package soy.iko.opencode.ui.chat

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.heightIn
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.text.KeyboardActions
import androidx.compose.foundation.text.KeyboardOptions
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Check
import androidx.compose.material.icons.filled.Search
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Icon
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.ModalBottomSheet
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.Text
import androidx.compose.material3.TextButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.saveable.rememberSaveable
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.platform.LocalSoftwareKeyboardController
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.semantics.Role
import androidx.compose.ui.semantics.contentDescription
import androidx.compose.ui.semantics.role
import androidx.compose.ui.semantics.selected
import androidx.compose.ui.semantics.semantics
import androidx.compose.ui.text.input.ImeAction
import androidx.compose.ui.unit.dp
import androidx.compose.foundation.layout.Box
import soy.iko.opencode.data.model.Agent
import soy.iko.opencode.R

/** Bottom sheet that lists every agent and lets the user pick one. */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun AgentPickerSheet(
    agents: List<Agent>,
    selected: String?,
    loading: Boolean,
    error: Boolean,
    onSelect: (Agent?) -> Unit,
    onRetry: () -> Unit,
    onDismiss: () -> Unit,
) {
    ModalBottomSheet(onDismissRequest = onDismiss) {
        Text(
            stringResource(R.string.agent),
            style = MaterialTheme.typography.titleMedium,
            modifier = Modifier.padding(start = 24.dp, end = 24.dp, bottom = 8.dp),
        )
        if (loading) {
            val loadingLabel = stringResource(R.string.loading)
            Box(
                modifier = Modifier.fillMaxWidth().padding(vertical = 24.dp),
                contentAlignment = Alignment.Center,
            ) {
                CircularProgressIndicator(Modifier.semantics { contentDescription = loadingLabel })
            }
        } else if (error && agents.isEmpty()) {
            Column(
                modifier = Modifier.fillMaxWidth().padding(horizontal = 24.dp, vertical = 16.dp),
                horizontalAlignment = Alignment.CenterHorizontally,
            ) {
                Text(
                    stringResource(R.string.load_failed),
                    style = MaterialTheme.typography.bodyMedium,
                    color = MaterialTheme.colorScheme.error,
                )
                TextButton(onClick = onRetry) { Text(stringResource(R.string.retry)) }
            }
        } else if (agents.isEmpty()) {
            Text(
                stringResource(R.string.no_agents),
                style = MaterialTheme.typography.bodyMedium,
                color = MaterialTheme.colorScheme.onSurfaceVariant,
                modifier = Modifier.padding(horizontal = 24.dp, vertical = 16.dp),
            )
        } else {
            var query by rememberSaveable { mutableStateOf("") }
            val keyboardController = LocalSoftwareKeyboardController.current
            OutlinedTextField(
                value = query,
                onValueChange = { query = it },
                modifier = Modifier.fillMaxWidth().padding(horizontal = 24.dp, vertical = 8.dp),
                placeholder = { Text(stringResource(R.string.search_agents)) },
                leadingIcon = { Icon(Icons.Filled.Search, contentDescription = null) },
                singleLine = true,
                keyboardOptions = KeyboardOptions(imeAction = ImeAction.Search),
                keyboardActions = KeyboardActions(onSearch = { keyboardController?.hide() }),
            )
            val filtered = remember(agents, query) {
                val q = query.trim()
                if (q.isEmpty()) agents
                else agents.filter {
                    it.name.contains(q, ignoreCase = true) ||
                        it.displayDescription.contains(q, ignoreCase = true)
                }
            }
            // The "Default" option participates in the search too: show it when the query is
            // empty or matches its label/description. Without this it either always showed
            // (ignoring the filter) or, when a query matched no named agent, disappeared with
            // the whole list — leaving the default unselectable.
            val defaultLabel = stringResource(R.string.default_agent)
            val defaultDesc = stringResource(R.string.default_agent_desc)
            val q = query.trim()
            val defaultMatches = q.isEmpty() ||
                defaultLabel.contains(q, ignoreCase = true) ||
                defaultDesc.contains(q, ignoreCase = true)
            if (filtered.isEmpty() && !defaultMatches) {
                Text(
                    stringResource(R.string.no_agents_match, query.trim()),
                    style = MaterialTheme.typography.bodyMedium,
                    color = MaterialTheme.colorScheme.onSurfaceVariant,
                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 16.dp),
                )
            } else {
                LazyColumn(modifier = Modifier.fillMaxWidth().heightIn(max = 420.dp)) {
                if (defaultMatches) {
                item(key = "__default") {
                    Column(
                        modifier = Modifier
                            .fillMaxWidth()
                            .semantics(mergeDescendants = true) {
                                if (selected == null) this.selected = true
                            }
                            .clickable(role = Role.RadioButton) { onSelect(null); onDismiss() }
                            .padding(horizontal = 24.dp, vertical = 12.dp),
                    ) {
                        Row(verticalAlignment = Alignment.CenterVertically) {
                            Text(
                                stringResource(R.string.default_agent),
                                style = MaterialTheme.typography.bodyLarge,
                                color = if (selected == null) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.onSurface,
                                modifier = Modifier.weight(1f),
                            )
                            if (selected == null) {
                                Icon(
                                    Icons.Filled.Check,
                                    contentDescription = null,
                                    tint = MaterialTheme.colorScheme.primary,
                                    modifier = Modifier.size(18.dp),
                                )
                            }
                        }
                        Text(
                            stringResource(R.string.default_agent_desc),
                            style = MaterialTheme.typography.bodySmall,
                            color = MaterialTheme.colorScheme.onSurfaceVariant,
                        )
                    }
                }
                }
                items(filtered, key = { it.name }) { agent ->
                    val isSelected = agent.name == selected
                    Column(
                        modifier = Modifier
                            .fillMaxWidth()
                            .semantics(mergeDescendants = true) {
                                if (isSelected) this.selected = true
                            }
                            .clickable(role = Role.RadioButton) { onSelect(agent); onDismiss() }
                            .padding(horizontal = 24.dp, vertical = 12.dp),
                    ) {
                        Row(verticalAlignment = Alignment.CenterVertically) {
                            Text(
                                agent.name,
                                style = MaterialTheme.typography.bodyLarge,
                                color = if (isSelected) MaterialTheme.colorScheme.primary else MaterialTheme.colorScheme.onSurface,
                                modifier = Modifier.weight(1f),
                            )
                            if (isSelected) {
                                Icon(
                                    Icons.Filled.Check,
                                    contentDescription = null,
                                    tint = MaterialTheme.colorScheme.primary,
                                    modifier = Modifier.size(18.dp),
                                )
                            }
                        }
                        Text(
                            agent.displayDescription,
                            style = MaterialTheme.typography.bodySmall,
                            color = MaterialTheme.colorScheme.onSurfaceVariant,
                        )
                    }
                }
            }
            }
        }
    }
}