using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Gott.Models;
using Gott.Services;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;

namespace Gott.Endpoints;

public static class HistoryEndpoint
{
    public static void MapHistoryEndpoint(this IEndpointRouteBuilder app)
    {
        app.MapGet("/api/history", HandleHistory);
        app.MapGet("/api/history/poll", HandlePoll);
        app.MapPost("/api/archive", HandleArchive);
        app.MapGet("/api/archives", HandleListArchives);
        app.MapGet("/api/archive/{archiveId}", HandleGetArchive);
        app.MapGet("/api/attachments/{messageId}", HandleGetAttachments);
        app.MapPut("/api/messages/{messageId}/mark", HandleToggleMark);
        app.MapGet("/api/chains/{chainId}", HandleGetChain);
    }

    private static async Task HandleHistory(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.Query["sessionId"].FirstOrDefault();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            await ctx.Response.WriteAsJsonAsync(new { error = "sessionId required" });
            return;
        }

        const int messageLimit = 500;
        var beforeStr = ctx.Request.Query["beforeId"].FirstOrDefault();
        var beforeId = long.TryParse(beforeStr, out var b) ? b : 0;

        var totalCount = await db.GetActiveMessageCount(sessionId);

        List<MessageRecord> messages;
        if (beforeId > 0)
        {
            messages = await db.GetActiveMessagesBeforeId(sessionId, beforeId, messageLimit);
        }
        else
        {
            messages = await db.GetLatestActiveMessages(sessionId, messageLimit);
        }

        // Zähle wie viele Nachrichten es VOR der ältesten geladenen noch gibt
        var oldestLoadedId = messages.Count > 0 ? messages[0].Id : 0;
        var remainingOlder = oldestLoadedId > 0
            ? await db.GetActiveMessageCountBeforeId(sessionId, oldestLoadedId)
            : 0;

        // Nach Chain gruppieren (Reihenfolge beibehalten)
        var chainIds = messages.Select(m => m.ChainId).Distinct().ToList();
        var chains = await db.GetActiveChains(sessionId);
        var chainMap = chains.ToDictionary(c => c.ChainId);

        var result = new List<object>();
        foreach (var chainId in chainIds)
        {
            chainMap.TryGetValue(chainId, out var chain);
            var chainMessages = messages.Where(m => m.ChainId == chainId).ToList();
            result.Add(new { chain, messages = chainMessages });
        }

        await ctx.Response.WriteAsJsonAsync(new
        {
            entries = result,
            hasMore = remainingOlder > 0,
            remainingCount = remainingOlder,
            totalCount,
            loadedCount = messages.Count
        });
    }

    private static async Task HandlePoll(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.Query["sessionId"].FirstOrDefault();
        var afterStr = ctx.Request.Query["afterId"].FirstOrDefault();
        var afterId = long.TryParse(afterStr, out var a) ? a : 0;

        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var messages = await db.GetActiveMessagesAfterId(sessionId, afterId);
        await ctx.Response.WriteAsJsonAsync(messages);
    }

    private static async Task HandleArchive(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.Query["sessionId"].FirstOrDefault();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var archive = await db.CreateArchive(sessionId);
        if (archive == null)
        {
            ctx.Response.StatusCode = 204;
            return;
        }
        await ctx.Response.WriteAsJsonAsync(archive);
    }

    private static async Task HandleListArchives(HttpContext ctx, DatabaseService db)
    {
        var sessionId = ctx.Request.Query["sessionId"].FirstOrDefault();
        if (string.IsNullOrEmpty(sessionId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var archives = await db.GetArchives(sessionId);
        await ctx.Response.WriteAsJsonAsync(archives);
    }

    private static async Task HandleGetAttachments(HttpContext ctx, DatabaseService db)
    {
        var messageIdStr = ctx.Request.RouteValues["messageId"]?.ToString();
        if (!long.TryParse(messageIdStr, out var messageId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var attachments = await db.GetAttachments(messageId);
        // Ohne Base64-Data zurückgeben (zu groß), stattdessen als separater Download
        var result = new List<object>();
        foreach (var att in attachments)
        {
            result.Add(new
            {
                att.Id,
                att.MessageId,
                att.Type,
                att.MediaType,
                att.FileName,
                att.Data,
                att.CreatedAt
            });
        }
        await ctx.Response.WriteAsJsonAsync(result);
    }

    private static async Task HandleToggleMark(HttpContext ctx, DatabaseService db)
    {
        var messageIdStr = ctx.Request.RouteValues["messageId"]?.ToString();
        if (!long.TryParse(messageIdStr, out var messageId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var isMarked = await db.ToggleMessageMark(messageId);
        await ctx.Response.WriteAsJsonAsync(new { messageId, isMarked });
    }

    private static async Task HandleGetChain(HttpContext ctx, DatabaseService db)
    {
        var chainId = ctx.Request.RouteValues["chainId"]?.ToString();
        if (string.IsNullOrEmpty(chainId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var chain = await db.GetChain(chainId);
        if (chain == null)
        {
            ctx.Response.StatusCode = 404;
            return;
        }

        await ctx.Response.WriteAsJsonAsync(chain);
    }

    private static async Task HandleGetArchive(HttpContext ctx, DatabaseService db)
    {
        var archiveId = ctx.Request.RouteValues["archiveId"]?.ToString();
        if (string.IsNullOrEmpty(archiveId))
        {
            ctx.Response.StatusCode = 400;
            return;
        }

        var chains = await db.GetArchiveChains(archiveId);
        var result = new List<object>();
        foreach (var chain in chains)
        {
            var messages = await db.GetChainMessages(chain.ChainId);
            result.Add(new { chain, messages });
        }

        await ctx.Response.WriteAsJsonAsync(result);
    }
}