// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See License.txt for license information.

package store

import (
	"fmt"
	"net/http"
	"regexp"
	"strconv"
	"strings"

	l4g "github.com/alecthomas/log4go"
	"github.com/mattermost/mattermost-server/einterfaces"
	"github.com/mattermost/mattermost-server/model"
	"github.com/mattermost/mattermost-server/utils"
)

type SqlPostStore struct {
	SqlStore
}

const (
	LAST_POST_TIME_CACHE_SIZE = 25000
	LAST_POST_TIME_CACHE_SEC  = 900 // 15 minutes

	LAST_POSTS_CACHE_SIZE = 1000
	LAST_POSTS_CACHE_SEC  = 900 // 15 minutes
)

var lastPostTimeCache = utils.NewLru(LAST_POST_TIME_CACHE_SIZE)
var lastPostsCache = utils.NewLru(LAST_POSTS_CACHE_SIZE)

func ClearPostCaches() {
	lastPostTimeCache.Purge()
	lastPostsCache.Purge()
}

func NewSqlPostStore(sqlStore SqlStore) PostStore {
	s := &SqlPostStore{sqlStore}

	for _, db := range sqlStore.GetAllConns() {
		table := db.AddTableWithName(model.Post{}, "Posts").SetKeys(false, "Id")
		table.ColMap("Id").SetMaxSize(26)
		table.ColMap("UserId").SetMaxSize(26)
		table.ColMap("ChannelId").SetMaxSize(26)
		table.ColMap("RootId").SetMaxSize(26)
		table.ColMap("ParentId").SetMaxSize(26)
		table.ColMap("OriginalId").SetMaxSize(26)
		table.ColMap("Message").SetMaxSize(4000)
		table.ColMap("Type").SetMaxSize(26)
		table.ColMap("Hashtags").SetMaxSize(1000)
		table.ColMap("Props").SetMaxSize(8000)
		table.ColMap("Filenames").SetMaxSize(4000)
		table.ColMap("FileIds").SetMaxSize(150)
	}

	return s
}

func (s SqlPostStore) CreateIndexesIfNotExists() {
	s.CreateIndexIfNotExists("idx_posts_update_at", "Posts", "UpdateAt")
	s.CreateIndexIfNotExists("idx_posts_create_at", "Posts", "CreateAt")
	s.CreateIndexIfNotExists("idx_posts_delete_at", "Posts", "DeleteAt")
	s.CreateIndexIfNotExists("idx_posts_channel_id", "Posts", "ChannelId")
	s.CreateIndexIfNotExists("idx_posts_root_id", "Posts", "RootId")
	s.CreateIndexIfNotExists("idx_posts_user_id", "Posts", "UserId")
	s.CreateIndexIfNotExists("idx_posts_is_pinned", "Posts", "IsPinned")

	s.CreateFullTextIndexIfNotExists("idx_posts_message_txt", "Posts", "Message")
	s.CreateFullTextIndexIfNotExists("idx_posts_hashtags_txt", "Posts", "Hashtags")
}

func (s SqlPostStore) Save(post *model.Post) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		if len(post.Id) > 0 {
			result.Err = model.NewLocAppError("SqlPostStore.Save",
				"store.sql_post.save.existing.app_error", nil, "id="+post.Id)
			storeChannel <- result
			close(storeChannel)
			return
		}

		post.PreSave()
		if result.Err = post.IsValid(); result.Err != nil {
			storeChannel <- result
			close(storeChannel)
			return
		}

		if err := s.GetMaster().Insert(post); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.Save", "store.sql_post.save.app_error", nil, "id="+post.Id+", "+err.Error())
		} else {
			time := post.UpdateAt

			if post.Type != model.POST_JOIN_LEAVE && post.Type != model.POST_JOIN_CHANNEL && post.Type != model.POST_LEAVE_CHANNEL &&
				post.Type != model.POST_ADD_REMOVE && post.Type != model.POST_ADD_TO_CHANNEL && post.Type != model.POST_REMOVE_FROM_CHANNEL {
				s.GetMaster().Exec("UPDATE Channels SET LastPostAt = :LastPostAt, TotalMsgCount = TotalMsgCount + 1 WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": post.ChannelId})
			} else {
				// don't update TotalMsgCount for unimportant messages so that the channel isn't marked as unread
				s.GetMaster().Exec("UPDATE Channels SET LastPostAt = :LastPostAt WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": post.ChannelId})
			}

			if len(post.RootId) > 0 {
				s.GetMaster().Exec("UPDATE Posts SET UpdateAt = :UpdateAt WHERE Id = :RootId", map[string]interface{}{"UpdateAt": time, "RootId": post.RootId})
			}

			result.Data = post
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) Update(newPost *model.Post, oldPost *model.Post) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		newPost.UpdateAt = model.GetMillis()

		oldPost.DeleteAt = newPost.UpdateAt
		oldPost.UpdateAt = newPost.UpdateAt
		oldPost.OriginalId = oldPost.Id
		oldPost.Id = model.NewId()

		if result.Err = newPost.IsValid(); result.Err != nil {
			storeChannel <- result
			close(storeChannel)
			return
		}

		if _, err := s.GetMaster().Update(newPost); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.Update", "store.sql_post.update.app_error", nil, "id="+newPost.Id+", "+err.Error())
		} else {
			time := model.GetMillis()
			s.GetMaster().Exec("UPDATE Channels SET LastPostAt = :LastPostAt  WHERE Id = :ChannelId", map[string]interface{}{"LastPostAt": time, "ChannelId": newPost.ChannelId})

			if len(newPost.RootId) > 0 {
				s.GetMaster().Exec("UPDATE Posts SET UpdateAt = :UpdateAt WHERE Id = :RootId", map[string]interface{}{"UpdateAt": time, "RootId": newPost.RootId})
			}

			// mark the old post as deleted
			s.GetMaster().Insert(oldPost)

			result.Data = newPost
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) Overwrite(post *model.Post) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		post.UpdateAt = model.GetMillis()

		if result.Err = post.IsValid(); result.Err != nil {
			storeChannel <- result
			close(storeChannel)
			return
		}

		if _, err := s.GetMaster().Update(post); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.Overwrite", "store.sql_post.overwrite.app_error", nil, "id="+post.Id+", "+err.Error())
		} else {
			result.Data = post
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetFlaggedPosts(userId string, offset int, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)
	go func() {
		result := StoreResult{}
		pl := model.NewPostList()

		var posts []*model.Post
		if _, err := s.GetReplica().Select(&posts, "SELECT * FROM Posts WHERE Id IN (SELECT Name FROM Preferences WHERE UserId = :UserId AND Category = :Category) AND DeleteAt = 0 ORDER BY CreateAt DESC LIMIT :Limit OFFSET :Offset", map[string]interface{}{"UserId": userId, "Category": model.PREFERENCE_CATEGORY_FLAGGED_POST, "Offset": offset, "Limit": limit}); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetFlaggedPosts", "store.sql_post.get_flagged_posts.app_error", nil, err.Error())
		} else {
			for _, post := range posts {
				pl.AddPost(post)
				pl.AddOrder(post.Id)
			}
		}

		result.Data = pl

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetFlaggedPostsForTeam(userId, teamId string, offset int, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)
	go func() {
		result := StoreResult{}
		pl := model.NewPostList()

		var posts []*model.Post

		query := `
            SELECT
                A.*
            FROM
                (SELECT
                    *
                FROM
                    Posts
                WHERE
                    Id
                IN
                    (SELECT
                        Name
                    FROM
                        Preferences
                    WHERE
                        UserId = :UserId
                        AND Category = :Category)
                        AND DeleteAt = 0
                ) as A
            INNER JOIN Channels as B
                ON B.Id = A.ChannelId
            WHERE B.TeamId = :TeamId OR B.TeamId = ''
            ORDER BY CreateAt DESC
            LIMIT :Limit OFFSET :Offset`

		if _, err := s.GetReplica().Select(&posts, query, map[string]interface{}{"UserId": userId, "Category": model.PREFERENCE_CATEGORY_FLAGGED_POST, "Offset": offset, "Limit": limit, "TeamId": teamId}); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetFlaggedPostsForTeam", "store.sql_post.get_flagged_posts.app_error", nil, err.Error())
		} else {
			for _, post := range posts {
				pl.AddPost(post)
				pl.AddOrder(post.Id)
			}
		}

		result.Data = pl

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetFlaggedPostsForChannel(userId, channelId string, offset int, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)
	go func() {
		result := StoreResult{}
		pl := model.NewPostList()

		var posts []*model.Post
		query := `
			SELECT 
				* 
			FROM Posts 
			WHERE 
				Id IN (SELECT Name FROM Preferences WHERE UserId = :UserId AND Category = :Category) 
				AND ChannelId = :ChannelId
				AND DeleteAt = 0 
			ORDER BY CreateAt DESC 
			LIMIT :Limit OFFSET :Offset`

		if _, err := s.GetReplica().Select(&posts, query, map[string]interface{}{"UserId": userId, "Category": model.PREFERENCE_CATEGORY_FLAGGED_POST, "ChannelId": channelId, "Offset": offset, "Limit": limit}); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetFlaggedPostsForChannel", "store.sql_post.get_flagged_posts.app_error", nil, err.Error())
		} else {
			for _, post := range posts {
				pl.AddPost(post)
				pl.AddOrder(post.Id)
			}
		}

		result.Data = pl

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) Get(id string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}
		pl := model.NewPostList()

		if len(id) == 0 {
			result.Err = model.NewLocAppError("SqlPostStore.GetPost", "store.sql_post.get.app_error", nil, "id="+id)
			storeChannel <- result
			close(storeChannel)
			return
		}

		var post model.Post
		err := s.GetReplica().SelectOne(&post, "SELECT * FROM Posts WHERE Id = :Id AND DeleteAt = 0", map[string]interface{}{"Id": id})
		if err != nil {
			result.Err = model.NewAppError("SqlPostStore.GetPost", "store.sql_post.get.app_error", nil, "id="+id+err.Error(), http.StatusNotFound)
			storeChannel <- result
			close(storeChannel)
			return
		}

		pl.AddPost(&post)
		pl.AddOrder(id)

		rootId := post.RootId

		if rootId == "" {
			rootId = post.Id
		}

		if len(rootId) == 0 {
			result.Err = model.NewLocAppError("SqlPostStore.GetPost", "store.sql_post.get.app_error", nil, "root_id="+rootId)
			storeChannel <- result
			close(storeChannel)
			return
		}

		var posts []*model.Post
		_, err = s.GetReplica().Select(&posts, "SELECT * FROM Posts WHERE (Id = :Id OR RootId = :RootId) AND DeleteAt = 0", map[string]interface{}{"Id": rootId, "RootId": rootId})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetPost", "store.sql_post.get.app_error", nil, "root_id="+rootId+err.Error())
			storeChannel <- result
			close(storeChannel)
			return
		} else {
			for _, p := range posts {
				pl.AddPost(p)
			}
		}

		result.Data = pl

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetSingle(id string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		var post model.Post
		err := s.GetReplica().SelectOne(&post, "SELECT * FROM Posts WHERE Id = :Id AND DeleteAt = 0", map[string]interface{}{"Id": id})
		if err != nil {
			result.Err = model.NewAppError("SqlPostStore.GetSingle", "store.sql_post.get.app_error", nil, "id="+id+err.Error(), http.StatusNotFound)
		}

		result.Data = &post

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

type etagPosts struct {
	Id       string
	UpdateAt int64
}

func (s SqlPostStore) InvalidateLastPostTimeCache(channelId string) {
	lastPostTimeCache.Remove(channelId)
	lastPostsCache.Remove(channelId)
}

func (s SqlPostStore) GetEtag(channelId string, allowFromCache bool) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}
		metrics := einterfaces.GetMetricsInterface()

		if allowFromCache {
			if cacheItem, ok := lastPostTimeCache.Get(channelId); ok {
				if metrics != nil {
					metrics.IncrementMemCacheHitCounter("Last Post Time")
				}
				result.Data = fmt.Sprintf("%v.%v", model.CurrentVersion, cacheItem.(int64))
				storeChannel <- result
				close(storeChannel)
				return
			} else {
				if metrics != nil {
					metrics.IncrementMemCacheMissCounter("Last Post Time")
				}
			}
		} else {
			if metrics != nil {
				metrics.IncrementMemCacheMissCounter("Last Post Time")
			}
		}

		var et etagPosts
		err := s.GetReplica().SelectOne(&et, "SELECT Id, UpdateAt FROM Posts WHERE ChannelId = :ChannelId ORDER BY UpdateAt DESC LIMIT 1", map[string]interface{}{"ChannelId": channelId})
		if err != nil {
			result.Data = fmt.Sprintf("%v.%v", model.CurrentVersion, model.GetMillis())
		} else {
			result.Data = fmt.Sprintf("%v.%v", model.CurrentVersion, et.UpdateAt)
		}

		lastPostTimeCache.AddWithExpiresInSecs(channelId, et.UpdateAt, LAST_POST_TIME_CACHE_SEC)

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) Delete(postId string, time int64) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		_, err := s.GetMaster().Exec("Update Posts SET DeleteAt = :DeleteAt, UpdateAt = :UpdateAt WHERE Id = :Id OR RootId = :RootId", map[string]interface{}{"DeleteAt": time, "UpdateAt": time, "Id": postId, "RootId": postId})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.Delete", "store.sql_post.delete.app_error", nil, "id="+postId+", err="+err.Error())
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) permanentDelete(postId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		_, err := s.GetMaster().Exec("DELETE FROM Posts WHERE Id = :Id OR RootId = :RootId", map[string]interface{}{"Id": postId, "RootId": postId})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.Delete", "store.sql_post.permanent_delete.app_error", nil, "id="+postId+", err="+err.Error())
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) permanentDeleteAllCommentByUser(userId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		_, err := s.GetMaster().Exec("DELETE FROM Posts WHERE UserId = :UserId AND RootId != ''", map[string]interface{}{"UserId": userId})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.permanentDeleteAllCommentByUser", "store.sql_post.permanent_delete_all_comments_by_user.app_error", nil, "userId="+userId+", err="+err.Error())
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) PermanentDeleteByUser(userId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		// First attempt to delete all the comments for a user
		if r := <-s.permanentDeleteAllCommentByUser(userId); r.Err != nil {
			result.Err = r.Err
			storeChannel <- result
			close(storeChannel)
			return
		}

		// Now attempt to delete all the root posts for a user.  This will also
		// delete all the comments for each post.
		found := true
		count := 0

		for found {
			var ids []string
			_, err := s.GetMaster().Select(&ids, "SELECT Id FROM Posts WHERE UserId = :UserId LIMIT 1000", map[string]interface{}{"UserId": userId})
			if err != nil {
				result.Err = model.NewLocAppError("SqlPostStore.PermanentDeleteByUser.select", "store.sql_post.permanent_delete_by_user.app_error", nil, "userId="+userId+", err="+err.Error())
				storeChannel <- result
				close(storeChannel)
				return
			} else {
				found = false
				for _, id := range ids {
					found = true
					if r := <-s.permanentDelete(id); r.Err != nil {
						result.Err = r.Err
						storeChannel <- result
						close(storeChannel)
						return
					}
				}
			}

			// This is a fail safe, give up if more than 10K messages
			count = count + 1
			if count >= 10 {
				result.Err = model.NewLocAppError("SqlPostStore.PermanentDeleteByUser.toolarge", "store.sql_post.permanent_delete_by_user.too_many.app_error", nil, "userId="+userId)
				storeChannel <- result
				close(storeChannel)
				return
			}
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) PermanentDeleteByChannel(channelId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		if _, err := s.GetMaster().Exec("DELETE FROM Posts WHERE ChannelId = :ChannelId", map[string]interface{}{"ChannelId": channelId}); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.PermanentDeleteByChannel", "store.sql_post.permanent_delete_by_channel.app_error", nil, "channel_id="+channelId+", "+err.Error())
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPosts(channelId string, offset int, limit int, allowFromCache bool) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}
		metrics := einterfaces.GetMetricsInterface()

		if limit > 1000 {
			result.Err = model.NewLocAppError("SqlPostStore.GetLinearPosts", "store.sql_post.get_posts.app_error", nil, "channelId="+channelId)
			storeChannel <- result
			close(storeChannel)
			return
		}

		if allowFromCache && offset == 0 && limit == 60 {
			if cacheItem, ok := lastPostsCache.Get(channelId); ok {
				if metrics != nil {
					metrics.IncrementMemCacheHitCounter("Last Posts Cache")
				}

				result.Data = cacheItem.(*model.PostList)
				storeChannel <- result
				close(storeChannel)
				return
			} else {
				if metrics != nil {
					metrics.IncrementMemCacheMissCounter("Last Posts Cache")
				}
			}
		} else {
			if metrics != nil {
				metrics.IncrementMemCacheMissCounter("Last Posts Cache")
			}
		}

		rpc := s.getRootPosts(channelId, offset, limit)
		cpc := s.getParentsPosts(channelId, offset, limit)

		if rpr := <-rpc; rpr.Err != nil {
			result.Err = rpr.Err
		} else if cpr := <-cpc; cpr.Err != nil {
			result.Err = cpr.Err
		} else {
			posts := rpr.Data.([]*model.Post)
			parents := cpr.Data.([]*model.Post)

			list := model.NewPostList()

			for _, p := range posts {
				list.AddPost(p)
				list.AddOrder(p.Id)
			}

			for _, p := range parents {
				list.AddPost(p)
			}

			list.MakeNonNil()

			if offset == 0 && limit == 60 {
				lastPostsCache.AddWithExpiresInSecs(channelId, list, LAST_POSTS_CACHE_SEC)
			}

			result.Data = list
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPostsSince(channelId string, time int64, allowFromCache bool) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}
		metrics := einterfaces.GetMetricsInterface()

		if allowFromCache {
			// If the last post in the channel's time is less than or equal to the time we are getting posts since,
			// we can safely return no posts.
			if cacheItem, ok := lastPostTimeCache.Get(channelId); ok && cacheItem.(int64) <= time {
				if metrics != nil {
					metrics.IncrementMemCacheHitCounter("Last Post Time")
				}
				list := model.NewPostList()
				result.Data = list
				storeChannel <- result
				close(storeChannel)
				return
			} else {
				if metrics != nil {
					metrics.IncrementMemCacheMissCounter("Last Post Time")
				}
			}
		} else {
			if metrics != nil {
				metrics.IncrementMemCacheMissCounter("Last Post Time")
			}
		}

		var posts []*model.Post
		_, err := s.GetReplica().Select(&posts,
			`(SELECT
			    *
			FROM
			    Posts
			WHERE
			    (UpdateAt > :Time
			        AND ChannelId = :ChannelId)
			LIMIT 1000)
			UNION
			(SELECT
			    *
			FROM
			    Posts
			WHERE
			    Id
			IN
			    (SELECT * FROM (SELECT
			        RootId
			    FROM
			        Posts
			    WHERE
			        UpdateAt > :Time
			            AND ChannelId = :ChannelId
			    LIMIT 1000) temp_tab))
			ORDER BY CreateAt DESC`,
			map[string]interface{}{"ChannelId": channelId, "Time": time})

		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetPostsSince", "store.sql_post.get_posts_since.app_error", nil, "channelId="+channelId+err.Error())
		} else {

			list := model.NewPostList()

			var latestUpdate int64 = 0

			for _, p := range posts {
				list.AddPost(p)
				if p.UpdateAt > time {
					list.AddOrder(p.Id)
				}
				if latestUpdate < p.UpdateAt {
					latestUpdate = p.UpdateAt
				}
			}

			lastPostTimeCache.AddWithExpiresInSecs(channelId, latestUpdate, LAST_POST_TIME_CACHE_SEC)

			result.Data = list
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPostsBefore(channelId string, postId string, numPosts int, offset int) StoreChannel {
	return s.getPostsAround(channelId, postId, numPosts, offset, true)
}

func (s SqlPostStore) GetPostsAfter(channelId string, postId string, numPosts int, offset int) StoreChannel {
	return s.getPostsAround(channelId, postId, numPosts, offset, false)
}

func (s SqlPostStore) getPostsAround(channelId string, postId string, numPosts int, offset int, before bool) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		var direction string
		var sort string
		if before {
			direction = "<"
			sort = "DESC"
		} else {
			direction = ">"
			sort = "ASC"
		}

		var posts []*model.Post
		var parents []*model.Post
		_, err1 := s.GetReplica().Select(&posts,
			`(SELECT
			    *
			FROM
			    Posts
			WHERE
				(CreateAt `+direction+` (SELECT CreateAt FROM Posts WHERE Id = :PostId)
			        AND ChannelId = :ChannelId
					AND DeleteAt = 0)
			ORDER BY CreateAt `+sort+`
			LIMIT :NumPosts
			OFFSET :Offset)`,
			map[string]interface{}{"ChannelId": channelId, "PostId": postId, "NumPosts": numPosts, "Offset": offset})
		_, err2 := s.GetReplica().Select(&parents,
			`(SELECT
			    *
			FROM
			    Posts
			WHERE
			    Id
			IN
			    (SELECT * FROM (SELECT
			        RootId
			    FROM
			        Posts
			    WHERE
					(CreateAt `+direction+` (SELECT CreateAt FROM Posts WHERE Id = :PostId)
						AND ChannelId = :ChannelId
						AND DeleteAt = 0)
					ORDER BY CreateAt `+sort+`
					LIMIT :NumPosts
					OFFSET :Offset)
			    temp_tab))
			ORDER BY CreateAt DESC`,
			map[string]interface{}{"ChannelId": channelId, "PostId": postId, "NumPosts": numPosts, "Offset": offset})

		if err1 != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_around.get.app_error", nil, "channelId="+channelId+err1.Error())
		} else if err2 != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_around.get_parent.app_error", nil, "channelId="+channelId+err2.Error())
		} else {

			list := model.NewPostList()

			// We need to flip the order if we selected backwards
			if before {
				for _, p := range posts {
					list.AddPost(p)
					list.AddOrder(p.Id)
				}
			} else {
				l := len(posts)
				for i := range posts {
					list.AddPost(posts[l-i-1])
					list.AddOrder(posts[l-i-1].Id)
				}
			}

			for _, p := range parents {
				list.AddPost(p)
			}

			result.Data = list
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) getRootPosts(channelId string, offset int, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		var posts []*model.Post
		_, err := s.GetReplica().Select(&posts, "SELECT * FROM Posts WHERE ChannelId = :ChannelId AND DeleteAt = 0 ORDER BY CreateAt DESC LIMIT :Limit OFFSET :Offset", map[string]interface{}{"ChannelId": channelId, "Offset": offset, "Limit": limit})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetLinearPosts", "store.sql_post.get_root_posts.app_error", nil, "channelId="+channelId+err.Error())
		} else {
			result.Data = posts
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) getParentsPosts(channelId string, offset int, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		var posts []*model.Post
		_, err := s.GetReplica().Select(&posts,
			`SELECT
			    q2.*
			FROM
			    Posts q2
			        INNER JOIN
			    (SELECT DISTINCT
			        q3.RootId
			    FROM
			        (SELECT
			        RootId
			    FROM
			        Posts
			    WHERE
			        ChannelId = :ChannelId1
			            AND DeleteAt = 0
			    ORDER BY CreateAt DESC
			    LIMIT :Limit OFFSET :Offset) q3
			    WHERE q3.RootId != '') q1
			    ON q1.RootId = q2.Id OR q1.RootId = q2.RootId
			WHERE
			    ChannelId = :ChannelId2
			        AND DeleteAt = 0
			ORDER BY CreateAt`,
			map[string]interface{}{"ChannelId1": channelId, "Offset": offset, "Limit": limit, "ChannelId2": channelId})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetLinearPosts", "store.sql_post.get_parents_posts.app_error", nil, "channelId="+channelId+err.Error())
		} else {
			result.Data = posts
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

var specialSearchChar = []string{
	"<",
	">",
	"+",
	"-",
	"(",
	")",
	"~",
	"@",
	":",
}

func (s SqlPostStore) Search(teamId string, userId string, params *model.SearchParams) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		if !*utils.Cfg.ServiceSettings.EnablePostSearch {
			list := model.NewPostList()
			result.Data = list

			result.Err = model.NewLocAppError("SqlPostStore.Search", "store.sql_post.search.disabled", nil, fmt.Sprintf("teamId=%v userId=%v params=%v", teamId, userId, params.ToJson()))
			storeChannel <- result
			close(storeChannel)
			return
		}

		queryParams := map[string]interface{}{
			"TeamId": teamId,
			"UserId": userId,
		}

		termMap := map[string]bool{}
		terms := params.Terms

		if terms == "" && len(params.InChannels) == 0 && len(params.FromUsers) == 0 {
			result.Data = []*model.Post{}
			storeChannel <- result
			close(storeChannel)
			return
		}

		searchType := "Message"
		if params.IsHashtag {
			searchType = "Hashtags"
			for _, term := range strings.Split(terms, " ") {
				termMap[strings.ToUpper(term)] = true
			}
		}

		// these chars have special meaning and can be treated as spaces
		for _, c := range specialSearchChar {
			terms = strings.Replace(terms, c, " ", -1)
		}

		var posts []*model.Post

		searchQuery := `
			SELECT
				*
			FROM
				Posts
			WHERE
				DeleteAt = 0
				AND Type NOT LIKE '` + model.POST_SYSTEM_MESSAGE_PREFIX + `%'
				POST_FILTER
				AND ChannelId IN (
					SELECT
						Id
					FROM
						Channels,
						ChannelMembers
					WHERE
						Id = ChannelId
							AND (TeamId = :TeamId OR TeamId = '')
							AND UserId = :UserId
							AND DeleteAt = 0
							CHANNEL_FILTER)
				SEARCH_CLAUSE
				ORDER BY CreateAt DESC
			LIMIT 100`

		if len(params.InChannels) > 1 {
			inClause := ":InChannel0"
			queryParams["InChannel0"] = params.InChannels[0]

			for i := 1; i < len(params.InChannels); i++ {
				paramName := "InChannel" + strconv.FormatInt(int64(i), 10)
				inClause += ", :" + paramName
				queryParams[paramName] = params.InChannels[i]
			}

			searchQuery = strings.Replace(searchQuery, "CHANNEL_FILTER", "AND Name IN ("+inClause+")", 1)
		} else if len(params.InChannels) == 1 {
			queryParams["InChannel"] = params.InChannels[0]
			searchQuery = strings.Replace(searchQuery, "CHANNEL_FILTER", "AND Name = :InChannel", 1)
		} else {
			searchQuery = strings.Replace(searchQuery, "CHANNEL_FILTER", "", 1)
		}

		if len(params.FromUsers) > 1 {
			inClause := ":FromUser0"
			queryParams["FromUser0"] = params.FromUsers[0]

			for i := 1; i < len(params.FromUsers); i++ {
				paramName := "FromUser" + strconv.FormatInt(int64(i), 10)
				inClause += ", :" + paramName
				queryParams[paramName] = params.FromUsers[i]
			}

			searchQuery = strings.Replace(searchQuery, "POST_FILTER", `
				AND UserId IN (
					SELECT
						Id
					FROM
						Users,
						TeamMembers
					WHERE
						TeamMembers.TeamId = :TeamId
						AND Users.Id = TeamMembers.UserId
						AND Username IN (`+inClause+`))`, 1)
		} else if len(params.FromUsers) == 1 {
			queryParams["FromUser"] = params.FromUsers[0]
			searchQuery = strings.Replace(searchQuery, "POST_FILTER", `
				AND UserId IN (
					SELECT
						Id
					FROM
						Users,
						TeamMembers
					WHERE
						TeamMembers.TeamId = :TeamId
						AND Users.Id = TeamMembers.UserId
						AND Username = :FromUser)`, 1)
		} else {
			searchQuery = strings.Replace(searchQuery, "POST_FILTER", "", 1)
		}

		if terms == "" {
			// we've already confirmed that we have a channel or user to search for
			searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", "", 1)
		} else if *utils.Cfg.SqlSettings.DriverName == model.DATABASE_DRIVER_POSTGRES {
			// Parse text for wildcards
			if wildcard, err := regexp.Compile("\\*($| )"); err == nil {
				terms = wildcard.ReplaceAllLiteralString(terms, ":* ")
			}

			if params.OrTerms {
				terms = strings.Join(strings.Fields(terms), " | ")
			} else {
				terms = strings.Join(strings.Fields(terms), " & ")
			}

			searchClause := fmt.Sprintf("AND %s @@  to_tsquery(:Terms)", searchType)
			searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", searchClause, 1)
		} else if *utils.Cfg.SqlSettings.DriverName == model.DATABASE_DRIVER_MYSQL {
			searchClause := fmt.Sprintf("AND MATCH (%s) AGAINST (:Terms IN BOOLEAN MODE)", searchType)
			searchQuery = strings.Replace(searchQuery, "SEARCH_CLAUSE", searchClause, 1)

			if !params.OrTerms {
				splitTerms := strings.Fields(terms)
				for i, t := range strings.Fields(terms) {
					splitTerms[i] = "+" + t
				}

				terms = strings.Join(splitTerms, " ")
			}
		}

		queryParams["Terms"] = terms

		list := model.NewPostList()

		_, err := s.GetSearchReplica().Select(&posts, searchQuery, queryParams)
		if err != nil {
			l4g.Warn(utils.T("store.sql_post.search.warn"), err.Error())
			// Don't return the error to the caller as it is of no use to the user. Instead return an empty set of search results.
		} else {
			for _, p := range posts {
				if searchType == "Hashtags" {
					exactMatch := false
					for _, tag := range strings.Split(p.Hashtags, " ") {
						if termMap[strings.ToUpper(tag)] {
							exactMatch = true
						}
					}
					if !exactMatch {
						continue
					}
				}
				list.AddPost(p)
				list.AddOrder(p.Id)
			}
		}

		list.MakeNonNil()

		result.Data = list

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) AnalyticsUserCountsWithPostsByDay(teamId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		query :=
			`SELECT DISTINCT
			        DATE(FROM_UNIXTIME(Posts.CreateAt / 1000)) AS Name,
			        COUNT(DISTINCT Posts.UserId) AS Value
			FROM Posts`

		if len(teamId) > 0 {
			query += " INNER JOIN Channels ON Posts.ChannelId = Channels.Id AND Channels.TeamId = :TeamId AND"
		} else {
			query += " WHERE"
		}

		query += ` Posts.CreateAt >= :StartTime AND Posts.CreateAt <= :EndTime
			GROUP BY DATE(FROM_UNIXTIME(Posts.CreateAt / 1000))
			ORDER BY Name DESC
			LIMIT 30`

		if *utils.Cfg.SqlSettings.DriverName == model.DATABASE_DRIVER_POSTGRES {
			query =
				`SELECT
					TO_CHAR(DATE(TO_TIMESTAMP(Posts.CreateAt / 1000)), 'YYYY-MM-DD') AS Name, COUNT(DISTINCT Posts.UserId) AS Value
				FROM Posts`

			if len(teamId) > 0 {
				query += " INNER JOIN Channels ON Posts.ChannelId = Channels.Id AND Channels.TeamId = :TeamId AND"
			} else {
				query += " WHERE"
			}

			query += ` Posts.CreateAt >= :StartTime AND Posts.CreateAt <= :EndTime
				GROUP BY DATE(TO_TIMESTAMP(Posts.CreateAt / 1000))
				ORDER BY Name DESC
				LIMIT 30`
		}

		end := utils.MillisFromTime(utils.EndOfDay(utils.Yesterday()))
		start := utils.MillisFromTime(utils.StartOfDay(utils.Yesterday().AddDate(0, 0, -31)))

		var rows model.AnalyticsRows
		_, err := s.GetReplica().Select(
			&rows,
			query,
			map[string]interface{}{"TeamId": teamId, "StartTime": start, "EndTime": end})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.AnalyticsUserCountsWithPostsByDay", "store.sql_post.analytics_user_counts_posts_by_day.app_error", nil, err.Error())
		} else {
			result.Data = rows
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) AnalyticsPostCountsByDay(teamId string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		query :=
			`SELECT
			        DATE(FROM_UNIXTIME(Posts.CreateAt / 1000)) AS Name,
			        COUNT(Posts.Id) AS Value
			    FROM Posts`

		if len(teamId) > 0 {
			query += " INNER JOIN Channels ON Posts.ChannelId = Channels.Id AND Channels.TeamId = :TeamId AND"
		} else {
			query += " WHERE"
		}

		query += ` Posts.CreateAt <= :EndTime
			            AND Posts.CreateAt >= :StartTime
			GROUP BY DATE(FROM_UNIXTIME(Posts.CreateAt / 1000))
			ORDER BY Name DESC
			LIMIT 30`

		if *utils.Cfg.SqlSettings.DriverName == model.DATABASE_DRIVER_POSTGRES {
			query =
				`SELECT
					TO_CHAR(DATE(TO_TIMESTAMP(Posts.CreateAt / 1000)), 'YYYY-MM-DD') AS Name, Count(Posts.Id) AS Value
				FROM Posts`

			if len(teamId) > 0 {
				query += " INNER JOIN Channels ON Posts.ChannelId = Channels.Id  AND Channels.TeamId = :TeamId AND"
			} else {
				query += " WHERE"
			}

			query += ` Posts.CreateAt <= :EndTime
				            AND Posts.CreateAt >= :StartTime
				GROUP BY DATE(TO_TIMESTAMP(Posts.CreateAt / 1000))
				ORDER BY Name DESC
				LIMIT 30`
		}

		end := utils.MillisFromTime(utils.EndOfDay(utils.Yesterday()))
		start := utils.MillisFromTime(utils.StartOfDay(utils.Yesterday().AddDate(0, 0, -31)))

		var rows model.AnalyticsRows
		_, err := s.GetReplica().Select(
			&rows,
			query,
			map[string]interface{}{"TeamId": teamId, "StartTime": start, "EndTime": end})
		if err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.AnalyticsPostCountsByDay", "store.sql_post.analytics_posts_count_by_day.app_error", nil, err.Error())
		} else {
			result.Data = rows
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) AnalyticsPostCount(teamId string, mustHaveFile bool, mustHaveHashtag bool) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		query :=
			`SELECT
			    COUNT(Posts.Id) AS Value
			FROM
			    Posts,
			    Channels
			WHERE
			    Posts.ChannelId = Channels.Id`

		if len(teamId) > 0 {
			query += " AND Channels.TeamId = :TeamId"
		}

		if mustHaveFile {
			query += " AND (Posts.FileIds != '[]' OR Posts.Filenames != '[]')"
		}

		if mustHaveHashtag {
			query += " AND Posts.Hashtags != ''"
		}

		if v, err := s.GetReplica().SelectInt(query, map[string]interface{}{"TeamId": teamId}); err != nil {
			result.Err = model.NewLocAppError("SqlPostStore.AnalyticsPostCount", "store.sql_post.analytics_posts_count.app_error", nil, err.Error())
		} else {
			result.Data = v
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPostsCreatedAt(channelId string, time int64) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		query := `SELECT * FROM Posts WHERE CreateAt = :CreateAt`

		var posts []*model.Post
		_, err := s.GetReplica().Select(&posts, query, map[string]interface{}{"CreateAt": time})

		if err != nil {
			result.Err = model.NewAppError("SqlPostStore.GetPostsCreatedAt", "store.sql_post.get_posts_created_att.app_error", nil, "channelId="+channelId+err.Error(), http.StatusInternalServerError)
		} else {
			result.Data = posts
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPostsByIds(postIds []string) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		inClause := `'` + strings.Join(postIds, `', '`) + `'`

		query := `SELECT * FROM Posts WHERE Id in (` + inClause + `) and DeleteAt = 0 ORDER BY CreateAt DESC`

		var posts []*model.Post
		_, err := s.GetReplica().Select(&posts, query, map[string]interface{}{})

		if err != nil {
			l4g.Error(err)
			result.Err = model.NewAppError("SqlPostStore.GetPostsCreatedAt", "store.sql_post.get_posts_by_ids.app_error", nil, "", http.StatusInternalServerError)
		} else {
			result.Data = posts
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}

func (s SqlPostStore) GetPostsBatchForIndexing(startTime int64, limit int) StoreChannel {
	storeChannel := make(StoreChannel, 1)

	go func() {
		result := StoreResult{}

		var posts []*model.PostForIndexing
		_, err1 := s.GetSearchReplica().Select(&posts,
			`(SELECT
			    Posts.*,
			    Channels.TeamId,
			    ParentPosts.CreateAt ParentCreateAt
			FROM
				Posts
			LEFT JOIN
				Channels
			ON
				Posts.ChannelId = Channels.Id
			LEFT JOIN
				Posts ParentPosts
			ON
				Posts.RootId = ParentPosts.Id
			WHERE
				Posts.CreateAt >= :StartTime
			ORDER BY CreateAt ASC
			LIMIT :NumPosts)`,
			map[string]interface{}{"StartTime": startTime, "NumPosts": limit})

		if err1 != nil {
			result.Err = model.NewLocAppError("SqlPostStore.GetPostContext", "store.sql_post.get_posts_batch_for_indexing.get.app_error", nil, err1.Error())
		} else {
			result.Data = posts
		}

		storeChannel <- result
		close(storeChannel)
	}()

	return storeChannel
}