// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Formats.Tar;
using System.IO.Compression;
using System.Text.Json;
using System.Text.RegularExpressions;
using Aspire.Cli.Agents.AspireSkills;
 
namespace Aspire.Cli.Agents.Hooks;
 
/// <summary>
/// Reads skills and references from the embedded skill manifest, and MCP tools from the canonical hook.
/// </summary>
internal sealed partial class AgentTelemetryCatalog
{
    private static readonly Lazy<AgentTelemetryCatalog> s_bundled = new(LoadBundled);
 
    internal static AgentTelemetryCatalog Bundled => s_bundled.Value;
 
    internal IReadOnlySet<string> Skills { get; }
    internal IReadOnlySet<string> Tools { get; }
    internal IReadOnlySet<string> References { get; }
 
    private AgentTelemetryCatalog(HashSet<string> skills, HashSet<string> tools, HashSet<string> references)
    {
        Skills = skills;
        Tools = tools;
        References = references;
    }
 
    internal static AgentTelemetryCatalog Parse(SkillBundleManifest manifest, string script)
    {
        if (manifest.Skills is not { Length: > 0 })
        {
            throw new InvalidDataException("The bundled skill manifest must contain skills.");
        }
 
        var skills = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        var references = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
        foreach (var skill in manifest.Skills)
        {
            if (skill?.Name is not { Length: > 0 } name)
            {
                throw new InvalidDataException("The bundled skill manifest contains an unnamed skill.");
            }
 
            AspireSkillsBundleProvider.ValidateSkillName(name);
            if (!skills.Add(name))
            {
                throw new InvalidDataException($"The bundled skill manifest contains duplicate skill '{name}'.");
            }
 
            if (skill.Files is not { Length: > 0 } files)
            {
                throw new InvalidDataException($"The bundled skill '{name}' is missing its file inventory.");
            }
            foreach (var file in files)
            {
                var path = AspireSkillsBundleProvider.NormalizeRelativePath(file?.RelativePath).Replace('\\', '/');
                // SKILL.md is an invocation, not a reference. Evals, scripts, and other manifest
                // assets must not become new telemetry dimensions merely because they are shipped.
                if (path.StartsWith(AspireSkillsBundleLayout.ReferencesDirectoryName + "/", StringComparison.Ordinal))
                {
                    references.Add($"{name}/{path}");
                }
            }
        }
 
        // The manifest does not yet describe MCP tools. Retain the canonical tool allowlist until
        // structured tool metadata is available, without parsing shell declarations for skills.
        // The script contains one shell declaration in this form:
        //   ASPIRE_MCP_TOOLS="doctor list_resources ..."
        // McpToolsDeclaration matches the entire declaration and captures the quoted text as "values".
        var declarations = McpToolsDeclaration().Matches(script);
        if (declarations.Count != 1)
        {
            throw new InvalidDataException("The bundled telemetry hook must declare ASPIRE_MCP_TOOLS exactly once.");
        }
 
        // A null separator makes string.Split treat all Unicode whitespace as delimiters. Removing
        // empty entries allows the captured tool identifiers to be separated by repeated whitespace.
        var tools = declarations[0].Groups["values"].Value.Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries);
        if (tools.Length == 0 || tools.Any(tool => !ToolIdentifier().IsMatch(tool)))
        {
            throw new InvalidDataException("The bundled telemetry hook contains an invalid MCP tool allowlist.");
        }
 
        return new(skills, new HashSet<string>(tools, StringComparer.OrdinalIgnoreCase), references);
    }
 
    private static AgentTelemetryCatalog LoadBundled()
    {
        // Read only compiled resources, never user-installed skills or scripts. No extraction,
        // network lookup, or skill-content reads are needed on the hook path.
        using var archive = typeof(AgentTelemetryCatalog).Assembly.GetManifestResourceStream(EmbeddedAspireSkillsBundleProvider.ArchiveResourceName)
            ?? throw new InvalidDataException("The bundled skills archive is missing.");
        var manifest = ReadManifest(archive);
        using var stream = typeof(AgentTelemetryCatalog).Assembly.GetManifestResourceStream(TelemetryHookInstaller.ShellResourceName)
            ?? throw new InvalidDataException("The bundled telemetry hook is missing.");
        using var reader = new StreamReader(stream);
        return Parse(manifest, reader.ReadToEnd());
    }
 
    internal static SkillBundleManifest ReadManifest(Stream archive)
    {
        using var gzip = new GZipStream(archive, CompressionMode.Decompress, leaveOpen: true);
        using var tar = new TarReader(gzip);
        SkillBundleManifest? manifest = null;
        while (tar.GetNextEntry() is { } entry)
        {
            // The manifest is at the archive root or one wrapper directory below it:
            // The manifest is either at the root or inside one versioned wrapper directory.
            var parts = entry.Name.Split('/', StringSplitOptions.RemoveEmptyEntries);
            if (parts is not ([AspireSkillsBundleLayout.ManifestFileName] or [_, AspireSkillsBundleLayout.ManifestFileName]))
            {
                continue;
            }
            if (manifest is not null || entry.DataStream is null ||
                entry.EntryType is not (TarEntryType.RegularFile or TarEntryType.V7RegularFile))
            {
                throw new InvalidDataException("The bundled skills archive must contain one regular skill manifest.");
            }
            manifest = JsonSerializer.Deserialize(entry.DataStream, AspireSkillsJsonSerializerContext.Default.SkillBundleManifest)
                ?? throw new InvalidDataException("The bundled skill manifest is empty.");
        }
 
        return manifest ?? throw new InvalidDataException($"The bundled skills archive is missing {AspireSkillsBundleLayout.ManifestFileName}.");
    }
 
    // ASPIRE_MCP_TOOLS="doctor list_resources ..." is literal, whitespace-separated data.
    [GeneratedRegex("""^ASPIRE_MCP_TOOLS="(?<values>[^"]*)"[ \t]*\r?$""", RegexOptions.Multiline)]
    private static partial Regex McpToolsDeclaration();
 
    [GeneratedRegex("""\A[a-zA-Z0-9_-]+\z""")]
    private static partial Regex ToolIdentifier();
}