import { query } from "./_generated/server";
import { v } from "convex/values";
import { getAppSettings, requireUserId } from "./lib/helpers";
import {
  buildSchedule,
  currentBalanceFromSchedule,
  totalMonthlyPaymentActiveLoans,
  totalRemainingDebt,
} from "./lib/amortization";
import { monthKeyFromBasis } from "./lib/month";

export const summary = query({
  args: {
    from: v.string(),
    to: v.string(),
    accountId: v.optional(v.id("accounts")),
    basis: v.union(v.literal("effective"), v.literal("booking")),
  },
  returns: v.object({
    income: v.number(),
    expenses: v.number(),
    fixedCosts: v.number(),
    variableCosts: v.number(),
    balance: v.number(),
    savingsRate: v.union(v.number(), v.null()),
    totalLoanPayment: v.number(),
    totalRemainingDebt: v.number(),
    monthlyTrend: v.array(
      v.object({
        month: v.string(),
        income: v.number(),
        expenses: v.number(),
        balance: v.number(),
      }),
    ),
    categoryBreakdown: v.array(
      v.object({
        categoryId: v.optional(v.id("categories")),
        name: v.string(),
        amount: v.number(),
        block: v.optional(v.union(v.literal("wiederkehrend"), v.literal("variabel"))),
        color: v.string(),
      }),
    ),
    recentTransactions: v.array(
      v.object({
        _id: v.id("transactions"),
        bookingDate: v.optional(v.string()),
        description: v.string(),
        amount: v.number(),
        categoryId: v.optional(v.id("categories")),
        isPending: v.boolean(),
      }),
    ),
    activeLoans: v.array(
      v.object({
        _id: v.id("loans"),
        name: v.string(),
        monthlyPayment: v.optional(v.number()),
        currentBalance: v.number(),
        remainingMonths: v.number(),
        payoffDate: v.string(),
      }),
    ),
  }),
  handler: async (ctx, args) => {
    const userId = await requireUserId(ctx);
    await getAppSettings(ctx, userId);

    const categories = await ctx.db
      .query("categories")
      .withIndex("by_user", (q) => q.eq("userId", userId))
      .collect();
    const categoryById = new Map(categories.map((c) => [c._id, c]));

    let transactions = await ctx.db
      .query("transactions")
      .withIndex("by_user", (q) => q.eq("userId", userId))
      .collect();

    if (args.accountId) {
      transactions = transactions.filter((tx) => tx.accountId === args.accountId);
    }

    transactions = transactions.filter((tx) => {
      const month = monthKeyFromBasis(tx, args.basis);
      if (!month) return false;
      const monthStart = `${month}-01`;
      const monthEnd = `${month}-31`;
      return monthStart >= `${args.from.slice(0, 7)}-01` && monthEnd <= `${args.to.slice(0, 7)}-31`;
    });

    // Filter by date range using month keys
    transactions = transactions.filter((tx) => {
      const month = monthKeyFromBasis(tx, args.basis);
      if (!month) return false;
      return month >= args.from.slice(0, 7) && month <= args.to.slice(0, 7);
    });

    let income = 0;
    let expenses = 0;
    let fixedCosts = 0;
    let variableCosts = 0;

    const monthlyMap = new Map<string, { income: number; expenses: number }>();
    const categoryMap = new Map<string, { categoryId?: typeof categories[0]["_id"]; name: string; amount: number; block?: typeof categories[0]["block"]; color: string }>();

    for (const tx of transactions) {
      const month = monthKeyFromBasis(tx, args.basis)!;
      const entry = monthlyMap.get(month) ?? { income: 0, expenses: 0 };
      if (tx.amount > 0) {
        income += tx.amount;
        entry.income += tx.amount;
      } else {
        expenses += tx.amount;
        entry.expenses += tx.amount;
        const cat = tx.categoryId ? categoryById.get(tx.categoryId) : undefined;
        if (cat?.block === "wiederkehrend") fixedCosts += tx.amount;
        if (cat?.block === "variabel") variableCosts += tx.amount;

        const key = tx.categoryId ?? "none";
        const catEntry = categoryMap.get(key) ?? {
          categoryId: tx.categoryId,
          name: cat?.name ?? "Ohne Kategorie",
          amount: 0,
          block: cat?.block,
          color: cat?.color ?? "#94a3b8",
        };
        catEntry.amount += tx.amount;
        categoryMap.set(key, catEntry);
      }
      monthlyMap.set(month, entry);
    }

    const balance = income + expenses;
    const savingsRate = income > 0 ? balance / income : null;

    const monthlyTrend = [...monthlyMap.entries()]
      .sort(([a], [b]) => a.localeCompare(b))
      .map(([month, data]) => ({
        month,
        income: Math.round(data.income * 100) / 100,
        expenses: Math.round(data.expenses * 100) / 100,
        balance: Math.round((data.income + data.expenses) * 100) / 100,
      }));

    const categoryBreakdown = [...categoryMap.values()]
      .sort((a, b) => a.amount - b.amount)
      .map((c) => ({ ...c, amount: Math.round(c.amount * 100) / 100 }));

    const recentTransactions = (await ctx.db
      .query("transactions")
      .withIndex("by_user_booking", (q) => q.eq("userId", userId))
      .order("desc")
      .take(10))
      .filter((tx) => !args.accountId || tx.accountId === args.accountId)
      .map((tx) => ({
        _id: tx._id,
        bookingDate: tx.bookingDate,
        description: tx.description,
        amount: tx.amount,
        categoryId: tx.categoryId,
        isPending: tx.isPending,
      }));

    const loans = await ctx.db
      .query("loans")
      .withIndex("by_user_status", (q) => q.eq("userId", userId).eq("status", "aktiv"))
      .collect();

    const activeLoans = loans.map((loan) => {
      const startDate = new Date(loan.startDate);
      const scheduleResult = buildSchedule({
        principal: loan.principal,
        annualRate: loan.annualInterestRate,
        startDate,
        monthlyPayment: loan.monthlyPayment,
        termMonths: loan.termMonths,
      });
      const currentBalance =
        loan.currentBalance ??
        currentBalanceFromSchedule(scheduleResult.schedule, startDate);
      const monthsElapsed = Math.max(
        0,
        (new Date().getFullYear() - startDate.getFullYear()) * 12 +
          (new Date().getMonth() - startDate.getMonth()),
      );
      return {
        _id: loan._id,
        name: loan.name,
        monthlyPayment: loan.monthlyPayment,
        currentBalance,
        remainingMonths: Math.max(0, scheduleResult.termMonths - monthsElapsed),
        payoffDate: scheduleResult.payoffDate.toISOString().slice(0, 10),
      };
    });

    return {
      income: Math.round(income * 100) / 100,
      expenses: Math.round(expenses * 100) / 100,
      fixedCosts: Math.round(fixedCosts * 100) / 100,
      variableCosts: Math.round(variableCosts * 100) / 100,
      balance: Math.round(balance * 100) / 100,
      savingsRate: savingsRate === null ? null : Math.round(savingsRate * 1000) / 1000,
      totalLoanPayment: totalMonthlyPaymentActiveLoans(loans),
      totalRemainingDebt: totalRemainingDebt(loans),
      monthlyTrend,
      categoryBreakdown,
      recentTransactions,
      activeLoans,
    };
  },
});