using System.Text.RegularExpressions;

namespace Jint
{
    public interface IParsingOptions
    {
        /// <summary>
        /// Gets or sets whether to create compiled <see cref="Regex"/> instances when adapting regular expressions.
        /// Defaults to <see langword="null"/>, which means that in the case of non-prepared scripts and modules
        /// regular expressions will be interpreted, otherwise they will be compiled.
        /// </summary>
        bool? CompileRegex { get; init; }

        /// <summary>
        /// Gets or sets the default timeout for created <see cref="Regex"/> instances.
        /// Defaults to <see langword="null"/>, which means that in the case of non-prepared scripts and modules
        /// the <see cref="Options.ConstraintOptions.RegexTimeout"/> setting should apply,
        /// otherwise the default of the <see cref="ParserOptions.RegexTimeout"/> setting (10 seconds).
        /// </summary>
        /// <remarks>
        /// Please note that <see cref="Options.ConstraintOptions.RegexTimeout"/> setting will be ignored
        /// if this option is set to a value other than <see langword="null"/>.
        /// </remarks>
        TimeSpan? RegexTimeout { get; init; }

        /// <summary>
        /// Gets or sets whether to parse the source code in tolerant mode.
        /// Defaults to <see langword="true"/>.
        /// </summary>
        /// <remarks>
        /// Please note that there is a plan to change the default to <see langword="false"/> in the next major version.
        /// </remarks>
        bool Tolerant { get; init; }
    }

    public sealed record class ScriptParsingOptions : IParsingOptions
    {
        private static readonly ParserOptions _defaultParserOptions = Engine.BaseParserOptions with
        {
            AllowReturnOutsideFunction = true,
            RegExpParseMode = RegExpParseMode.AdaptToInterpreted,
        };

        public static readonly ScriptParsingOptions Default = new();

        /// <summary>
        /// Gets or sets whether to allow return statements at the top level.
        /// Defaults to <see langword="true"/>.
        /// </summary>
        /// <remarks>
        /// Please note that there is a plan to change the default to <see langword="false"/> in the next major version.
        /// </remarks>
        public bool AllowReturnOutsideFunction { get; init; } = _defaultParserOptions.AllowReturnOutsideFunction;

        /// <inheritdoc/>
        public bool? CompileRegex { get; init; }

        /// <inheritdoc/>
        public TimeSpan? RegexTimeout { get; init; }

        /// <inheritdoc/>
        public bool Tolerant { get; init; } = _defaultParserOptions.Tolerant;

        internal ParserOptions ApplyTo(ParserOptions parserOptions, RegExpParseMode defaultRegExpParseMode, TimeSpan defaultRegexTimeout) => parserOptions with
        {
            AllowReturnOutsideFunction = AllowReturnOutsideFunction,
            RegExpParseMode = CompileRegex is null
                ? defaultRegExpParseMode
                : (CompileRegex.Value ? RegExpParseMode.AdaptToCompiled : RegExpParseMode.AdaptToInterpreted),
            RegexTimeout = RegexTimeout ?? defaultRegexTimeout,
            Tolerant = Tolerant,
        };

        internal ParserOptions GetParserOptions() => ReferenceEquals(this, Default)
            ? _defaultParserOptions
            : ApplyTo(_defaultParserOptions, _defaultParserOptions.RegExpParseMode, _defaultParserOptions.RegexTimeout);

        internal ParserOptions GetParserOptions(Options engineOptions)
            => ApplyTo(_defaultParserOptions, _defaultParserOptions.RegExpParseMode, engineOptions.Constraints.RegexTimeout);
    }

    public sealed record class ModuleParsingOptions : IParsingOptions
    {
        private static readonly ParserOptions _defaultParserOptions = Engine.BaseParserOptions with
        {
            RegExpParseMode = RegExpParseMode.AdaptToInterpreted,
        };

        public static readonly ModuleParsingOptions Default = new();

        /// <inheritdoc/>
        public bool? CompileRegex { get; init; }

        /// <inheritdoc/>
        public TimeSpan? RegexTimeout { get; init; }

        /// <inheritdoc/>
        public bool Tolerant { get; init; } = _defaultParserOptions.Tolerant;

        internal ParserOptions ApplyTo(ParserOptions baseOptions, RegExpParseMode defaultRegExpParseMode, TimeSpan defaultRegexTimeout) => baseOptions with
        {
            RegExpParseMode = CompileRegex is null
                ? defaultRegExpParseMode
                : (CompileRegex.Value ? RegExpParseMode.AdaptToCompiled : RegExpParseMode.AdaptToInterpreted),
            RegexTimeout = RegexTimeout ?? defaultRegexTimeout,
            Tolerant = Tolerant,
        };

        internal ParserOptions GetParserOptions() => ReferenceEquals(this, Default)
            ? _defaultParserOptions
            : ApplyTo(_defaultParserOptions, _defaultParserOptions.RegExpParseMode, _defaultParserOptions.RegexTimeout);

        internal ParserOptions GetParserOptions(Options engineOptions)
            => ApplyTo(_defaultParserOptions, _defaultParserOptions.RegExpParseMode, engineOptions.Constraints.RegexTimeout);
    }
}
