const driver = require("../../graph_db");
const { graphIdToNumber } = require("../relations/friend_graph");

const GRAPH = { database: process.env.GRAPH_DB_NAME };

async function likePost(userId, postId) {
  const { records } = await driver.executeQuery(
    `MATCH (me:Person {db_id: $me})
     MERGE (p:Post {db_id: $postId})
     MERGE (me)-[l:LIKES]->(p)
     SET l.created_at = coalesce(l.created_at, datetime())
     RETURN me`,
    { me: Number(userId), postId: Number(postId) },
    GRAPH,
  );
  return records.length > 0;
}

async function unlikePost(userId, postId) {
  await driver.executeQuery(
    `MATCH (me:Person {db_id: $me})-[l:LIKES]->(p:Post {db_id: $postId})
     DELETE l`,
    { me: Number(userId), postId: Number(postId) },
    GRAPH,
  );
}

async function likeDataForPosts(userId, postIds) {
  const ids = postIds.map(Number);
  if (ids.length === 0) return new Map();
  const { records } = await driver.executeQuery(
    `MATCH (p:Post) WHERE p.db_id IN $ids
     OPTIONAL MATCH (p)<-[l:LIKES]-(:Person)
     WITH p, count(l) AS like_count
     OPTIONAL MATCH (me:Person {db_id: $me})-[:LIKES]->(p)
     RETURN p.db_id AS id, like_count, count(me) > 0 AS liked_by_me`,
    { ids, me: Number(userId) },
    GRAPH,
  );
  const result = new Map();
  for (const record of records) {
    result.set(graphIdToNumber(record.get("id")), {
      like_count: Number(record.get("like_count")),
      liked_by_me: Boolean(record.get("liked_by_me")),
    });
  }
  return result;
}

async function deletePostNode(postId) {
  await driver.executeQuery(
    "MATCH (p:Post {db_id: $postId}) DETACH DELETE p",
    { postId: Number(postId) },
    GRAPH,
  );
}

async function deletePostsByAuthor(authorId) {
  await driver.executeQuery(
    "MATCH (p:Post {author_id: $authorId}) DETACH DELETE p",
    { authorId: Number(authorId) },
    GRAPH,
  );
}

module.exports = {
  likePost,
  unlikePost,
  likeDataForPosts,
  deletePostNode,
  deletePostsByAuthor,
};