package com.peachpasswords.ui.settings

import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
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.systemBarsPadding
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.rounded.ArrowBack
import androidx.compose.material3.Icon
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.CompositionLocalProvider
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.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.unit.sp
import androidx.compose.ui.unit.dp
import androidx.hilt.navigation.compose.hiltViewModel
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.peachpasswords.ui.components.RuneGridBackground
import com.peachpasswords.ui.components.PeachTopBar
import com.peachpasswords.ui.theme.LocalPeachAccent
import com.peachpasswords.ui.theme.LocalPeachColors
import com.peachpasswords.ui.theme.PeachSpacing
import com.peachpasswords.ui.theme.peachColors
import com.peachpasswords.ui.theme.peachDark
import com.peachpasswords.ui.theme.PeachType
import android.content.Context
import dagger.hilt.android.qualifiers.ApplicationContext
import com.peachpasswords.ui.onboarding.ONBOARD_KEY
import com.peachpasswords.ui.onboarding.ONBOARD_PREFS
import com.peachpasswords.sync.SyncFreshStartResetter
import com.peachpasswords.vault.VaultRepository
import dagger.hilt.android.lifecycle.HiltViewModel
import kotlinx.coroutines.launch
import javax.inject.Inject

@HiltViewModel
class PanicViewModel @Inject constructor(
    private val vault: VaultRepository,
    private val syncFreshStart: SyncFreshStartResetter,
    @ApplicationContext private val appContext: Context,
) : ViewModel() {
    val entryCount: Int get() = vault.getEntries().size

    fun destroy(onDone: () -> Unit) = viewModelScope.launch {
        vault.destroyVault()
        syncFreshStart.reset()
        // Destroying the vault puts the app back to factory state, so clear the
        // "already onboarded" flag too — otherwise the next launch skipped the
        // intro and dropped straight onto create-vault, which is not what a
        // fresh start should look like.
        appContext.getSharedPreferences(ONBOARD_PREFS, Context.MODE_PRIVATE)
            .edit().remove(ONBOARD_KEY).apply()
        onDone()
    }
}

@Composable
fun PanicScreen(
    onBack: () -> Unit,
    onDestroyed: () -> Unit,
    vm: PanicViewModel = hiltViewModel(),
) {
    var step by remember { mutableStateOf(1) }
    val entryCount = remember { vm.entryCount }

    // Panic always renders dark regardless of app theme: its tokens must stay
    // readable on the intentional near-black field below (keep the user's accent).
    val accent = LocalPeachAccent.current
    val darkPalette = remember(accent) { peachDark(accent) }

    CompositionLocalProvider(LocalPeachColors provides darkPalette) {
    // The panic flow is intentionally cold: no bloom, a flat near-black field so
    // it reads as a dead-end rather than another lit-up screen in the app.
    Box(modifier = Modifier.fillMaxSize().background(Color(0xFF0C0A06))) {
        // Browser parity: the final step runs a drifting rune field with runes
        // flaring and dying behind it. The earlier steps stay deliberately cold
        // and flat — the chaos is what marks this as the point of no return.
        if (step == 3) {
            RuneGridBackground(
                modifier = Modifier.fillMaxSize(),
                alpha = 0.22f,
                glowing = true,
            )
        }
        Column(
            modifier = Modifier
                .fillMaxSize()
                .systemBarsPadding()
                .padding(horizontal = PeachSpacing.lg, vertical = PeachSpacing.md),
        ) {
            PeachTopBar(
                title = "Panic",
                leading = {
                    Icon(
                        Icons.AutoMirrored.Rounded.ArrowBack,
                        contentDescription = "back",
                        tint = peachColors.T0,
                        modifier = Modifier
                            .size(22.dp)
                            .clip(RoundedCornerShape(PeachSpacing.sm))
                            .clickable(onClick = onBack),
                    )
                },
            )
            Box(
                modifier = Modifier.fillMaxSize().padding(horizontal = PeachSpacing.sm),
                contentAlignment = Alignment.Center,
            ) {
                Column(verticalArrangement = Arrangement.Center) {
                    when (step) {
                        1 -> Step1(onCancel = onBack, onContinue = { step = 2 })
                        2 -> Step2(entryCount = entryCount, onBack = { step = 1 }, onContinue = { step = 3 })
                        else -> Step3(onBack = { step = 2 }, onDestroy = { vm.destroy(onDestroyed) })
                    }
                }
            }
        }
    }
    }
}

@Composable
private fun Step1(onCancel: () -> Unit, onContinue: () -> Unit) {
    Headline("destroy vault", 44.sp, peachColors.Breach)
    Spacer(Modifier.height(PeachSpacing.lg))
    Text(
        "This will permanently delete your vault and all saved passwords from this device. This cannot be undone.",
        color = peachColors.T1,
        style = PeachType.body,
    )
    Spacer(Modifier.height(PeachSpacing.xl))
    Column(
        modifier = Modifier.fillMaxWidth(),
        verticalArrangement = Arrangement.spacedBy(PeachSpacing.sm),
    ) {
        GhostButton("Cancel", peachColors.T1, onCancel)
        DangerButton("I understand, continue", enabled = true, onClick = onContinue)
    }
}

@Composable
private fun Step2(entryCount: Int, onBack: () -> Unit, onContinue: () -> Unit) {
    Headline("are you sure?", 32.sp, peachColors.Breach)
    Spacer(Modifier.height(PeachSpacing.lg))
    Text(
        "You will lose access to all $entryCount saved passwords.",
        color = peachColors.T1,
        style = PeachType.body,
    )
    Spacer(Modifier.height(PeachSpacing.xl))
    Column(
        modifier = Modifier.fillMaxWidth(),
        verticalArrangement = Arrangement.spacedBy(PeachSpacing.sm),
    ) {
        GhostButton("Go back", peachColors.T1, onBack)
        DangerButton("Yes, destroy it", enabled = true, onClick = onContinue)
    }
}

@Composable
private fun Step3(onBack: () -> Unit, onDestroy: () -> Unit) {
    // Chaos: the final step is designed to look like a point of no return.
    // Bright red header, three single-sentence warnings, one solid red button.
    // The user has already confirmed at Step1 and Step2; this screen is
    // deliberately stark rather than carrying a third confirmation gate, so
    // the only escape is the "No — take me back" line under the button.
    Column(modifier = Modifier.fillMaxSize()) {
        // Red header bar — the visual claim that this screen is different.
        Box(
            modifier = Modifier
                .fillMaxWidth()
                .background(peachColors.Breach)
                .padding(vertical = 12.dp, horizontal = PeachSpacing.lg),
            contentAlignment = Alignment.Center,
        ) {
            Text(
                "THIS IS YOUR LAST CHANCE",
                color = peachColors.ShellTopSolid,
                style = PeachType.sortPill.copy(
                    fontSize = 12.sp,
                    fontStyle = FontStyle.Italic,
                ),
            )
        }
        Spacer(Modifier.height(PeachSpacing.lg))
        Text(
            "Your vault is about to be permanently destroyed.",
            color = peachColors.T0,
            style = PeachType.body,
        )
        Spacer(Modifier.height(PeachSpacing.lg))
        Text("There is no recovery.", color = peachColors.Breach, style = PeachType.body)
        Text("There is no support.", color = peachColors.Breach, style = PeachType.body)
        Text("There is no undo.", color = peachColors.Breach, style = PeachType.body)
        Spacer(Modifier.height(PeachSpacing.lg))
        // Hairline divider, matches the body-copy t3 token used elsewhere.
        Box(
            modifier = Modifier
                .fillMaxWidth()
                .height(1.dp)
                .background(peachColors.T3.copy(alpha = 0.25f)),
        )
        Spacer(Modifier.weight(1f))
        ChaosDestroyButton("DESTROY MY VAULT FOREVER", onClick = onDestroy)
        Spacer(Modifier.height(PeachSpacing.sm))
        Box(
            modifier = Modifier.fillMaxWidth(),
            contentAlignment = Alignment.Center,
        ) {
            Text(
                "No — take me back",
                color = peachColors.T2,
                style = PeachType.sortPill.copy(fontSize = 11.sp),
                modifier = Modifier
                    .clip(RoundedCornerShape(999.dp))
                    .clickable(onClick = onBack)
                    .padding(horizontal = PeachSpacing.lg, vertical = 8.dp),
            )
        }
    }
}

@Composable
private fun ChaosDestroyButton(label: String, onClick: () -> Unit) {
    Box(
        modifier = Modifier
            .fillMaxWidth()
            .clip(RoundedCornerShape(10.dp))
            .background(peachColors.Breach)
            .clickable(onClick = onClick)
            .padding(vertical = 14.dp),
        contentAlignment = Alignment.Center,
    ) {
        Text(
            label,
            color = peachColors.ShellTopSolid,
            style = PeachType.sortPill.copy(
                fontSize = 12.sp,
                fontStyle = FontStyle.Italic,
            ),
        )
    }
}

@Composable
private fun Headline(text: String, fontSize: androidx.compose.ui.unit.TextUnit, color: Color) {
    Text(
        text,
        color = color,
        style = TextStyle(
            fontFamily = PeachType.Display,
            fontStyle = FontStyle.Italic,
            fontSize = fontSize,
        ),
    )
}

@Composable
private fun GhostButton(label: String, color: Color, onClick: () -> Unit) {
    Box(
        modifier = Modifier
            .fillMaxWidth()
            .clip(RoundedCornerShape(999.dp))
            .border(1.dp, color.copy(alpha = 0.4f), RoundedCornerShape(999.dp))
            .clickable(onClick = onClick)
            .padding(horizontal = PeachSpacing.lg, vertical = 11.dp),
        contentAlignment = Alignment.Center,
    ) {
        Text(label, color = color, style = PeachType.sortPill.copy(fontSize = 11.sp))
    }
}

@Composable
private fun DangerButton(label: String, enabled: Boolean, onClick: () -> Unit) {
    val alpha = if (enabled) 1f else 0.4f
    Box(
        modifier = Modifier
            .fillMaxWidth()
            .clip(RoundedCornerShape(999.dp))
            .background(peachColors.BreachBg.copy(alpha = peachColors.BreachBg.alpha * alpha))
            .border(1.dp, peachColors.Breach.copy(alpha = 0.55f * alpha), RoundedCornerShape(999.dp))
            .clickable(enabled = enabled, onClick = onClick)
            .padding(horizontal = PeachSpacing.lg, vertical = 11.dp),
        contentAlignment = Alignment.Center,
    ) {
        Text(
            label,
            color = peachColors.Breach.copy(alpha = alpha),
            style = PeachType.sortPill.copy(fontSize = 11.sp),
        )
    }
}