package com.schoolapp.cleverclass

import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.content.SharedPreferences.Editor
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
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.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.ArrowBack
import androidx.compose.material.icons.outlined.Delete
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.BottomAppBar
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Divider
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
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.material3.TopAppBarDefaults
import androidx.compose.runtime.Composable
import androidx.compose.runtime.DisposableEffect
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.graphics.Color
import androidx.compose.ui.unit.dp
import com.schoolapp.cleverclass.ui.theme.CleverClassTheme
import com.schoolapp.cleverclass.ui.theme.TextOnColouredButton
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch

private val subjects = listOf(
    "Mathe", "Deutsch", "Englisch", "Französisch", "Latein",
    "Physik", "Chemie", "Biologie", "Informatik",
    "Geographie", "Wirtschaft", "Geschichte", "Politik und Gesellschaft",
    "Ethik", "Evangelisch", "Katholisch",
    "Kunst", "Musik", "Sport"
)

private val saWeights = listOf(
    2, 2, 2, 2, 2,
    1, 1, 0, 0,
    0, 0, 0, 0,
    0, 0, 0,
    0, 0, 0
)

private val colorsA = listOf(
    Color(0xFF536DFE),
    Color(0xFF18FFFF),
    Color(0xFF448AFF),
    Color(0xFF64FFDA),
    Color(0xFF40C4FF)
)
private val colorsB = listOf(
    Color(0xFFFFFF00),
    Color(0xFFFFAB40),
    Color(0xFFFFD740),
    Color(0xFFEEFF41)
)
private val colorsC = listOf(
    Color(0xFFFF5252),
    Color(0xFFFF4081),
    Color(0xFFFF6052),
    Color(0xFFFF6E40)
)


class NotenActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            CleverClassTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    NotenContent(activity = this)
                }
            }
        }
    }
}

// Content of Noten
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun NotenContent(activity: ComponentActivity){
    val sharedPreferences = activity.getSharedPreferences("gradeAverages", Context.MODE_PRIVATE)
    val editor = sharedPreferences.edit()

    var allAverage by remember {
        mutableStateOf(calculateAllAverage(loadAllAverages(sharedPreferences)))
    }
    var showDeleteConfirmation by remember {
        mutableStateOf(false)
    }

    Scaffold(
        topBar = {
            TopAppBar(
                colors = TopAppBarDefaults.centerAlignedTopAppBarColors(MaterialTheme.colorScheme.primaryContainer),
                title = {
                    Text(text = "Noten",
                        style = MaterialTheme.typography.headlineSmall,
                        color = MaterialTheme.colorScheme.onPrimaryContainer
                    )},
                navigationIcon = {
                    IconButton(onClick = { activity.finish() }) {
                        Icon(
                            imageVector = Icons.Filled.ArrowBack,
                            contentDescription = null,
                            modifier = Modifier.size(28.dp),
                            tint = MaterialTheme.colorScheme.onPrimaryContainer
                        )
                    }
                },
                actions = {
                    IconButton(onClick = { showDeleteConfirmation = true }) {
                        Icon(
                            imageVector = Icons.Outlined.Delete,
                            contentDescription = null,
                            modifier = Modifier.size(28.dp),
                            tint = MaterialTheme.colorScheme.onPrimaryContainer
                        )
                    }
                },
                modifier = Modifier.fillMaxWidth()
            )
        },
        bottomBar = {
            BottomAppBar(
                containerColor = MaterialTheme.colorScheme.primaryContainer,
                modifier = Modifier
                    .fillMaxWidth()
                    .height(64.dp)
            ) {
                Row (modifier = Modifier
                    .fillMaxWidth()
                    .align(Alignment.CenterVertically)){
                    Spacer(modifier = Modifier.width(16.dp))
                    Text(text = "Gesamtschnitt:",
                        style = MaterialTheme.typography.headlineSmall)
                    Spacer(modifier = Modifier.weight(1f))
                    Text(
                        text = "Ø" + formatFloat(allAverage),
                        style = MaterialTheme.typography.headlineSmall)
                    Spacer(modifier = Modifier.width(16.dp))
                }
            }
        }
    ) {innerPadding ->
        Column(
            horizontalAlignment = Alignment.CenterHorizontally,
            modifier = Modifier
                .verticalScroll(rememberScrollState())
                .padding(innerPadding)
        )
        {
            GroopTitle("Hauptfächer", true)
            for (i in 0..4){
                FachButton(
                    color = colorsA[i],
                    subject = subjects[i],
                    saWeight = saWeights[i],
                    activity = activity,
                    sharedPreferences = sharedPreferences,
                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
                )
            }

            GroopTitle("Naturwissenschaften", false)
            for (i in 5..8){
                FachButton(
                    color = colorsB[i - 5],
                    subject = subjects[i],
                    saWeight = saWeights[i],
                    activity = activity,
                    sharedPreferences = sharedPreferences,
                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
                )
            }

            GroopTitle("Gesellschaftswissenschaften", false)
            for (i in 9..12){
                FachButton(
                    color = colorsC[i - 9],
                    subject = subjects[i],
                    saWeight = saWeights[i],
                    activity = activity,
                    sharedPreferences = sharedPreferences,
                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
                )
            }

            GroopTitle("Religionen", false)
            for (i in 13..15){
                FachButton(
                    color = colorsA[i - 13],
                    subject = subjects[i],
                    saWeight = saWeights[i],
                    activity = activity,
                    sharedPreferences = sharedPreferences,
                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
                )
            }

            GroopTitle("Sonstiges", false)
            for (i in 16..18){
                FachButton(
                    color = colorsB[i - 16],
                    subject = subjects[i],
                    saWeight = saWeights[i],
                    activity = activity,
                    sharedPreferences = sharedPreferences,
                    onAvgChange = { allAverage = calculateAllAverage(loadAllAverages(sharedPreferences)) }
                )
            }

            Spacer(modifier = Modifier.height(16.dp))
        }
    }

    if (showDeleteConfirmation){
        AlertDialog(
            onDismissRequest = { showDeleteConfirmation = false },
            text = { Text(text = "Möchten Sie wirklich alle Noten aus Allen Fächern löschen?", color = MaterialTheme.colorScheme.onPrimaryContainer, style = MaterialTheme.typography.labelMedium) },
            confirmButton = {
                Row(modifier = Modifier.fillMaxWidth()){
                    Text(
                        text = "Bestätigen",
                        color = MaterialTheme.colorScheme.secondary,
                        style = MaterialTheme.typography.labelMedium,
                        modifier = Modifier.clickable {
                            deleteAll(editor, activity)
                            showDeleteConfirmation = false
                        }
                    )

                    Spacer(modifier = Modifier.weight(1f))

                    Text(
                        text = "Abbrechen",
                        color = MaterialTheme.colorScheme.secondary,
                        style = MaterialTheme.typography.labelMedium,
                        modifier = Modifier.clickable { showDeleteConfirmation = false }
                    )
                }
            },
            containerColor = MaterialTheme.colorScheme.primaryContainer
        )
    }
}

@Composable
fun FachButton(
    color : Color,
    subject : String,
    saWeight: Int,
    activity: ComponentActivity,
    sharedPreferences: SharedPreferences,
    onAvgChange: () -> Unit){
    var avg by remember {
        mutableStateOf(sharedPreferences.getFloat(subject, 0.0f))
    }

    Button(
        onClick = {
            val intent = Intent(activity, FachActivity::class.java).apply {
                putExtra(FachActivity.NAME_KEY, subject)
                putExtra(FachActivity.WEIGHT_KEY, saWeight)
            }
            activity.startActivity(intent) },
        shape = RoundedCornerShape(40),
        colors = ButtonDefaults.outlinedButtonColors(containerColor = color),
        modifier = Modifier
            .fillMaxWidth()
            .height(64.dp)
            .padding(start = 16.dp, end = 16.dp, top = 16.dp)
    ) {
        Row(modifier = Modifier.fillMaxWidth()) {
            Text(text = subject,
                color = TextOnColouredButton,
                style = MaterialTheme.typography.labelMedium)
            Spacer(modifier = Modifier.weight(1f))
            Text(text = if (avg != 0.0f) "Ø${formatFloat(avg)}" else "---",
                color = TextOnColouredButton,
                style = MaterialTheme.typography.labelMedium)
        }
    }

    // changes state when Shared Preference is updated
    val observer = remember {
        SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
            if (key == subject) {
                avg = sharedPreferences.getFloat(subject, 0.0f)
                onAvgChange()
            }
        }
    }

    // handles observer creation and disposal
    DisposableEffect(Unit) {
        sharedPreferences.registerOnSharedPreferenceChangeListener(observer)
        onDispose {
            sharedPreferences.unregisterOnSharedPreferenceChangeListener(observer)
        }
    }
}

@Composable
fun GroopTitle(name: String, top: Boolean){
    if(!top) {
        Spacer(modifier = Modifier.height(32.dp))
        Divider()
    }
    Spacer(modifier = Modifier.height(32.dp))
    Text(text = name, style = MaterialTheme.typography.headlineSmall, color = MaterialTheme.colorScheme.onBackground)
    Spacer(modifier = Modifier.height(12.dp))
}

fun calculateAllAverage(avgs: List<Float>): Float{
    var total = 0.0f
    var number = 0

    avgs.forEach{ avg ->
        if (avg != 0.0f && !avg.isNaN()){
            total += avg
            number += 1
        }
    }
    return (total / number)
}

fun loadAllAverages(sharedPreferences: SharedPreferences): List<Float>{
    val avgs = emptyList<Float>().toMutableList()

    subjects.forEach { name ->
        avgs += sharedPreferences.getFloat(name, 0.0f)
    }

    return avgs
}

fun deleteAll(editor: Editor, context: Context){
    subjects.forEach{name ->
        editor.putFloat(name, 0.0f).apply()
        CoroutineScope(Dispatchers.IO).launch {
            GradeStoreManager.saveGrades(context, emptyList(), name)
        }
    }
}