using System;
using System.Collections.Generic;

namespace StellaOps.Signals.Parsing;

/// <summary>
/// Resolves callgraph parsers for specific languages.
/// </summary>
public interface ICallgraphParserResolver
{
    /// <summary>
    /// Resolves a parser for the supplied language.
    /// </summary>
    ICallgraphParser Resolve(string language);
}

internal sealed class CallgraphParserResolver : ICallgraphParserResolver
{
    private readonly IReadOnlyDictionary<string, ICallgraphParser> parsersByLanguage;

    public CallgraphParserResolver(IEnumerable<ICallgraphParser> parsers)
    {
        ArgumentNullException.ThrowIfNull(parsers);

        var map = new Dictionary<string, ICallgraphParser>(StringComparer.OrdinalIgnoreCase);
        foreach (var parser in parsers)
        {
            map[parser.Language] = parser;
        }

        parsersByLanguage = map;
    }

    public ICallgraphParser Resolve(string language)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(language);

        if (parsersByLanguage.TryGetValue(language, out var parser))
        {
            return parser;
        }

        throw new CallgraphParserNotFoundException(language);
    }
}