import { useState } from "react";
import { Pressable, ScrollView, StyleSheet, Text, View } from "react-native";
import * as Device from "expo-device";
import * as Notifications from "expo-notifications";
import { fetchHealth, registerPushToken } from "../../lib/api";

const USER_ID = "seed-user-primary";

// Q-1 驗收：APP 能呼叫 api 的 /health 並顯示結果。
// Q-3 推播通知：請求權限、取得 Expo push token、註冊到後端——實機／模擬器才能真的收到推播，
// 這裡的按鈕操作與畫面回饋在沒有實體裝置的環境下也能驗證到「流程本身有沒有跑起來、有沒有回報錯誤」。
export default function SettingsScreen() {
  const [healthStatus, setHealthStatus] = useState<string | null>(null);
  const [healthError, setHealthError] = useState<string | null>(null);
  const [pushStatus, setPushStatus] = useState<string | null>(null);

  async function checkHealth() {
    setHealthError(null);
    try {
      const result = await fetchHealth();
      setHealthStatus(result.status);
    } catch {
      setHealthError("無法連線到 api 服務");
    }
  }

  async function enablePushNotifications() {
    setPushStatus("請求權限中…");
    if (!Device.isDevice) {
      setPushStatus("推播僅能在實機或支援的模擬器上取得 token（目前環境無法取得真實 token）");
      return;
    }
    const { status } = await Notifications.requestPermissionsAsync();
    if (status !== "granted") {
      setPushStatus("使用者未授權推播通知");
      return;
    }
    try {
      const tokenResponse = await Notifications.getExpoPushTokenAsync();
      await registerPushToken(USER_ID, tokenResponse.data, "expo");
      setPushStatus(`已註冊推播 token：${tokenResponse.data}`);
    } catch (err) {
      setPushStatus(`推播 token 取得失敗：${err instanceof Error ? err.message : String(err)}`);
    }
  }

  return (
    <ScrollView style={styles.container} contentContainerStyle={styles.content}>
      <Text style={styles.title}>設定</Text>

      <View style={styles.card}>
        <Text style={styles.cardTitle}>API 連線狀態</Text>
        <Pressable style={styles.button} onPress={checkHealth}>
          <Text style={styles.buttonText}>檢查連線</Text>
        </Pressable>
        {healthStatus && <Text style={styles.line}>狀態：{healthStatus}</Text>}
        {healthError && <Text style={styles.error}>{healthError}</Text>}
      </View>

      <View style={styles.card}>
        <Text style={styles.cardTitle}>推播通知</Text>
        <Pressable style={styles.button} onPress={enablePushNotifications}>
          <Text style={styles.buttonText}>開啟推播通知</Text>
        </Pressable>
        {pushStatus && <Text style={styles.line}>{pushStatus}</Text>}
      </View>
    </ScrollView>
  );
}

const styles = StyleSheet.create({
  container: { flex: 1, backgroundColor: "#FFF5F7" },
  content: { padding: 20, gap: 24 },
  title: { fontSize: 22, fontWeight: "bold", color: "#FF7E9D" },
  card: { gap: 10 },
  cardTitle: { fontSize: 15, fontWeight: "bold", color: "#222" },
  button: { alignSelf: "flex-start", backgroundColor: "#FF7E9D", borderRadius: 999, paddingHorizontal: 16, paddingVertical: 8 },
  buttonText: { color: "#fff", fontWeight: "bold" },
  line: { fontSize: 13, color: "#222" },
  error: { color: "#FF7E9D", fontSize: 12 },
});