/**
 * Timeline item storage operations
 * @module storage/items
 */

import { ObjectId } from "mongodb";

import {
  buildPaginationQuery,
  buildPaginationSort,
  generatePagingCursors,
  parseLimit,
} from "../utils/pagination.js";

/**
 * Get items collection from application
 * @param {object} application - Indiekit application
 * @returns {object} MongoDB collection
 */
function getCollection(application) {
  return application.collections.get("microsub_items");
}

/**
 * Add an item to a channel
 * @param {object} application - Indiekit application
 * @param {object} data - Item data
 * @param {ObjectId} data.channelId - Channel ObjectId
 * @param {ObjectId} data.feedId - Feed ObjectId
 * @param {string} data.uid - Unique item identifier
 * @param {object} data.item - jf2 item data
 * @returns {Promise<object|null>} Created item or null if duplicate
 */
export async function addItem(application, { channelId, feedId, uid, item }) {
  const collection = getCollection(application);

  // Check for duplicate
  const existing = await collection.findOne({ channelId, uid });
  if (existing) {
    return; // Duplicate, don't add
  }

  const document = {
    channelId,
    feedId,
    uid,
    type: item.type || "entry",
    url: item.url,
    name: item.name || undefined,
    content: item.content || undefined,
    summary: item.summary || undefined,
    published: item.published ? new Date(item.published) : new Date(), // Keep as Date for query compatibility
    updated: item.updated ? new Date(item.updated) : undefined, // Keep as Date for query compatibility
    author: item.author || undefined,
    category: item.category || [],
    photo: item.photo || [],
    video: item.video || [],
    audio: item.audio || [],
    likeOf: item["like-of"] || item.likeOf || [],
    repostOf: item["repost-of"] || item.repostOf || [],
    bookmarkOf: item["bookmark-of"] || item.bookmarkOf || [],
    inReplyTo: item["in-reply-to"] || item.inReplyTo || [],
    source: item._source || undefined,
    readBy: [], // Array of user IDs who have read this item
    createdAt: new Date().toISOString(),
  };

  await collection.insertOne(document);
  return document;
}

/**
 * Get timeline items for a channel
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {object} options - Query options
 * @param {string} [options.before] - Before cursor
 * @param {string} [options.after] - After cursor
 * @param {number} [options.limit] - Items per page
 * @param {string} [options.userId] - User ID for read state
 * @param {boolean} [options.showRead] - Whether to show read items (default: false)
 * @returns {Promise<object>} Timeline with items and paging
 */
export async function getTimelineItems(application, channelId, options = {}) {
  const collection = getCollection(application);
  const objectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;
  const limit = parseLimit(options.limit);

  // Base query - filter out read items unless showRead is true,
  // and always exclude stripped dedup skeletons (no content to display)
  const baseQuery = { channelId: objectId, _stripped: { $ne: true } };
  if (options.userId && !options.showRead) {
    baseQuery.readBy = { $ne: options.userId };
  }

  const query = buildPaginationQuery({
    before: options.before,
    after: options.after,
    baseQuery,
  });

  const sort = buildPaginationSort(options.before);

  // Fetch one extra to check if there are more
  const items = await collection
    // eslint-disable-next-line unicorn/no-array-callback-reference -- query is MongoDB query object
    .find(query)
    // eslint-disable-next-line unicorn/no-array-sort -- MongoDB cursor method, not Array#sort
    .sort(sort)
    .limit(limit + 1)
    .toArray();

  const hasMore = items.length > limit;
  if (hasMore) {
    items.pop();
  }

  // Transform to jf2 format
  const jf2Items = items.map((item) => transformToJf2(item, options.userId));

  // Generate paging cursors
  const paging = generatePagingCursors(items, limit, hasMore, options.before);

  return {
    items: jf2Items,
    paging,
  };
}

/**
 * Extract URL string from a media value
 * @param {object|string} media - Media value (can be string URL or object)
 * @returns {string|undefined} URL string
 */
function extractMediaUrl(media) {
  if (!media) {
    return;
  }
  if (typeof media === "string") {
    return media;
  }
  if (typeof media === "object") {
    return media.value || media.url || media.src;
  }
}

/**
 * Normalize media array to URL strings
 * @param {Array} mediaArray - Array of media items
 * @returns {Array} Array of URL strings
 */
function normalizeMediaArray(mediaArray) {
  if (!mediaArray || !Array.isArray(mediaArray)) {
    return [];
  }
  return mediaArray.map((media) => extractMediaUrl(media)).filter(Boolean);
}

/**
 * Normalize author object to ensure photo is a URL string
 * @param {object} author - Author object
 * @returns {object} Normalized author
 */
function normalizeAuthor(author) {
  if (!author) {
    return;
  }
  return {
    ...author,
    photo: extractMediaUrl(author.photo),
  };
}

/**
 * Transform database item to jf2 format
 * @param {object} item - Database item
 * @param {string} [userId] - User ID for read state
 * @returns {object} jf2 item
 */
function transformToJf2(item, userId) {
  const jf2 = {
    type: item.type,
    uid: item.uid,
    url: item.url,
    published: item.published?.toISOString(), // Convert Date to ISO string
    _id: item._id.toString(),
    _is_read: userId ? item.readBy?.includes(userId) : false,
  };

  // Optional fields
  if (item.name) jf2.name = item.name;
  if (item.content) jf2.content = item.content;
  if (item.summary) jf2.summary = item.summary;
  if (item.updated) jf2.updated = item.updated.toISOString(); // Convert Date to ISO string
  if (item.author) jf2.author = normalizeAuthor(item.author);
  if (item.category?.length > 0) jf2.category = item.category;

  // Normalize media arrays to ensure they contain URL strings
  const photos = normalizeMediaArray(item.photo);
  const videos = normalizeMediaArray(item.video);
  const audios = normalizeMediaArray(item.audio);

  if (photos.length > 0) jf2.photo = photos;
  if (videos.length > 0) jf2.video = videos;
  if (audios.length > 0) jf2.audio = audios;

  // Interaction types
  if (item.likeOf?.length > 0) jf2["like-of"] = item.likeOf;
  if (item.repostOf?.length > 0) jf2["repost-of"] = item.repostOf;
  if (item.bookmarkOf?.length > 0) jf2["bookmark-of"] = item.bookmarkOf;
  if (item.inReplyTo?.length > 0) jf2["in-reply-to"] = item.inReplyTo;

  // Source
  if (item.source) jf2._source = item.source;

  return jf2;
}

/**
 * Get an item by ID (MongoDB _id or uid)
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} id - Item ObjectId or uid string
 * @param {string} [userId] - User ID for read state
 * @returns {Promise<object|undefined>} jf2 item or undefined
 */
export async function getItemById(application, id, userId) {
  const collection = getCollection(application);

  let item;

  // Try MongoDB ObjectId first
  try {
    const objectId = typeof id === "string" ? new ObjectId(id) : id;
    item = await collection.findOne({ _id: objectId });
  } catch {
    // Invalid ObjectId format, will try uid lookup
  }

  // If not found by _id, try uid
  if (!item) {
    item = await collection.findOne({ uid: id });
  }

  if (!item) {
    return;
  }

  return transformToJf2(item, userId);
}

/**
 * Get items by UIDs
 * @param {object} application - Indiekit application
 * @param {Array} uids - Array of item UIDs
 * @param {string} [userId] - User ID for read state
 * @returns {Promise<Array>} Array of jf2 items
 */
export async function getItemsByUids(application, uids, userId) {
  const collection = getCollection(application);

  const items = await collection.find({ uid: { $in: uids } }).toArray();
  return items.map((item) => transformToJf2(item, userId));
}

/**
 * Count read items in a channel
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {string} userId - User ID
 * @returns {Promise<number>} Number of read items
 */
export async function countReadItems(application, channelId, userId) {
  const collection = getCollection(application);
  const objectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  return collection.countDocuments({
    channelId: objectId,
    readBy: userId,
  });
}

/**
 * Mark items as read
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {Array} entryIds - Array of entry IDs to mark as read (can be ObjectId, uid, or URL)
 * @param {string} userId - User ID
 * @returns {Promise<number>} Number of items updated
 */
// Maximum number of full read items to keep per channel before stripping content.
// Items beyond this limit are converted to lightweight dedup skeletons (channelId,
// uid, readBy) so the poller doesn't re-ingest them as new unread entries.
const MAX_FULL_READ_ITEMS = 200;

/**
 * Cleanup old read items by stripping content but preserving dedup skeletons.
 * This prevents the vicious cycle where deleted read items get re-ingested as
 * unread by the poller because the dedup record (channelId + uid) was destroyed.
 *
 * AP items (feedId: null) are hard-deleted instead of stripped, since no poller
 * re-ingests them — they arrive via inbox push and don't need dedup skeletons.
 *
 * @param {object} collection - MongoDB collection
 * @param {ObjectId} channelObjectId - Channel ObjectId
 * @param {string} userId - User ID
 */
async function cleanupOldReadItems(collection, channelObjectId, userId) {
  const readCount = await collection.countDocuments({
    channelId: channelObjectId,
    readBy: userId,
  });

  if (readCount > MAX_FULL_READ_ITEMS) {
    // Find old read items beyond the retention limit
    const itemsToCleanup = await collection
      .find({
        channelId: channelObjectId,
        readBy: userId,
        _stripped: { $ne: true },
      })
      .sort({ published: -1, _id: -1 })
      .skip(MAX_FULL_READ_ITEMS)
      .project({ _id: 1, feedId: 1 })
      .toArray();

    if (itemsToCleanup.length === 0) return;

    // Separate AP items (feedId: null) from RSS items (feedId: ObjectId)
    const apItemIds = [];
    const rssItemIds = [];
    for (const item of itemsToCleanup) {
      if (item.feedId) {
        rssItemIds.push(item._id);
      } else {
        apItemIds.push(item._id);
      }
    }

    // Hard-delete AP items — no poller to re-ingest, skeletons are useless
    if (apItemIds.length > 0) {
      const deleted = await collection.deleteMany({
        _id: { $in: apItemIds },
      });
      console.info(
        `[Microsub] Deleted ${deleted.deletedCount} old AP read items`,
      );
    }

    // Strip RSS items to dedup skeletons — poller would re-ingest if deleted
    if (rssItemIds.length > 0) {
      const stripped = await collection.updateMany(
        { _id: { $in: rssItemIds } },
        {
          $set: { _stripped: true },
          $unset: {
            name: "",
            content: "",
            summary: "",
            author: "",
            category: "",
            photo: "",
            video: "",
            audio: "",
            likeOf: "",
            repostOf: "",
            bookmarkOf: "",
            inReplyTo: "",
            source: "",
          },
        },
      );
      console.info(
        `[Microsub] Stripped ${stripped.modifiedCount} old RSS read items (keeping ${MAX_FULL_READ_ITEMS} full)`,
      );
    }
  }
}

/**
 * Cleanup all read items across all channels (startup cleanup).
 * RSS items are stripped to dedup skeletons; AP items are hard-deleted.
 * @param {object} application - Indiekit application
 * @returns {Promise<number>} Total number of items cleaned up
 */
export async function cleanupAllReadItems(application) {
  const collection = getCollection(application);
  const channelsCollection = application.collections.get("microsub_channels");

  const channels = await channelsCollection.find({}).toArray();
  let totalCleaned = 0;

  for (const channel of channels) {
    const readByUsers = await collection.distinct("readBy", {
      channelId: channel._id,
      readBy: { $exists: true, $ne: [] },
    });

    for (const userId of readByUsers) {
      if (!userId) continue;

      const readCount = await collection.countDocuments({
        channelId: channel._id,
        readBy: userId,
        _stripped: { $ne: true },
      });

      if (readCount > MAX_FULL_READ_ITEMS) {
        const itemsToCleanup = await collection
          .find({
            channelId: channel._id,
            readBy: userId,
            _stripped: { $ne: true },
          })
          .sort({ published: -1, _id: -1 })
          .skip(MAX_FULL_READ_ITEMS)
          .project({ _id: 1, feedId: 1 })
          .toArray();

        if (itemsToCleanup.length > 0) {
          const apItemIds = [];
          const rssItemIds = [];
          for (const item of itemsToCleanup) {
            if (item.feedId) {
              rssItemIds.push(item._id);
            } else {
              apItemIds.push(item._id);
            }
          }

          // Hard-delete AP items
          if (apItemIds.length > 0) {
            const deleted = await collection.deleteMany({
              _id: { $in: apItemIds },
            });
            totalCleaned += deleted.deletedCount;
            console.info(
              `[Microsub] Startup cleanup: deleted ${deleted.deletedCount} AP items from channel "${channel.name}"`,
            );
          }

          // Strip RSS items to skeletons
          if (rssItemIds.length > 0) {
            const stripped = await collection.updateMany(
              { _id: { $in: rssItemIds } },
              {
                $set: { _stripped: true },
                $unset: {
                  name: "",
                  content: "",
                  summary: "",
                  author: "",
                  category: "",
                  photo: "",
                  video: "",
                  audio: "",
                  likeOf: "",
                  repostOf: "",
                  bookmarkOf: "",
                  inReplyTo: "",
                  source: "",
                },
              },
            );
            totalCleaned += stripped.modifiedCount;
            console.info(
              `[Microsub] Startup cleanup: stripped ${stripped.modifiedCount} RSS items from channel "${channel.name}"`,
            );
          }
        }
      }
    }
  }

  if (totalCleaned > 0) {
    console.info(
      `[Microsub] Startup cleanup complete: ${totalCleaned} total items cleaned`,
    );
  }

  return totalCleaned;
}

export async function markItemsRead(application, channelId, entryIds, userId) {
  const collection = getCollection(application);
  const channelObjectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  console.info(
    `[Microsub] markItemsRead called for channel ${channelId}, entries:`,
    entryIds,
    `userId: ${userId}`,
  );

  // Handle "last-read-entry" special value
  if (entryIds.includes("last-read-entry")) {
    // Mark all items in channel as read
    const result = await collection.updateMany(
      { channelId: channelObjectId },
      { $addToSet: { readBy: userId } },
    );
    console.info(
      `[Microsub] Marked all items as read: ${result.modifiedCount} updated`,
    );

    // Cleanup old read items, keeping only the most recent
    await cleanupOldReadItems(collection, channelObjectId, userId);

    return result.modifiedCount;
  }

  // Convert string IDs to ObjectIds where possible
  const objectIds = entryIds
    .map((id) => {
      try {
        return new ObjectId(id);
      } catch {
        return;
      }
    })
    .filter(Boolean);

  // Build query to match by _id, uid, or url (Microsub spec uses URLs as entry identifiers)
  const result = await collection.updateMany(
    {
      channelId: channelObjectId,
      $or: [
        ...(objectIds.length > 0 ? [{ _id: { $in: objectIds } }] : []),
        { uid: { $in: entryIds } },
        { url: { $in: entryIds } },
      ],
    },
    { $addToSet: { readBy: userId } },
  );

  console.info(
    `[Microsub] markItemsRead result: ${result.modifiedCount} items updated`,
  );

  return result.modifiedCount;
}

/**
 * Mark items as unread
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {Array} entryIds - Array of entry IDs to mark as unread (can be ObjectId, uid, or URL)
 * @param {string} userId - User ID
 * @returns {Promise<number>} Number of items updated
 */
export async function markItemsUnread(
  application,
  channelId,
  entryIds,
  userId,
) {
  const collection = getCollection(application);
  const channelObjectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  // Convert string IDs to ObjectIds where possible
  const objectIds = entryIds
    .map((id) => {
      try {
        return new ObjectId(id);
      } catch {
        return;
      }
    })
    .filter(Boolean);

  // Match by _id, uid, or url
  const result = await collection.updateMany(
    {
      channelId: channelObjectId,
      $or: [
        ...(objectIds.length > 0 ? [{ _id: { $in: objectIds } }] : []),
        { uid: { $in: entryIds } },
        { url: { $in: entryIds } },
      ],
    },
    { $pull: { readBy: userId } },
  );

  return result.modifiedCount;
}

/**
 * Remove items from channel
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {Array} entryIds - Array of entry IDs to remove (can be ObjectId, uid, or URL)
 * @returns {Promise<number>} Number of items removed
 */
export async function removeItems(application, channelId, entryIds) {
  const collection = getCollection(application);
  const channelObjectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  // Convert string IDs to ObjectIds where possible
  const objectIds = entryIds
    .map((id) => {
      try {
        return new ObjectId(id);
      } catch {
        return;
      }
    })
    .filter(Boolean);

  // Match by _id, uid, or url
  const result = await collection.deleteMany({
    channelId: channelObjectId,
    $or: [
      ...(objectIds.length > 0 ? [{ _id: { $in: objectIds } }] : []),
      { uid: { $in: entryIds } },
      { url: { $in: entryIds } },
    ],
  });

  return result.deletedCount;
}

/**
 * Delete all items for a channel
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @returns {Promise<number>} Number of deleted items
 */
export async function deleteItemsForChannel(application, channelId) {
  const collection = getCollection(application);
  const objectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  const result = await collection.deleteMany({ channelId: objectId });
  return result.deletedCount;
}

/**
 * Delete items for a specific feed
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} feedId - Feed ObjectId
 * @returns {Promise<number>} Number of deleted items
 */
export async function deleteItemsForFeed(application, feedId) {
  const collection = getCollection(application);
  const objectId = typeof feedId === "string" ? new ObjectId(feedId) : feedId;

  const result = await collection.deleteMany({ feedId: objectId });
  return result.deletedCount;
}

// Retention period for unread count (only count recent items)
const UNREAD_RETENTION_DAYS = 30;

/**
 * Get unread count for a channel
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {string} userId - User ID
 * @returns {Promise<number>} Unread count
 */
export async function getUnreadCount(application, channelId, userId) {
  const collection = getCollection(application);
  const objectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  // Only count items from the last UNREAD_RETENTION_DAYS, exclude stripped skeletons
  const cutoffDate = new Date();
  cutoffDate.setDate(cutoffDate.getDate() - UNREAD_RETENTION_DAYS);

  return collection.countDocuments({
    channelId: objectId,
    readBy: { $ne: userId },
    published: { $gte: cutoffDate },
    _stripped: { $ne: true },
  });
}

/**
 * Search items by text
 * @param {object} application - Indiekit application
 * @param {ObjectId|string} channelId - Channel ObjectId
 * @param {string} query - Search query
 * @param {number} [limit] - Max results
 * @returns {Promise<Array>} Array of matching items
 */
export async function searchItems(application, channelId, query, limit = 20) {
  const collection = getCollection(application);
  const objectId =
    typeof channelId === "string" ? new ObjectId(channelId) : channelId;

  // Use regex search (consider adding text index for better performance)
  const escapedQuery = query.replaceAll(
    /[$()*+.?[\\\]^{|}]/g,
    String.raw`\$&`,
  );
  const regex = new RegExp(escapedQuery, "i");
  const items = await collection
    .find({
      channelId: objectId,
      $or: [
        { name: regex },
        { "content.text": regex },
        { "content.html": regex },
        { summary: regex },
      ],
    })
    // eslint-disable-next-line unicorn/no-array-sort -- MongoDB cursor method, not Array#sort
    .sort({ published: -1 })
    .limit(limit)
    .toArray();

  return items.map((item) => transformToJf2(item));
}

/**
 * Delete items by author URL (for blocking)
 * @param {object} application - Indiekit application
 * @param {string} userId - User ID (for filtering user's channels)
 * @param {string} authorUrl - Author URL to delete items from
 * @returns {Promise<number>} Number of deleted items
 */
export async function deleteItemsByAuthorUrl(application, userId, authorUrl) {
  const collection = getCollection(application);
  const channelsCollection = application.collections.get("microsub_channels");

  // Get all channel IDs for this user
  const userChannels = await channelsCollection.find({ userId }).toArray();
  const channelIds = userChannels.map((c) => c._id);

  // Delete all items from blocked author in user's channels
  const result = await collection.deleteMany({
    channelId: { $in: channelIds },
    "author.url": authorUrl,
  });

  return result.deletedCount;
}

/**
 * Create indexes for efficient queries
 * @param {object} application - Indiekit application
 * @returns {Promise<void>}
 */
export async function createIndexes(application) {
  const collection = getCollection(application);

  // Primary query indexes
  await collection.createIndex({ channelId: 1, published: -1 });
  await collection.createIndex({ channelId: 1, uid: 1 }, { unique: true });
  await collection.createIndex({ feedId: 1 });

  // URL matching index for mark_read operations
  await collection.createIndex({ channelId: 1, url: 1 });

  // Full-text search index with weights
  // Higher weight = more importance in relevance scoring
  await collection.createIndex(
    {
      name: "text",
      "content.text": "text",
      "content.html": "text",
      summary: "text",
      "author.name": "text",
    },
    {
      name: "text_search",
      weights: {
        name: 10, // Titles most important
        summary: 5, // Summaries second
        "content.text": 3, // Content third
        "content.html": 2, // HTML content lower
        "author.name": 1, // Author names lowest
      },
      default_language: "english",
    },
  );
}