import React, { useState, useEffect, useCallback } from "react";
import {
  View,
  Pressable,
  ActivityIndicator,
  FlatList,
  ListRenderItem,
} from "react-native";
import { Text } from "@/components/ui/text";
import { Card } from "@/components/ui/card";
import { useSirouRouter } from "@sirou/react-native";
import { AppRoutes } from "@/lib/routes";
import { Plus, Send, FileText, Clock, ChevronRight } from "@/lib/icons";
import { ScreenWrapper } from "@/components/ScreenWrapper";
import { StandardHeader } from "@/components/StandardHeader";
import { Button } from "@/components/ui/button";
import { EmptyState } from "@/components/EmptyState";
import { api } from "@/lib/api";
import { useAuthStore } from "@/lib/auth-store";
import { PERMISSION_MAP, hasPermission } from "@/lib/permissions";

interface ProformaItem {
  id: string;
  proformaNumber: string;
  customerName: string;
  customerEmail: string;
  customerPhone: string;
  amount: any;
  currency: string;
  issueDate: string;
  dueDate: string;
  description: string;
  notes: string;
  taxAmount: any;
  discountAmount: any;
  pdfPath: string;
  userId: string;
  items: any[];
  createdAt: string;
  updatedAt: string;
}

const dummyData: ProformaItem = {
  id: "dummy-1",
  proformaNumber: "PF-001",
  customerName: "John Doe",
  customerEmail: "john@example.com",
  customerPhone: "+1234567890",
  amount: { value: 1000, currency: "USD" },
  currency: "USD",
  issueDate: "2026-03-10T11:51:36.134Z",
  dueDate: "2026-03-10T11:51:36.134Z",
  description: "Dummy proforma",
  notes: "Test notes",
  taxAmount: { value: 100, currency: "USD" },
  discountAmount: { value: 50, currency: "USD" },
  pdfPath: "dummy.pdf",
  userId: "user-1",
  items: [
    {
      id: "item-1",
      description: "Test item",
      quantity: 1,
      unitPrice: { value: 1000, currency: "USD" },
      total: { value: 1000, currency: "USD" }
    }
  ],
  createdAt: "2026-03-10T11:51:36.134Z",
  updatedAt: "2026-03-10T11:51:36.134Z"
};

export default function ProformaScreen() {
  const nav = useSirouRouter<AppRoutes>();
  const permissions = useAuthStore((s) => s.permissions);
  const [proformas, setProformas] = useState<ProformaItem[]>([]);
  const [loading, setLoading] = useState(true);
  const [refreshing, setRefreshing] = useState(false);
  const [page, setPage] = useState(1);
  const [hasMore, setHasMore] = useState(true);
  const [loadingMore, setLoadingMore] = useState(false);

  // Check permissions
  const canCreateProformas = hasPermission(permissions, PERMISSION_MAP["proforma:create"]);

  const fetchProformas = useCallback(
    async (pageNum: number, isRefresh = false) => {
      const { isAuthenticated } = useAuthStore.getState();
      if (!isAuthenticated) return;

      try {
        if (!isRefresh) {
          pageNum === 1 ? setLoading(true) : setLoadingMore(true);
        }

        const response = await api.proforma.getAll({
          query: { page: pageNum, limit: 10 },
        });

        let newProformas = response.data;
        
        
        const newData = newProformas;
        if (isRefresh) {
          setProformas(newData);
        } else {
          setProformas((prev) =>
            pageNum === 1 ? newData : [...prev, ...newData],
          );
        }
        setHasMore(response.meta.hasNextPage);
        setPage(pageNum);
      } catch (err: any) {
        console.error("[Proforma] Fetch error:", err);
        setHasMore(false); 
      } finally {
        setLoading(false);
        setRefreshing(false);
        setLoadingMore(false);
      }
    },
    [],
  );

  useEffect(() => {
    fetchProformas(1);
  }, [fetchProformas]);

  const onRefresh = () => {
    setRefreshing(true);
    fetchProformas(1, true);
  };

  const loadMore = () => {
    if (hasMore && !loadingMore && !loading) {
      fetchProformas(page + 1);
    }
  };

  const renderProformaItem: ListRenderItem<ProformaItem> = ({ item }) => {
    const amountVal =
      typeof item.amount === "object" ? item.amount.value : item.amount;
    const issuedStr = item.issueDate
      ? new Date(item.issueDate).toLocaleDateString()
      : "";
    const dueStr = item.dueDate ? new Date(item.dueDate).toLocaleDateString() : "";
    const itemsCount = Array.isArray(item.items) ? item.items.length : 0;

    return (
      <View className="px-[16px]">
        <Pressable
          onPress={() => nav.go("proforma/[id]", { id: item.id })}
          className="mb-3"
        >
          <Card className="rounded-[12px] bg-card overflow-hidden border border-border/40">
            <View className="p-4">
              <View className="flex-row items-start">
                <View className="bg-primary/10 p-2.5 rounded-[12px] border border-primary/10 mr-3">
                  <FileText color="#ea580c" size={18} strokeWidth={2.5} />
                </View>

                <View className="flex-1">
                  <View className="flex-row justify-between">
                    <View className="flex-1 pr-2">
                      <Text className="text-foreground font-semibold" numberOfLines={1}>
                        {item.proformaNumber || "Proforma"}
                      </Text>
                      <Text variant="muted" className="text-xs mt-0.5" numberOfLines={1}>
                        {item.customerName || "Customer"}
                      </Text>
                    </View>

                    <View className="items-end">
                      <Text className="text-foreground font-bold text-base">
                        {item.currency || "$"}
                        {amountVal?.toLocaleString?.() ?? amountVal ?? "0"}
                      </Text>
                    
                    </View>
                  </View>

                  <View className="mt-2 flex-row items-center justify-between">
                    <Text variant="muted" className="text-[10px] font-medium">
                      Issued: {issuedStr} | Due: {dueStr} | {itemsCount} item{itemsCount !== 1 ? "s" : ""}
                    </Text>
                  </View>

                  
                </View>
              </View>
            </View>
          </Card>
        </Pressable>
      </View>
    );
  };

  return (
    <ScreenWrapper className="bg-background">
      <FlatList
        data={proformas}
        renderItem={renderProformaItem}
        keyExtractor={(item) => item.id}
        contentContainerStyle={{  paddingBottom: 150 }}
        showsVerticalScrollIndicator={false}
        onRefresh={onRefresh}
        refreshing={refreshing}
        onEndReached={loadMore}
        onEndReachedThreshold={0.5}
        ListHeaderComponent={
          <>
            <StandardHeader />
            <View className="px-[16px] pt-6">
              {/* {canCreateProformas && ( */}
                <Button
                  className="mb-4 h-10 rounded-[10px] bg-primary shadow-lg shadow-primary/30"
                  onPress={() => nav.go("proforma/create")}
                >
                  <Plus color="white" size={20} strokeWidth={3} />
                  <Text className="text-white text-xs font-semibold uppercase tracking-widest ml-2">
                    Create New Proforma
                  </Text>
                </Button>
              {/* )} */}
            </View>
          </>
        }
        ListFooterComponent={
          loadingMore ? (
            <ActivityIndicator color="#ea580c" className="py-4" />
          ) : null
        }
        ListEmptyComponent={
          !loading ? (
            <View className="px-[16px] py-6">
              <EmptyState
                title="No proformas yet"
                description="Create your first proforma to get started with invoicing."
                hint="Tap the button above to create a new proforma."
                previewLines={3}
              />
            </View>
          ) : (
            <View className="py-20">
              <ActivityIndicator size="large" color="#ea580c" />
            </View>
          )
        }
      />
    </ScreenWrapper>
  );
}