using System;
using System.Collections.Generic;
using System.Data.Common;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Dapper;
using Microsoft.Data.Sqlite;
using Serilog;
using SharpRss.Core;
using SharpRss.Models;

namespace SharpRss
{
    internal static class DbAccess
    {
        private static readonly string ConnectionString = $"Data Source={Path.Combine(Environment.CurrentDirectory, "sharp_rss.sqlite")};";
        private static bool _isInitialized;

        public static async Task SetSyndicationAsync(SyndicationContainer synContainer)
        {
            if (synContainer.Category != null)
            {
                CategoryModel? catModel = await SetCategoryAsync(synContainer.Category);
                if (catModel != null)
                    synContainer.SyndicationModel.CategoryId = catModel.Id;
            }
            if (synContainer.SyndicationModel != null)
                await SetSyndicationAsync(synContainer.SyndicationModel);
            if (synContainer.SyndicationItems != null && synContainer.SyndicationItems.Any())
                await SetSyndicationItemsAsync(synContainer.SyndicationItems);
        }

        public static async Task<HashSet<CategoryModel>> GetCategoriesAsync()
        {
            HashSet<CategoryModel> categories = new HashSet<CategoryModel>();
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            await using DbDataReader reader = await dbc.ExecuteReaderAsync("SELECT * FROM category");
            while (await reader.ReadAsync())
            {
                CategoryModel categoryModel = new CategoryModel()
                {
                    Id = reader["id"].ToString(),
                    Name = reader["name"].ToString(),
                    HexColor = reader["hex_color"].ToString(),
                    Icon = reader["icon"].ToString()
                };
                categoryModel.SyndicationCount = await dbc.ExecuteScalarAsync<int>($"SELECT COUNT(*) FROM feed WHERE category_id=@CatId", new { CatId = categoryModel.Id });
                categories.Add(categoryModel);
            }
            return categories;
        }
        public static async Task<CategoryModel?> SetCategoryAsync(CategoryModel category)
        {
            CategoryModel? modelReturn = null;
            if (category == null) return modelReturn;
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            int affected = await dbc.ExecuteAsync("INSERT OR REPLACE INTO category (id, hex_color, icon, name) VALUES (IFNULL((SELECT id FROM category WHERE name=@Name), @Id), @HexColor, @Icon, @Name)",
                new { category.Id, category.HexColor, category.Icon, category.Name });
            if (affected <= 0) return modelReturn;
            var catModel = await GetCategoriesAsync();
            modelReturn = catModel.Where(x => x.Name == category.Name).ToHashSet().FirstOrDefault() ?? null;
            return modelReturn;
        }
        public static async Task<bool> DeleteCategory(CategoryModel category)
        {
            if (category == null) return false;
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            int affected = await dbc.ExecuteAsync("DELETE FROM category WHERE id=@Id; UPDATE feed SET category_id=NULL WHERE category_id=@Id",new { category.Id });
            return affected > 0;
        }

        public static async Task SetSyndicationAsync(SyndicationModel syndication)
        {
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            int affected = await dbc.ExecuteAsync(@"INSERT OR REPLACE INTO feed
                (encoded_url,
                title,
                category_id,
                feed_type,
                feed_version,
                description,
                language,
                copyright,
                publication_date,
                last_updated,
                categories,
                image_url)
                VALUES (
                @EncodedUrl,
                @Title,
                @CategoryId,
                @FeedType,
                @FeedVersion,
                @Description,
                @Language,
                @Copyright,
                @PublicationDate,
                @LastUpdated,
                @Categories,
                @ImageUrl)",
                new
                {
                    EncodedUrl = syndication.EncodedUrl,
                    Title = syndication.Title ?? string.Empty,
                    CategoryId = syndication.CategoryId ?? string.Empty,
                    FeedType = syndication.SyndicationType ?? string.Empty,
                    FeedVersion = syndication.SyndicationVersion ?? string.Empty,
                    Description = syndication.Description ?? string.Empty,
                    Language = syndication.Language ?? string.Empty,
                    Copyright = syndication.Copyright ?? string.Empty,
                    PublicationDate = syndication.PublicationDate?.ToUnixTimeMilliseconds() ?? 0,
                    LastUpdated = syndication.SynUpdatedDate?.ToUnixTimeMilliseconds() ?? 0,
                    Categories = syndication.Categories != null && syndication.Categories.Any() ? SyndicationManager.FormatStringArrayToString(syndication.Categories) : string.Empty,
                    ImageUrl = syndication.ImageUrl ?? string.Empty
                });
            if (affected == 0)
                Log.Warning("Failed to add feed: {FeedUrl}", syndication.EncodedUrl);
        }
        public static async Task<HashSet<SyndicationModel>> GetSyndicationsAsync(string[]? categoryIds = null)
        {
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            HashSet<SyndicationModel> feeds = new HashSet<SyndicationModel>();
            await using DbDataReader reader = await dbc.ExecuteReaderAsync(categoryIds == null ? "SELECT * FROM feed" : "SELECT * FROM feed WHERE category_id IN(@CatIds)", new { CatIds = categoryIds });
            while (await reader.ReadAsync())
            {
                SyndicationModel syndicationModel = new SyndicationModel()
                {
                    EncodedUrl = reader["encoded_url"].ToString(),
                    Title = reader["title"].ToString(),
                    CategoryId = reader["category_id"].ToString(),
                    SyndicationType = reader["feed_type"].ToString(),
                    SyndicationVersion = reader["feed_version"].ToString(),
                    Description = reader["description"].ToString(),
                    Language = reader["language"].ToString(),
                    Copyright = reader["copyright"].ToString(),
                    PublicationDate = DateTimeOffset.FromUnixTimeMilliseconds(long.Parse(reader["publication_date"].ToString())),
                    SynUpdatedDate = DateTimeOffset.FromUnixTimeMilliseconds(long.Parse(reader["last_updated"].ToString())),
                    Categories = SyndicationManager.StringToStringArray(reader["categories"].ToString()),
                    ImageUrl = reader["image_url"].ToString()
                };
                syndicationModel.ItemCount = await dbc.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM feed_item WHERE encoded_feed_url=@EncodedFeedUrl", new { EncodedFeedUrl = syndicationModel.EncodedUrl });
                feeds.Add(syndicationModel);
            }
            return feeds;
        }
        public static async Task<bool> DeleteSyndicationAsync(SyndicationModel syndication, bool deleteItems = false)
        {
            if (syndication == null) return false;
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            int affected = await dbc.ExecuteAsync("DELETE FROM feed WHERE encoded_url=@EncodedUrl", new { EncodedUrl = syndication.EncodedUrl });
            if (affected > 0 && deleteItems)
                await dbc.ExecuteAsync("DELETE FROM feed_item WHERE encoded_feed_url=@EncodedUrl", new { EncodedUrl = syndication.EncodedUrl });
            return affected > 0;
        }
        
        public static async Task SetSyndicationItemsAsync(HashSet<SyndicationItemModel> items)
        {
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            int totalAffected = 0;
            await using SqliteTransaction dbTransaction = dbc.BeginTransaction();
            foreach (SyndicationItemModel item in items)
            {
                int affected = await dbc.ExecuteAsync(@"INSERT OR REPLACE INTO feed_item (id, encoded_feed_url, read, title, description, link, last_updated, publishing_date, authors, categories, content)
                    VALUES (@Id, @EncodedFeedUrl, @Read, @Title, @Description, @Link, @LastUpdated, @PublishingDate, @Authors, @Categories, @Content)",
                    transaction: dbTransaction,
                    param: new
                    {
                        Id = item.Id ?? string.Empty,
                        EncodedFeedUrl = item.EncodedSyndicationUrl ?? string.Empty,
                        Read = item.Read.ToString(),
                        Title = item.Title ?? string.Empty,
                        Description = item.Description ?? string.Empty,
                        Link = item.Link ?? string.Empty,
                        LastUpdated = item.ItemUpdatedDate?.ToUnixTimeMilliseconds() ?? 0,
                        PublishingDate = item.PublishingDate?.ToUnixTimeMilliseconds() ?? 0,
                        Authors = item.Authors != null && item.Authors.Any() ? SyndicationManager.FormatStringArrayToString(item.Authors) : string.Empty,
                        Categories = item.Categories != null && item.Categories.Any() ? SyndicationManager.FormatStringArrayToString(item.Categories) : string.Empty,
                        Content = item.Content ?? string.Empty
                    });
                totalAffected += affected;
            }
            dbTransaction.Commit();
        }
        
        public static async Task<HashSet<SyndicationItemModel>> GetSyndicationItemsAsync(string[]? encodedFeedUrls)
        {
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            HashSet<SyndicationItemModel> items = new HashSet<SyndicationItemModel>();
            FeedCache fCache = new FeedCache();
            await using DbDataReader reader = await dbc.ExecuteReaderAsync(encodedFeedUrls == null ? "SELECT * FROM feed_item" : $"SELECT * FROM feed_item WHERE encoded_feed_url IN({FormatParametersFromArray(encodedFeedUrls)})");
            //NOTE(dbg): While debugging this part of the function the code below (Reader.ReadAsync) will return 0, because the debugger already reads the items from the reader.
            while (await reader.ReadAsync())
            {
                SyndicationItemModel syndicationItemModel = new SyndicationItemModel()
                {
                    Id = reader["id"].ToString(),
                    EncodedSyndicationUrl = reader["encoded_feed_url"].ToString(),
                    Read = bool.Parse(reader["read"].ToString()),
                    Title = reader["title"].ToString(),
                    Description = reader["description"].ToString(),
                    Link = reader["link"].ToString(),
                    ItemUpdatedDate = DateTimeOffset.FromUnixTimeMilliseconds(long.Parse(reader["last_updated"].ToString())),
                    PublishingDate = DateTimeOffset.FromUnixTimeMilliseconds(long.Parse(reader["publishing_date"].ToString())),
                    Authors = SyndicationManager.StringToStringArray(reader["authors"].ToString()),
                    Categories = SyndicationManager.StringToStringArray(reader["categories"].ToString()),
                    Content = reader["content"].ToString()
                };
                syndicationItemModel.SyndicationParent = fCache.CacheFeed(syndicationItemModel.EncodedSyndicationUrl) ?? new SyndicationModel();
                items.Add(syndicationItemModel);
            }
            Log.Debug("Fetching feed items resulted: {ItemCount} item(s)", items.Count);
            return items;
        }
        public static async void Initialize()
        {
            if (_isInitialized) return;
            Log.Verbose("Checking database...");
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            Log.Verbose("Checking table: {Table}", "category");
            await dbc.ExecuteAsync("CREATE TABLE IF NOT EXISTS category (id STRING PRIMARY KEY, name STRING NOT NULL, hex_color STRING NOT NULL, icon STRING)");

            Log.Verbose("Checking table: {Table}", "feed");
            await dbc.ExecuteAsync("CREATE TABLE IF NOT EXISTS feed (encoded_url STRING PRIMARY KEY, title STRING, category_id STRING, feed_type STRING, feed_version STRING, description STRING, language STRING, copyright STRING, publication_date INT, last_updated INT, categories STRING, image_url STRING)");

            Log.Verbose("Checking table: {Table}", "feed_item");
            await dbc.ExecuteAsync("CREATE TABLE IF NOT EXISTS feed_item (id STRING PRIMARY KEY, encoded_feed_url STRING, read STRING, title STRING, description STRING, link STRING, last_updated INT, publishing_date INT, authors STRING, categories STRING, content STRING)");
            Log.Verbose("Checking database done!");
            _isInitialized = true;
        }
        
        private static string FormatParametersFromArray(string[] dbParams)
        {
            string[] formatted = dbParams.Select(s => $"'{s}'").ToArray();
            return string.Join(", ", formatted);
        }
        public static async Task<int> GetSyndicationCountAsync(string[] encodedSyndicationUrls)
        {
            await using SqliteConnection dbc = new SqliteConnection(ConnectionString);
            dbc.Open();
            return await dbc.ExecuteScalarAsync<int>("SELECT COUNT(*) FROM feed WHERE encoded_url IN(@Urls)");
        }
    }
}