package sh.moritz.watchcalculator.presentation

import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.horizontalScroll
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxSize
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.foundation.rememberScrollState
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.ArrowBack
import androidx.compose.material.icons.filled.Check
import androidx.compose.material.icons.filled.Close
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.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clipToBounds
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.wear.compose.material.Button
import androidx.wear.compose.material.Icon
import androidx.wear.compose.material.MaterialTheme
import androidx.wear.compose.material.OutlinedButton
import androidx.wear.compose.material.Text
import androidx.wear.compose.material.dialog.Alert
import androidx.wear.compose.material.dialog.Confirmation
import androidx.wear.tooling.preview.devices.WearDevices
import kotlinx.coroutines.Job
import sh.moritz.watchcalculator.presentation.theme.WatchCalculatorTheme

class CalculatorUI {
	@Composable
	public fun Draw(modifier: Modifier) {
		var formula by remember { mutableStateOf("") }
		var page by remember { mutableStateOf(CURRENT_PAGE.ENTRY) }
		Column() {
			when (page) {
				CURRENT_PAGE.ENTRY -> {
					val buttonMod = modifier
						.padding(2.dp)
						.height(25.dp)
						.width(35.dp)
					val scrollState = rememberScrollState()

					// Auto-scroll to the end whenever the formula changes
					LaunchedEffect(formula) {
						scrollState.scrollTo(scrollState.maxValue)
					}

					val fullExpression = fun(): Boolean {
						if (formula.isEmpty()) {
							return false
						}

						if (formula.last().isDigit()) {
							return true
						}

						return false
					}

					Row(
						modifier = modifier
							.fillMaxWidth()
							.background(MaterialTheme.colors.background)
							.padding(top = 24.dp),
						verticalAlignment = Alignment.CenterVertically
					) {
						Box(
							modifier = Modifier
								.fillMaxWidth(0.7f)
								.horizontalScroll(scrollState) // allow horizontal growth
								.clipToBounds(), // clip overflow
							contentAlignment = Alignment.CenterEnd,
						) {
							Text(
								text = formula,
								color = Color.White,
								fontSize = 30.sp,
								maxLines = 1,
								softWrap = false,
								overflow = TextOverflow.Clip
							)
						}
						Icon(
							imageVector = Icons.Default.ArrowBack,
							contentDescription = "delete input",
							modifier = Modifier
								.padding(start = 8.dp)
								.clickable {
									if (!formula.isEmpty()) {
										formula = formula.substring(0, formula.length - 1)
									}
								}
						)
					}
					Row(
						modifier = modifier
							.background(MaterialTheme.colors.background)
							.align(Alignment.CenterHorizontally),
					) {
					}
					Row(
						modifier = modifier
							.background(MaterialTheme.colors.background)
							.align(Alignment.CenterHorizontally),
					) {
						Button(onClick = { formula += "7" }, modifier = buttonMod) { Text("7") }
						Button(onClick = { formula += "8" }, modifier = buttonMod) { Text("8") }
						Button(onClick = { formula += "9" }, modifier = buttonMod) { Text("9") }
						Button(
							onClick = { formula += "+" },
							modifier = buttonMod,
							enabled = fullExpression()
						) { Text("+") }
					}
					Row(
						modifier = modifier
							.background(MaterialTheme.colors.background)
							.align(Alignment.CenterHorizontally),
					) {
						Button(onClick = { formula += "4" }, modifier = buttonMod) { Text("4") }
						Button(onClick = { formula += "5" }, modifier = buttonMod) { Text("5") }
						Button(onClick = { formula += "6" }, modifier = buttonMod) { Text("6") }
						Button(
							onClick = { formula += "-" },
							modifier = buttonMod,
							enabled = fullExpression()
						) { Text("-") }
					}
					Row(
						modifier = modifier
							.background(MaterialTheme.colors.background)
							.align(Alignment.CenterHorizontally),
					) {
						Button(onClick = { formula += "1" }, modifier = buttonMod) { Text("1") }
						Button(onClick = { formula += "2" }, modifier = buttonMod) { Text("2") }
						Button(onClick = { formula += "3" }, modifier = buttonMod) { Text("3") }
						Button(
							onClick = { formula += "×" },
							modifier = buttonMod,
							enabled = fullExpression()
						) { Text("×") }
					}
					Row(
						modifier = modifier
							.background(MaterialTheme.colors.background)
							.align(Alignment.CenterHorizontally),
					) {
						var timeout by remember { mutableStateOf<Job?>(null) }

						Button(
							onClick = { page = CURRENT_PAGE.DELETE_INPUT_CONFIRMATION },
							modifier = buttonMod,
							enabled = !formula.isEmpty()
						) { Text("C") }
						Button(onClick = { formula += "0" }, modifier = buttonMod) { Text("0") }
						Button(
							onClick = { page = CURRENT_PAGE.RESULT },
							modifier = buttonMod,
							enabled = fullExpression()
						) { Text("=") }
						Button(
							onClick = { formula += "÷" },
							modifier = buttonMod,
							enabled = fullExpression()
						) { Text("÷") }
					}
				}

				CURRENT_PAGE.DELETE_INPUT_CONFIRMATION -> {
					var deleted by remember { mutableStateOf(false) }
					if (!deleted) {
						Alert(
							title = { Text("Clear input?") },
							negativeButton = {
								OutlinedButton(onClick = {
									page = CURRENT_PAGE.ENTRY
								}) { Icon(Icons.Default.Close, "don't clear") }
							},
							positiveButton = {
								Button(onClick = {
									formula = ""
									deleted = true
								}) { Icon(Icons.Default.Check, "clear input") }
							},
							content = {}
						)
					} else {
						Confirmation(
							onTimeout = {
								deleted = false
								page = CURRENT_PAGE.ENTRY
							},
							icon = { Icon(Icons.Default.Check, "success") },
							durationMillis = 500L,
							content = { Text("input has been cleared") },
							//backgroundColor = TODO(),
							//contentColor = TODO(),
							//iconColor = TODO(),
							//verticalArrangement = TODO(),
							//contentPadding = TODO(),
							//content = TODO()
						)
					}
				}

				CURRENT_PAGE.RESULT -> {
					Column(
						verticalArrangement = Arrangement.Center,
						modifier = Modifier
							.fillMaxSize()
							.clickable(
								enabled = true,
								onClickLabel = "Back to the calculator",
								onClick = {
									formula = ""
									page = CURRENT_PAGE.ENTRY
								}
							),
					) {
						Text(
							FormulaSolver(formula).Solve(),
							color = MaterialTheme.colors.primary,
							textAlign = TextAlign.Center,
							fontSize = 40.sp,
							modifier = Modifier.fillMaxWidth(),
						)
					}
				}
			}
		}
	}
}

@Preview(device = WearDevices.LARGE_ROUND, showSystemUi = true)
@Composable
private fun PreviewCalculator() {
	WatchCalculatorTheme {
		CalculatorUI().Draw(Modifier)
	}
}

private enum class CURRENT_PAGE() {
	ENTRY,
	RESULT,
	DELETE_INPUT_CONFIRMATION,
}