using System.ComponentModel;
using System.Text.Json;
using Microsoft.EntityFrameworkCore;
using ModelContextProtocol.Server;
using MoneyMap.Data;
using MoneyMap.Services;

namespace MoneyMap.Mcp.Tools;

[McpServerToolType]
public static class DashboardTools
{
    private static readonly JsonSerializerOptions JsonOptions = new() { WriteIndented = true };

    [McpServerTool(Name = "get_dashboard"), Description("Get dashboard overview: top spending categories, recent transactions, and aggregate stats.")]
    public static async Task<string> GetDashboard(
        [Description("Number of top categories to show (default 8)")] int? topCategoriesCount = null,
        [Description("Number of recent transactions to show (default 20)")] int? recentTransactionsCount = null,
        IDashboardService dashboardService = default!)
    {
        var data = await dashboardService.GetDashboardDataAsync(
            topCategoriesCount ?? 8,
            recentTransactionsCount ?? 20);

        return JsonSerializer.Serialize(data, JsonOptions);
    }

    [McpServerTool(Name = "get_monthly_trend"), Description("Get month-over-month spending totals for trend analysis.")]
    public static async Task<string> GetMonthlyTrend(
        [Description("Number of months to include (default 6)")] int? months = null,
        [Description("Filter to a specific category")] string? category = null,
        MoneyMapContext db = default!)
    {
        var monthCount = months ?? 6;
        var endDate = DateTime.Today;
        var startDate = new DateTime(endDate.Year, endDate.Month, 1).AddMonths(-(monthCount - 1));

        var q = db.Transactions
            .Where(t => t.Date >= startDate && t.Date <= endDate)
            .Where(t => t.Amount < 0)
            .Where(t => t.TransferToAccountId == null)
            .ExcludeTransfers();

        if (!string.IsNullOrWhiteSpace(category))
            q = q.Where(t => t.Category == category);

        var monthly = await q
            .GroupBy(t => new { t.Date.Year, t.Date.Month })
            .Select(g => new
            {
                Year = g.Key.Year,
                Month = g.Key.Month,
                Total = g.Sum(t => Math.Abs(t.Amount)),
                Count = g.Count()
            })
            .OrderBy(x => x.Year).ThenBy(x => x.Month)
            .ToListAsync();

        var result = monthly.Select(m => new
        {
            Period = $"{m.Year}-{m.Month:D2}",
            m.Total,
            m.Count
        }).ToList();

        return JsonSerializer.Serialize(new { Category = category ?? "All Spending", Months = result }, JsonOptions);
    }
}