using System.Text.Json;
using System.Text.Json.Serialization;
using StellaOps.Symbols.Core.Models;

namespace StellaOps.Symbols.Ingestor.Cli;

/// <summary>
/// Writes symbol manifests to various formats.
/// </summary>
public static class ManifestWriter
{
    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        WriteIndented = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        Converters = { new JsonStringEnumConverter() },
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
    };

    /// <summary>
    /// Writes manifest to JSON file.
    /// </summary>
    public static async Task<string> WriteJsonAsync(
        SymbolManifest manifest,
        string outputDir,
        CancellationToken cancellationToken = default)
    {
        Directory.CreateDirectory(outputDir);

        var fileName = $"{manifest.DebugId}.symbols.json";
        var filePath = Path.Combine(outputDir, fileName);

        var json = JsonSerializer.Serialize(manifest, JsonOptions);
        await File.WriteAllTextAsync(filePath, json, cancellationToken).ConfigureAwait(false);

        return filePath;
    }

    /// <summary>
    /// Writes DSSE envelope to file.
    /// </summary>
    public static async Task<string> WriteDsseAsync(
        string payload,
        string payloadType,
        string signature,
        string keyId,
        string outputDir,
        string debugId,
        CancellationToken cancellationToken = default)
    {
        Directory.CreateDirectory(outputDir);

        var envelope = new DsseEnvelope
        {
            PayloadType = payloadType,
            Payload = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(payload)),
            Signatures =
            [
                new DsseSignature { KeyId = keyId, Sig = signature }
            ]
        };

        var fileName = $"{debugId}.symbols.dsse.json";
        var filePath = Path.Combine(outputDir, fileName);

        var json = JsonSerializer.Serialize(envelope, JsonOptions);
        await File.WriteAllTextAsync(filePath, json, cancellationToken).ConfigureAwait(false);

        return filePath;
    }

    /// <summary>
    /// Reads manifest from JSON file.
    /// </summary>
    public static async Task<SymbolManifest?> ReadJsonAsync(
        string filePath,
        CancellationToken cancellationToken = default)
    {
        var json = await File.ReadAllTextAsync(filePath, cancellationToken).ConfigureAwait(false);
        return JsonSerializer.Deserialize<SymbolManifest>(json, JsonOptions);
    }
}

/// <summary>
/// DSSE envelope structure.
/// </summary>
public sealed class DsseEnvelope
{
    [JsonPropertyName("payloadType")]
    public string PayloadType { get; set; } = string.Empty;

    [JsonPropertyName("payload")]
    public string Payload { get; set; } = string.Empty;

    [JsonPropertyName("signatures")]
    public List<DsseSignature> Signatures { get; set; } = [];
}

/// <summary>
/// DSSE signature.
/// </summary>
public sealed class DsseSignature
{
    [JsonPropertyName("keyid")]
    public string KeyId { get; set; } = string.Empty;

    [JsonPropertyName("sig")]
    public string Sig { get; set; } = string.Empty;
}