using System.Text.Json;
using System.Text.Json.Serialization;

namespace AcDream.Core.Plugins;

public sealed record PluginManifest(
    string Id,
    string DisplayName,
    string Version,
    string EntryDll,
    int ApiVersion,
    IReadOnlyList<string> Dependencies)
{
    public static PluginManifest Parse(string json)
    {
        PluginManifestDto? dto;
        try
        {
            dto = JsonSerializer.Deserialize<PluginManifestDto>(json, JsonOptions);
        }
        catch (JsonException ex)
        {
            throw new PluginManifestException($"invalid json: {ex.Message}", ex);
        }

        if (dto is null)
            throw new PluginManifestException("manifest is empty");

        Require(dto.Id, nameof(dto.Id));
        Require(dto.DisplayName, nameof(dto.DisplayName));
        Require(dto.Version, nameof(dto.Version));
        Require(dto.EntryDll, nameof(dto.EntryDll));
        if (dto.ApiVersion <= 0)
            throw new PluginManifestException("apiVersion must be >= 1");

        return new PluginManifest(
            dto.Id!,
            dto.DisplayName!,
            dto.Version!,
            dto.EntryDll!,
            dto.ApiVersion,
            dto.Dependencies ?? Array.Empty<string>());
    }

    private static void Require(string? value, string fieldName)
    {
        if (string.IsNullOrWhiteSpace(value))
            throw new PluginManifestException(
                $"missing required field: {char.ToLowerInvariant(fieldName[0])}{fieldName[1..]}");
    }

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        PropertyNameCaseInsensitive = true,
    };

    private sealed class PluginManifestDto
    {
        public string? Id { get; set; }
        public string? DisplayName { get; set; }
        public string? Version { get; set; }
        public string? EntryDll { get; set; }
        public int ApiVersion { get; set; }
        public IReadOnlyList<string>? Dependencies { get; set; }
    }
}

public sealed class PluginManifestException : Exception
{
    public PluginManifestException(string message) : base(message) { }
    public PluginManifestException(string message, Exception inner) : base(message, inner) { }
}