namespace LyricFlow.Core.Services;

public static class NltkPathResolver
{
    // MARK: - Public Resolution
    #region Public Resolution

    public static string? ResolveCmudictPath(string? configuredPath = null)
    {
        return ResolveResourceFile(configuredPath, "LYRICFLOW_CMUDICT_PATH", ["cmudict", "cmudict"]);
    }

    public static string? ResolveWordNetPath(string? configuredPath = null)
    {
        foreach (var candidate in EnumerateCandidates(configuredPath, "LYRICFLOW_WORDNET_PATH", ["wordnet"]))
        {
            if (Directory.Exists(candidate))
            {
                return candidate;
            }
        }

        foreach (var candidate in EnumerateZipCandidates(configuredPath, "LYRICFLOW_WORDNET_PATH"))
        {
            if (File.Exists(candidate))
            {
                return candidate;
            }
        }

        return null;
    }

    #endregion

    // MARK: - Shared Resolution Helpers
    #region Shared Resolution Helpers

    private static string? ResolveResourceFile(string? configuredPath, string envVar, string[] resourceSegments)
    {
        foreach (var candidate in EnumerateCandidates(configuredPath, envVar, resourceSegments))
        {
            if (File.Exists(candidate))
            {
                return candidate;
            }
        }

        return null;
    }

    #endregion

    // MARK: - Candidate Enumeration
    #region Candidate Enumeration

    private static IEnumerable<string> EnumerateCandidates(string? configuredPath, string envVar, string[] resourceSegments)
    {
        var roots = new List<string>();
        if (!string.IsNullOrWhiteSpace(configuredPath))
        {
            roots.Add(configuredPath);
        }

        var envPath = Environment.GetEnvironmentVariable(envVar);
        if (!string.IsNullOrWhiteSpace(envPath))
        {
            roots.Add(envPath);
        }

        var nltkDataEnv = Environment.GetEnvironmentVariable("NLTK_DATA");
        if (!string.IsNullOrWhiteSpace(nltkDataEnv))
        {
            roots.AddRange(
                nltkDataEnv.Split(Path.PathSeparator, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
                    .Select(root => Path.Combine(root, "corpora", Path.Combine(resourceSegments)))
            );
        }

        var appData = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
        if (!string.IsNullOrWhiteSpace(appData))
        {
            roots.Add(Path.Combine(appData, "nltk_data", "corpora", Path.Combine(resourceSegments)));
        }

        var home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
        if (!string.IsNullOrWhiteSpace(home))
        {
            roots.Add(Path.Combine(home, "nltk_data", "corpora", Path.Combine(resourceSegments)));
        }

        roots.Add(Path.Combine(AppContext.BaseDirectory, "nltk_data", "corpora", Path.Combine(resourceSegments)));

        return roots
            .Where(root => !string.IsNullOrWhiteSpace(root))
            .Select(Path.GetFullPath);
    }

    #endregion

    // MARK: - Zip Candidates
    #region Zip Candidates

    private static IEnumerable<string> EnumerateZipCandidates(string? configuredPath, string envVar)
    {
        var roots = new List<string>();
        if (!string.IsNullOrWhiteSpace(configuredPath))
        {
            roots.Add(configuredPath);
        }

        var envPath = Environment.GetEnvironmentVariable(envVar);
        if (!string.IsNullOrWhiteSpace(envPath))
        {
            roots.Add(envPath);
        }

        var nltkDataEnv = Environment.GetEnvironmentVariable("NLTK_DATA");
        if (!string.IsNullOrWhiteSpace(nltkDataEnv))
        {
            roots.AddRange(
                nltkDataEnv.Split(Path.PathSeparator, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
                    .Select(root => Path.Combine(root, "corpora", "wordnet.zip"))
            );
        }

        var appData = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
        if (!string.IsNullOrWhiteSpace(appData))
        {
            roots.Add(Path.Combine(appData, "nltk_data", "corpora", "wordnet.zip"));
        }

        var home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
        if (!string.IsNullOrWhiteSpace(home))
        {
            roots.Add(Path.Combine(home, "nltk_data", "corpora", "wordnet.zip"));
        }

        roots.Add(Path.Combine(AppContext.BaseDirectory, "nltk_data", "corpora", "wordnet.zip"));

        return roots
            .Where(root => !string.IsNullOrWhiteSpace(root))
            .Select(Path.GetFullPath);
    }

    #endregion
}