using Microsoft.Data.Sqlite;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Elwig.Helpers.Billing {
    public class Billing {

        protected readonly int Year;
        protected readonly AppDbContext Context;
        protected readonly Dictionary<string, string> Attributes;
        protected readonly Dictionary<string, (decimal?, decimal?)> Modifiers;
        protected readonly Dictionary<string, (string, string?, string?, string?, int?, int?, decimal?)> AreaComTypes;

        public Billing(int year) {
            Year = year;
            Context = new AppDbContext();
            Attributes = Context.WineAttributes.ToDictionary(a => a.AttrId, a => a.Name);
            Modifiers = Context.Modifiers.Where(m => m.Year == Year).ToDictionary(m => m.ModId, m => (m.Abs, m.Rel));
            AreaComTypes = Context.AreaCommitmentTypes.ToDictionary(v => v.VtrgId, v => (v.SortId, v.AttrId1, v.AttrId2, v.Discriminator, v.MinKgPerHa, v.MaxKgPerHa, v.PenaltyAmount));
        }

        public async Task FinishSeason() {
            using var cnx = await AppDbContext.ConnectAsync();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"""
                    UPDATE season
                    SET (start_date, end_date) = (SELECT MIN(date), MAX(date) FROM delivery WHERE year = {Year})
                    WHERE year = {Year}
                    """;
                await cmd.ExecuteNonQueryAsync();
            }

            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"DELETE FROM delivery_part_bin WHERE year = {Year}";
                await cmd.ExecuteNonQueryAsync();
            }
        }

        public async Task CalculateBins(bool allowAttrsIntoLowerBins, bool avoidUnderDeliveries, bool honorGebunden) {
            var attrVals = Context.WineAttributes.ToDictionary(a => a.AttrId, a => a.FillLowerBins);
            var attrForced = attrVals.Where(a => a.Value == 0).Select(a => a.Key).ToArray();
            using var cnx = await AppDbContext.ConnectAsync();
            var memberOblRig = await GetMemberRightsObligations(cnx, Year);
            var inserts = new List<(int, int, int, string, int)>();

            var deliveries = new List<(int, int, int, string, int, double, string, string[], string[], bool?)>();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"""
                    SELECT mgnr, did, dpnr, sortid, weight, kmw, qualid, attributes, modifiers, gebunden
                    FROM v_delivery
                    WHERE year = {Year}
                    ORDER BY mgnr, sortid, abgewertet ASC, {(honorGebunden ? "gebunden IS NOT NULL DESC, gebunden DESC," : "")}
                             COALESCE(LENGTH(attributes), 0) ASC, attribute_prio DESC, COALESCE(attributes, '~'),
                             kmw DESC, lsnr, dpnr
                    """;
                var reader = await cmd.ExecuteReaderAsync();
                while (await reader.ReadAsync()) {
                    deliveries.Add((
                        reader.GetInt32(0), reader.GetInt32(1), reader.GetInt32(2), reader.GetString(3), reader.GetInt32(4),
                        reader.GetDouble(5), reader.GetString(6),
                        reader.IsDBNull(7) ? Array.Empty<string>() : reader.GetString(7).Split(",").Order().ToArray(),
                        reader.IsDBNull(8) ? Array.Empty<string>() : reader.GetString(8).Split(",").Order().ToArray(),
                        reader.IsDBNull(9) ? null : reader.GetBoolean(9)
                    ));
                }
            }

            int lastMgNr = 0;
            Dictionary<string, int>? rights = null;
            Dictionary<string, int>? obligations = null;
            Dictionary<string, int> used = new();
            foreach (var (mgnr, did, dpnr, sortid, weight, kmw, qualid, attributes, modifiers, gebunden) in deliveries) {
                if (lastMgNr != mgnr) {
                    var or = memberOblRig.GetValueOrDefault(mgnr, (new(), new()));
                    rights = or.Item2;
                    obligations = or.Item1;
                    used = new();
                }
                if ((honorGebunden && gebunden == false) ||
                    obligations == null || rights == null ||
                    obligations.Count == 0 || rights.Count == 0 ||
                    qualid == "WEI" || qualid == "RSW" || qualid == "LDW")
                {
                    // Explizit als ungebunden markiert,
                    // Mitglied hat keine Flächenbindungen, oder
                    // Nicht mindestens Qualitätswein (QUW)
                    // -> ungebunden
                    inserts.Add((did, dpnr, 0, "_", weight));
                    continue;
                }

                if (attributes.Length > 2)
                    throw new NotSupportedException();

                int w = weight;
                foreach (var p in Utils.Permutate(attributes, attributes.Intersect(attrForced))) {
                    var c = p.Count();
                    var key = sortid + string.Join("", p);
                    if (rights.ContainsKey(key) && obligations.ContainsKey(key)) {
                        int i = 4;
                        if (c == 1) {
                            i = (p.ElementAt(0) == attributes[0]) ? 2 : 3;
                        } else if (c == 0) {
                            i = 1;
                        }
                        var u = used.GetValueOrDefault(key, 0);
                        var vr = Math.Max(0, Math.Min(rights[key] - u, w));
                        var vo = Math.Max(0, Math.Min(obligations[key] - u, w));
                        var v = (c == 0 || p.Select(a => attrVals[a]).Min() == 2) ? vr : vo;
                        used[key] = u + v;
                        inserts.Add((did, dpnr, i, key[2..], v));
                        w -= v;
                    }
                    if (w == 0 || !allowAttrsIntoLowerBins) break;
                }
                inserts.Add((did, dpnr, 0, "_", w));
                lastMgNr = mgnr;
            }

            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"""
                    INSERT INTO delivery_part_bin (year, did, dpnr, binnr, discr, value)
                    VALUES {string.Join(",\n       ", inserts.Select(i => $"({Year}, {i.Item1}, {i.Item2}, {i.Item3}, '{i.Item4}', {i.Item5})"))}
                    ON CONFLICT DO UPDATE
                    SET discr = excluded.discr, value = value + excluded.value
                    """;
                await cmd.ExecuteNonQueryAsync();
            }

            // TODO add second round to avoid under deliveries
        }

        public static async Task<Dictionary<int, (Dictionary<string, int>, Dictionary<string, int>)>> GetMemberRightsObligations(SqliteConnection cnx, int year, int? mgnr = null) {
            var members = new Dictionary<int, (Dictionary<string, int>, Dictionary<string, int>)>();

            using var cmd = cnx.CreateCommand();
            cmd.CommandText = $"""
                SELECT mgnr, t.vtrgid,
                       SUM(COALESCE(area * min_kg_per_ha, 0)) / 10000 AS min_kg,
                       SUM(COALESCE(area * max_kg_per_ha, 0)) / 10000 AS max_kg
                FROM area_commitment c
                JOIN area_commitment_type t ON t.vtrgid = c.vtrgid
                WHERE ({(mgnr == null ? "NULL" : mgnr)} IS NULL OR mgnr = {(mgnr == null ? "NULL" : mgnr)}) AND
                      (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
                """;

            var reader = await cmd.ExecuteReaderAsync();
            while (await reader.ReadAsync()) {
                var m = reader.GetInt32(0);
                var vtrgid = reader.GetString(1);
                if (!members.ContainsKey(m)) members[m] = (new(), new());
                members[m].Item1[vtrgid] = reader.GetInt32(2);
                members[m].Item2[vtrgid] = reader.GetInt32(3);
            }

            return members;
        }

        public static async Task<(Dictionary<string, int>, Dictionary<string, int>)> GetMemberRightsObligations(SqliteConnection cnx, int year, int mgnr) {
            var members = await GetMemberRightsObligations(cnx, year, (int?)mgnr);
            return members.GetValueOrDefault(mgnr, (new(), new()));
        }

        public static async Task<Dictionary<string, int>> GetMemberBinWeights(int mgnr, int year, SqliteConnection cnx) {
            var bins = new Dictionary<string, int>();

            using var cmd = cnx.CreateCommand();
            cmd.CommandText = $"""
                SELECT bin, weight
                FROM v_delivery_bin
                WHERE (year, mgnr) = ({year}, {mgnr})
                """;

            var reader = await cmd.ExecuteReaderAsync();
            while (await reader.ReadAsync()) {
                var bin = reader.GetString(0);
                bins[bin] = reader.GetInt32(1);
            }

            return bins;
        }
    }
}