using System.Text.Json;

namespace QuantEngine.Core.Infrastructure
{
    public sealed class OperationalReportData
    {
        public string SchemaVersion { get; init; } = "n/a";
        public string SourceJson { get; init; } = "n/a";
        public string GeneratedAt { get; init; } = "n/a";
        public int SectionCount { get; init; }
        public List<OperationalReportSection> Sections { get; init; } = new();
    }

    public sealed record OperationalReportSection(string Name, string Title, string Preview);

    public static class OperationalReportLoader
    {
        public static OperationalReportData Load(string path)
        {
            if (!File.Exists(path))
            {
                return new OperationalReportData();
            }

            using var stream = File.OpenRead(path);
            using var doc = JsonDocument.Parse(stream);
            var root = doc.RootElement;

            var sections = new List<OperationalReportSection>();
            if (root.TryGetProperty("sections", out var sectionArray) && sectionArray.ValueKind == JsonValueKind.Array)
            {
                foreach (var section in sectionArray.EnumerateArray())
                {
                    var name = section.TryGetProperty("name", out var nameProp) ? nameProp.GetString() ?? string.Empty : string.Empty;
                    var title = section.TryGetProperty("title", out var titleProp) ? titleProp.GetString() ?? string.Empty : string.Empty;
                    var markdown = section.TryGetProperty("markdown", out var markdownProp) ? markdownProp.GetString() ?? string.Empty : string.Empty;
                    sections.Add(new OperationalReportSection(name, title, Preview(markdown)));
                }
            }

            return new OperationalReportData
            {
                SchemaVersion = root.TryGetProperty("schema_version", out var schema) ? schema.GetString() ?? "n/a" : "n/a",
                SourceJson = root.TryGetProperty("source_json", out var sourceJson) ? sourceJson.GetString() ?? "n/a" : "n/a",
                GeneratedAt = root.TryGetProperty("generated_at", out var generatedAt) ? generatedAt.GetString() ?? "n/a" : "n/a",
                SectionCount = root.TryGetProperty("section_count", out var count) ? count.GetInt32() : sections.Count,
                Sections = sections
            };
        }

        private static string Preview(string markdown)
        {
            if (string.IsNullOrWhiteSpace(markdown))
            {
                return "n/a";
            }

            var trimmed = markdown.Replace("\r", " ").Replace("\n", " ").Trim();
            return trimmed.Length <= 80 ? trimmed : trimmed[..80] + "...";
        }
    }
}