package com.example.aiapp

import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.text.KeyboardOptions
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.text.input.KeyboardType
import androidx.compose.ui.unit.dp

/**
 * The controls for whatever settings a provider says it takes.
 *
 * One composable for both screens that offer them — the spawn form and the session settings dialog
 * — and for every provider, because the server declares the list (see `DriverKind::params`) rather
 * than this file knowing it. A driver that grows a setting gets a control here with no change to
 * the app, which is the whole point: the values that suit one machine ship as defaults, and every
 * one of them stays reachable from a phone.
 *
 * [values] is the whole map and [onChange] hands back the whole map. A key absent from it means the
 * setting is unset, which is what every [ParamSpec.unset] describes — so clearing a field and never
 * touching it are deliberately the same state.
 */
@Composable
fun ProviderParamFields(
    specs: List<ParamSpec>,
    values: Map<String, String>,
    onChange: (Map<String, String>) -> Unit,
    /**
     * Whether to say which settings wait for a restart. False on a spawn form, where nothing is
     * running yet and every setting is about to be read — saying it there would be a warning about
     * a state the reader cannot be in.
     */
    warnAboutRestart: Boolean,
    modifier: Modifier = Modifier,
) {
    if (specs.isEmpty()) return
    Column(modifier.fillMaxWidth()) {
        specs.forEach { spec ->
            val set = { value: String ->
                onChange(
                    // Blank clears rather than storing an empty string: the server reads an absent
                    // key as "use the default", and an empty one would be a value it then failed
                    // to parse.
                    if (value.isBlank()) values - spec.key else values + (spec.key to value)
                )
            }
            when (spec.kind) {
                "choice" -> {
                    // The first option is what unset means, so selecting it clears the key — see
                    // `ParamKind::Choice`. Without that the picker could show a default it could
                    // not return to.
                    val default = spec.options.firstOrNull().orEmpty()
                    ChipGroup(
                        label = spec.label + restartSuffix(spec, warnAboutRestart),
                        options = spec.options,
                        selected = values[spec.key] ?: default,
                        onSelect = { chosen -> set(if (chosen == default) "" else chosen) },
                    )
                }
                else ->
                    OutlinedTextField(
                        value = values[spec.key].orEmpty(),
                        onValueChange = set,
                        label = { Text(spec.label + restartSuffix(spec, warnAboutRestart)) },
                        placeholder = { Text(spec.unset) },
                        singleLine = true,
                        keyboardOptions = KeyboardOptions(keyboardType = keyboardFor(spec.kind)),
                        modifier = Modifier.fillMaxWidth(),
                    )
            }
            Spacer(Modifier.height(16.dp))
        }
        if (warnAboutRestart && specs.any { it.restart }) {
            Text(
                "A setting marked “on restart” is saved now and read when this session's process " +
                    "next starts.",
                style = MaterialTheme.typography.bodySmall,
                color = MaterialTheme.colorScheme.onSurfaceVariant,
            )
        }
    }
}

/**
 * Marks a control whose value will not take effect yet.
 *
 * On the label rather than beside it, because the reader decides whether to change the thing before
 * they touch it — a note underneath is read after the decision.
 */
private fun restartSuffix(spec: ParamSpec, warn: Boolean): String =
    if (warn && spec.restart) " (on restart)" else ""

/**
 * The keyboard for a value's shape. A number field that opens the letter keyboard is one every
 * entry is made harder by, and these are nearly all numbers.
 */
private fun keyboardFor(kind: String): KeyboardType =
    when (kind) {
        "integer" -> KeyboardType.Number
        "decimal" -> KeyboardType.Decimal
        else -> KeyboardType.Text
    }

/**
 * How long typing has to stop before edited settings are sent.
 *
 * Long enough that a number is one request rather than one per digit, short enough that closing the
 * dialog straight after typing still saves — the save runs on the screen behind it, which outlives
 * the dialog, so this delay is not a window the value can be lost in.
 */
const val PARAM_SAVE_DELAY_MS = 700L