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

namespace Elwig.Helpers.Billing {
    public class Billing {

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

        public Billing(int year, int avnr) {
            Year = year;
            AvNr = avnr;
            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));
        }

        protected async Task DeleteInDb() {
            using var cnx = await AppDbContext.ConnectAsync();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"DELETE FROM payment_delivery_part WHERE (year, avnr) = ({Year}, {AvNr})";
                await cmd.ExecuteNonQueryAsync();
            }
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"DELETE FROM payment_member WHERE (year, avnr) = ({Year}, {AvNr})";
                await cmd.ExecuteNonQueryAsync();
            }
        }

        public async Task Calculate() {
            await DeleteInDb();
            var tasks = new List<Task>();
            foreach (var mgnr in Context.Members.Select(m => m.MgNr)) {
                tasks.Add(Task.Run(() => CalculateMember(mgnr)));
            }
            await Task.WhenAll(tasks);
        }

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

            using var cmd = cnx.CreateCommand();
            cmd.CommandText = $"""
                SELECT 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 = {mgnr} AND (year_from IS NULL OR year_from <= {year}) AND (year_to IS NULL OR year_to >= {year})
                GROUP BY t.vtrgid
                ORDER BY LENGTH(t.vtrgid) DESC, t.vtrgid
                """;

            var reader = await cmd.ExecuteReaderAsync();
            while (await reader.ReadAsync()) {
                var vtrgid = reader.GetString(0);
                obligations[vtrgid] = reader.GetInt32(1);
                rights[vtrgid] = reader.GetInt32(2);
            }

            return (rights, obligations);
        }

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

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

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

            return buckets;
        }

        protected async Task CalculateMember(int mgnr) {
            using var cnx = await AppDbContext.ConnectAsync();
            var (rights, obligations) = await GetMemberRightsObligations(mgnr, Year, cnx);

            var deliveries = new List<(int, int, string, int, double, string, string[], string[])>();
            using (var cmd = cnx.CreateCommand()) {
                cmd.CommandText = $"""
                    SELECT did, dpnr, sortid, weight, kmw, qualid, attributes, modifiers
                    FROM v_delivery
                    WHERE (year, mgnr) = ({Year}, {mgnr})
                    ORDER BY kmw DESC, weight DESC, did, dpnr
                    """;
                var reader = await cmd.ExecuteReaderAsync();
                while (await reader.ReadAsync()) {
                    deliveries.Add((
                        reader.GetInt32(0), reader.GetInt32(1), reader.GetString(2), reader.GetInt32(3),
                        reader.GetDouble(4), reader.GetString(5), reader.GetString(6).Split(","), reader.GetString(7).Split(",")
                    ));
                }
            }

            foreach (var (did, dpnr, sortid, weight, kmw, qualid, attributes, modifiers) in deliveries) {
                if (qualid == "WEI" || qualid == "RSW" || qualid == "LDW") {
                    // Nicht mindestens Qualitätswein (QUW)
                    using var cmd = cnx.CreateCommand();
                    // TODO
                    cmd.CommandText = $"""
                        INSERT INTO payment_delivery_part (year, did, dpnr, avnr, mod_abs, mod_rel, )
                        VALUES ({Year}, {did}, {dpnr}, {AvNr}, )
                        """;
                    await cmd.ExecuteNonQueryAsync();
                    continue;
                }

                // TODO
            }

        }
    }
}