package soy.iko.opencode.ui.chat

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.heightIn
import androidx.compose.foundation.layout.padding
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.automirrored.filled.PlaylistPlay
import androidx.compose.material.icons.filled.Close
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.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.ModalBottomSheet
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.Text
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.TextButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
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.focus.FocusRequester
import androidx.compose.ui.focus.focusRequester
import androidx.compose.ui.hapticfeedback.HapticFeedbackType
import androidx.compose.ui.platform.LocalHapticFeedback
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.semantics
import androidx.compose.ui.text.input.ImeAction
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.unit.dp
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.ui.platform.LocalConfiguration
import soy.iko.opencode.data.model.Command
import soy.iko.opencode.data.network.NetworkConfig
import soy.iko.opencode.R

/** Bottom sheet that lists slash-commands; selecting one invokes it. */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun CommandPickerSheet(
    commands: List<Command>,
    loading: Boolean,
    error: Boolean,
    onSelect: (Command) -> Unit,
    onRetry: () -> Unit,
    onDismiss: () -> Unit,
) {
    // Persist only the command *name* (a savable String), not the Command itself: a
    // kotlinx @Serializable Command is neither Parcelable nor java.io.Serializable, so
    // routing it through rememberSaveable crashes on rotation while the confirm dialog
    // is open. Re-resolve the full Command from the current list for rendering.
    var pendingCommandName by rememberSaveable { mutableStateOf<String?>(null) }
    val pendingCommand = pendingCommandName?.let { name -> commands.firstOrNull { it.name == name } }
    ModalBottomSheet(onDismissRequest = onDismiss) {
        Text(
            stringResource(R.string.commands),
            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 && commands.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 (commands.isEmpty()) {
            Text(
                stringResource(R.string.no_commands),
                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
            val haptics = LocalHapticFeedback.current
            // Auto-focus the search field (and raise the keyboard) when the sheet opens, but skip
            // it for a short list that's faster to scan by eye than to filter.
            val searchFocus = remember { FocusRequester() }
            LaunchedEffect(Unit) {
                if (commands.size > NetworkConfig.pickerSearchAutofocusThreshold) {
                    runCatching { searchFocus.requestFocus() }
                }
            }
            OutlinedTextField(
                value = query,
                onValueChange = { query = it },
                modifier = Modifier.fillMaxWidth().padding(horizontal = 24.dp, vertical = 8.dp).focusRequester(searchFocus),
                placeholder = { Text(stringResource(R.string.search_commands)) },
                leadingIcon = { Icon(Icons.Filled.Search, contentDescription = null) },
                trailingIcon = if (query.isNotEmpty()) {
                    {
                        IconButton(onClick = { query = "" }) {
                            Icon(Icons.Filled.Close, contentDescription = stringResource(R.string.clear_search))
                        }
                    }
                } else null,
                singleLine = true,
                keyboardOptions = KeyboardOptions(imeAction = ImeAction.Search),
                keyboardActions = KeyboardActions(onSearch = { keyboardController?.hide() }),
            )
            val filtered = remember(commands, query) {
                val q = query.trim()
                if (q.isEmpty()) commands
                else commands.filter {
                    it.name.contains(q, ignoreCase = true) ||
                        it.displayDescription.contains(q, ignoreCase = true)
                }
            }
            if (filtered.isEmpty()) {
                Text(
                    stringResource(R.string.no_commands_match, query.trim()),
                    style = MaterialTheme.typography.bodyMedium,
                    color = MaterialTheme.colorScheme.onSurfaceVariant,
                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 16.dp),
                )
            } else {
                // Responsive height: half the viewport rather than a hardcoded 420dp cap.
                LazyColumn(modifier = Modifier.fillMaxHeight(0.5f)) {
                    // distinctBy the name so duplicate command names from the server can't
                    // crash the list with LazyColumn's "Key was already used".
                    items(filtered.distinctBy { it.name }, key = { it.name }) { cmd ->
                        Column(
                            modifier = Modifier
                                .fillMaxWidth()
                                .clickable(role = Role.Button) {
                                    haptics.performHapticFeedback(HapticFeedbackType.TextHandleMove)
                                    if (isDestructiveCommand(cmd.name)) {
                                        pendingCommandName = cmd.name
                                    } else {
                                        onSelect(cmd)
                                        onDismiss()
                                    }
                                }
                                .padding(horizontal = 24.dp, vertical = 12.dp),
                        ) {
                            androidx.compose.foundation.layout.Row(
                                verticalAlignment = androidx.compose.ui.Alignment.CenterVertically,
                            ) {
                                Icon(Icons.AutoMirrored.Filled.PlaylistPlay, contentDescription = null)
                                Text(
                                    "/${cmd.name}",
                                    style = MaterialTheme.typography.bodyLarge,
                                    modifier = Modifier.padding(start = 8.dp),
                                )
                            }
                            Text(
                                cmd.displayDescription,
                                style = MaterialTheme.typography.bodySmall,
                                color = MaterialTheme.colorScheme.onSurfaceVariant,
                                maxLines = 2,
                                overflow = TextOverflow.Ellipsis,
                                modifier = Modifier.padding(start = 28.dp, top = 2.dp),
                            )
                        }
                    }
                }
            }
        }
    }

    // Confirmation for commands whose name suggests they may discard work or reset state,
    // so a tap doesn't irrevocably run e.g. /clear or /compact without consent.
    pendingCommand?.let { cmd ->
        AlertDialog(
            onDismissRequest = { pendingCommandName = null },
            title = { Text(stringResource(R.string.run_command_title, cmd.name)) },
            text = { Text(stringResource(R.string.run_command_text, "/${cmd.name}")) },
            confirmButton = {
                TextButton(onClick = {
                    pendingCommandName = null
                    onSelect(cmd)
                    onDismiss()
                }) { Text(stringResource(R.string.run)) }
            },
            dismissButton = {
                TextButton(onClick = { pendingCommandName = null }) { Text(stringResource(R.string.cancel)) }
            },
        )
    }
}

/**
 * Heuristic for commands that may be destructive (discard work / reset state) and so
 * warrant a confirmation step before invocation. Matches common opencode slash-command
 * names; non-matching commands invoke immediately.
 */
private fun isDestructiveCommand(name: String): Boolean {
    val n = name.lowercase()
    return n in setOf("clear", "compact", "delete", "reset", "remove", "wipe", "drop", "purge") ||
        n.startsWith("clear") || n.startsWith("compact") || n.startsWith("reset")
}