using Dapper;
using Mono.Data.Sqlite;
using Rac.Entities;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.IO;
using System.Linq;

namespace Rac.Tools
{
    internal class DataAccess
    {
        private readonly string _dbFilePath;

        public DataAccess(string dbFilePath)
        {
            _dbFilePath = dbFilePath;

            CreateDatabaseIfNotExist();
        }

        private void CreateDatabaseIfNotExist()
        {
            if (File.Exists(_dbFilePath)) return;

            using (var conn = GetConnection())
            {
                conn.Execute(
                    //Create table:Config
                    "CREATE TABLE Configs("
                     + $"{nameof(ConfigEntry.Key)} VARCHAR(16) PRIMARY KEY,"
                     + $"{nameof(ConfigEntry.Value)} VARCHAR(512)"
                     + ");" +

                     //Create table:Archive
                     "CREATE TABLE Archives("
                     + $"{nameof(ArchiveEntry.Url)} VARCHAR(512) PRIMARY KEY,"
                     + $"{nameof(ArchiveEntry.LastWriteTime)} DATETIME,"
                     + $"{nameof(ArchiveEntry.StatusCode)} INT,"
                     + $"{nameof(ArchiveEntry.StatusDescription)} VARCHAR(128),"
                     + $"{nameof(ArchiveEntry.Headers)} VARCHAR(512),"
                     + $"{nameof(ArchiveEntry.Content)} BLOB"
                     + ");" +

                     //Create table:PageLinks
                     "CREATE TABLE ResourceLinks("
                     + $"{nameof(ResourceLinkEntry.Resource)} VARCHAR(512),"
                     + $"{nameof(ResourceLinkEntry.Link)} VARCHAR(512),"
                     + $"{nameof(ResourceLinkEntry.Included)} BOOLEAN,"
                     + $"{nameof(ResourceLinkEntry.Remark)} VARCHAR(512),"
                     + $"PRIMARY KEY ({nameof(ResourceLinkEntry.Resource)},{nameof(ResourceLinkEntry.Link)})"
                     + ");"

                     //Init Data
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.HomeUrl)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.HostsInclude)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.UrlPrefixExclude)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.OwsPort)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.Parallel)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.DefaultCharset)}');"
                     + $"INSERT INTO Configs ({nameof(ConfigEntry.Key)}) VALUES ('{nameof(ConfigAdapter.ExtractWebRoot)}');"
                );
            }
        }

        private int BulkOperation<T>(IEnumerable<T> items, Func<T, DbConnection, int> proc)
        {
            var count = 0;
            using (var conn = GetConnection())
            {
                using (var t = conn.BeginTransaction())
                {
                    count += items.Sum(p => proc(p, conn));

                    t.Commit();
                }
            }

            return count;
        }

        private DbConnection GetConnection()
        {
            var conn = new SqliteConnection("Data Source=" + _dbFilePath);
            conn.Open();
            return conn;
        }

        // --- common ---

        public Dictionary<string, string> GetConfigs()
        {
            using (var conn = GetConnection())
                return conn.Query<ConfigEntry>("select * from Configs")
                           .ToDictionary(p => p.Key, p => p.Value);
        }

        // --- for crawler ---

        public string[] GetNonDumpedUrls(int num)
        {
            using (var conn = GetConnection())
                return conn.Query<ArchiveEntry>($"select {nameof(ArchiveEntry.Url)} from Archives WHERE {nameof(ArchiveEntry.StatusCode)} IS NULL LIMIT @num", new { num })
                           .Select(p => p.Url).ToArray();
        }

        public int CreateArchiveEntryIfNotExist(string url, DbConnection conn = null)
        {
            int Run(IDbConnection con) => 1 != con.ExecuteScalar<int>($"SELECT 1 FROM Archives WHERE {nameof(ArchiveEntry.Url)}=@url", new { url })
                ? con.Execute($"INSERT INTO Archives ({nameof(ArchiveEntry.Url)},{nameof(ArchiveEntry.LastWriteTime)}) VALUES(@url,@now)", new { url, now = DateTime.Now })
                : 0;

            if (null != conn)
                return Run(conn);

            using (conn = GetConnection())
                return Run(conn);
        }

        public int UpdateArchiveEntity(ArchiveEntry entryToUpdate, DbConnection conn = null)
        {
            entryToUpdate.LastWriteTime = DateTime.Now;

            int Run(IDbConnection con) => con.Execute(
                "UPDATE Archives SET "
                + $"{nameof(ArchiveEntry.LastWriteTime)}=@{nameof(ArchiveEntry.LastWriteTime)},"
                + $"{nameof(ArchiveEntry.StatusCode)}=@{nameof(ArchiveEntry.StatusCode)},"
                + $"{nameof(ArchiveEntry.StatusDescription)}=@{nameof(ArchiveEntry.StatusDescription)},"
                + $"{nameof(ArchiveEntry.Headers)}=@{nameof(ArchiveEntry.Headers)},"
                + $"{nameof(ArchiveEntry.Content)}=@{nameof(ArchiveEntry.Content)} " +
                $"WHERE {nameof(ArchiveEntry.Url)}=@{nameof(ArchiveEntry.Url)}", entryToUpdate);

            if (null != conn)
                return Run(conn);

            using (conn = GetConnection())
                return Run(conn);
        }

        public int AddPageLink(ResourceLinkEntry entry, DbConnection conn = null)
        {
            int Run(IDbConnection con)
            {
                if (1 != con.ExecuteScalar<int>(
                        "SELECT 1 FROM ResourceLinks WHERE "
                        + $"{nameof(ResourceLinkEntry.Resource)}=@{nameof(ResourceLinkEntry.Resource)} "
                        + $"AND {nameof(ResourceLinkEntry.Link)}=@{nameof(ResourceLinkEntry.Link)}"
                        , entry))

                    return con.Execute(
                        "INSERT INTO ResourceLinks ("
                        + $"{nameof(ResourceLinkEntry.Resource)},"
                        + $"{nameof(ResourceLinkEntry.Link)},"
                        + $"{nameof(ResourceLinkEntry.Included)},"
                        + $"{nameof(ResourceLinkEntry.Remark)}" +
                        ") VALUES ("
                        + $"@{nameof(ResourceLinkEntry.Resource)},"
                        + $"@{nameof(ResourceLinkEntry.Link)},"
                        + $"@{nameof(ResourceLinkEntry.Included)},"
                        + $"@{nameof(ResourceLinkEntry.Remark)}" +
                        ")", entry);

                return 0;
            }

            if (null != conn)
                return Run(conn);

            using (conn = GetConnection())
                return Run(conn);
        }

        public int BulkAddNewArchiveEntry(IEnumerable<string> urls)
        {
            return BulkOperation(urls, CreateArchiveEntryIfNotExist);
        }

        public int BulkUpdateArchiveEntry(IEnumerable<ArchiveEntry> items)
        {
            return BulkOperation(items, UpdateArchiveEntity);
        }

        public int BulkAddResourceLink(string page, bool included, string remark, params string[] links)
        {
            return BulkOperation(links.Select(p => new ResourceLinkEntry { Resource = page, Link = p, Included = included, Remark = remark }), AddPageLink);
        }

        public int BulkAddResourceLink(IEnumerable<ResourceLinkEntry> items)
        {
            return BulkOperation(items, AddPageLink);
        }

        public string GetReferer(string url)
        {
            using (var conn = GetConnection())
            {
                return conn.Query<string>($"SELECT Resource FROM ResourceLinks WHERE {nameof(ResourceLinkEntry.Link)}=@url", new { url }).FirstOrDefault();
            }
        }

        // --- for offline server & extractor ---

        public ArchiveEntry GetEntry(string url)
        {
            using (var conn = GetConnection())
            {
                return conn.Query<ArchiveEntry>($"SELECT * FROM Archives WHERE {nameof(ArchiveEntry.Url)}=@url", new { url }).FirstOrDefault();
            }
        }

        // --- for extractor  ---

        public string[] GetAllUrl()
        {
            using (var conn = GetConnection())
            {
                return conn.Query<string>($"SELECT {nameof(ArchiveEntry.Url)} FROM Archives").ToArray();
            }
        }

    }
}