using PolyTrader.Web.Configuration;
using Microsoft.Extensions.DependencyInjection;
using System.IO;
using System.Globalization;
using System.Collections.Generic;
using System;
using System.Linq;
using System.Text.Json;
using System.Threading;
using System.Threading.Channels;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using PolyTraderSharp.Services;

namespace PolyTrader.Web.Endpoints
{
    public static class LogsEndpoints
    {
        /// <summary>Wie im Desktop-Viewer: Schutz bei sehr grossen Tagen.</summary>
        internal const int MaxMatches = 20000;

        /// <summary>Etwas mehr als ein Jahr - aeltere Tage lassen sich weiter direkt ueber das Datum abrufen.</summary>
        internal const int MaxListedDays = 400;

        /// <summary>Ordner der Tagesdateien. Ohne Registrierung derselbe wie im TerminalLogger.</summary>
        private static string ResolveLogDirectory(IServiceProvider sp) =>
            sp.GetService<LogDirectory>()?.Path
            ?? Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Logs");

        public static IEndpointRouteBuilder MapLogsEndpoints(this IEndpointRouteBuilder routes)
        {
            var group = routes.MapGroup("/api/logs");

            group.MapGet("/", (TerminalLogger logger, int? minutes) =>
            {
                var span = TimeSpan.FromMinutes(minutes.GetValueOrDefault(60));
                var history = logger.GetHistory(span)
                    .Select(e => new
                    {
                        time = e.Timestamp.ToString("HH:mm:ss"),
                        timestamp = e.Timestamp,
                        level = e.Level.ToString(),
                        cid = e.CorrelationId,
                        msg = e.Message
                    })
                    .ToList();

                return Results.Ok(history);
            });

            group.MapGet("/stream", async (HttpContext context, TerminalLogger logger, CancellationToken ct) =>
            {
                context.Response.Headers.ContentType = "text/event-stream";
                context.Response.Headers.CacheControl = "no-cache";
                context.Response.Headers.Connection = "keep-alive";

                var channel = Channel.CreateUnbounded<LogMessageEventArgs>(new UnboundedChannelOptions
                {
                    SingleWriter = false,
                    SingleReader = true
                });

                void Handler(object? _, LogMessageEventArgs e)
                {
                    channel.Writer.TryWrite(e);
                }

                logger.OnLogMessage += Handler;

                try
                {
                    await context.Response.WriteAsync(": connected\n\n", ct);
                    await context.Response.Body.FlushAsync(ct);

                    while (!ct.IsCancellationRequested)
                    {
                        var log = await channel.Reader.ReadAsync(ct);
                        var payload = JsonSerializer.Serialize(new
                        {
                            time = log.Timestamp.ToString("HH:mm:ss"),
                            level = log.Level.ToString(),
                            cid = log.CorrelationId,
                            msg = log.Message
                        });

                        await context.Response.WriteAsync($"data: {payload}\n\n", ct);
                        await context.Response.Body.FlushAsync(ct);
                    }
                }
                catch (OperationCanceledException)
                {
                    // Client hat Verbindung getrennt
                }
                finally
                {
                    logger.OnLogMessage -= Handler;
                    channel.Writer.TryComplete();
                }
            });

            // ---- Log-Viewer (#564) ---------------------------------------------------------------
            // Gegenstueck zum Tab "Log Viewer" im Desktop (TerminalWindow.LoadViewer): Tagesdateien
            // Logs/yyyy-MM-dd.jsonl, gefiltert nach Level, Korrelations-ID und Text, hoechstens
            // MaxMatches Treffer. Der Live-Stream zeigt nur, was seit dem Prozessstart aufgelaufen ist.

            group.MapGet("/files", (IServiceProvider sp) =>
            {
                string dir = ResolveLogDirectory(sp);
                if (!Directory.Exists(dir))
                    return Results.Ok(new List<object>());

                var files = Directory.EnumerateFiles(dir, "*.jsonl")
                    .Select(p => (Full: p, Name: Path.GetFileNameWithoutExtension(p)))
                    .Where(f => DateOnly.TryParseExact(f.Name, "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out _))
                    .OrderByDescending(f => f.Name, StringComparer.Ordinal)
                    .Take(MaxListedDays)
                    .Select(f => (object)new { date = f.Name, sizeBytes = new FileInfo(f.Full).Length })
                    .ToList();

                return Results.Ok(files);
            });

            group.MapGet("/file", (IServiceProvider sp, string? date, string? level, string? cid, string? q, int? page, int? pageSize) =>
            {
                if (string.IsNullOrWhiteSpace(date)
                    || !DateOnly.TryParseExact(date.Trim(), "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var day))
                    return Results.BadRequest(new { error = "Datum fehlt oder ist ungültig – erwartet yyyy-MM-dd." });

                // Der Dateiname entsteht aus dem GEPRUEFTEN Datum, nie aus der Eingabe. Ein "../" kann so
                // gar nicht erst in den Pfad gelangen.
                string path = Path.Combine(ResolveLogDirectory(sp), $"{day:yyyy-MM-dd}.jsonl");
                if (!File.Exists(path))
                    return Results.NotFound(new { error = $"Für den {day:dd.MM.yyyy} gibt es keine Logdatei." });

                string levelFilter = string.IsNullOrWhiteSpace(level) || level.Trim().Equals("Alle", StringComparison.OrdinalIgnoreCase)
                    ? string.Empty : level.Trim();
                string cidFilter = cid?.Trim() ?? string.Empty;
                string textFilter = q?.Trim() ?? string.Empty;

                var matches = new List<LogJson.ParsedLogLine>();
                bool truncated = false;
                int unreadable = 0;

                // FileShare.ReadWrite: Der Logger haengt an die Tagesdatei laufend Zeilen an.
                using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete))
                using (var reader = new StreamReader(fs))
                {
                    string? line;
                    while ((line = reader.ReadLine()) != null)
                    {
                        var parsed = LogJson.ParseLine(line);
                        if (parsed == null)
                        {
                            if (!string.IsNullOrWhiteSpace(line)) unreadable++;
                            continue;
                        }
                        if (levelFilter.Length > 0 && !parsed.Level.Equals(levelFilter, StringComparison.OrdinalIgnoreCase)) continue;
                        if (cidFilter.Length > 0 && !parsed.Cid.Contains(cidFilter, StringComparison.OrdinalIgnoreCase)) continue;
                        if (textFilter.Length > 0 && !parsed.Message.Contains(textFilter, StringComparison.OrdinalIgnoreCase)) continue;

                        if (matches.Count >= MaxMatches)
                        {
                            truncated = true;
                            break;
                        }
                        matches.Add(parsed);
                    }
                }

                int size = Math.Clamp(pageSize ?? 500, 50, 2000);
                int totalPages = Math.Max(1, (int)Math.Ceiling(matches.Count / (double)size));
                int current = Math.Clamp(page ?? 1, 1, totalPages);

                return Results.Ok(new
                {
                    date = day.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture),
                    total = matches.Count,
                    truncated,
                    maxMatches = MaxMatches,
                    unreadableLines = unreadable,
                    page = current,
                    pageSize = size,
                    totalPages,
                    items = matches.Skip((current - 1) * size).Take(size)
                        .Select(p => new { time = p.Time, level = p.Level, cid = p.Cid, msg = p.Message })
                        .ToList()
                });
            });

            return routes;
        }
    }
}