package cc.unitmesh.devins.ui.task

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Add
import androidx.compose.material.icons.filled.PlayArrow
import androidx.compose.material3.*
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import cc.unitmesh.devins.ui.session.StatusBadge
import cc.unitmesh.session.Session
import kotlinx.coroutines.launch
import kotlinx.datetime.Instant
import kotlinx.datetime.TimeZone
import kotlinx.datetime.toLocalDateTime

/**
 * TaskListScreen - 任务列表界面
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun TaskListScreen(
    viewModel: TaskViewModel,
    onTaskClick: (Session) -> Unit
) {
    val currentProject by viewModel.currentProject.collectAsState()
    val tasks by viewModel.tasks.collectAsState()
    val isLoading by viewModel.isLoading.collectAsState()
    val errorMessage by viewModel.errorMessage.collectAsState()
    val scope = rememberCoroutineScope()
    
    var showCreateDialog by remember { mutableStateOf(false) }
    
    Scaffold(
        topBar = {
            TopAppBar(
                title = { 
                    Column {
                        Text("任务列表")
                        currentProject?.let {
                            Text(
                                text = it.name,
                                style = MaterialTheme.typography.bodySmall
                            )
                        }
                    }
                }
            )
        },
        floatingActionButton = {
            if (currentProject != null) {
                FloatingActionButton(
                    onClick = { showCreateDialog = true },
                    containerColor = MaterialTheme.colorScheme.primary
                ) {
                    Icon(Icons.Default.Add, contentDescription = "创建任务")
                }
            }
        }
    ) { paddingValues ->
        Column(
            modifier = Modifier
                .fillMaxSize()
                .padding(paddingValues)
        ) {
            // Error message
            errorMessage?.let { error ->
                Card(
                    colors = CardDefaults.cardColors(
                        containerColor = MaterialTheme.colorScheme.errorContainer
                    ),
                    modifier = Modifier
                        .fillMaxWidth()
                        .padding(16.dp)
                ) {
                    Row(
                        modifier = Modifier.padding(12.dp),
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Text(
                            text = error,
                            color = MaterialTheme.colorScheme.onErrorContainer,
                            style = MaterialTheme.typography.bodySmall,
                            modifier = Modifier.weight(1f)
                        )
                        TextButton(onClick = { viewModel.clearError() }) {
                            Text("关闭")
                        }
                    }
                }
            }
            
            // No project selected
            if (currentProject == null) {
                Box(
                    modifier = Modifier.fillMaxSize(),
                    contentAlignment = Alignment.Center
                ) {
                    Text(
                        text = "请先选择一个项目",
                        style = MaterialTheme.typography.bodyLarge,
                        color = MaterialTheme.colorScheme.onSurfaceVariant
                    )
                }
            } else if (isLoading) {
                Box(
                    modifier = Modifier.fillMaxSize(),
                    contentAlignment = Alignment.Center
                ) {
                    CircularProgressIndicator()
                }
            } else if (tasks.isEmpty()) {
                Box(
                    modifier = Modifier.fillMaxSize(),
                    contentAlignment = Alignment.Center
                ) {
                    Column(
                        horizontalAlignment = Alignment.CenterHorizontally,
                        verticalArrangement = Arrangement.spacedBy(8.dp)
                    ) {
                        Text(
                            text = "还没有任务",
                            style = MaterialTheme.typography.bodyLarge,
                            color = MaterialTheme.colorScheme.onSurfaceVariant
                        )
                        Text(
                            text = "点击 + 创建新任务",
                            style = MaterialTheme.typography.bodySmall,
                            color = MaterialTheme.colorScheme.onSurfaceVariant
                        )
                    }
                }
            } else {
                LazyColumn(
                    modifier = Modifier.fillMaxSize(),
                    contentPadding = PaddingValues(16.dp),
                    verticalArrangement = Arrangement.spacedBy(12.dp)
                ) {
                    items(tasks) { task ->
                        TaskCard(
                            task = task,
                            onClick = { onTaskClick(task) },
                            onExecute = {
                                viewModel.executeTask(task)
                                onTaskClick(task)
                            }
                        )
                    }
                }
            }
        }
    }
    
    // Create task dialog
    if (showCreateDialog) {
        CreateTaskDialog(
            viewModel = viewModel,
            onDismiss = { showCreateDialog = false }
        )
    }
}

@Composable
fun TaskCard(
    task: Session,
    onClick: () -> Unit,
    onExecute: () -> Unit
) {
    Card(
        modifier = Modifier
            .fillMaxWidth()
            .clickable(onClick = onClick),
        elevation = CardDefaults.cardElevation(defaultElevation = 2.dp)
    ) {
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .padding(16.dp),
            verticalAlignment = Alignment.CenterVertically
        ) {
            Column(modifier = Modifier.weight(1f)) {
                Row(
                    verticalAlignment = Alignment.CenterVertically,
                    horizontalArrangement = Arrangement.spacedBy(8.dp)
                ) {
                    StatusBadge(task.status)
                    Text(
                        text = formatTimestamp(task.createdAt),
                        style = MaterialTheme.typography.bodySmall,
                        color = MaterialTheme.colorScheme.onSurfaceVariant
                    )
                }
                
                Spacer(modifier = Modifier.height(8.dp))
                
                Text(
                    text = task.task,
                    style = MaterialTheme.typography.bodyMedium,
                    maxLines = 3
                )
            }
            
            IconButton(onClick = onExecute) {
                Icon(
                    Icons.Default.PlayArrow,
                    contentDescription = "执行任务",
                    tint = MaterialTheme.colorScheme.primary
                )
            }
        }
    }
}

private fun formatTimestamp(timestamp: Long): String {
    val instant = Instant.fromEpochMilliseconds(timestamp)
    val dateTime = instant.toLocalDateTime(TimeZone.currentSystemDefault())
    return "${dateTime.year}-${dateTime.monthNumber.toString().padStart(2, '0')}-${dateTime.dayOfMonth.toString().padStart(2, '0')} " +
            "${dateTime.hour.toString().padStart(2, '0')}:${dateTime.minute.toString().padStart(2, '0')}"
}