using System;
using NPoco;
using Umbraco.Cms.Core.Cache;
using Umbraco.Cms.Core.Persistence;
using Umbraco.Cms.Core.Persistence.Querying;
using Umbraco.Cms.Core.Scoping;
using Umbraco.Cms.Infrastructure.Persistence.SqlSyntax;

namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
{
    /// <summary>
    /// Base repository class for all <see cref="IRepository"/> instances
    /// </summary>
    public abstract class RepositoryBase : IRepository
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="RepositoryBase"/> class.
        /// </summary>
        protected RepositoryBase(IScopeAccessor scopeAccessor, AppCaches appCaches)
        {
            ScopeAccessor = scopeAccessor ?? throw new ArgumentNullException(nameof(scopeAccessor));
            AppCaches = appCaches ?? throw new ArgumentNullException(nameof(appCaches));
        }

        /// <summary>
        /// Gets the <see cref="AppCaches"/>
        /// </summary>
        protected AppCaches AppCaches { get; }

        /// <summary>
        /// Gets the <see cref="IScopeAccessor"/>
        /// </summary>
        protected IScopeAccessor ScopeAccessor { get; }

        /// <summary>
        /// Gets the AmbientScope
        /// </summary>
        protected IScope AmbientScope
        {
            get
            {
                IScope scope = ScopeAccessor.AmbientScope;
                if (scope == null)
                {
                    throw new InvalidOperationException("Cannot run a repository without an ambient scope.");
                }

                return scope;
            }
        }

        /// <summary>
        /// Gets the repository's database.
        /// </summary>
        protected IUmbracoDatabase Database => AmbientScope.Database;

        /// <summary>
        /// Gets the Sql context.
        /// </summary>
        protected ISqlContext SqlContext => AmbientScope.SqlContext;

        /// <summary>
        /// Gets the <see cref="ISqlSyntaxProvider"/>
        /// </summary>
        protected ISqlSyntaxProvider SqlSyntax => SqlContext.SqlSyntax;

        /// <summary>
        /// Creates an<see cref="Sql{ISqlContext}"/> expression
        /// </summary>
        protected Sql<ISqlContext> Sql() => SqlContext.Sql();

        /// <summary>
        /// Creates a <see cref="Sql{ISqlContext}"/> expression
        /// </summary>
        protected Sql<ISqlContext> Sql(string sql, params object[] args) => SqlContext.Sql(sql, args);

        /// <summary>
        /// Creates a new query expression
        /// </summary>
        protected IQuery<T> Query<T>() => SqlContext.Query<T>();
    }
}