)</span></span>
              : null
            }
          </span>

          <Slot
            fill="commentInfoBar"
            data={this.props.data}
            root={this.props.root}
            comment={comment}
            commentId={comment.id}
            inline
          />

          { (currentUser &&
              (comment.user.id === currentUser.id))

              /* User can edit/delete their own comment for a short window after posting */
              ? <span className={cn(styles.topRight)}>
                  {
                    commentIsStillEditable(comment) &&
                    <a
                      className={cn(styles.link, {[styles.active]: this.state.isEditing})}
                      onClick={this.onClickEdit}>Edit</a>
                  }
                </span>

              /* TopRightMenu allows currentUser to ignore other users' comments */
              : <span className={cn(styles.topRight, styles.topRightMenu)}>
                  <TopRightMenu
                    comment={comment}
                    ignoreUser={ignoreUser}
                    addNotification={addNotification} />
                </span>
          }

          {
            this.state.isEditing
            ? <EditableCommentContent
                editComment={this.props.editComment.bind(null, comment.id, asset.id)}
                addNotification={addNotification}
                asset={asset}
                comment={comment}
                currentUser={currentUser}
                maxCharCount={maxCharCount}
                parentId={parentId}
                stopEditing={this.stopEditing}
                />
            : <div>
                <Content body={comment.body} />
                <Slot fill="commentContent" />
              </div>
          }

          <div className="commentActionsLeft comment__action-container">
            <Slot
              fill="commentReactions"
              data={this.props.data}
              root={this.props.root}
              comment={comment}
              commentId={comment.id}
              inline
            />
            <ActionButton>
              <IfUserCanModifyBest user={currentUser}>
                <BestButton
                  isBest={commentIsBest(comment)}
                  addBest={addBestTag}
                  removeBest={removeBestTag}
                />
              </IfUserCanModifyBest>
            </ActionButton>
            {!disableReply &&
              <ActionButton>
                <ReplyButton
                  onClick={() => setActiveReplyBox(comment.id)}
                  parentCommentId={parentId || comment.id}
                  currentUserId={currentUser && currentUser.id}
                  banned={false}
                />
              </ActionButton>}
            <Slot
              fill="commentActions"
              data={this.props.data}
              root={this.props.root}
              comment={comment}
              commentId={comment.id}
              inline
            />
          </div>
          <div className="commentActionsRight comment__action-container">
            <ActionButton>
              <PermalinkButton articleURL={asset.url} commentId={comment.id} />
            </ActionButton>
            <ActionButton>
              <FlagComment
                flaggedByCurrentUser={!!myFlag}
                flag={myFlag}
                id={comment.id}
                author_id={comment.user.id}
                postFlag={postFlag}
                postDontAgree={postDontAgree}
                deleteAction={deleteAction}
                showSignInDialog={showSignInDialog}
                currentUser={currentUser}
              />
            </ActionButton>
          </div>
        </div>
        {activeReplyBox === comment.id
          ? <ReplyBox
              commentPostedHandler={() => {
                setActiveReplyBox('');
              }}
              charCountEnable={charCountEnable}
              maxCharCount={maxCharCount}
              setActiveReplyBox={setActiveReplyBox}
              parentId={parentId || comment.id}
              addNotification={addNotification}
              authorId={currentUser.id}
              postComment={postComment}
              assetId={asset.id}
            />
          : null}

        <TransitionGroup>
        {view.map((reply) => {
          return commentIsIgnored(reply)
            ? <IgnoredCommentTombstone key={reply.id} />
            : <Comment
                data={this.props.data}
                root={this.props.root}
                setActiveReplyBox={setActiveReplyBox}
                disableReply={disableReply}
                activeReplyBox={activeReplyBox}
                addNotification={addNotification}
                parentId={comment.id}
                postComment={postComment}
                editComment={this.props.editComment}
                depth={depth + 1}
                asset={asset}
                highlighted={highlighted}
                currentUser={currentUser}
                postFlag={postFlag}
                deleteAction={deleteAction}
                addCommentTag={addCommentTag}
                removeCommentTag={removeCommentTag}
                ignoreUser={ignoreUser}
                charCountEnable={charCountEnable}
                maxCharCount={maxCharCount}
                showSignInDialog={showSignInDialog}
                commentIsIgnored={commentIsIgnored}
                liveUpdates={liveUpdates}
                reactKey={reply.id}
                key={reply.id}
                comment={reply}
              />;
        })}
        </TransitionGroup>
        <div className="coral-load-more-replies">
          <LoadMore
            topLevel={false}
            replyCount={replyCount}
            moreComments={hasMoreComments}
            loadMore={this.loadNewReplies}
          />
        </div>
      </div>
    );
  }
}

export default Comment;

// return whether the comment is editable
function commentIsStillEditable (comment) {
  const editing = comment && comment.editing;
  if (!editing) {return false;}
  const editableUntil = getEditableUntilDate(comment);
  const editWindowExpired = (editableUntil - new Date) < 0;
  return !editWindowExpired;
}

// return number of milliseconds before edit window expires
function editWindowRemainingMs (comment) {
  const editableUntil = getEditableUntilDate(comment);
  if (!editableUntil) {return;}
  const now = new Date();
  const editWindowRemainingMs = (editableUntil - now);
  return editWindowRemainingMs;
}