import { BlurView } from "expo-blur";
import React, { useEffect, useMemo, useState } from "react";
import {
  FlatList,
  Image,
  Platform,
  StyleSheet,
  Text,
  TouchableOpacity,
  View,
} from "react-native";
import Animated, { useAnimatedRef } from "react-native-reanimated";
import Sortable from "react-native-sortables";
import { icons } from "../../assets";
import { Palette } from "../../styles";
import { FONT_FAMILY } from "../../styles/Fonts";
import {
  formatStructureLabel,
  getSegmentMeta,
  OPTIONAL_STRUCTURE_SEGMENTS,
  sanitizeStructureList,
} from "../../utils/songStructure";
import CreateLyricsHeader from "./components/CreateLyricsHeader";

const randomSuffix = () => Math.random().toString(36).slice(2, 8);
const createItemId = (type) => `${type}-${Date.now()}-${randomSuffix()}`;
const createSortableItem = (type, index = 0) => ({
  id: `${type}-${index}-${randomSuffix()}`,
  type,
  value: type,
});

const buildInitialItems = (structure = []) =>
  sanitizeStructureList(structure).map((type, index) =>
    createSortableItem(type, index)
  );

const CustomizeSongStructure = ({ baseStructure = [], onChange }) => {
  const scrollRef = useAnimatedRef();
  const sanitizedBase = useMemo(
    () => sanitizeStructureList(baseStructure),
    [baseStructure]
  );
  const [sortableItems, setSortableItems] = useState(() =>
    buildInitialItems(sanitizedBase)
  );

  useEffect(() => {
    setSortableItems((prev) => {
      const prevTypes = prev.map((item) => item.type);
      if (
        prevTypes.length === sanitizedBase.length &&
        prevTypes.every((type, index) => type === sanitizedBase[index])
      ) {
        return prev;
      }
      return buildInitialItems(sanitizedBase);
    });
  }, [sanitizedBase]);

  useEffect(() => {
    const values = sortableItems.map((item) => item.type).filter(Boolean);
    onChange?.(values);
  }, [sortableItems, onChange]);

  const labeledItems = useMemo(() => {
    const counts = {};
    return sortableItems.map((item) => {
      const baseType = item.type || item.value;
      const nextCount = (counts[baseType] || 0) + 1;
      counts[baseType] = nextCount;
      return {
        ...item,
        type: baseType,
        value: baseType,
        label: formatStructureLabel(baseType, nextCount),
        sortable: true,
      };
    });
  }, [sortableItems]);

  const optionalSegments = useMemo(
    () =>
      OPTIONAL_STRUCTURE_SEGMENTS.map((type) => {
        const meta = getSegmentMeta(type);
        return { type, label: meta?.label || formatStructureLabel(type, 1) };
      }),
    []
  );

  const selectedTypes = useMemo(() => {
    const set = new Set();
    sortableItems.forEach((item) => {
      if (item?.type) set.add(item.type);
      else if (item?.value) set.add(item.value);
    });
    return set;
  }, [sortableItems]);

  const toggleOptionalSegment = (type) => {
    setSortableItems((prev) => {
      const existsIndex = prev.findIndex((item) => item.type === type);
      if (existsIndex !== -1) {
        return prev.filter((item) => item.type !== type);
      }
      const meta = getSegmentMeta(type);
      let next = [...prev];
      if (meta?.exclusiveGroup) {
        next = next.filter((item) => {
          const itemMeta = getSegmentMeta(item.type || item.value);
          return itemMeta?.exclusiveGroup !== meta.exclusiveGroup;
        });
      }
      next.push(createSortableItem(type, next.length));
      return next;
    });
  };

  const Row = ({ item: rowData, onPress }) => {
    const isButton = typeof onPress === "function";
    const Wrapper = isButton ? TouchableOpacity : View;
    const selected = rowData?.selected;
    const icon = rowData?.icon;
    return (
      <Wrapper
        onPress={onPress}
        activeOpacity={0.8}
        style={isButton ? styles.touchable : undefined}
      >
        <View
          style={[
            styles.itemContainer,
            selected && styles.selectedItem,
            rowData?.sortable && styles.sortableItem,
          ]}
        >
          <BlurView
            intensity={Platform.OS !== "ios" ? 10 : 30}
            style={[
              styles.rowBlur,
              selected && styles.selectedBlur,
              isButton && styles.buttonBlur,
            ]}
          >
            <View style={styles.rowContent}>
              <Text style={styles.rowText}>{rowData?.label || ""}</Text>
            </View>
            {rowData?.sortable ? (
              <Sortable.Handle>
                <Image source={icons.dragDots} style={styles.handleIcon} />
              </Sortable.Handle>
            ) : (
              <Image
                source={icon || (selected ? icons.check : icons.add)}
                style={[styles.optionIcon]}
              />
            )}
          </BlurView>
        </View>
      </Wrapper>
    );
  };

  return (
    <View style={{ flex: 1, gap: 10, marginTop: 16 }}>
      <CreateLyricsHeader
        title="Personnalise la structure de ta chanson"
        subTitle="Réorganise par glisser-déposer"
      />
      <View style={{ flex: 1 }}>
        <Animated.ScrollView
          ref={scrollRef}
          contentContainerStyle={{ paddingVertical: 4, paddingBottom: 24 }}
          showsVerticalScrollIndicator={false}
        >
          <>
            <Sortable.Grid
              columns={1}
              rowGap={12}
              data={labeledItems}
              renderItem={({ item }) => <Row item={item} />}
              customHandle
              scrollableRef={scrollRef}
              onDragEnd={({ data: newData }) => {
                const next = (newData || []).map((it, index) => {
                  const nextType = it?.type || it?.value;
                  return {
                    id: it?.id || createItemId(nextType || `section-${index}`),
                    type: nextType,
                    value: nextType,
                  };
                });
                setSortableItems(next.filter((item) => item.type));
              }}
            />
            <FlatList
              data={optionalSegments}
              gap={12}
              renderItem={({ item }) => {
                const selected = selectedTypes.has(item.type);
                return (
                  <View style={{ marginTop: 12 }}>
                    <Row
                      item={{
                        ...item,
                        sortable: false,
                        selected,
                      }}
                      onPress={() => toggleOptionalSegment(item.type)}
                    />
                  </View>
                );
              }}
              keyExtractor={(item) => item.type}
              contentContainerStyle={{ paddingBottom: 24 }}
              scrollEnabled={false}
              nestedScrollEnabled={false}
            />
          </>
        </Animated.ScrollView>
      </View>
    </View>
  );
};

export default CustomizeSongStructure;

const styles = StyleSheet.create({
  touchable: {
    width: "100%",
  },
  itemContainer: {
    height: 54,
    backgroundColor: Palette.glass,
    borderRadius: 14,
    overflow: "hidden",
    shadowColor: "#00000040",
    shadowOffset: {
      width: 0,
      height: 2,
    },
    shadowOpacity: 0.25,
    shadowRadius: 3.84,
    elevation: 5,
  },
  sortableItem: {
    marginBottom: 0,
  },
  selectedItem: {
    borderWidth: 1,
    borderColor: Palette.white,
  },
  rowBlur: {
    flex: 1,
    backgroundColor: Palette.glass,
    justifyContent: "center",
    paddingHorizontal: 12,
    flexDirection: "row",
    alignItems: "center",
    height: "100%",
  },
  buttonBlur: {
    justifyContent: "space-between",
  },
  selectedBlur: {
    backgroundColor: Palette.transparentWhite,
  },
  rowContent: {
    flex: 1,
    justifyContent: "center",
  },
  rowText: {
    fontSize: 16,
    color: Palette.white,
    fontFamily: FONT_FAMILY.InterRegular,
  },
  handleIcon: {
    width: 22,
    height: 22,
    tintColor: Palette.white,
  },
  optionIcon: {
    width: 20,
    height: 20,
    tintColor: Palette.white,
  },
});