import { CheckAssignmentCompletion } from '@/lib/progress';
import { supabase } from '@/lib/supabase';
import type { Task } from '@/lib/types';
import { Session } from '@supabase/supabase-js';
import { router, Stack, useFocusEffect, useLocalSearchParams } from 'expo-router';
import { useCallback, useEffect, useState } from 'react';
import { Alert, Pressable, Text, View } from 'react-native';

export default function ViewDetailsTask() {
  const { tId } = useLocalSearchParams<{ tId: string }>();
  const [task, SetTask] = useState<Task | null>(null);
  const [session, SetSession] = useState<Session | null>(null);

  useEffect(() => {
    supabase.auth.getSession().then(({ data }) => SetSession(data.session ?? null));

    const { data: sub } = supabase.auth.onAuthStateChange((_event, newSession) => {
      SetSession(newSession);
    });

    return () => sub.subscription.unsubscribe();
  }, []);

  const GetTask = async (taskId: string) => {
    const { data, error } = await supabase
      .from('tasks')
      .select('*')
      .eq('tId', taskId)
      .single();

    if (error) {
      Alert.alert('Task could not be fetched, please try again');
      return;
    }

    SetTask(data ?? null);
  };

  useFocusEffect(
    useCallback(() => {
      if (session && tId) {
        GetTask(tId);
      }
    }, [session, tId])
  );

  const DeleteTask = async (taskId: string) => {
    Alert.alert(
      'Delete Task',
      'Are you sure you want to delete this task?',
      [
        {
          text: 'Cancel',
          style: 'cancel',
        },
        {
          text: 'Delete',
          style: 'destructive',
          onPress: async () => {
            const { error } = await supabase
              .from('tasks')
              .delete()
              .eq('tId', taskId);

            if (error) {
              Alert.alert('Task could not be deleted, please try again');
              return;
            }

            const aId = task?.aId;

            if (aId) {
              try {
                await CheckAssignmentCompletion(aId);
              } catch {
                Alert.alert('Failed to update assignment completion state');
              }
            }

            Alert.alert('Task deleted successfully!');
            router.back();
          },
        },
      ]
    );
  };

  if (!task) {
    return (
      <View className="flex-1 bg-app-bg px-5 pt-6">
        <Stack.Screen
          options={{
            title: 'Task Details',
            headerRight: () => (
              <Pressable
                className="rounded-full bg-app-subtle px-4 py-2"
                onPress={async () => await supabase.auth.signOut()}
              >
                <Text className="text-sm font-semibold text-text-secondary">
                  Logout
                </Text>
              </Pressable>
            ),
          }}
        />

        <View className="rounded-3xl border border-app-border bg-app-surface p-5">
          <Text className="text-2xl font-bold text-text-main">
            Task not found
          </Text>
          <Text className="mt-2 text-base text-text-secondary">
            The task could not be loaded.
          </Text>

          <Pressable
            className="mt-5 h-12 items-center justify-center rounded-2xl bg-accent"
            onPress={() => router.back()}
          >
            <Text className="text-base font-bold text-text-inverse">
              Go back
            </Text>
          </Pressable>
        </View>
      </View>
    );
  }

  const isOwner = session?.user.id === task.uId;

  return (
    <View className="flex-1 bg-app-bg px-5 pt-6">
      <Stack.Screen
        options={{
          title: 'Task Details',
          headerRight: () => (
            <Pressable
              className="rounded-full bg-app-subtle px-4 py-2"
              onPress={async () => await supabase.auth.signOut()}
            >
              <Text className="text-sm font-semibold text-text-secondary">
                Logout
              </Text>
            </Pressable>
          ),
        }}
      />

      <View className="rounded-3xl border border-app-border bg-app-surface p-5">
        <View className="flex-row items-start">
          <View
            className={`mr-3 mt-1 h-6 w-6 items-center justify-center rounded-md border-2 ${
              task.isCompleted
                ? 'border-accent bg-accent'
                : 'border-app-border bg-app-subtle'
            }`}
          >
            {task.isCompleted && (
              <Text className="text-sm font-bold text-text-inverse">✓</Text>
            )}
          </View>

          <View className="flex-1">
            <Text
              className={`text-2xl font-bold ${
                task.isCompleted ? 'text-text-secondary' : 'text-text-main'
              }`}
            >
              {task.title}
            </Text>

            {task.description ? (
              <Text className="mt-3 text-base leading-6 text-text-secondary">
                {task.description}
              </Text>
            ) : (
              <Text className="mt-3 text-base text-text-muted">
                No description added.
              </Text>
            )}

            <View className="mt-4 flex-row flex-wrap">
              <View className="mr-2 mb-2 rounded-full bg-app-subtle px-3 py-1">
                <Text className="text-xs font-semibold text-text-secondary">
                  {task.isCompleted ? 'Completed' : 'In progress'}
                </Text>
              </View>
            </View>

            <Text className="mt-2 text-sm text-text-muted">
              Last changed: {task.lastChanged}
            </Text>
          </View>
        </View>

        {isOwner && (
          <View className="mt-5 flex-row border-t border-app-border pt-5">
            <Pressable
              className="mr-3 flex-1 items-center justify-center rounded-2xl border border-app-border bg-app-subtle py-3"
              onPress={() =>
                router.push({
                  pathname: '/task/editTask',
                  params: { tId: task.tId },
                })
              }
            >
              <Text className="text-sm font-bold text-text-secondary">
                Edit
              </Text>
            </Pressable>

            <Pressable
              className="flex-1 items-center justify-center rounded-2xl border border-app-border bg-app-surface py-3"
              onPress={() => DeleteTask(task.tId)}
            >
              <Text className="text-sm font-bold text-status-danger">
                Delete
              </Text>
            </Pressable>
          </View>
        )}
      </View>
    </View>
  );
}