using DbSyncKit.Templates.Interface;

using Fluid;

using System;

namespace DbSyncKit.Templates.SQLite

{

/// <summary>

/// Implementation of <see cref="IQueryTemplates"/> for SQLite database, providing templates for various SQL queries.

/// </summary>

public class QueryTemplates : IQueryTemplates, IDisposable

{

#region Public Properties

/// <summary>

/// Gets the template for a SELECT query.

/// </summary>

public IFluidTemplate SelectTemplate => _selectQueryTemplate.Value;

/// <summary>

/// Gets the template for an INSERT query.

/// </summary>

public IFluidTemplate InsertTemplate => _insertQueryTemplate.Value;

/// <summary>

/// Gets the template for an UPDATE query.

/// </summary>

public IFluidTemplate UpdateTemplate => _updateQueryTemplate.Value;

/// <summary>

/// Gets the template for a DELETE query.

/// </summary>

public IFluidTemplate DeleteTemplate => _deleteQueryTemplate.Value;

/// <summary>

/// Gets the template for a COMMENT query.

/// </summary>

public IFluidTemplate CommentTemplate => _commentQueryTemplate.Value;

#endregion

#region Private Properties

private static readonly Lazy<IFluidTemplate> _selectQueryTemplate = new Lazy<IFluidTemplate>(CreateSelectQueryTemplate);

private static readonly Lazy<IFluidTemplate> _insertQueryTemplate = new Lazy<IFluidTemplate>(CreateInsertQueryTemplate);

private static readonly Lazy<IFluidTemplate> _updateQueryTemplate = new Lazy<IFluidTemplate>(CreateUpdateQueryTemplate);

private static readonly Lazy<IFluidTemplate> _deleteQueryTemplate = new Lazy<IFluidTemplate>(CreateDeleteQueryTemplate);

private static readonly Lazy<IFluidTemplate> _commentQueryTemplate = new Lazy<IFluidTemplate>(CreateCommentQueryTemplate);

private static readonly FluidParser parser = new FluidParser();

#endregion

#region Templates

/// <summary>

/// Creates a template for a SELECT query.

/// </summary>

private static IFluidTemplate CreateSelectQueryTemplate()

{

var str = @"SELECT {{ Columns | join: ', ' }} FROM {{ TableName }};";

return parser.Parse(str);

}

/// <summary>

/// Creates a template for an INSERT query.

/// </summary>

private static IFluidTemplate CreateInsertQueryTemplate()

{

var str = @"

INSERT INTO {{ TableName }} ({{ Columns | join: ', ' }}) VALUES ({{ Values | join: ', ' }});";

return parser.Parse(str);

}

/// <summary>

/// Creates a template for an UPDATE query.

/// </summary>

private static IFluidTemplate CreateUpdateQueryTemplate()

{

var str = @"

UPDATE {{ TableName }} SET {{ Set | join: ', ' }} WHERE {{ Where | join: ' AND ' }};";

return parser.Parse(str);

}

/// <summary>

/// Creates a template for a DELETE query.

/// </summary>

private static IFluidTemplate CreateDeleteQueryTemplate()

{

var str = @"

DELETE FROM {{ TableName }} WHERE {{ Where | join: ' AND ' }};";

return parser.Parse(str);

}

/// <summary>

/// Creates a template for a COMMENT query.

/// </summary>

private static IFluidTemplate CreateCommentQueryTemplate()

{

var str = @"{% unless isMultiLine %}-- {{ Comment }}{% else %}

/*

{{ Comment }}

*/

{% endunless %}";

return parser.Parse(str);

}

#endregion

/// <summary>

/// Performs application-defined tasks associated with freeing, releasing, or resetting resources.

/// </summary>

public void Dispose()

{

// No additional resources to release.

}

}

}