using MeetingAssistant.MeetingNotes;
using YamlDotNet.Core;
using YamlDotNet.Serialization;

namespace MeetingAssistant.Summary;

public sealed record ProjectMetadata(string Id, string DisplayName, string Description)
{
    public static async Task<string> BuildContextAsync(BoundMeetingProject project, CancellationToken cancellationToken = default)
    {
        var metadata = await ReadAsync(project, cancellationToken);
        var context = $"# {metadata.Id}\nDisplay name: {metadata.DisplayName}\nDescription: {metadata.Description}";
        var agentsPath = Path.Combine(project.Path, "AGENTS.md");
        if (File.Exists(agentsPath))
        {
            var instructions = await File.ReadAllTextAsync(agentsPath, cancellationToken);
            if (!string.IsNullOrWhiteSpace(instructions)) context += "\n\n" + instructions.Trim();
        }
        return context;
    }

    public static bool IsValidContent(string content) => Parse(content) is not null;

    public static async Task<ProjectMetadata> ReadAsync(BoundMeetingProject project, CancellationToken cancellationToken = default)
    {
        var path = Path.Combine(project.Path, "PROJECT.md");
        var metadata = File.Exists(path) ? Parse(await File.ReadAllTextAsync(path, cancellationToken)) : null;
        return new(project.Name,
            string.IsNullOrWhiteSpace(metadata?.Name) ? project.Name : metadata.Name.Trim(),
            metadata?.Description?.Trim() ?? "");
    }

    private static Frontmatter? Parse(string content)
    {
        try
        {
            var document = MarkdownDocumentParser.SplitOptional(content);
            if (!document.HasFrontmatter) return null;
            var metadata = FrontmatterYamlDeserializer.Create().Deserialize<Frontmatter>(document.Frontmatter);
            return string.IsNullOrWhiteSpace(metadata?.Name) || metadata.Description is null || metadata.Description.Length > 256
                ? null
                : metadata;
        }
        catch (YamlException) { return null; }
        catch (InvalidDataException) { return null; }
    }

    private sealed class Frontmatter
    {
        [YamlMember(Alias = "name")]
        public string? Name { get; set; }
        [YamlMember(Alias = "description")]
        public string? Description { get; set; }
    }
}