import { CameraView, useCameraPermissions } from "expo-camera";
import * as ImagePicker from "expo-image-picker";
import { router } from "expo-router";
import { useRef, useState } from "react";
import { Alert, Image, Pressable, ScrollView, View } from "react-native";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { Ionicons } from "@expo/vector-icons";
import { useTranslation } from "react-i18next";
import { Button } from "@/components/ui/Button";
import { Card } from "@/components/ui/Card";
import { Screen } from "@/components/ui/Screen";
import { Text } from "@/components/ui/Text";
import { usePrescriptionStore } from "@/lib/stores/prescriptionStore";
import { colors, gutter } from "@/lib/theme";
import { routes } from "@/lib/routes";

export default function RxScanScreen() {
  const insets = useSafeAreaInsets();
  const { t } = useTranslation();
  const [permission, requestPermission] = useCameraPermissions();
  const cameraRef = useRef<CameraView>(null);
  const draftImages = usePrescriptionStore((s) => s.draftImages);
  const setDraftImages = usePrescriptionStore((s) => s.setDraftImages);
  const [ready, setReady] = useState(false);

  const capture = async () => {
    const photo = await cameraRef.current?.takePictureAsync({ quality: 0.7 });
    if (photo?.uri) setDraftImages([...draftImages, photo.uri]);
  };

  const pick = async () => {
    const res = await ImagePicker.launchImageLibraryAsync({
      allowsMultipleSelection: true,
      quality: 0.7,
    });
    if (!res.canceled) {
      setDraftImages([...draftImages, ...res.assets.map((a) => a.uri)]);
    }
  };

  const removeAt = (uri: string) => {
    setDraftImages(draftImages.filter((u) => u !== uri));
  };

  if (!permission?.granted) {
    return (
      <Screen>
        <View
          style={{
            flex: 1,
            paddingTop: insets.top + 24,
            paddingHorizontal: gutter,
            justifyContent: "center",
            gap: 14,
          }}
        >
          <Text variant="h1">Scan prescription</Text>
          <Text variant="body" color={colors.muted}>
            Allow camera access to photograph your prescription, or upload existing photos.
          </Text>
          <Card elevated={false}>
            <Text variant="bodySm" color={colors.muted}>
              Tips: place the Rx on a flat surface, include the full page, and avoid glare.
            </Text>
          </Card>
          <Button title="Grant camera permission" onPress={requestPermission} />
          <Button title="Upload from photos" variant="outline" onPress={pick} />
          {draftImages.length ? (
            <Button
              title={`Continue with ${draftImages.length} photo${draftImages.length === 1 ? "" : "s"}`}
              variant="soft"
              onPress={() => router.push(routes.rxReview)}
            />
          ) : null}
          <Button title="Cancel" variant="ghost" onPress={() => router.back()} />
        </View>
      </Screen>
    );
  }

  return (
    <View style={{ flex: 1, backgroundColor: "#000" }}>
      <CameraView
        ref={cameraRef}
        style={{ flex: 1 }}
        facing="back"
        onCameraReady={() => setReady(true)}
      >
        <View
          style={{
            position: "absolute",
            top: insets.top + 8,
            left: 16,
            right: 16,
            flexDirection: "row",
            justifyContent: "space-between",
            alignItems: "center",
          }}
        >
          <Pressable onPress={() => router.back()} hitSlop={8}>
            <Ionicons name="close" size={28} color="#fff" />
          </Pressable>
          <Text variant="label" color="#fff">
            {t("common.scanRx")}
          </Text>
          <Text variant="caption" color="rgba(255,255,255,0.75)">
            {draftImages.length} saved
          </Text>
        </View>

        <View
          style={{
            position: "absolute",
            top: "20%",
            left: "8%",
            right: "8%",
            bottom: "30%",
            borderWidth: 2,
            borderColor: colors.brand,
            borderRadius: 16,
          }}
        />
        <Text
          variant="caption"
          color="rgba(255,255,255,0.85)"
          center
          style={{ position: "absolute", top: "16%", alignSelf: "center", width: "80%" }}
        >
          Align the full prescription inside the frame
        </Text>

        <View
          style={{
            position: "absolute",
            bottom: 36,
            left: 0,
            right: 0,
            alignItems: "center",
            gap: 12,
          }}
        >
          <ScrollView horizontal contentContainerStyle={{ gap: 8, paddingHorizontal: 16 }}>
            {draftImages.map((uri) => (
              <Pressable key={uri} onLongPress={() => removeAt(uri)}>
                <Image
                  source={{ uri }}
                  style={{ width: 56, height: 56, borderRadius: 8 }}
                />
              </Pressable>
            ))}
          </ScrollView>
          {draftImages.length ? (
            <Text variant="micro" color="rgba(255,255,255,0.7)">
              Long-press a thumbnail to remove
            </Text>
          ) : null}
          <View style={{ flexDirection: "row", gap: 24, alignItems: "center" }}>
            <Pressable onPress={pick} accessibilityLabel="Upload photos">
              <Ionicons name="images" size={28} color="#fff" />
            </Pressable>
            <Pressable
              disabled={!ready}
              onPress={capture}
              accessibilityLabel="Capture"
              style={{
                width: 72,
                height: 72,
                borderRadius: 36,
                backgroundColor: colors.brand,
                borderWidth: 4,
                borderColor: "#fff",
                opacity: ready ? 1 : 0.5,
              }}
            />
            <Pressable
              onPress={() => {
                if (!draftImages.length) {
                  Alert.alert("Add a photo", "Capture or upload at least one image first.");
                  return;
                }
                router.push(routes.rxReview);
              }}
              accessibilityLabel="Continue to review"
            >
              <Ionicons
                name="checkmark-circle"
                size={34}
                color={draftImages.length ? colors.brand : "#666"}
              />
            </Pressable>
          </View>
        </View>
      </CameraView>
    </View>
  );
}