using System.ComponentModel;
using System.Text.Json;
using ModelContextProtocol.Server;
using MoneyMap.Models;
using MoneyMap.Services;

namespace MoneyMap.Mcp.Tools;

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

    [McpServerTool(Name = "get_budget_status"), Description("Get all active budgets with current period spending vs. limit.")]
    public static async Task<string> GetBudgetStatus(
        [Description("Date to calculate status for (defaults to today)")] string? asOfDate = null,
        IBudgetService budgetService = default!)
    {
        DateTime? date = null;
        if (!string.IsNullOrWhiteSpace(asOfDate) && DateTime.TryParse(asOfDate, out var parsed))
            date = parsed;

        var statuses = await budgetService.GetAllBudgetStatusesAsync(date);

        var result = statuses.Select(s => new
        {
            s.Budget.Id,
            Category = s.Budget.DisplayName,
            s.Budget.Amount,
            Period = s.Budget.Period.ToString(),
            s.PeriodStart,
            s.PeriodEnd,
            s.Spent,
            s.Remaining,
            PercentUsed = Math.Round(s.PercentUsed, 1),
            s.IsOverBudget
        }).ToList();

        return JsonSerializer.Serialize(result, JsonOptions);
    }

    [McpServerTool(Name = "create_budget"), Description("Create a new budget for a category or total spending.")]
    public static async Task<string> CreateBudget(
        [Description("Budget amount limit")] decimal amount,
        [Description("Period: Weekly, Monthly, or Yearly")] string period,
        [Description("Start date for period calculation, e.g. 2026-01-01")] string startDate,
        [Description("Category name (omit for total spending budget)")] string? category = null,
        IBudgetService budgetService = default!)
    {
        if (!Enum.TryParse<BudgetPeriod>(period, true, out var budgetPeriod))
            return $"Invalid period '{period}'. Must be Weekly, Monthly, or Yearly.";

        var budget = new Budget
        {
            Category = category,
            Amount = amount,
            Period = budgetPeriod,
            StartDate = DateTime.Parse(startDate),
            IsActive = true
        };

        var result = await budgetService.CreateBudgetAsync(budget);

        return JsonSerializer.Serialize(new { result.Success, result.Message, BudgetId = budget.Id }, JsonOptions);
    }

    [McpServerTool(Name = "update_budget"), Description("Update an existing budget's amount, period, or active status.")]
    public static async Task<string> UpdateBudget(
        [Description("Budget ID to update")] int budgetId,
        [Description("New budget amount")] decimal? amount = null,
        [Description("New period: Weekly, Monthly, or Yearly")] string? period = null,
        [Description("Set active/inactive")] bool? isActive = null,
        IBudgetService budgetService = default!)
    {
        var budget = await budgetService.GetBudgetByIdAsync(budgetId);
        if (budget == null)
            return "Budget not found";

        if (amount.HasValue)
            budget.Amount = amount.Value;

        if (!string.IsNullOrWhiteSpace(period))
        {
            if (!Enum.TryParse<BudgetPeriod>(period, true, out var budgetPeriod))
                return $"Invalid period '{period}'. Must be Weekly, Monthly, or Yearly.";
            budget.Period = budgetPeriod;
        }

        if (isActive.HasValue)
            budget.IsActive = isActive.Value;

        var result = await budgetService.UpdateBudgetAsync(budget);

        return JsonSerializer.Serialize(new { result.Success, result.Message }, JsonOptions);
    }
}