package agzam.vyatsu.ui.info

import agzam.vyatsu.data.static.CALLS
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.WindowInsets
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
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.shape.RoundedCornerShape
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.LinearProgressIndicator
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.unit.dp
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleEventObserver
import androidx.lifecycle.compose.LocalLifecycleOwner
import kotlinx.coroutines.delay
import java.time.LocalTime
import java.time.format.DateTimeFormatter
import java.time.temporal.ChronoUnit



@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun CallsScreen() {

    var now by remember {
        mutableStateOf(LocalTime.now())
    }

    val lifecycleOwner = LocalLifecycleOwner.current

    DisposableEffect(lifecycleOwner) {
        val observer = LifecycleEventObserver { _, event ->
            if (event == Lifecycle.Event.ON_RESUME) {
                now = LocalTime.now()
            }
        }

        lifecycleOwner.lifecycle.addObserver(observer)

        onDispose {
            lifecycleOwner.lifecycle.removeObserver(observer)
        }
    }

    LaunchedEffect(Unit) {
        while (true) {
            now = LocalTime.now()
            delay(15_000L)
        }
    }

    val intervals = remember {
        val formatter = DateTimeFormatter.ofPattern("H:mm")

        CALLS.mapIndexed { index, call ->
            CallInterval(
                number = index + 1,
                start = LocalTime.parse(call.start, formatter),
                end = LocalTime.parse(call.end, formatter)
            )
        }
    }

    val current = intervals.firstOrNull {
        !now.isBefore(it.start) && now.isBefore(it.end)
    }

    val next = intervals.firstOrNull {
        now.isBefore(it.start)
    }

    Scaffold(
        contentWindowInsets = WindowInsets(0.dp),
        topBar = {
            TopAppBar(
                windowInsets = WindowInsets(0.dp),
                title = {
                    Text(
                        text = "Звонки",
                        style = MaterialTheme.typography.headlineSmall,
                        fontWeight = FontWeight.SemiBold
                    )
                }
            )
        }
    ) { innerPadding ->

        LazyColumn(
            modifier = Modifier
                .fillMaxSize()
                .padding(innerPadding),
            contentPadding = PaddingValues(
                horizontal = 16.dp,
                vertical = 12.dp
            ),
            verticalArrangement = Arrangement.spacedBy(12.dp)
        ) {

            item {
                CallsStatusCard(
                    now = now,
                    current = current,
                    next = next,
                    first = intervals.firstOrNull()
                )
            }

            items(
                items = intervals,
                key = { it.number }
            ) { interval ->

                val isCurrent =
                    current?.number == interval.number

                CallCard(
                    interval = interval,
                    now = now,
                    isCurrent = isCurrent
                )
            }
        }
    }
}

private data class CallInterval(
    val number: Int,
    val start: LocalTime,
    val end: LocalTime
)

@Composable
private fun CallCard(
    interval: CallInterval,
    now: LocalTime,
    isCurrent: Boolean
) {
    val isFinished = !now.isBefore(interval.end)

    val status = when {
        isCurrent -> "Идёт сейчас"
        isFinished -> "Завершена"
        else -> "Впереди"
    }

    val totalSeconds = ChronoUnit.SECONDS.between(
        interval.start,
        interval.end
    ).coerceAtLeast(1)

    val elapsedSeconds = ChronoUnit.SECONDS.between(
        interval.start,
        now
    )

    val progress = (
            elapsedSeconds.toFloat() / totalSeconds
            ).coerceIn(0f, 1f)

    Card(
        modifier = Modifier.fillMaxWidth(),
        shape = RoundedCornerShape(20.dp),
        colors = CardDefaults.cardColors(
            containerColor = if (isCurrent) {
                MaterialTheme.colorScheme.primaryContainer
            } else {
                MaterialTheme.colorScheme.surfaceContainerLow
            }
        )
    ) {
        Column(
            modifier = Modifier.padding(16.dp),
            verticalArrangement = Arrangement.spacedBy(12.dp)
        ) {
            Row(
                verticalAlignment = Alignment.CenterVertically,
                horizontalArrangement = Arrangement.spacedBy(16.dp)
            ) {

                Surface(
                    modifier = Modifier.size(56.dp),
                    shape = RoundedCornerShape(16.dp),
                    color = if (isCurrent) {
                        MaterialTheme.colorScheme.primary
                    } else {
                        MaterialTheme.colorScheme.secondaryContainer
                    },
                    contentColor = if (isCurrent) {
                        MaterialTheme.colorScheme.onPrimary
                    } else {
                        MaterialTheme.colorScheme.onSecondaryContainer
                    }
                ) {
                    Box(
                        contentAlignment = Alignment.Center
                    ) {
                        Text(
                            text = interval.number.toString(),
                            style = MaterialTheme.typography.headlineMedium,
                            fontWeight = FontWeight.Bold
                        )
                    }
                }

                Column(
                    modifier = Modifier.weight(1f),
                    verticalArrangement = Arrangement.spacedBy(4.dp)
                ) {
                    Text(
                        text = if (isCurrent) {
                            "Текущая пара"
                        } else {
                            "Пара"
                        },
                        style = MaterialTheme.typography.titleMedium,
                        fontWeight = FontWeight.SemiBold
                    )

                    Text(
                        text = status,
                        style = MaterialTheme.typography.bodySmall
                    )
                }

                Column(
                    horizontalAlignment = Alignment.End,
                    verticalArrangement = Arrangement.spacedBy(4.dp)
                ) {
                    Text(
                        text = interval.start.toString(),
                        style = MaterialTheme.typography.titleMedium,
                        fontWeight = FontWeight.SemiBold
                    )

                    Text(
                        text = interval.end.toString(),
                        style = MaterialTheme.typography.bodyMedium,
                    )
                }
            }
        }
    }
}

@Composable
private fun CallsStatusCard(
    now: LocalTime,
    current: CallInterval?,
    next: CallInterval?,
    first: CallInterval?
) {
    val title: String
    val subtitle: String
    val progress: Float

    when {
        current != null -> {
            title = "Сейчас идёт ${current.number} пара"
            subtitle = "До конца ${minutesUntil(now, current.end)} мин"

            val total = ChronoUnit.SECONDS.between(
                current.start,
                current.end
            ).coerceAtLeast(1)

            val elapsed = ChronoUnit.SECONDS.between(
                current.start,
                now
            )

            progress = (
                    elapsed.toFloat() / total
                    ).coerceIn(0f, 1f)
        }

        next != null -> {
            title = if (first?.number == next.number) {
                "Занятия ещё не начались"
            } else {
                "Сейчас перемена"
            }

            subtitle = "До ${next.number} пары ${minutesUntil(now, next.start)} мин"
            progress = 0f
        }

        else -> {
            title = "Занятия закончились"
            subtitle = "На сегодня пар больше нет"
            progress = 1f
        }
    }

    Card(
        modifier = Modifier.fillMaxWidth(),
        shape = RoundedCornerShape(24.dp),
        colors = CardDefaults.cardColors(
            containerColor = MaterialTheme.colorScheme.secondaryContainer
        )
    ) {
        Column(
            modifier = Modifier.padding(20.dp),
            verticalArrangement = Arrangement.spacedBy(12.dp)
        ) {
            Text(
                text = title,
                style = MaterialTheme.typography.titleMedium,
                fontWeight = FontWeight.SemiBold
            )

            Text(
                text = subtitle,
                style = MaterialTheme.typography.headlineSmall
            )

            if (current != null) {
                LinearProgressIndicator(
                    progress = { progress },
                    modifier = Modifier.fillMaxWidth(),
                    color = MaterialTheme.colorScheme.primary,
                    trackColor = MaterialTheme.colorScheme.surfaceContainerHighest
                )
            }
        }
    }
}

private fun minutesUntil(
    now: LocalTime,
    target: LocalTime
): Long {
    val seconds = ChronoUnit.SECONDS.between(
        now,
        target
    ).coerceAtLeast(0)

    return (seconds + 59) / 60
}

/*
// Агзам
@Composable
fun CallsScreen() {
    LazyColumn(
        Modifier
            .fillMaxWidth()
            .windowInsetsPadding(WindowInsets.statusBars)
    ) {
        itemsIndexed(CALLS) { index, call ->
            Row(Modifier.fillMaxWidth().padding(horizontal = 16.dp, vertical = 12.dp)) {
                Text(
                    "${index + 1} пара",
                    style = MaterialTheme.typography.bodyLarge,
                    modifier = Modifier.weight(1f)
                )
                Text(
                    "${call.start} – ${call.end}",
                    style = MaterialTheme.typography.bodyLarge,
                    color = MaterialTheme.colorScheme.onSurfaceVariant
                )
            }
            HorizontalDivider(Modifier.padding(horizontal = 16.dp))
        }
    }
}

 */