package com.craigvg.lichun_android.ui.screens.retention

import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.filled.ArrowBack
import androidx.compose.material.icons.filled.AttachMoney
import androidx.compose.material.icons.filled.Flag
import androidx.compose.material.icons.filled.Star
import androidx.compose.material.icons.filled.Verified
import androidx.compose.material.icons.filled.MyLocation
import androidx.compose.material3.*
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.alpha
import androidx.compose.ui.draw.clip
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.hilt.navigation.compose.hiltViewModel
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import com.craigvg.lichun_android.domain.models.ActiveLifeGoal
import com.craigvg.lichun_android.domain.models.CompletedLifeGoal
import com.craigvg.lichun_android.ui.theme.AppColors
import com.craigvg.lichun_android.ui.theme.AppSpacing
import com.craigvg.lichun_android.ui.theme.AppTypography
import com.craigvg.lichun_android.viewmodel.GameStateViewModel

/**
 * Life Goals screen (Wave 2) — surfaces the player's forward-looking aspirations
 * from the cached `lifeGoalsUpdate` snapshot: active goals with progress bars +
 * rewards, the overall life score, and completed goals. `justCompleted` goals are
 * surfaced as a one-time celebratory snackbar.
 *
 * Android parity with iOS LifeGoalsView.swift (T012b).
 */
@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun LifeGoalsScreen(
    gameStateViewModel: GameStateViewModel = hiltViewModel(),
    onBack: () -> Unit = {}
) {
    val snapshot by gameStateViewModel.lifeGoals.collectAsStateWithLifecycle()
    val activeGoals = snapshot?.active ?: emptyList()
    val completedGoals = snapshot?.completed ?: emptyList()
    val lifeScore = snapshot?.lifeScore ?: 0
    val justCompleted = snapshot?.justCompleted ?: emptyList()

    val snackbarHostState = remember { SnackbarHostState() }
    // Surface a one-time celebration for goals that completed this update tick.
    LaunchedEffect(justCompleted.map { it.id }) {
        val goal = justCompleted.firstOrNull() ?: return@LaunchedEffect
        val extra = if (justCompleted.size > 1) " (+${justCompleted.size - 1} more)" else ""
        snackbarHostState.showSnackbar("Goal achieved: ${goal.title}$extra")
    }

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text("Life Goals", style = AppTypography.headline) },
                navigationIcon = {
                    IconButton(onClick = onBack) {
                        Icon(Icons.AutoMirrored.Filled.ArrowBack, "Back", tint = AppColors.primaryText)
                    }
                },
                colors = TopAppBarDefaults.topAppBarColors(containerColor = AppColors.surfaceElevated)
            )
        },
        snackbarHost = { SnackbarHost(snackbarHostState) },
        containerColor = AppColors.background
    ) { padding ->
        Column(
            modifier = Modifier
                .fillMaxSize()
                .padding(padding)
                .verticalScroll(rememberScrollState())
                .padding(horizontal = AppSpacing.md)
        ) {
            Spacer(Modifier.height(AppSpacing.md))

            LifeScoreHeader(
                score = lifeScore,
                activeCount = activeGoals.size,
                completedCount = completedGoals.size
            )

            Spacer(Modifier.height(AppSpacing.lg))

            if (activeGoals.isEmpty() && completedGoals.isEmpty()) {
                LifeGoalsEmptyState()
            } else {
                if (activeGoals.isNotEmpty()) {
                    Text("Active Goals", style = AppTypography.headline, color = AppColors.primaryText)
                    Spacer(Modifier.height(AppSpacing.sm))
                    activeGoals.forEach { goal ->
                        ActiveLifeGoalCard(goal)
                        Spacer(Modifier.height(AppSpacing.sm))
                    }
                    Spacer(Modifier.height(AppSpacing.md))
                }

                if (completedGoals.isNotEmpty()) {
                    Text("Completed", style = AppTypography.headline, color = AppColors.primaryText)
                    Spacer(Modifier.height(AppSpacing.sm))
                    completedGoals.forEach { goal ->
                        CompletedLifeGoalCard(goal)
                        Spacer(Modifier.height(AppSpacing.sm))
                    }
                }
            }

            Spacer(Modifier.height(AppSpacing.xl))
        }
    }
}

@Composable
private fun LifeScoreHeader(score: Int, activeCount: Int, completedCount: Int) {
    Card(
        modifier = Modifier.fillMaxWidth(),
        shape = RoundedCornerShape(AppSpacing.cornerRadius),
        colors = CardDefaults.cardColors(containerColor = AppColors.surfaceElevated)
    ) {
        Column(
            modifier = Modifier
                .fillMaxWidth()
                .padding(AppSpacing.md),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            Box(
                modifier = Modifier
                    .size(76.dp)
                    .background(AppColors.prestige.copy(alpha = 0.18f), CircleShape),
                contentAlignment = Alignment.Center
            ) {
                Icon(
                    Icons.Default.MyLocation,
                    contentDescription = null,
                    tint = AppColors.prestige,
                    modifier = Modifier.size(36.dp)
                )
            }
            Spacer(Modifier.height(AppSpacing.sm))
            Text("$score", style = AppTypography.displayTitle, color = AppColors.primaryText)
            Text("Life Score", style = AppTypography.body, color = AppColors.secondaryText)
            Spacer(Modifier.height(AppSpacing.sm))
            Row(horizontalArrangement = Arrangement.spacedBy(AppSpacing.lg)) {
                StatPill(activeCount, "Active", AppColors.intelligence)
                StatPill(completedCount, "Completed", AppColors.success)
            }
        }
    }
}

@Composable
private fun StatPill(value: Int, label: String, color: androidx.compose.ui.graphics.Color) {
    Column(horizontalAlignment = Alignment.CenterHorizontally) {
        Text("$value", style = AppTypography.headline, color = color)
        Text(label, style = AppTypography.caption, color = AppColors.secondaryText)
    }
}

@Composable
private fun ActiveLifeGoalCard(goal: ActiveLifeGoal) {
    val fraction = (goal.progressPercent.coerceIn(0, 100)).toFloat() / 100f
    Card(
        modifier = Modifier.fillMaxWidth(),
        shape = RoundedCornerShape(AppSpacing.cornerRadius),
        colors = CardDefaults.cardColors(containerColor = AppColors.surfaceElevated),
        elevation = CardDefaults.cardElevation(defaultElevation = 2.dp)
    ) {
        Column(modifier = Modifier.padding(AppSpacing.md)) {
            Row(verticalAlignment = Alignment.CenterVertically) {
                Box(
                    modifier = Modifier
                        .size(44.dp)
                        .background(AppColors.prestige.copy(alpha = 0.15f), CircleShape),
                    contentAlignment = Alignment.Center
                ) {
                    Icon(Icons.Default.Flag, null, tint = AppColors.prestige, modifier = Modifier.size(20.dp))
                }
                Spacer(Modifier.width(AppSpacing.sm))
                Column(modifier = Modifier.weight(1f)) {
                    Text(goal.title, style = AppTypography.bodyBold, color = AppColors.primaryText)
                    if (goal.description.isNotEmpty()) {
                        Text(
                            goal.description,
                            style = AppTypography.caption,
                            color = AppColors.secondaryText,
                            maxLines = 2
                        )
                    }
                }
            }

            Spacer(Modifier.height(AppSpacing.sm))

            Row(verticalAlignment = Alignment.CenterVertically) {
                Box(
                    modifier = Modifier
                        .weight(1f)
                        .height(8.dp)
                        .clip(RoundedCornerShape(4.dp))
                        .background(AppColors.prestige.copy(alpha = 0.2f))
                ) {
                    Box(
                        modifier = Modifier
                            .fillMaxWidth(fraction)
                            .fillMaxHeight()
                            .clip(RoundedCornerShape(4.dp))
                            .background(AppColors.prestige)
                    )
                }
                Spacer(Modifier.width(8.dp))
                Text("${goal.progressPercent}%", style = AppTypography.captionBold, color = AppColors.prestige)
            }

            if (goal.target > 0) {
                Spacer(Modifier.height(AppSpacing.xxs))
                Text("${goal.current}/${goal.target}", style = AppTypography.caption, color = AppColors.secondaryText)
            }

            Spacer(Modifier.height(AppSpacing.xs))
            Row(horizontalArrangement = Arrangement.spacedBy(AppSpacing.sm)) {
                if (goal.reward > 0) {
                    RewardBadge(Icons.Default.AttachMoney, "$${goal.reward}", AppColors.money)
                }
                if (goal.lifeScore > 0) {
                    RewardBadge(Icons.Default.Star, "+${goal.lifeScore} score", AppColors.prestige)
                }
            }
        }
    }
}

@Composable
private fun RewardBadge(icon: androidx.compose.ui.graphics.vector.ImageVector, text: String, color: androidx.compose.ui.graphics.Color) {
    Row(
        verticalAlignment = Alignment.CenterVertically,
        modifier = Modifier
            .clip(RoundedCornerShape(AppSpacing.smallCornerRadius))
            .background(color.copy(alpha = 0.12f))
            .padding(horizontal = AppSpacing.sm, vertical = 4.dp)
    ) {
        Icon(icon, null, tint = color, modifier = Modifier.size(12.dp))
        Spacer(Modifier.width(4.dp))
        Text(text, style = AppTypography.captionBold, color = color)
    }
}

@Composable
private fun CompletedLifeGoalCard(goal: CompletedLifeGoal) {
    Card(
        modifier = Modifier
            .fillMaxWidth()
            .alpha(0.85f),
        shape = RoundedCornerShape(AppSpacing.cornerRadius),
        colors = CardDefaults.cardColors(containerColor = AppColors.success.copy(alpha = 0.1f))
    ) {
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .padding(AppSpacing.md),
            verticalAlignment = Alignment.CenterVertically
        ) {
            Box(
                modifier = Modifier
                    .size(40.dp)
                    .background(AppColors.success.copy(alpha = 0.15f), CircleShape),
                contentAlignment = Alignment.Center
            ) {
                Icon(Icons.Default.Verified, null, tint = AppColors.success, modifier = Modifier.size(20.dp))
            }
            Spacer(Modifier.width(AppSpacing.sm))
            Text(goal.title, style = AppTypography.bodyBold, color = AppColors.primaryText, modifier = Modifier.weight(1f))
        }
    }
}

@Composable
private fun LifeGoalsEmptyState() {
    Box(modifier = Modifier.fillMaxWidth(), contentAlignment = Alignment.Center) {
        Column(
            horizontalAlignment = Alignment.CenterHorizontally,
            modifier = Modifier.padding(AppSpacing.xl)
        ) {
            Icon(
                Icons.Default.MyLocation,
                null,
                tint = AppColors.disabledText,
                modifier = Modifier.size(56.dp)
            )
            Spacer(Modifier.height(AppSpacing.md))
            Text("No life goals yet", style = AppTypography.headline, color = AppColors.primaryText, textAlign = TextAlign.Center)
            Spacer(Modifier.height(AppSpacing.xs))
            Text(
                "Keep living and your aspirations will appear here as you grow through each life stage.",
                style = AppTypography.body,
                color = AppColors.secondaryText,
                textAlign = TextAlign.Center
            )
        }
    }
}