import React, { useState, useEffect } from 'react';
import {
  Group,
  Member,
  Subscription,
  OneOffExpense,
  SettlementRecord,
  MemberBalance,
  DebtTransaction,
} from './types';
import {
  INITIAL_GROUPS,
  INITIAL_MEMBERS,
  INITIAL_SUBSCRIPTIONS,
  INITIAL_ONE_OFF_EXPENSES,
  INITIAL_SETTLEMENTS,
} from './data/initialData';
import { calculateAllMemberBalances, calculateSimplifiedDebts, getMonthlyCost } from './utils/splitCalculator';
import { Header } from './components/Header';
import { Dashboard } from './components/Dashboard';
import { SubscriptionList } from './components/SubscriptionList';
import { SubscriptionModal } from './components/SubscriptionModal';
import { OneOffExpenseList } from './components/OneOffExpenseList';
import { OneOffExpenseModal } from './components/OneOffExpenseModal';
import { GroupMemberManager } from './components/GroupMemberManager';
import { SettlementModal } from './components/SettlementModal';
import { SettlementLog } from './components/SettlementLog';
import { BreakdownModal } from './components/BreakdownModal';
import { MemberBreakdownModal } from './components/MemberBreakdownModal';
import { ShareReportModal } from './components/ShareReportModal';

export default function App() {
  // Persistence Keys
  const STORAGE_KEY_GROUPS = 'subsplit_groups_v1';
  const STORAGE_KEY_MEMBERS = 'subsplit_members_v1';
  const STORAGE_KEY_SUBS = 'subsplit_subs_v1';
  const STORAGE_KEY_ONE_OFF = 'subsplit_one_off_v1';
  const STORAGE_KEY_SETTLEMENTS = 'subsplit_settlements_v1';

  // State
  const [groups, setGroups] = useState<Group[]>(() => {
    const saved = localStorage.getItem(STORAGE_KEY_GROUPS);
    return saved ? JSON.parse(saved) : INITIAL_GROUPS;
  });

  const [members, setMembers] = useState<Member[]>(() => {
    const saved = localStorage.getItem(STORAGE_KEY_MEMBERS);
    return saved ? JSON.parse(saved) : INITIAL_MEMBERS;
  });

  const [subscriptions, setSubscriptions] = useState<Subscription[]>(() => {
    const saved = localStorage.getItem(STORAGE_KEY_SUBS);
    return saved ? JSON.parse(saved) : INITIAL_SUBSCRIPTIONS;
  });

  const [oneOffExpenses, setOneOffExpenses] = useState<OneOffExpense[]>(() => {
    const saved = localStorage.getItem(STORAGE_KEY_ONE_OFF);
    return saved ? JSON.parse(saved) : INITIAL_ONE_OFF_EXPENSES;
  });

  const [settlements, setSettlements] = useState<SettlementRecord[]>(() => {
    const saved = localStorage.getItem(STORAGE_KEY_SETTLEMENTS);
    return saved ? JSON.parse(saved) : INITIAL_SETTLEMENTS;
  });

  // Save to LocalStorage
  useEffect(() => {
    localStorage.setItem(STORAGE_KEY_GROUPS, JSON.stringify(groups));
  }, [groups]);

  useEffect(() => {
    localStorage.setItem(STORAGE_KEY_MEMBERS, JSON.stringify(members));
  }, [members]);

  useEffect(() => {
    localStorage.setItem(STORAGE_KEY_SUBS, JSON.stringify(subscriptions));
  }, [subscriptions]);

  useEffect(() => {
    localStorage.setItem(STORAGE_KEY_ONE_OFF, JSON.stringify(oneOffExpenses));
  }, [oneOffExpenses]);

  useEffect(() => {
    localStorage.setItem(STORAGE_KEY_SETTLEMENTS, JSON.stringify(settlements));
  }, [settlements]);

  // Tab & Modal Navigation
  const [activeTab, setActiveTab] = useState<'dashboard' | 'subscriptions' | 'one-off' | 'members' | 'settlements'>('dashboard');

  // Modal States
  const [isSubModalOpen, setIsSubModalOpen] = useState(false);
  const [editingSub, setEditingSub] = useState<Subscription | null>(null);

  const [isOneOffModalOpen, setIsOneOffModalOpen] = useState(false);
  const [editingOneOff, setEditingOneOff] = useState<OneOffExpense | null>(null);

  const [isSettleModalOpen, setIsSettleModalOpen] = useState(false);
  const [settleFromId, setSettleFromId] = useState<string | undefined>();
  const [settleToId, setSettleToId] = useState<string | undefined>();
  const [settleDefaultAmount, setSettleDefaultAmount] = useState<number | undefined>();

  const [breakdownSub, setBreakdownSub] = useState<Subscription | null>(null);
  const [selectedMemberBalance, setSelectedMemberBalance] = useState<MemberBalance | null>(null);
  const [isShareReportOpen, setIsShareReportOpen] = useState(false);

  // Computed Balances & Debts
  const balances: MemberBalance[] = calculateAllMemberBalances(subscriptions, oneOffExpenses, members, groups, settlements);
  const debts: DebtTransaction[] = calculateSimplifiedDebts(balances);

  const activeSubs = subscriptions.filter((s) => s.status === 'active');
  const totalMonthlyCost = activeSubs.reduce(
    (acc, s) => acc + getMonthlyCost(s.cost, s.billingCycle),
    0
  );

  // Handlers for Subscriptions
  const handleSaveSub = (sub: Subscription) => {
    const exists = subscriptions.some((s) => s.id === sub.id);
    if (exists) {
      setSubscriptions(subscriptions.map((s) => (s.id === sub.id ? sub : s)));
    } else {
      setSubscriptions([...subscriptions, sub]);
    }
  };

  const handleDeleteSub = (subId: string) => {
    if (window.confirm('Are you sure you want to delete this subscription?')) {
      setSubscriptions(subscriptions.filter((s) => s.id !== subId));
    }
  };

  const handleToggleSubStatus = (subId: string) => {
    setSubscriptions(
      subscriptions.map((s) =>
        s.id === subId ? { ...s, status: s.status === 'active' ? 'paused' : 'active' } : s
      )
    );
  };

  // Handlers for One-Off Expenses
  const handleSaveOneOff = (expense: OneOffExpense) => {
    const exists = oneOffExpenses.some((e) => e.id === expense.id);
    if (exists) {
      setOneOffExpenses(oneOffExpenses.map((e) => (e.id === expense.id ? expense : e)));
    } else {
      setOneOffExpenses([expense, ...oneOffExpenses]);
    }
  };

  const handleDeleteOneOff = (expenseId: string) => {
    if (window.confirm('Delete this one-off shared charge?')) {
      setOneOffExpenses(oneOffExpenses.filter((e) => e.id !== expenseId));
    }
  };

  // Handlers for Members & Groups
  const handleAddMember = (m: Omit<Member, 'id'>) => {
    const newMember: Member = { ...m, id: `mem-${Date.now()}` };
    setMembers([...members, newMember]);
  };

  const handleEditMember = (m: Member) => {
    setMembers(members.map((item) => (item.id === m.id ? m : item)));
  };

  const handleDeleteMember = (memberId: string) => {
    if (window.confirm('Remove this member?')) {
      setMembers(members.filter((m) => m.id !== memberId));
    }
  };

  const handleAddGroup = (g: Omit<Group, 'id'>) => {
    const newGroup: Group = { ...g, id: `grp-${Date.now()}` };
    setGroups([...groups, newGroup]);
  };

  const handleEditGroup = (g: Group) => {
    setGroups(groups.map((item) => (item.id === g.id ? g : item)));
  };

  const handleDeleteGroup = (groupId: string) => {
    if (window.confirm('Delete this family group? Members in this group will become individual.')) {
      setGroups(groups.filter((g) => g.id !== groupId));
      setMembers(members.map((m) => (m.groupId === groupId ? { ...m, groupId: undefined } : m)));
    }
  };

  // Settlement Handlers
  const handleOpenSettleModal = (fromId?: string, toId?: string, defaultAmt?: number) => {
    setSettleFromId(fromId);
    setSettleToId(toId);
    setSettleDefaultAmount(defaultAmt);
    setIsSettleModalOpen(true);
  };

  const handleSaveSettlement = (record: Omit<SettlementRecord, 'id'>) => {
    const newRecord: SettlementRecord = { ...record, id: `settle-${Date.now()}` };
    setSettlements([newRecord, ...settlements]);
  };

  const handleDeleteSettlement = (id: string) => {
    setSettlements(settlements.filter((s) => s.id !== id));
  };

  const handleResetData = () => {
    if (window.confirm('Reset all subscriptions, one-off charges, members, and settlement records to initial seed data?')) {
      setGroups(INITIAL_GROUPS);
      setMembers(INITIAL_MEMBERS);
      setSubscriptions(INITIAL_SUBSCRIPTIONS);
      setOneOffExpenses(INITIAL_ONE_OFF_EXPENSES);
      setSettlements(INITIAL_SETTLEMENTS);
    }
  };

  return (
    <div className="min-h-screen bg-slate-100/70 text-slate-900 font-sans antialiased pb-16">
      {/* Top Header & Navigation */}
      <Header
        activeTab={activeTab}
        setActiveTab={setActiveTab}
        totalActiveSubs={activeSubs.length}
        totalOneOffCount={oneOffExpenses.length}
        totalMonthlyCost={totalMonthlyCost}
        onOpenAddSub={() => {
          setEditingSub(null);
          setIsSubModalOpen(true);
        }}
        onOpenAddExpense={() => {
          setEditingOneOff(null);
          setIsOneOffModalOpen(true);
        }}
        onOpenRecordSettlement={() => handleOpenSettleModal()}
        onOpenShareReport={() => setIsShareReportOpen(true)}
        onResetData={handleResetData}
      />

      {/* Main Container */}
      <main className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
        {activeTab === 'dashboard' && (
          <Dashboard
            balances={balances}
            debts={debts}
            subscriptions={subscriptions}
            oneOffExpenses={oneOffExpenses}
            settlements={settlements}
            members={members}
            groups={groups}
            onOpenSettleModal={handleOpenSettleModal}
            onOpenBreakdownModal={(sub) => setBreakdownSub(sub)}
            onOpenMemberBreakdownModal={(bal) => setSelectedMemberBalance(bal)}
            onOpenAddExpense={() => {
              setEditingOneOff(null);
              setIsOneOffModalOpen(true);
            }}
            onOpenAddSub={() => {
              setEditingSub(null);
              setIsSubModalOpen(true);
            }}
          />
        )}

        {activeTab === 'subscriptions' && (
          <SubscriptionList
            subscriptions={subscriptions}
            members={members}
            groups={groups}
            onAddSub={() => {
              setEditingSub(null);
              setIsSubModalOpen(true);
            }}
            onEditSub={(sub) => {
              setEditingSub(sub);
              setIsSubModalOpen(true);
            }}
            onDeleteSub={handleDeleteSub}
            onToggleStatus={handleToggleSubStatus}
            onOpenBreakdownModal={(sub) => setBreakdownSub(sub)}
          />
        )}

        {activeTab === 'one-off' && (
          <OneOffExpenseList
            expenses={oneOffExpenses}
            members={members}
            groups={groups}
            onAddExpense={() => {
              setEditingOneOff(null);
              setIsOneOffModalOpen(true);
            }}
            onEditExpense={(exp) => {
              setEditingOneOff(exp);
              setIsOneOffModalOpen(true);
            }}
            onDeleteExpense={handleDeleteOneOff}
          />
        )}

        {activeTab === 'members' && (
          <GroupMemberManager
            members={members}
            groups={groups}
            onAddMember={handleAddMember}
            onEditMember={handleEditMember}
            onDeleteMember={handleDeleteMember}
            onAddGroup={handleAddGroup}
            onEditGroup={handleEditGroup}
            onDeleteGroup={handleDeleteGroup}
          />
        )}

        {activeTab === 'settlements' && (
          <SettlementLog
            settlements={settlements}
            members={members}
            onOpenSettleModal={() => handleOpenSettleModal()}
            onDeleteSettlement={handleDeleteSettlement}
          />
        )}
      </main>

      {/* Subscription Modal (Create / Edit) */}
      <SubscriptionModal
        isOpen={isSubModalOpen}
        onClose={() => setIsSubModalOpen(false)}
        onSave={handleSaveSub}
        initialData={editingSub}
        members={members}
        groups={groups}
      />

      {/* One-Off Expense Modal (Create / Edit) */}
      <OneOffExpenseModal
        isOpen={isOneOffModalOpen}
        onClose={() => setIsOneOffModalOpen(false)}
        onSave={handleSaveOneOff}
        initialData={editingOneOff}
        members={members}
        groups={groups}
      />

      {/* Settlement Payment Modal */}
      <SettlementModal
        isOpen={isSettleModalOpen}
        onClose={() => setIsSettleModalOpen(false)}
        onSaveSettlement={handleSaveSettlement}
        members={members}
        defaultFromId={settleFromId}
        defaultToId={settleToId}
        defaultAmount={settleDefaultAmount}
      />

      {/* Subscription Math Breakdown Modal */}
      <BreakdownModal
        subscription={breakdownSub}
        onClose={() => setBreakdownSub(null)}
        members={members}
        groups={groups}
      />

      {/* Member Balance Statement Modal */}
      <MemberBreakdownModal
        balance={selectedMemberBalance}
        onClose={() => setSelectedMemberBalance(null)}
        members={members}
        groups={groups}
      />

      {/* Share/Export Chat Report Modal */}
      <ShareReportModal
        isOpen={isShareReportOpen}
        onClose={() => setIsShareReportOpen(false)}
        balances={balances}
        debts={debts}
        subscriptions={subscriptions}
        oneOffExpenses={oneOffExpenses}
      />
    </div>
  );
}