import { authClient } from "@/src/lib/auth-client";
import { apiRequest } from "@/src/lib/api-client";
import { useAuthStore } from "@/src/stores/auth.store";
import { useJoinWithCode } from "@/src/hooks/useInvite";
import { useRouter } from "expo-router";
import { useRef, useState } from "react";
import {
  ActivityIndicator,
  KeyboardAvoidingView,
  Platform,
  Pressable,
  Text,
  TextInput,
  View,
} from "react-native";
import { useTranslation } from "react-i18next";
import { Ionicons } from "@expo/vector-icons";

// Which top-level path the user is on
type Mode = "choose" | "create" | "join";

// ── OTP Box Input ─────────────────────────────────────────────────────────────

function OtpInput({
  onComplete,
  hasError,
}: {
  onComplete: (code: string) => void;
  hasError: boolean;
}) {
  const [digits, setDigits] = useState<string[]>(["", "", "", "", "", ""]);
  const refs = useRef<Array<TextInput | null>>([]);

  function handleChange(text: string, index: number) {
    // Handle paste: if pasted text fills all 6 slots
    if (text.length === 6) {
      const upper = text.toUpperCase();
      const filled = upper.split("").slice(0, 6);
      setDigits(filled);
      refs.current[5]?.focus();
      onComplete(upper);
      return;
    }

    // Handle paste into a single box that is actually 2 chars (current + new char)
    const char = text.slice(-1).toUpperCase();
    const newDigits = [...digits];
    newDigits[index] = char;
    setDigits(newDigits);

    if (char && index < 5) {
      refs.current[index + 1]?.focus();
    }

    if (newDigits.every((d) => d !== "")) {
      onComplete(newDigits.join(""));
    }
  }

  function handleKeyPress(key: string, index: number) {
    if (key === "Backspace") {
      const newDigits = [...digits];
      if (digits[index] === "" && index > 0) {
        newDigits[index - 1] = "";
        setDigits(newDigits);
        refs.current[index - 1]?.focus();
      } else {
        newDigits[index] = "";
        setDigits(newDigits);
      }
    }
  }

  return (
    <View style={{ flexDirection: "row", gap: 8, justifyContent: "center" }}>
      {digits.map((digit, i) => (
        <TextInput
          key={i}
          ref={(el) => {
            refs.current[i] = el;
          }}
          value={digit}
          onChangeText={(text) => handleChange(text, i)}
          onKeyPress={({ nativeEvent }) => handleKeyPress(nativeEvent.key, i)}
          autoCapitalize="characters"
          autoCorrect={false}
          maxLength={2}
          selectTextOnFocus
          style={{
            width: 48,
            height: 56,
            borderRadius: 12,
            borderWidth: 1.5,
            borderColor: hasError ? "#dc2626" : digit ? "#2563EB" : "#e5e7eb",
            backgroundColor: "#f9fafb",
            textAlign: "center",
            fontSize: 24,
            fontWeight: "700",
            color: "#111827",
          }}
        />
      ))}
    </View>
  );
}

// ── Main Screen ───────────────────────────────────────────────────────────────

export default function OnboardingScreen() {
  const router = useRouter();
  const { t } = useTranslation();
  const { setActiveHousehold, setHouseholds, households } = useAuthStore();
  const [mode, setMode] = useState<Mode>("choose");
  const [householdName, setHouseholdName] = useState("");
  const [isCreating, setIsCreating] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [pendingCode, setPendingCode] = useState("");

  const { mutate: joinWithCode, isPending: isJoining } = useJoinWithCode();

  async function handleCreateHousehold() {
    if (!householdName.trim()) {
      setError(t('onboarding.enterHouseholdName'));
      return;
    }
    setIsCreating(true);
    setError(null);
    try {
      const result = await authClient.organization.create({
        name: householdName.trim(),
        slug: householdName.trim().toLowerCase().replace(/\s+/g, "-"),
      });
      if (result.error) {
        setError(result.error.message ?? t('onboarding.createError'));
        return;
      }
      if (result.data?.id) {
        const organizationId = result.data.id;
        const newHousehold = { id: organizationId, name: householdName.trim(), role: "owner" };
        // Bridge: create households row + seed default categories
        await apiRequest("/api/households/setup", {
          method: "POST",
          headers: { "x-household-id": organizationId },
        });
        // Append to existing list, keep current active household
        setHouseholds([...households, newHousehold]);
        // Only switch if this is the first household (initial onboarding)
        if (households.length === 0) {
          setActiveHousehold(organizationId);
          router.replace("/(auth)/setup");
        } else {
          router.back();
        }
      }
    } catch {
      setError(t('onboarding.createError'));
    } finally {
      setIsCreating(false);
    }
  }

  function handleCodeComplete(code: string) {
    setPendingCode(code);
  }

  function handleJoinSubmit() {
    const code = pendingCode.trim().toUpperCase();
    if (code.length !== 6) {
      setError(t('onboarding.enterInviteCode'));
      return;
    }
    setError(null);
    joinWithCode(code, {
      onSuccess: async (data) => {
        const newHousehold = {
          id: data.householdId,
          name: data.householdName,
          role: "member",
        };
        setHouseholds([...households, newHousehold]);
        setActiveHousehold(data.householdId);
        router.replace("/(app)/haushalt");
      },
      onError: (err) => {
        const msg = err.message ?? t('invite.invalidCode');
        if (msg.toLowerCase().includes("already")) {
          setError(t('invite.alreadyMember'));
        } else {
          setError(t('invite.invalidCode'));
        }
      },
    });
  }

  // ── Choose screen ────────────────────────────────────────────────────────────

  if (mode === "choose") {
    return (
      <KeyboardAvoidingView
        behavior={Platform.OS === "ios" ? "padding" : "height"}
        className="flex-1 bg-white"
      >
        <View className="flex-1 justify-center px-6">
          <Text className="mb-2 text-3xl font-bold text-gray-900">
            {t('invite.setupTitle')}
          </Text>
          <Text className="mb-10 text-base text-gray-500">
            {t('onboarding.setupSubtitle')}
          </Text>

          {/* Create new */}
          <Pressable
            onPress={() => { setError(null); setMode("create"); }}
            className="mb-4 rounded-xl border border-gray-200 bg-white p-5 active:opacity-70"
          >
            <View className="flex-row items-center gap-4">
              <View className="w-11 h-11 rounded-full bg-blue-50 items-center justify-center">
                <Ionicons name="add-circle-outline" size={24} color="#2563EB" />
              </View>
              <View className="flex-1">
                <Text className="text-base font-semibold text-gray-900">
                  {t('invite.createNew')}
                </Text>
                <Text className="text-sm text-gray-400">{t('invite.createNewSub')}</Text>
              </View>
              <Ionicons name="chevron-forward" size={18} color="#9ca3af" />
            </View>
          </Pressable>

          {/* Join with code */}
          <Pressable
            onPress={() => { setError(null); setMode("join"); }}
            className="rounded-xl border border-gray-200 bg-white p-5 active:opacity-70"
          >
            <View className="flex-row items-center gap-4">
              <View className="w-11 h-11 rounded-full bg-blue-50 items-center justify-center">
                <Ionicons name="key-outline" size={24} color="#2563EB" />
              </View>
              <View className="flex-1">
                <Text className="text-base font-semibold text-gray-900">
                  {t('invite.enterCode')}
                </Text>
                <Text className="text-sm text-gray-400">{t('invite.enterCodeSub')}</Text>
              </View>
              <Ionicons name="chevron-forward" size={18} color="#9ca3af" />
            </View>
          </Pressable>
        </View>
      </KeyboardAvoidingView>
    );
  }

  // ── Create screen ────────────────────────────────────────────────────────────

  if (mode === "create") {
    return (
      <KeyboardAvoidingView
        behavior={Platform.OS === "ios" ? "padding" : "height"}
        className="flex-1 bg-white"
      >
        <View className="flex-1 justify-center px-6">
          {/* Back */}
          <Pressable
            onPress={() => { setError(null); setMode("choose"); }}
            className="mb-6 flex-row items-center gap-1 self-start active:opacity-60"
          >
            <Ionicons name="chevron-back" size={18} color="#6b7280" />
            <Text className="text-sm text-gray-500">{t('common.back')}</Text>
          </Pressable>

          <Text className="mb-2 text-3xl font-bold text-gray-900">
            {t('onboarding.setupTitle')}
          </Text>
          <Text className="mb-8 text-base text-gray-500">
            {t('onboarding.setupSubtitle')}
          </Text>

          {error && (
            <View className="mb-4 rounded-lg bg-red-50 p-3">
              <Text className="text-sm text-red-600">{error}</Text>
            </View>
          )}

          <View className="mb-4">
            <Text className="mb-1.5 text-sm font-medium text-gray-700">
              {t('onboarding.householdNameLabel')}
            </Text>
            <TextInput
              className="rounded-xl border border-gray-200 bg-gray-50 px-4 py-3 text-base text-gray-900"
              placeholder={t('onboarding.householdNamePlaceholder')}
              value={householdName}
              onChangeText={setHouseholdName}
              autoComplete="off"
            />
          </View>

          <Pressable
            onPress={handleCreateHousehold}
            disabled={isCreating}
            className="items-center rounded-xl bg-blue-600 py-4 active:opacity-80"
          >
            {isCreating ? (
              <ActivityIndicator color="white" />
            ) : (
              <Text className="text-base font-semibold text-white">
                {t('onboarding.createHousehold')}
              </Text>
            )}
          </Pressable>
        </View>
      </KeyboardAvoidingView>
    );
  }

  // ── Join screen ──────────────────────────────────────────────────────────────

  return (
    <KeyboardAvoidingView
      behavior={Platform.OS === "ios" ? "padding" : "height"}
      className="flex-1 bg-white"
    >
      <View className="flex-1 justify-center px-6">
        {/* Back */}
        <Pressable
          onPress={() => { setError(null); setPendingCode(""); setMode("choose"); }}
          className="mb-6 flex-row items-center gap-1 self-start active:opacity-60"
        >
          <Ionicons name="chevron-back" size={18} color="#6b7280" />
          <Text className="text-sm text-gray-500">{t('common.back')}</Text>
        </Pressable>

        <Text className="mb-2 text-3xl font-bold text-gray-900">
          {t('invite.joinTitle')}
        </Text>
        <Text className="mb-8 text-base text-gray-500">
          {t('invite.joinHint')}
        </Text>

        <OtpInput onComplete={handleCodeComplete} hasError={!!error} />

        {error && (
          <View className="mt-4 rounded-lg bg-red-50 p-3">
            <Text className="text-sm text-red-600 text-center">{error}</Text>
          </View>
        )}

        <Pressable
          onPress={handleJoinSubmit}
          disabled={isJoining || pendingCode.length !== 6}
          className="mt-8 items-center rounded-xl bg-blue-600 py-4 active:opacity-80 disabled:opacity-40"
        >
          {isJoining ? (
            <ActivityIndicator color="white" />
          ) : (
            <Text className="text-base font-semibold text-white">
              {t('invite.joinButton')}
            </Text>
          )}
        </Pressable>
      </View>
    </KeyboardAvoidingView>
  );
}