// -------------------------------------------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
// -------------------------------------------------------------------------------------------------

using System.Collections.Generic;
using System.IO;
using System.Linq;
using EnsureThat;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.SqlServer.TransactSql.ScriptDom;
using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;

namespace Microsoft.Health.Extensions.BuildTimeCodeGenerator.Sql;

/// <summary>
/// Base class for generating C# types based on the CREATE TABLE, CREATE TABLE TYPE, CREATE PROCEDURE AND CREATE OR ALTER PROCEDURE statements in one or more .sql files.
/// </summary>
public abstract class SqlModelGenerator : ICodeGenerator
{
    private readonly string[] _sqlFiles;

    protected SqlModelGenerator(string[] args)
    {
        EnsureArg.IsNotNull(args, nameof(args));

        _sqlFiles = args;
    }

    protected abstract SqlVisitor[] Visitors { get; }

    public (MemberDeclarationSyntax[], UsingDirectiveSyntax[]) Generate(string typeName)
    {
        IEnumerable<TSqlFragment> sqlFragments = ParseSqlFiles();

        var visitors = Visitors;

        foreach (TSqlFragment sqlFragment in sqlFragments)
        {
            foreach (var sqlVisitor in visitors)
            {
                sqlFragment.Accept(sqlVisitor);
            }
        }

        MemberDeclarationSyntax[] members = visitors
            .SelectMany(v => v.MembersToAdd)
            .OrderBy(m => m, MemberSorting.Comparer)
            .ToArray();

        return (
            WrapMembers(members, typeName),
            new[]
            {
                UsingDirective(ParseName("Microsoft.Health.SqlServer.Features.Client")),
                UsingDirective(ParseName("Microsoft.Health.SqlServer.Features.Schema.Model")),
            });
    }

    protected abstract MemberDeclarationSyntax[] WrapMembers(MemberDeclarationSyntax[] members, string containingTypeName);

    private IEnumerable<TSqlFragment> ParseSqlFiles()
    {
        foreach (var sqlFile in _sqlFiles)
        {
            using (var stream = File.OpenRead(sqlFile))
            using (var reader = new StreamReader(stream))
            {
                var parser = new TSql150Parser(true);
                yield return parser.Parse(reader, out var errors);
            }
        }
    }
}