using System;
using BTCPayServer.Abstractions.Models;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Migrations;
using Microsoft.Extensions.Options;
using Npgsql.EntityFrameworkCore.PostgreSQL.Migrations;
using Npgsql.EntityFrameworkCore.PostgreSQL.Migrations.Operations;

namespace BTCPayServer.Abstractions.Contracts
{
    public abstract class BaseDbContextFactory<T> where T: DbContext
    {
        private readonly IOptions<DatabaseOptions> _options;
        private readonly string _schemaPrefix;

        public BaseDbContextFactory(IOptions<DatabaseOptions> options, string schemaPrefix)
        {
            _options = options;
            _schemaPrefix = schemaPrefix;
        }

        public abstract T CreateContext();

        class CustomNpgsqlMigrationsSqlGenerator : NpgsqlMigrationsSqlGenerator
        {
            public CustomNpgsqlMigrationsSqlGenerator(MigrationsSqlGeneratorDependencies dependencies, IMigrationsAnnotationProvider annotations, Npgsql.EntityFrameworkCore.PostgreSQL.Infrastructure.Internal.INpgsqlOptions opts) : base(dependencies, annotations, opts)
            {
            }

            protected override void Generate(NpgsqlCreateDatabaseOperation operation, IModel model, MigrationCommandListBuilder builder)
            {
                builder
                    .Append("CREATE DATABASE ")
                    .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(operation.Name));

                // POSTGRES gotcha: Indexed Text column (even if PK) are not used if we are not using C locale
                builder
                    .Append(" TEMPLATE ")
                    .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier("template0"));

                builder
                    .Append(" LC_CTYPE ")
                    .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier("C"));

                builder
                    .Append(" LC_COLLATE ")
                    .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier("C"));

                builder
                    .Append(" ENCODING ")
                    .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier("UTF8"));

                if (operation.Tablespace != null)
                {
                    builder
                        .Append(" TABLESPACE ")
                        .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(operation.Tablespace));
                }

                builder.AppendLine(Dependencies.SqlGenerationHelper.StatementTerminator);

                EndStatement(builder, suppressTransaction: true);
            }
        }

        public void ConfigureBuilder(DbContextOptionsBuilder builder)
        {
            switch (_options.Value.DatabaseType)
            {
                case DatabaseType.Sqlite:
                    builder.UseSqlite(_options.Value.ConnectionString, o =>
                    {
                        if (!string.IsNullOrEmpty(_schemaPrefix))
                        {
                            o.MigrationsHistoryTable(_schemaPrefix);
                        }
                    });
                    break;
                case DatabaseType.Postgres:
                    builder
                        .UseNpgsql(_options.Value.ConnectionString, o =>
                        {
                            o.EnableRetryOnFailure(10);
                            if (!string.IsNullOrEmpty(_schemaPrefix))
                            {
                                o.MigrationsHistoryTable(_schemaPrefix);
                            }
                        })
                        .ReplaceService<IMigrationsSqlGenerator, CustomNpgsqlMigrationsSqlGenerator>();
                    break;
                case DatabaseType.MySQL:
                    builder.UseMySql(_options.Value.ConnectionString, o =>
                    {
                        o.EnableRetryOnFailure(10);
                            
                        if (!string.IsNullOrEmpty(_schemaPrefix))
                        {
                            o.MigrationsHistoryTable(_schemaPrefix);
                        }
                    });
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }
        }
        
    }
}