package com.example.aiapp

import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.width
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp

/**
 * Something a session can be asked to do to itself, rather than something to say to it.
 *
 * These are the two this app understands, and understanding them is what lets it show them: a
 * suggestion while one is being typed, a name in the settings screen that sends one, and a bubble
 * that stays up while the session is too busy to run it. Anything else beginning with "/" is passed
 * through, because a dialect's own vocabulary grows without this list.
 */
data class SessionCommand(
    /** With the slash, as it is typed and as it is sent. */
    val name: String,
    /** One line, in the suggestion list: what it does, not how. */
    val summary: String,
    /** What follows the name, named for the reader, or null when nothing does. */
    val argument: String?,
) {
    /** What to put in the box when this is picked: ready to send, or ready to be finished. */
    fun typed(): String = if (argument == null) name else "$name "
}

val SESSION_COMMANDS =
    listOf(
        SessionCommand(
            "/compact",
            "Summarise the conversation so far and carry on from the summary",
            null,
        ),
        SessionCommand(
            "/clear",
            "Start fresh: drop the conversation from the session's context, keeping it on screen",
            null,
        ),
        SessionCommand("/rename", "Change what this session is called", "name"),
    )

/**
 * The commands worth offering for what has been typed so far.
 *
 * Only for a line that starts with a slash and has not yet become a whole command with an argument
 * -- once there is something after "/rename ", the reader is writing the name and a list of
 * commands underneath it is in the way.
 */
fun suggestedCommands(input: String): List<SessionCommand> {
    if (!input.startsWith("/") || input.contains(' ')) return emptyList()
    return SESSION_COMMANDS.filter { it.name.startsWith(input) }
}

/**
 * The commands matching what is being typed, above the box they are being typed into.
 *
 * Above rather than over: a list that covers the transcript hides what the command is about, and
 * the reader is usually looking at the thing they mean to act on.
 */
@Composable
fun CommandSuggestions(
    commands: List<SessionCommand>,
    onPick: (SessionCommand) -> Unit,
    modifier: Modifier = Modifier,
) {
    if (commands.isEmpty()) return
    Card(modifier.fillMaxWidth().padding(horizontal = 16.dp)) {
        Column(Modifier.padding(vertical = 4.dp)) {
            commands.forEach { command ->
                Row(
                    Modifier.fillMaxWidth()
                        .clickable { onPick(command) }
                        .padding(horizontal = 12.dp, vertical = 8.dp),
                    verticalAlignment = Alignment.CenterVertically,
                ) {
                    Text(
                        // The command in the colour commands are, so the suggestion and the bubble
                        // it becomes are visibly the same thing.
                        if (command.argument == null) command.name
                        else "${command.name} <${command.argument}>",
                        style = MaterialTheme.typography.titleSmall,
                        color = commandColor,
                    )
                    Spacer(Modifier.width(12.dp))
                    Text(
                        command.summary,
                        style = MaterialTheme.typography.bodySmall,
                        color = MaterialTheme.colorScheme.onSurfaceVariant,
                    )
                }
            }
        }
    }
}

/**
 * A command, where the reader put it: at their end of the conversation.
 *
 * Blue rather than the colour of something they said, because they did not say it to the model --
 * it is an instruction to the session, and the reply to it is the session changing rather than
 * anything appearing here.
 *
 * [waiting] is a command the session is too busy to run yet, which is a state with a spinner and a
 * reason: pressing Compact in the middle of a long turn otherwise does nothing visible for minutes.
 */
@Composable
fun CommandBubble(text: String, waiting: Boolean = false) {
    Box(Modifier.fillMaxWidth()) {
        Card(
            colors = CardDefaults.cardColors(containerColor = commandColor),
            modifier = Modifier.align(Alignment.CenterEnd).padding(start = 48.dp),
        ) {
            Column(Modifier.padding(12.dp)) {
                // Stated beside the fill rather than inherited: a semantic colour has to carry its
                // own contrast, because the surface under it will not change to rescue it.
                Text(text, color = MaterialTheme.colorScheme.inverseOnSurface)
                if (waiting) {
                    Spacer(Modifier.height(6.dp))
                    Row(verticalAlignment = Alignment.CenterVertically) {
                        CircularProgressIndicator(
                            modifier = Modifier.width(12.dp).height(12.dp),
                            strokeWidth = 2.dp,
                            color = MaterialTheme.colorScheme.inverseOnSurface,
                        )
                        Spacer(Modifier.width(6.dp))
                        Text(
                            "waiting for this turn to end",
                            style = MaterialTheme.typography.bodySmall,
                            color = MaterialTheme.colorScheme.inverseOnSurface,
                        )
                    }
                }
            }
        }
    }
}