namespace MeetingAssistant.Workflow;

internal sealed class WorkflowRulesEditorMarkdownLinkResolver
{
    private static readonly string[] ImageUriSchemes = ["http", "https", "file"];
    private readonly IReadOnlyList<string> rootPaths;
    private readonly IReadOnlyList<string> recursiveRootPaths;
    private readonly Dictionary<string, string> resolvedFiles = new(StringComparer.OrdinalIgnoreCase);

    public WorkflowRulesEditorMarkdownLinkResolver(
        IEnumerable<string> rootPaths,
        IEnumerable<string>? recursiveRootPaths = null)
    {
        this.rootPaths = rootPaths
            .Where(path => !string.IsNullOrWhiteSpace(path))
            .Select(path => Path.GetFullPath(path))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToArray();
        this.recursiveRootPaths = (recursiveRootPaths ?? [])
            .Where(path => !string.IsNullOrWhiteSpace(path))
            .Select(path => Path.GetFullPath(path))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToArray();
    }

    public static WorkflowRulesEditorMarkdownLinkResolver Empty { get; } = new([]);

    public static WorkflowRulesEditorMarkdownLinkResolver FromOptions(MeetingAssistantOptions options)
    {
        var artifactRoots = new[]
        {
            VaultPath.Resolve(options.Vault, options.Vault.AssistantContextFolder),
            VaultPath.Resolve(options.Vault, options.Vault.MeetingNotesFolder),
            VaultPath.Resolve(options.Vault, options.Vault.SummariesFolder),
            VaultPath.Resolve(options.Vault, options.Vault.TranscriptsFolder),
            VaultPath.Resolve(options.Vault, options.Vault.ProjectsFolder)
        };

        return new WorkflowRulesEditorMarkdownLinkResolver([
            ..artifactRoots,
            Environment.CurrentDirectory,
            AppContext.BaseDirectory
        ], artifactRoots);
    }

    public bool TryResolveImageUri(string? target, out Uri uri)
    {
        uri = null!;
        if (string.IsNullOrWhiteSpace(target))
        {
            return false;
        }

        if (Uri.TryCreate(target, UriKind.Absolute, out uri!) &&
            ImageUriSchemes.Contains(uri.Scheme, StringComparer.OrdinalIgnoreCase))
        {
            return true;
        }

        if (TryResolveExistingFilePath(target, out var path))
        {
            uri = new Uri(path);
            return true;
        }

        return false;
    }

    public string ResolveOpenTarget(string? target)
    {
        if (string.IsNullOrWhiteSpace(target))
        {
            return "";
        }

        if (Uri.TryCreate(target, UriKind.Absolute, out var uri))
        {
            return uri.Scheme.Equals("file", StringComparison.OrdinalIgnoreCase)
                ? uri.LocalPath
                : uri.ToString();
        }

        return TryResolveExistingFilePath(target, out var path)
            ? path
            : target;
    }

    private bool TryResolveExistingFilePath(string target, out string path)
    {
        path = "";
        if (Path.IsPathRooted(target) && File.Exists(target))
        {
            path = Path.GetFullPath(target);
            return true;
        }

        if (resolvedFiles.TryGetValue(target, out var cachedPath))
        {
            path = cachedPath;
            return true;
        }

        if (TryResolveDirectRelativePath(target, out path) ||
            TryFindRelativePathInRoots(target, out path))
        {
            resolvedFiles[target] = path;
            return true;
        }

        return false;
    }

    private bool TryResolveDirectRelativePath(string target, out string path)
    {
        foreach (var root in rootPaths)
        {
            try
            {
                var candidate = Path.GetFullPath(target, root);
                if (File.Exists(candidate))
                {
                    path = candidate;
                    return true;
                }
            }
            catch
            {
            }
        }

        path = "";
        return false;
    }

    private bool TryFindRelativePathInRoots(string target, out string path)
    {
        path = "";
        var normalizedSuffix = NormalizeRelativePath(target);
        if (string.IsNullOrWhiteSpace(normalizedSuffix))
        {
            return false;
        }

        var fileName = Path.GetFileName(normalizedSuffix);
        if (string.IsNullOrWhiteSpace(fileName))
        {
            return false;
        }

        foreach (var root in recursiveRootPaths.Where(Directory.Exists))
        {
            try
            {
                var match = Directory
                    .EnumerateFiles(root, fileName, SearchOption.AllDirectories)
                    .Where(candidate => NormalizeRelativePath(Path.GetRelativePath(root, candidate))
                        .EndsWith(normalizedSuffix, StringComparison.OrdinalIgnoreCase))
                    .OrderByDescending(File.GetLastWriteTimeUtc)
                    .FirstOrDefault();
                if (match is not null)
                {
                    path = match;
                    return true;
                }
            }
            catch
            {
            }
        }

        return false;
    }

    private static string NormalizeRelativePath(string path)
    {
        return path
            .Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar)
            .TrimStart(Path.DirectorySeparatorChar);
    }
}