// Copyright (c) Duende Software. All rights reserved.
// See LICENSE in the project root for license information.

using Duende.ValueObjectsGenerator;

// Simple argument parsing — this is internal tooling, no framework needed
string? path = null;
string? ns = null;

for (var i = 0; i < args.Length; i++)
{
    if (args[i] == "--path" && i + 1 < args.Length)
    {
        path = args[++i];
    }
    else if (args[i] == "--namespace" && i + 1 < args.Length)
    {
        ns = args[++i];
    }
}

if (path is null || ns is null)
{
    Console.Error.WriteLine("Usage: ValueObjectsGenerator --path <projectDir> --namespace <rootNamespace>");
    return 1;
}

if (!Directory.Exists(path))
{
    Console.Error.WriteLine($"Directory not found: {path}");
    return 1;
}

try
{
    return Run(path, ns);
}
catch (Exception ex) when (ex is IOException or UnauthorizedAccessException or InvalidOperationException or ArgumentException)
{
    Console.Error.WriteLine($"ValueObjectsGenerator failed: {ex.Message}");
    return 1;
}

static int Run(string path, string ns)
{
    var valueObjects = FileScanner.Scan(path, ns);

    var written = 0;
    var skipped = 0;
    var expectedFiles = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

    // Generate per-type .g.cs files next to their source files
    foreach (var vo in valueObjects)
    {
        var sourceDir = Path.GetDirectoryName(vo.SourceFilePath)!;
        var outputPath = Path.Combine(sourceDir, $"{vo.TypeName}.g.cs");

        var content = vo.Kind switch
        {
            ValueObjectKind.StringValue => StringValueCodeGenerator.Generate(vo),
            ValueObjectKind.ValueOf => ValueOfCodeGenerator.Generate(vo),
            _ => throw new InvalidOperationException($"Unknown kind: {vo.Kind}")
        };

        _ = expectedFiles.Add(Path.GetFullPath(outputPath));

        if (WriteIfChanged(outputPath, content))
        {
            written++;
        }
        else
        {
            skipped++;
        }
    }

    // Generate infrastructure files in {path}/Internal/ValueObjects/
    var valueObjectsDir = Path.Combine(path, "Internal", "ValueObjects");
    _ = Directory.CreateDirectory(valueObjectsDir);

    TrackAndWrite(ref written, ref skipped, expectedFiles,
        Path.Combine(valueObjectsDir, "IValueOf.g.cs"), InfrastructureCodeGenerator.GetInterfaceSource(ns));

    TrackAndWrite(ref written, ref skipped, expectedFiles,
        Path.Combine(valueObjectsDir, "ValueOfTypeConverter.g.cs"), InfrastructureCodeGenerator.GetTypeConverterSource(ns));

    TrackAndWrite(ref written, ref skipped, expectedFiles,
        Path.Combine(valueObjectsDir, "CharsetExtensions.g.cs"), InfrastructureCodeGenerator.GetCharSetsSource(ns));

    // Clean up orphaned .g.cs files that were previously generated by this tool
    var deleted = CleanOrphanedFiles(path, expectedFiles);

    Console.WriteLine($"ValueObjectsGenerator: {valueObjects.Count} value objects — {written} files written, {skipped} unchanged, {deleted} orphans deleted.");
    return 0;
}

static void TrackAndWrite(ref int written, ref int skipped, HashSet<string> expectedFiles, string filePath, string content)
{
    _ = expectedFiles.Add(Path.GetFullPath(filePath));
    if (WriteIfChanged(filePath, content))
    {
        written++;
    }
    else
    {
        skipped++;
    }
}

// Deletes orphaned .g.cs files that were previously generated by this tool but are no longer expected.
// Only deletes files that contain the ValueObjectsGenerator marker comment.
static int CleanOrphanedFiles(string rootPath, HashSet<string> expectedFiles)
{
    const string marker = "// <auto-generated by=\"ValueObjectsGenerator\"/>";
    var deleted = 0;

    foreach (var file in Directory.EnumerateFiles(rootPath, "*.g.cs", SearchOption.AllDirectories))
    {
        var fullPath = Path.GetFullPath(file);

        // Skip files in obj/ and bin/ directories
        var normalized = fullPath.Replace('\\', '/');
        if (normalized.Contains("/obj/", StringComparison.Ordinal) ||
            normalized.Contains("/bin/", StringComparison.Ordinal))
        {
            continue;
        }

        // Skip files we just generated
        if (expectedFiles.Contains(fullPath))
        {
            continue;
        }

        // Only delete files that were generated by this tool (contain our marker)
        string? firstLine;
        using (var reader = new StreamReader(file))
        {
            firstLine = reader.ReadLine();
        }

        if (firstLine == marker)
        {
            File.Delete(file);
            Console.WriteLine($"  Deleted orphaned file: {file}");
            deleted++;
        }
    }

    return deleted;
}

// Writes content to path only if it differs from what's already there.
// Returns true if the file was written, false if unchanged or locked.
static bool WriteIfChanged(string filePath, string content)
{
    if (File.Exists(filePath))
    {
        var existing = File.ReadAllText(filePath);
        // Normalize line endings for comparison
        if (existing.Replace("\r\n", "\n", StringComparison.Ordinal) == content.Replace("\r\n", "\n", StringComparison.Ordinal))
        {
            return false;
        }
    }

    // Use FileShare.ReadWrite so IDE language servers holding a shared lock don't block us.
    // FileMode.OpenOrCreate + SetLength(0) avoids the truncation that FileMode.Create requires
    // (which needs exclusive access on Windows).
    using var stream = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite);
    stream.SetLength(0);
    using var writer = new StreamWriter(stream, System.Text.Encoding.UTF8);
    writer.Write(content);
    return true;
}