using Microsoft.EntityFrameworkCore;
using Elwig.Models;
using System.Linq;
using System.Threading.Tasks;
using System.IO;
using System;
using System.Windows;
using Microsoft.Extensions.Logging;
using Microsoft.Data.Sqlite;
using System.Text.RegularExpressions;
using System.Collections.Generic;

namespace Elwig.Helpers {
    public class AppDbContext : DbContext {

        public DbSet<Country> Countries { get; private set; }
        public DbSet<Currency> Currencies { get; private set; }
        public DbSet<AT_Gem> Gemeinden { get; private set; }
        public DbSet<AT_Kg> Katastralgemeinden { get; private set; }
        public DbSet<AT_Ort> Orte { get; private set; }
        public DbSet<AT_Plz> Postleitzahlen { get; private set; }
        public DbSet<AT_PlzDest> PlzDestinations { get; private set; }
        public DbSet<PostalDest> PostalDestinations { get; private set; }
        public DbSet<WineOrigin> WineOrigins { get; private set; }
        public DbSet<WineQualLevel> WineQualityLevels { get; private set; }
        public DbSet<WineVar> WineVarieties { get; private set; }

        public DbSet<ClientParam> ClientParameters { get; private set; }
        public DbSet<WbKg> WbKgs { get; private set; }
        public DbSet<WbRd> WbRde { get; private set; }
        public DbSet<WineAttr> WineAttributes { get; private set; }
        public DbSet<WineCult> WineCultivations { get; private set; }
        public DbSet<Branch> Branches { get; private set; }
        public DbSet<AreaComType> AreaCommitmentTypes { get; private set; }
        public DbSet<Member> Members { get; private set; }
        public DbSet<BillingAddr> BillingAddresses { get; private set; }
        public DbSet<MemberTelNr> MemberTelephoneNrs { get; private set; }
        public DbSet<AreaCom> AreaCommitments { get; private set; }
        public DbSet<Season> Seasons { get; private set; }
        public DbSet<Modifier> Modifiers { get; private set; }
        public DbSet<Delivery> Deliveries { get; private set; }
        public DbSet<DeliveryPart> DeliveryParts { get; private set; }
        public DbSet<DeliveryPartAttr> DeliveryPartAttributes { get; private set; }
        public DbSet<DeliveryPartModifier> DeliveryPartModifiers { get; private set; }
        public DbSet<PaymentVar> PaymentVariants { get; private set; }
        public DbSet<PaymentMember> MemberPayments { get; private set; }
        public DbSet<Credit> Credits { get; private set; }

        private readonly StreamWriter? LogFile = null;
        public static DateTime LastWriteTime => File.GetLastWriteTime(App.Config.DatabaseFile);
        public DateTime SavedLastWriteTime { get; private set; }
        public bool HasBackendChanged => SavedLastWriteTime != LastWriteTime;

        public static string ConnectionString => $"Data Source=\"{App.Config.DatabaseFile}\"; Foreign Keys=True; Mode=ReadWrite; Cache=Default";

        private readonly Dictionary<int, Dictionary<int, Dictionary<string, (int, int)>>> _memberRightsAndObligations = new();
        private readonly Dictionary<int, Dictionary<int, Dictionary<string, int>>> _memberDeliveryBins = new();
        private readonly Dictionary<int, Dictionary<int, Dictionary<string, int>>> _memberPaymentBins = new();

        public AppDbContext() {
            if (App.Config.DatabaseLog != null) {
                try {
                    var file = File.Open(App.Config.DatabaseLog, FileMode.Append, FileAccess.Write, FileShare.Write);
                    LogFile = new(file) {
                        AutoFlush = true
                    };
                } catch (Exception e) {
                    MessageBox.Show($"Unable to open database log file:\n\n{e.Message}", "Database Log", MessageBoxButton.OK, MessageBoxImage.Error);
                }
            }
            SavedLastWriteTime = LastWriteTime;
            SavedChanges += OnSavedChanges;
        }

        public static SqliteConnection Connect() {
            var cnx = new SqliteConnection(ConnectionString);
            cnx.CreateFunction<string, string?, bool?>("REGEXP", (pattern, value) => value == null ? null : Regex.Match(value, pattern).Success, true);
            cnx.Open();
            return cnx;
        }

        public static async Task<SqliteConnection> ConnectAsync() {
            var cnx = new SqliteConnection(ConnectionString);
            cnx.CreateFunction<string, string?, bool?>("REGEXP", (pattern, value) => value == null ? null : Regex.Match(value, pattern).Success, true);
            await cnx.OpenAsync();
            return cnx;
        }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
            optionsBuilder.UseSqlite(ConnectionString);
            optionsBuilder.UseLazyLoadingProxies();
            optionsBuilder.LogTo(Log, LogLevel.Information);
            base.OnConfiguring(optionsBuilder);
        }

        public override void Dispose() {
            base.Dispose();
            LogFile?.Dispose();
            GC.SuppressFinalize(this);
        }

        private void OnSavedChanges(object? sender, SavedChangesEventArgs evt) {
            SavedLastWriteTime = LastWriteTime;
        }

        protected void Log(string msg) {
            LogFile?.WriteLine(msg);
        }

        public async Task<bool> MgNrExists(int mgnr) {
            return await Members.FindAsync(mgnr) != null;
        }

        public async Task<bool> FbNrExists(int fbnr) {
            return await AreaCommitments.FindAsync(fbnr) != null;
        }

        public async Task<bool> SortIdExists(string sortId) {
            return await WineVarieties.FindAsync(sortId) != null;
        }

        public async Task<bool> AttrIdExists(string attrId) {
            return await WineAttributes.FindAsync(attrId) != null;
        }

        public async Task<int> NextMgNr() {
            int c = await Members.Select(m => m.MgNr).MinAsync();
            (await Members.OrderBy(m => m.MgNr).Select(m => m.MgNr).ToListAsync())
                .ForEach(a => { if (a <= c + 1000) c = a; });
            return c + 1;
        }

        public async Task<int> NextFbNr() {
            int c = await AreaCommitments.Select(ac => ac.FbNr).MinAsync();
            (await AreaCommitments.OrderBy(ac => ac.FbNr).Select(ac => ac.FbNr).ToListAsync())
                .ForEach(a => { if (a <= c + 1000) c = a; });
            return c + 1;
        }

        public async Task<int> NextLNr(DateOnly date) {
            var dateStr = date.ToString("yyyy-MM-dd");
            int c = 0;
            (await Deliveries.Where(d => d.DateString == dateStr).Select(d => d.LNr).ToListAsync())
                .ForEach(a => { if (a <= c + 100) c = a; });
            return c + 1;
        }

        public async Task<int> NextDId(int year) {
            int c = 0;
            (await Deliveries.Where(d => d.Year == year).Select(d => d.DId).ToListAsync())
                .ForEach(a => { if (a <= c + 100) c = a; });
            return c + 1;
        }

        public async Task<int> NextDPNr(int year, int did) {
            int c = 0;
            (await DeliveryParts.Where(p => p.Year == year && p.DId == did).Select(d => d.DPNr).ToListAsync())
                .ForEach(a => { if (a <= c + 100) c = a; });
            return c + 1;
        }

        public async Task<WineQualLevel> GetWineQualityLevel(double kmw) {
            return await WineQualityLevels
                .Where(q => !q.IsPredicate && (q.MinKmw == null || q.MinKmw <= kmw))
                .OrderBy(q => q.MinKmw)
                .LastOrDefaultAsync();
        }

        public async Task UpdateDeliveryPartAttributes(DeliveryPart part, IEnumerable<WineAttr> attributes) {
            foreach (var a in WineAttributes) {
                var attr = part.PartAttributes.Where(pa => pa.AttrId == a.AttrId).FirstOrDefault();
                if (attributes.Contains(a)) {
                    DeliveryPartAttr dpa = attr ?? this.CreateProxy<DeliveryPartAttr>();
                    dpa.Year = part.Year;
                    dpa.DId = part.DId;
                    dpa.DPNr = part.DPNr;
                    dpa.AttrId = a.AttrId;
                    if (attr == null) {
                        await AddAsync(dpa);
                    } else {
                        Update(dpa);
                    }
                } else {
                    if (attr != null) {
                        Remove(attr);
                    }
                }
            }
        }

        public async Task UpdateDeliveryPartModifiers(DeliveryPart part, IEnumerable<Modifier> modifiers) {
            foreach (var m in Modifiers.Where(m => m.Year == part.Year)) {
                var mod = part.PartModifiers.Where(pa => pa.ModId == m.ModId).FirstOrDefault();
                if (modifiers.Contains(m)) {
                    DeliveryPartModifier dpm = mod ?? this.CreateProxy<DeliveryPartModifier>();
                    dpm.Year = part.Year;
                    dpm.DId = part.DId;
                    dpm.DPNr = part.DPNr;
                    dpm.ModId = m.ModId;
                    if (mod == null) {
                        await AddAsync(dpm);
                    } else {
                        Update(dpm);
                    }
                } else {
                    if (mod != null) {
                        Remove(mod);
                    }
                }
            }
        }

        private async Task FetchMemberRightsAndObligations(int year, SqliteConnection? cnx = null) {
            var ownCnx = cnx == null;
            cnx ??= await ConnectAsync();
            var bins = new Dictionary<int, Dictionary<string, (int, int)>>();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"""
                    SELECT mgnr, t.vtrgid,
                           ROUND(SUM(COALESCE(area * min_kg_per_ha, 0)) / 10000.0) AS min_kg,
                           ROUND(SUM(COALESCE(area * max_kg_per_ha, 0)) / 10000.0) AS max_kg
                    FROM area_commitment c
                    JOIN area_commitment_type t ON t.vtrgid = c.vtrgid
                    WHERE (year_from IS NULL OR year_from <= {year}) AND
                          (year_to IS NULL OR year_to >= {year})
                    GROUP BY mgnr, t.vtrgid
                    ORDER BY LENGTH(t.vtrgid) DESC, t.vtrgid
                    """;
                using var reader = await cmd.ExecuteReaderAsync();
                while (await reader.ReadAsync()) {
                    var mgnr = reader.GetInt32(0);
                    var vtrgid = reader.GetString(1);
                    if (!bins.ContainsKey(mgnr)) bins[mgnr] = new();
                    bins[mgnr][vtrgid] = (reader.GetInt32(3), reader.GetInt32(2));
                }
            }
            if (ownCnx) await cnx.DisposeAsync();
            _memberRightsAndObligations[year] = bins;
        }

        private async Task FetchMemberDeliveryBins(int year, SqliteConnection? cnx = null) {
            var ownCnx = cnx == null;
            cnx ??= await ConnectAsync();
            var bins = new Dictionary<int, Dictionary<string, int>>();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"SELECT mgnr, bin, weight FROM v_delivery_bin WHERE year = {year}";
                using var reader = await cmd.ExecuteReaderAsync();
                while (await reader.ReadAsync()) {
                    var mgnr = reader.GetInt32(0);
                    var bin = reader.GetString(1);
                    if (!bins.ContainsKey(mgnr)) bins[mgnr] = new();
                    bins[mgnr][bin] = reader.GetInt32(2);
                }
            }
            if (ownCnx) await cnx.DisposeAsync();
            _memberDeliveryBins[year] = bins;
        }

        private async Task FetchMemberPaymentBins(int year, SqliteConnection? cnx = null) {
            var ownCnx = cnx == null;
            cnx ??= await ConnectAsync();
            var bins = new Dictionary<int, Dictionary<string, int>>();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"SELECT mgnr, bin, weight FROM v_payment_bin WHERE year = {year}";
                using var reader = await cmd.ExecuteReaderAsync();
                while (await reader.ReadAsync()) {
                    var mgnr = reader.GetInt32(0);
                    var bin = reader.GetString(1);
                    if (!bins.ContainsKey(mgnr)) bins[mgnr] = new();
                    bins[mgnr][bin] = reader.GetInt32(2);
                }
            }
            if (ownCnx) await cnx.DisposeAsync();
            _memberPaymentBins[year] = bins;
        }

        public async Task<Dictionary<string, (int, int)>> GetMemberRightsAndObligations(int year, int mgnr, SqliteConnection? cnx = null) {
            if (!_memberRightsAndObligations.ContainsKey(year))
                await FetchMemberRightsAndObligations(year, cnx);
            return _memberRightsAndObligations[year].GetValueOrDefault(mgnr, new());
        }

        public async Task<Dictionary<string, int>> GetMemberDeliveryBins(int year, int mgnr, SqliteConnection? cnx = null) {
            if (!_memberDeliveryBins.ContainsKey(year))
                await FetchMemberDeliveryBins(year, cnx);
            return _memberDeliveryBins[year].GetValueOrDefault(mgnr, new());
        }

        public async Task<Dictionary<string, int>> GetMemberPaymentBins(int year, int mgnr, SqliteConnection? cnx = null) {
            if (!_memberPaymentBins.ContainsKey(year))
                await FetchMemberPaymentBins(year, cnx);
            return _memberPaymentBins[year].GetValueOrDefault(mgnr, new());
        }

        public async Task<Dictionary<string, (string, int, int, int, int)>> GetMemberBins(int year, int mgnr, SqliteConnection? cnx = null) {
            var ownCnx = cnx == null;
            cnx ??= await ConnectAsync();
            var rightsAndObligations = await GetMemberRightsAndObligations(year, mgnr, cnx);
            var deliveryBins = await GetMemberDeliveryBins(year, mgnr, cnx);
            var paymentBins = await GetMemberPaymentBins(year, mgnr, cnx);
            if (ownCnx) await cnx.DisposeAsync();

            var bins = new Dictionary<string, (string, int, int, int, int)>();
            foreach (var id in rightsAndObligations.Keys.Union(deliveryBins.Keys).Union(paymentBins.Keys)) {
                var variety = await WineVarieties.FindAsync(id[..2]);
                var attrIds = id[2..];
                var attrs = await WineAttributes.Where(a => attrIds.Contains(a.AttrId)).ToListAsync();
                var name = (variety?.Name ?? "") + (attrs.Count > 0 ? $" ({string.Join(" / ", attrs.Select(a => a.Name))})" : "");
                bins[id] = (
                    name,
                    rightsAndObligations.GetValueOrDefault(id).Item1,
                    rightsAndObligations.GetValueOrDefault(id).Item2,
                    deliveryBins.GetValueOrDefault(id),
                    paymentBins.GetValueOrDefault(id)
                );
            }
            return bins;
        }
    }
}