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.lazy.rememberLazyListState
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.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.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.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 androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.ui.platform.LocalConfiguration
import soy.iko.opencode.data.model.ModelOption
import soy.iko.opencode.data.network.NetworkConfig
import soy.iko.opencode.R

/**
 * Flat LazyColumn index of the selected model within the provider-grouped list (each group
 * preceded by a header row), so the sheet can scroll it into view on open. -1 when nothing
 * is selected or the selection isn't in the current list.
 */
private fun selectedModelIndex(
    grouped: Map<String, List<ModelOption>>,
    selected: ModelOption?,
): Int {
    if (selected == null) return -1
    var idx = 0
    for ((_, opts) in grouped) {
        idx++ // provider header
        val distinct = opts.distinctBy { it.providerID to it.modelID }
        val pos = distinct.indexOfFirst {
            it.providerID == selected.providerID && it.modelID == selected.modelID
        }
        if (pos >= 0) return idx + pos
        idx += distinct.size
    }
    return -1
}

/** Bottom sheet that lists every provider/model and lets the user pick one. */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun ModelPickerSheet(
    options: List<ModelOption>,
    selected: ModelOption?,
    loading: Boolean,
    error: Boolean,
    onSelect: (ModelOption) -> Unit,
    onRetry: () -> Unit,
    onDismiss: () -> Unit,
) {
    ModalBottomSheet(onDismissRequest = onDismiss) {
        Text(
            stringResource(R.string.model),
            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 && options.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 (options.isEmpty()) {
            Text(
                stringResource(R.string.no_models),
                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 so the
            // user can start typing to filter a long catalog without an extra tap. Skip it for a
            // short catalog that's faster to scan by eye than to filter.
            val searchFocus = remember { FocusRequester() }
            LaunchedEffect(Unit) {
                if (options.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_models)) },
                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(options, query) {
                val q = query.trim()
                if (q.isEmpty()) options
                else options.filter {
                    it.modelLabel.contains(q, ignoreCase = true) ||
                        it.providerLabel.contains(q, ignoreCase = true)
                }
            }
            if (filtered.isEmpty()) {
                Text(
                    stringResource(R.string.no_models_match, query.trim()),
                    style = MaterialTheme.typography.bodyMedium,
                    color = MaterialTheme.colorScheme.onSurfaceVariant,
                    modifier = Modifier.padding(horizontal = 24.dp, vertical = 16.dp),
                )
            } else {
                // Group by provider so a long catalog is scannable: a provider header
                // followed by its models, instead of a flat list mixing providers.
                val grouped = remember(filtered) { filtered.groupBy { it.providerID } }
                val listState = rememberLazyListState()
                // Flat LazyColumn index of the selected model (accounting for the provider
                // header rows), so we can scroll it into view when the sheet opens. -1 when
                // nothing is selected or the selection isn't in the current list.
                val selectedIndex = remember(grouped, selected) { selectedModelIndex(grouped, selected) }
                LaunchedEffect(Unit) {
                    if (selectedIndex >= 0) listState.scrollToItem(selectedIndex)
                }
                // Responsive height: half the viewport rather than a hardcoded 420dp cap, so
                // the sheet doesn't cramp in landscape or leave empty space on a tall phone.
                LazyColumn(state = listState, modifier = Modifier.fillMaxHeight(0.5f)) {
                    grouped.forEach { (providerID, opts) ->
                        item(key = "header_$providerID") {
                            Text(
                                opts.firstOrNull()?.providerLabel ?: providerID,
                                style = MaterialTheme.typography.labelMedium,
                                color = MaterialTheme.colorScheme.primary,
                                modifier = Modifier.padding(start = 24.dp, top = 12.dp, bottom = 4.dp),
                            )
                        }
                        // distinctBy the (provider, model) pair so a duplicate entry from the
                        // server can't crash the list with LazyColumn's "Key was already used".
                        items(opts.distinctBy { it.providerID to it.modelID }, key = { it.providerID to it.modelID }) { option ->
                    val isSelected = option.providerID == selected?.providerID &&
                        option.modelID == selected?.modelID
                    Column(
                        modifier = Modifier
                            .fillMaxWidth()
                            .semantics(mergeDescendants = true) {
                                if (isSelected) this.selected = true
                            }
                            .clickable(role = Role.RadioButton) {
                                haptics.performHapticFeedback(HapticFeedbackType.TextHandleMove)
                                onSelect(option)
                                onDismiss()
                            }
                            .padding(horizontal = 24.dp, vertical = 12.dp),
                    ) {
                        Row(verticalAlignment = Alignment.CenterVertically) {
                            Text(
                                option.modelLabel,
                                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),
                                )
                            }
                        }
                    }
                }
                    }
            }
        }
        }
    }
}