import FinancialCalendar from "../../../../islands/FinancialCalendar.tsx";
import { define } from "../../../../utils.ts";
import {
  getIncomesByUser,
  getObligationsByUser,
  Income,
  Obligation,
} from "../../../../services/financhalServices.ts";
import {
  getFinancialBalancesByUser,
  upsertFinancialBalance,
} from "../../../../services/userService.ts";
import {
  computeMonthlyBalances,
  generateRecurringIncomesForMonth,
  generateRecurringObligationsForMonth,
  invalidateMonthCache,
  type MonthlyBalanceCache,
} from "../../../../services/dailyBalanceCache.ts";
import { page } from "fresh";
import { getMonth, getYear } from "../../../../helpers.ts";
import { createPublicId } from "../../../../helpers.ts";
import { SessionCookie } from "../../../auth/callback.ts";

export const handler = define.handlers({
  GET: async (ctx) => {
    const params = ctx.params;
    let yearNum = parseInt(params.year, 10);
    let monthNum = parseInt(params.month, 10);
    if (isNaN(yearNum) || isNaN(monthNum)) {
      const fallback = `/calendar/financial-calendar/${getYear(new Date())}/${
        getMonth(new Date()) + 1
      }`;
      return new Response(null, {
        status: 302,
        headers: { Location: fallback },
      });
    }
    if (yearNum < 1900 || yearNum > 2100 || monthNum < 1 || monthNum > 12) {
      yearNum = getYear(new Date());
      monthNum = getMonth(new Date()) + 1;
    }

    const state = ctx.state;
    const stateData: SessionCookie = state.data;
    const publicId = stateData?.user_id
      ? await createPublicId(stateData.user_id)
      : "";
    const isEncrypted = stateData?.user_encrypted;

    let obligations: Obligation[] = [];
    let incomes: Income[] = [];
    let balance: number | null = null;
    let date: number | null = null;
    let monthlyCache: MonthlyBalanceCache | null = null;

    if (stateData?.user_id) {
      const rawObligations = await getObligationsByUser(stateData.user_id) ??
        [];
      const filteredObligations = rawObligations.filter((ob) =>
        ob.id && ob.user_id &&
        ob.frequency && ob.due_date && ob.created_on &&
        ob.updated_on
      );
      const rawIncomes = await getIncomesByUser(stateData.user_id) ?? [];
      const filteredIncomes = rawIncomes.filter((inc) =>
        inc.id && inc.user_id &&
        inc.frequency && inc.received_date && inc.created_on &&
        inc.updated_on
      );

      // Get base balance
      const financialBalances = await getFinancialBalancesByUser(
        stateData.user_id,
      );
      let baseBalance: { date: string; balance: number } | null = null;
      if (financialBalances) {
        balance = financialBalances.balance ?? null;
        date = financialBalances.balance_date ?? null;
        if (balance !== null && date !== null) {
          baseBalance = {
            date: new Date(date).toISOString().slice(0, 10),
            balance: balance,
          };
        }
      }

      // Compute or retrieve cached monthly balances
      monthlyCache = await computeMonthlyBalances(
        stateData.user_id,
        yearNum,
        monthNum,
        filteredIncomes,
        filteredObligations,
        baseBalance,
      );

      // Generate recurring entries for the current month for display
      // (used for day markers and list views - retains encrypted_data)
      obligations = generateRecurringObligationsForMonth(
        filteredObligations,
        yearNum,
        monthNum,
      );
      incomes = generateRecurringIncomesForMonth(
        filteredIncomes,
        yearNum,
        monthNum,
      );
    }
    return page({
      stateData,
      obligations,
      incomes,
      params,
      yearNum,
      monthNum,
      balance: balance!,
      date: date ? new Date(date).toISOString().slice(0, 10) : null,
      publicId,
      isEncrypted,
      urlRoute: `/calendar/financial-calendar/${yearNum}/${monthNum}`,
      stateId: state.stateId,
      monthlyCache,
    });
  },
  POST: async (ctx) => {
    const params = ctx.params;
    const formData = await ctx.req.formData();
    let balance: number | null = formData.get("balance")
      ? Number(formData.get("balance"))
      : null;
    let date: number | null = formData.get("date")
      ? Date.parse(formData.get("date") as string)
      : null;

    let yearNum = parseInt(params.year, 10);
    let monthNum = parseInt(params.month, 10);
    if (isNaN(yearNum) || isNaN(monthNum)) {
      const fallback = `/calendar/financial-calendar/${getYear(new Date())}/${
        getMonth(new Date()) + 1
      }`;
      return new Response(null, {
        status: 302,
        headers: { Location: fallback },
      });
    }
    if (yearNum < 1900 || yearNum > 2100 || monthNum < 1 || monthNum > 12) {
      yearNum = getYear(new Date());
      monthNum = getMonth(new Date()) + 1;
    }
    console.log("POST url", ctx.req.url);
    const state = ctx.state;
    const stateData: SessionCookie = state.data;
    const publicId = stateData?.user_id
      ? await createPublicId(stateData.user_id)
      : "";
    const isEncrypted = stateData?.user_encrypted;
    let obligations: Obligation[] = [];
    let incomes: Income[] = [];
    let monthlyCache: MonthlyBalanceCache | null = null;

    if (stateData?.user_id) {
      const rawObligations = await getObligationsByUser(stateData.user_id) ??
        [];
      const filteredObligations = rawObligations.filter((ob) =>
        ob.id && ob.user_id &&
        ob.frequency && ob.due_date && ob.created_on &&
        ob.updated_on
      );
      const rawIncomes = await getIncomesByUser(stateData.user_id) ?? [];
      const filteredIncomes = rawIncomes.filter((inc) =>
        inc.id && inc.user_id &&
        inc.frequency && inc.received_date && inc.created_on &&
        inc.updated_on
      );

      if (!balance || !date) {
        const financialBalances = await getFinancialBalancesByUser(
          stateData.user_id,
        );
        if (financialBalances) {
          const latestBalance = financialBalances;
          if (!balance) {
            balance = latestBalance.balance ? latestBalance.balance : null;
          }
          if (!date) {
            date = latestBalance.balance_date
              ? latestBalance.balance_date
              : null;
          }
        }
      } else {
        // Update balance and invalidate cache for this month
        await upsertFinancialBalance(
          stateData.user_id,
          balance,
          date,
        );
        // Invalidate cache so next request recomputes with new base balance
        await invalidateMonthCache(stateData.user_id, yearNum, monthNum);
      }

      // Compute or retrieve cached monthly balances
      let baseBalance: { date: string; balance: number } | null = null;
      if (balance !== null && date !== null) {
        baseBalance = {
          date: new Date(date).toISOString().slice(0, 10),
          balance: balance,
        };
      }

      monthlyCache = await computeMonthlyBalances(
        stateData.user_id,
        yearNum,
        monthNum,
        filteredIncomes,
        filteredObligations,
        baseBalance,
      );

      // Generate recurring entries for the current month for display
      // (used for day markers and list views - retains encrypted_data)
      obligations = generateRecurringObligationsForMonth(
        filteredObligations,
        yearNum,
        monthNum,
      );
      incomes = generateRecurringIncomesForMonth(
        filteredIncomes,
        yearNum,
        monthNum,
      );
    }
    return page({
      stateData,
      obligations,
      incomes,
      params,
      yearNum,
      monthNum,
      balance,
      date: date ? new Date(date).toISOString().slice(0, 10) : null,
      publicId,
      isEncrypted,
      urlRoute: `/calendar/financial-calendar/${yearNum}/${monthNum}`,
      stateId: state.stateId,
      monthlyCache,
    });
  },
});

export default define.page(
  (
    { data }: {
      data: {
        stateData: SessionCookie;
        obligations: Obligation[];
        incomes: Income[];
        yearNum: number;
        monthNum: number;
        balance?: string;
        date?: string;
        publicId: string;
        isEncrypted: boolean;
        urlRoute: string;
        stateId: string;
        monthlyCache?: MonthlyBalanceCache | null;
      };
    },
  ) => {
    return (
      <main class="calendar-route-shell">
        <div class="calendar-route-content">
          <FinancialCalendar
            obligations={data.obligations}
            incomes={data.incomes}
            yearNum={data.yearNum}
            monthNum={data.monthNum}
            oldBalance={data.balance}
            oldDate={data.date}
            userId={data.publicId}
            monthlyCache={data.monthlyCache}
          />
        </div>
      </main>
    );
  },
);