package agzam.vyatsu.ui.groups

import agzam.vyatsu.domain.model.Group
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.WindowInsets
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.systemBars
import androidx.compose.foundation.layout.windowInsetsPadding
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Clear
import androidx.compose.material.icons.filled.Refresh
import androidx.compose.material.icons.filled.Search
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.HorizontalDivider
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Scaffold
import androidx.compose.material3.SearchBar
import androidx.compose.material3.SearchBarDefaults
import androidx.compose.material3.Text
import androidx.compose.material3.TextButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

/**
 * Страница выбора группы
 * @author Agzam
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun GroupPickerScreen(viewModel: GroupPickerViewModel, onGroupPicked: (Group) -> Unit) {
    val state by viewModel.uiState.collectAsState()
    var isSearchActive by remember { mutableStateOf(false) }

    Scaffold { innerPadding ->
        Column(
            Modifier
                .fillMaxSize()
                .windowInsetsPadding(WindowInsets.systemBars)
                .padding(innerPadding)
                .padding(horizontal = 16.dp, vertical = 8.dp)
        ) {
            if (!isSearchActive) {
                Row(
                    Modifier
                        .fillMaxWidth()
                        .padding(bottom = 8.dp),
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    Text(
                        text = "Выберите группу",
                        style = MaterialTheme.typography.headlineSmall,
                        modifier = Modifier.weight(1f)
                    )
                    IconButton(onClick = { viewModel.refresh() }) {
                        Icon(Icons.Default.Refresh, contentDescription = "Обновить")
                    }
                }
            }

            if (state.isLoading && state.groups.isEmpty()) {
                Row(Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.Center) {
                    CircularProgressIndicator()
                }
                return@Column
            }
            if (state.error != null && state.groups.isEmpty()) {
                Column(Modifier.fillMaxWidth()) {
                    Text(state.error.orEmpty(), style = MaterialTheme.typography.bodyMedium, color = MaterialTheme.colorScheme.error)
                    TextButton(onClick = { viewModel.retry() }) { Text("Повторить") }
                }
                return@Column
            }
            SearchBar(
                modifier = Modifier.fillMaxWidth(),
                expanded = isSearchActive,
                onExpandedChange = { isSearchActive = it },
                inputField = {
                    SearchBarDefaults.InputField(
                        query = state.searchQuery,
                        onQueryChange = { viewModel.search(it) },
                        onSearch = { isSearchActive = false },
                        expanded = isSearchActive,
                        onExpandedChange = { isSearchActive = it },
                        placeholder = { Text("Поиск группы") },
                        leadingIcon = { Icon(Icons.Default.Search, contentDescription = null) },
                        trailingIcon = {
                            if (isSearchActive && state.searchQuery.isNotEmpty()) {
                                IconButton(onClick = { viewModel.search("") }) {
                                    Icon(Icons.Default.Clear, contentDescription = "Очистить")
                                }
                            }
                        }
                    )
                }
            ) {
                GroupList(
                    groups = state.filteredGroups,
                    onPick = { group ->
                        isSearchActive = false
                        onGroupPicked(group)
                    }
                )
            }

            if (!isSearchActive) {
                Spacer(modifier = Modifier.height(8.dp))
                GroupList(state.filteredGroups, onGroupPicked)
            }
        }
    }
}

@Composable
private fun GroupList(groups: List<Group>, onPick: (Group) -> Unit) {
    LazyColumn(modifier = Modifier.fillMaxSize()) {
        items(groups) { group ->
            Column(modifier = Modifier.fillMaxWidth() .clickable { onPick(group) }) {
                Box(
                    modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp, vertical = 8.dp).padding(horizontal = 16.dp),
                    contentAlignment = Alignment.CenterStart
                ) {
                    Text(group.name, style = MaterialTheme.typography.bodyMedium)
                    // XXX: стоит ли добавлять факультет или это засорит интерфейс
                    // Row(modifier = Modifier.fillMaxWidth(), verticalAlignment = Alignment.Bottom) {
                    // if (group.faculty.isNotEmpty()) Text(text = group.faculty + " · ", color = MaterialTheme.colorScheme.onSurfaceVariant)
                    // }
                }
            }
            HorizontalDivider(thickness = 1.dp, color = MaterialTheme.colorScheme.outlineVariant)
        }
    }
}