using System;
using System.Globalization;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using StellaOps.Signals.Options;
using StellaOps.Signals.Storage.Models;

namespace StellaOps.Signals.Storage;

/// <summary>
/// Stores callgraph artifacts on the local filesystem.
/// </summary>
internal sealed class FileSystemCallgraphArtifactStore : ICallgraphArtifactStore
{
    private readonly SignalsArtifactStorageOptions storageOptions;
    private readonly ILogger<FileSystemCallgraphArtifactStore> logger;

    public FileSystemCallgraphArtifactStore(IOptions<SignalsOptions> options, ILogger<FileSystemCallgraphArtifactStore> logger)
    {
        ArgumentNullException.ThrowIfNull(options);
        storageOptions = options.Value.Storage;
        this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
    }

    public async Task<StoredCallgraphArtifact> SaveAsync(CallgraphArtifactSaveRequest request, Stream content, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(request);
        ArgumentNullException.ThrowIfNull(content);

        var root = storageOptions.RootPath;
        var directory = Path.Combine(root, Sanitize(request.Language), Sanitize(request.Component), Sanitize(request.Version));
        Directory.CreateDirectory(directory);

        var fileName = string.IsNullOrWhiteSpace(request.FileName)
            ? FormattableString.Invariant($"artifact-{DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}.bin")
            : request.FileName.Trim();

        var destinationPath = Path.Combine(directory, fileName);

        await using (var fileStream = File.Create(destinationPath))
        {
            await content.CopyToAsync(fileStream, cancellationToken).ConfigureAwait(false);
        }

        var fileInfo = new FileInfo(destinationPath);
        logger.LogInformation("Stored callgraph artifact at {Path} (length={Length}).", destinationPath, fileInfo.Length);

        return new StoredCallgraphArtifact(
            Path.GetRelativePath(root, destinationPath),
            fileInfo.Length,
            request.Hash,
            request.ContentType);
    }

    private static string Sanitize(string value)
        => string.Join('_', value.Split(Path.GetInvalidFileNameChars(), StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)).ToLowerInvariant();
}