import React, {
  useCallback,
  useEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { Dimensions, FlatList, Modal, Text, View } from "react-native";
import { background } from "../../assets";
import BorderGradientButton from "../../components/BorderGradientButton";
import GradientButton from "../../components/GradientButton";
import MusicLandHeader from "../../components/MusicLandHeader";
import AppAlert from "../../components/Alert";
import firebase, { getFunctionsClient } from "../../config/firebase";
import Page from "../../layouts/Page";
import { Routes } from "../../navigation";
import { goBack, navigate } from "../../navigation/NavigationService";
import { useUser } from "../../providers/UserDataProvider";
import { gutters, Palette } from "../../styles";
import { FONT_FAMILY } from "../../styles/Fonts";
import { normalizeStructureType } from "../../utils/songStructure";
import { openCoinPackModal } from "../../utils/coinPackModal";
import ChooseGenre from "./ChooseGenre";
import ChooseInstruments from "./ChooseInstruments";
import ChooseRhythm from "./ChooseRhythm";
import CustomizeVoice from "./CustomizeVoice";
import CreateLyricsHeader from "../Writing/components/CreateLyricsHeader";

const { width: windowWidth } = Dimensions.get("window");
const MUSIC_GENERATION_COIN_COST = 8;
const CONFIRM_MODAL_MAX_WIDTH = 540;

const ComposeSong = () => {
  const scrollRef = useRef(null);
  const [selectedIndex, setSelectedIndex] = useState(0);
  const [progress, setProgress] = useState(18);
  const [parentLayout, setParentLayout] = useState(null);
  const containerWidth = parentLayout?.width || windowWidth || 1;
  const {
    selectedProjectId,
    selectedProject,
    updateProjectData,
    currentUserData,
    currentUID,
  } = useUser();

  const [genres, setGenres] = useState([]);
  const [voice, setVoice] = useState({});
  const [instruments, setInstruments] = useState([]);
  const [rhythm, setRhythm] = useState(null);
  const [isConfirmVisible, setIsConfirmVisible] = useState(false);
  const [isProcessingConfirmation, setIsProcessingConfirmation] =
    useState(false);

  const coinBalance = useMemo(() => {
    const value = currentUserData?.coins;
    if (typeof value === "number" && Number.isFinite(value)) {
      return value;
    }
    if (typeof value === "string") {
      const parsed = Number(value);
      if (Number.isFinite(parsed)) {
        return parsed;
      }
    }
    return 0;
  }, [currentUserData?.coins]);

  const formattedCoinBalance = useMemo(() => {
    try {
      return new Intl.NumberFormat("fr-FR", {
        maximumFractionDigits: 0,
      }).format(coinBalance);
    } catch (_error) {
      return `${coinBalance}`;
    }
  }, [coinBalance]);

  const isStepValid = useMemo(() => {
    switch (selectedIndex) {
      case 0:
        return Array.isArray(genres) && genres.length > 0;
      case 1:
        return !!(voice && typeof voice === "object" && voice.BASE);
      case 2:
        return Array.isArray(instruments) && instruments.length > 0;
      case 3:
        return !!rhythm;
      default:
        return true;
    }
  }, [selectedIndex, genres, voice, instruments, rhythm]);

  const musicConfig = useMemo(() => {
    let lyricsArr = [];
    if (Array.isArray(selectedProject?.lyrics)) {
      lyricsArr = selectedProject.lyrics.map((s) => ({
        type: normalizeStructureType(s?.type),
        lyrics: s?.lyrics || "",
      }));
    } else {
      const c = selectedProject?.lyrics?.couplet;
      const r = selectedProject?.lyrics?.refrain;
      if (c) lyricsArr.push({ type: "couplet", lyrics: c });
      if (r) lyricsArr.push({ type: "refrain", lyrics: r });
    }
    const voiceArray = Object.entries(voice || {})
      .filter(([, v]) => typeof v === "string" && v.trim())
      .map(([category, value]) => ({ category, value }));

    return {
      title: selectedProject?.title || "",
      lyrics: lyricsArr,
      genres: Array.isArray(genres) ? genres : [],
      voice: voiceArray,
      instruments: Array.isArray(instruments) ? instruments : [],
      tempo: rhythm || undefined,
      projectId: selectedProjectId || undefined,
    };
  }, [selectedProject, genres, voice, instruments, rhythm, selectedProjectId]);

  const steps = useMemo(
    () => [
      {
        key: "genres",
        render: () => <ChooseGenre selected={genres} setSelected={setGenres} />,
      },
      {
        key: "voice",
        render: () => (
          <CustomizeVoice selected={voice} setSelected={setVoice} />
        ),
      },
      {
        key: "instruments",
        render: () => (
          <ChooseInstruments
            selected={instruments}
            setSelected={setInstruments}
          />
        ),
      },
      {
        key: "rhythm",
        render: () => (
          <ChooseRhythm selected={rhythm} setSelected={setRhythm} />
        ),
      },
    ],
    [genres, voice, instruments, rhythm]
  );

  useEffect(() => {
    const nextProgress = 18 + selectedIndex * 9;
    if (nextProgress !== progress) {
      setProgress(nextProgress);
    }
    try {
      scrollRef.current?.scrollToIndex?.({
        index: selectedIndex,
        animated: true,
      });
    } catch (_) {}
  }, [selectedIndex, progress, containerWidth]);

  const getItemLayout = useCallback(
    (_data, index) => ({
      length: containerWidth,
      offset: containerWidth * index,
      index,
    }),
    [containerWidth]
  );

  const persistMusicConfig = useCallback(async () => {
    try {
      if (!selectedProjectId) return;
      await updateProjectData({
        musicConfig: {
          title: musicConfig?.title || "",
          lyrics: Array.isArray(musicConfig?.lyrics) ? musicConfig.lyrics : [],
          genres: Array.isArray(musicConfig?.genres) ? musicConfig.genres : [],
          voice: Array.isArray(musicConfig?.voice) ? musicConfig.voice : [],
          instruments: Array.isArray(musicConfig?.instruments)
            ? musicConfig.instruments
            : [],
          tempo: musicConfig?.tempo || "",
        },
        musicStatus: null,
        sunoTaskId: firebase.firestore.FieldValue.delete(),
        musicUrls: firebase.firestore.FieldValue.delete(),
      });
    } catch (_error) {}
  }, [musicConfig, selectedProjectId, updateProjectData]);

  const spendCoinsForGeneration = useCallback(async () => {
    if (!currentUID) {
      throw new Error("Utilisateur introuvable. Merci de réessayer.");
    }

    try {
      const functionsClient = getFunctionsClient();
      const createSongOrder =
        functionsClient.httpsCallable("orders-createSongOrder");

      await createSongOrder({
        amount: -MUSIC_GENERATION_COIN_COST,
        songId: selectedProjectId || null,
        source: "music_generation",
      });
    } catch (error) {
      const message =
        typeof error?.message === "string"
          ? error.message.replace(
              /^functions\.https\.HttpsError:\s*/iu,
              "",
            )
          : null;
      throw new Error(
        message ||
          "Une erreur est survenue lors de la création de la commande de crédits.",
      );
    }
  }, [currentUID, selectedProjectId]);

  const handleConfirmGeneration = useCallback(async () => {
    if (isProcessingConfirmation) return;
    setIsProcessingConfirmation(true);
    try {
      const availableCoins = Number.isFinite(coinBalance) ? coinBalance : 0;
      if (availableCoins < MUSIC_GENERATION_COIN_COST) {
        setIsConfirmVisible(false);
        AppAlert(
          "Crédits insuffisants",
          "Tu n'as pas assez de pièces pour générer une musique. Recharge ton compte pour continuer.",
        );
        openCoinPackModal();
        return;
      }

      await spendCoinsForGeneration();
      await persistMusicConfig();
      setIsConfirmVisible(false);
      navigate(Routes.GeneratingSong, { config: musicConfig });
    } catch (error) {
      setIsConfirmVisible(false);
      const message =
        error?.message ||
        "Une erreur est survenue lors du lancement de la génération.";
      AppAlert("Impossible de lancer la génération", message);
    } finally {
      setIsProcessingConfirmation(false);
    }
  }, [
    coinBalance,
    isProcessingConfirmation,
    musicConfig,
    persistMusicConfig,
    spendCoinsForGeneration,
  ]);

  const onPressNext = () => {
    if (selectedIndex === steps.length - 1) {
      setIsConfirmVisible(true);
      return;
    }
    setSelectedIndex((prev) => Math.min(prev + 1, steps.length - 1));
  };

  const onPressBack = () => {
    if (selectedIndex > 0) {
      setSelectedIndex((prev) => Math.max(prev - 1, 0));
    } else {
      goBack();
    }
  };

  return (
    <Page backgroundImg={background.studioBG2} headerType="NONE">
      <MusicLandHeader
        onPressBack={onPressBack}
        progress={progress}
        // logo={icons.musicLandStudio}
      />
      <View style={{ flex: 1, paddingBottom: gutters, gap: 48 }}>
        <View
          style={{ flex: 1 }}
          onLayout={(event) => setParentLayout(event.nativeEvent.layout)}
        >
          <FlatList
            ref={scrollRef}
            data={steps}
            keyExtractor={(item) => item.key}
            horizontal
            pagingEnabled
            scrollEnabled={false}
            showsHorizontalScrollIndicator={false}
            initialScrollIndex={selectedIndex}
            getItemLayout={getItemLayout}
            style={{ width: containerWidth }}
            renderItem={({ item }) => (
              <View
                style={{
                  width: containerWidth,
                  height: parentLayout?.height,
                  paddingHorizontal: gutters,
                }}
              >
                {item.render()}
              </View>
            )}
          />
        </View>
        {selectedIndex !== steps.length && (
          <GradientButton
            title={selectedIndex === steps.length - 1 ? "Générer" : "Suivant"}
            onPress={onPressNext}
            disabled={!isStepValid}
          />
        )}
      </View>
      <Modal
        animationType="slide"
        transparent
        visible={isConfirmVisible}
        onRequestClose={() => {
          if (isProcessingConfirmation) return;
          setIsConfirmVisible(false);
        }}
      >
        <View
          style={{
            flex: 1,
            justifyContent: "center",
            alignItems: "center",
            paddingHorizontal: gutters,
            paddingVertical: gutters * 1.5,
            backgroundColor: "rgba(0, 0, 0, 0.6)",
          }}
        >
          <CreateLyricsHeader
            containerStyle={{
              width: "100%",
              maxWidth: CONFIRM_MODAL_MAX_WIDTH,
              alignSelf: "center",
              paddingVertical: 24,
              paddingHorizontal: 24,
              gap: 24,
            }}
          >
            <View style={{ gap: 30, alignItems: "center" }}>
              <View
                style={{
                  paddingHorizontal: 15,
                  gap: 12,
                  alignItems: "center",
                }}
              >
                <Text
                  style={{
                    fontSize: 22,
                    color: Palette.white,
                    fontFamily: FONT_FAMILY.InterSemiBold,
                    textAlign: "center",
                  }}
                >
                  Générer la musique ?
                </Text>
                <Text
                  style={{
                    fontSize: 16,
                    color: Palette.white,
                    fontFamily: FONT_FAMILY.InterRegular,
                    textAlign: "center",
                  }}
                >
                  Cette action coûte {MUSIC_GENERATION_COIN_COST} pièces.
                  {"\n"}Souhaites-tu les utiliser pour lancer la génération ?
                </Text>
                <Text
                  style={{
                    fontSize: 14,
                    color: Palette.white,
                    fontFamily: FONT_FAMILY.InterMedium,
                    textAlign: "center",
                  }}
                >
                  Solde disponible : {formattedCoinBalance} pièces
                </Text>
              </View>
              <View style={{ width: "85%", alignSelf: "center", gap: 15 }}>
                <GradientButton
                  title="Confirmer"
                  onPress={handleConfirmGeneration}
                  disabled={isProcessingConfirmation}
                />
                <BorderGradientButton
                  title="Annuler"
                  onPress={() => {
                    if (isProcessingConfirmation) return;
                    setIsConfirmVisible(false);
                  }}
                  disabled={isProcessingConfirmation}
                />
              </View>
            </View>
          </CreateLyricsHeader>
        </View>
      </Modal>
    </Page>
  );
};

export default ComposeSong;