package com.vgmlr.varnish

import androidx.activity.compose.BackHandler
import androidx.activity.compose.rememberLauncherForActivityResult
import androidx.activity.result.contract.ActivityResultContracts
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.combinedClickable
import androidx.compose.foundation.gestures.awaitEachGesture
import androidx.compose.foundation.gestures.awaitFirstDown
import androidx.compose.foundation.interaction.MutableInteractionSource
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.Spacer
import androidx.compose.foundation.layout.WindowInsets
import androidx.compose.foundation.layout.asPaddingValues
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.navigationBars
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.statusBars
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.BlurOff
import androidx.compose.material.icons.filled.BlurOn
import androidx.compose.material.icons.outlined.Add
import androidx.compose.material.icons.outlined.Block
import androidx.compose.material.icons.outlined.Delete
import androidx.compose.material.icons.outlined.Folder
import androidx.compose.material.icons.outlined.Park
import androidx.compose.material.icons.outlined.Settings
import androidx.compose.material3.Icon
import androidx.compose.material3.LocalTextStyle
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.key
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.draw.drawWithCache
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.hapticfeedback.HapticFeedbackType
import androidx.compose.ui.input.pointer.PointerEventPass
import androidx.compose.ui.input.pointer.pointerInput
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.platform.LocalHapticFeedback
import androidx.compose.ui.text.TextMeasurer
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.drawText
import androidx.compose.ui.text.font.FontFamily
import androidx.compose.ui.text.rememberTextMeasurer
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.unit.Constraints
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.TextUnit
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.lifecycle.compose.collectAsStateWithLifecycle
import coil.compose.AsyncImage
import androidx.compose.material.icons.outlined.WarningAmber
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.ui.platform.LocalUriHandler
import androidx.compose.ui.graphics.compositeOver

private const val FADE = 0.4f
private const val PEEK = 0.4f
private val ROW_PAD = 4.dp
private val ROW_GAP = 12.dp
private val COUNT_GAP = 12.dp
private val SEAM = 3.dp
private val TILE_SHAPE = RoundedCornerShape(BTN_RADIUS + SEAM)
private val SEAM_MARK = SelectBorder.compositeOver(PageBg) // opaque ring
private val SHADES = listOf(0f, 0.4f, 0.7f)
private const val PATH_FADE = 0.2f

@Composable
fun HomeScreen(vm: VarnishViewModel) {
    val folders by vm.folders.collectAsStateWithLifecycle()
    val scanning by vm.scanning.collectAsStateWithLifecycle()
    val query by vm.query.collectAsStateWithLifecycle()
    val results by vm.searchResults.collectAsStateWithLifecycle()
    val settings by vm.settings.collectAsStateWithLifecycle()
    val blurSet by vm.folderBlur.collectAsStateWithLifecycle()

    var menu by remember { mutableStateOf(false) }
    var marked by remember { mutableStateOf<String?>(null) }
    var armDel by rememberArmed()
    var showVersion by remember { mutableStateOf(false) }
    val listState = rememberLazyListState()
    val searching = query.isNotBlank()

    LaunchedEffect(marked) { armDel = false }

    val picker = rememberLauncherForActivityResult(
        ActivityResultContracts.OpenDocumentTree()
    ) { uri ->
        val parent = uri?.let(vm.repo::treePath) ?: return@rememberLauncherForActivityResult
        vm.createFolder(parent, VarnishConfig.FOLDER_UNNAMED) { d ->
            d?.let { vm.open(Screen.Folder(it)) }
        }
    }

    BackHandler(enabled = menu || marked != null || query.isNotEmpty()) {
        when {
            menu -> menu = false
            marked != null -> marked = null
            else -> vm.setQuery("")
        }
    }

    val top = WindowInsets.statusBars.asPaddingValues().calculateTopPadding() + TOP_BAR_H
    val bottom = WindowInsets.navigationBars.asPaddingValues().calculateBottomPadding() +
            BTN + DOCK_PAD * 2

    Box(Modifier.fillMaxSize().background(PageBg)) {
        if (searching) {
            MediaBrowser(vm, results, folder = null, onTouch = { menu = false })
        } else {
            LazyColumn(
                state = listState,
                modifier = Modifier
                    .fillMaxSize()
                    .pointerInput(Unit) {
                        awaitEachGesture {
                            awaitFirstDown(requireUnconsumed = false, pass = PointerEventPass.Initial)
                            menu = false
                        }
                    }
                    .clickable(
                        interactionSource = remember { MutableInteractionSource() },
                        indication = null
                    ) { marked = null },
                contentPadding = PaddingValues(top = top, bottom = bottom)
            ) {
                items(folders, key = { it.path }) { f ->
                    FolderRow(
                        folder = f,
                        size = settings.folderImg.dp,
                        blurred = f.path in blurSet,
                        marked = marked == f.path,
                        onClick = {
                            if (marked != null) marked = null
                            else vm.open(Screen.Folder(f.path))
                        },
                        onLongPress = { marked = f.path }
                    )
                }
            }
            if (folders.isEmpty()) {
                Text(
                    if (scanning) "Scanning" else "Empty",
                    color = PageText.copy(alpha = FADE),
                    fontFamily = FontFamily.Monospace,
                    fontSize = 15.sp,
                    modifier = Modifier.align(Alignment.Center)
                )
            }
            folders.firstOrNull { it.path == marked }?.let { f ->
                val blurred = f.path in blurSet
                Dock {
                    VButton(
                        if (blurred) Icons.Filled.BlurOff else Icons.Filled.BlurOn,
                        if (blurred) "Unblur" else "Blur"
                    ) { vm.setFolderBlur(f.path, !blurred) }
                    VButton(
                        if (armDel) Icons.Outlined.WarningAmber else Icons.Outlined.Delete,
                        "Delete",
                        enabled = !f.locked,
                        iconSize = DEL_ICON,
                        bg = if (armDel) WarnBg else BtnBg
                    ) {
                        if (settings.confirmDelete && !armDel) {
                            armDel = true
                        } else {
                            vm.deleteFolder(f.path)
                            marked = null
                        }
                    }
                }
            }
        }

        TopBar(
            trailing = {
                MenuStack(
                    open = menu,
                    onOpenChange = { menu = it },
                    items = listOf(
                        MenuItem(Icons.Outlined.Add, "New Folder") { picker.launch(null) },
                        MenuItem(Icons.Outlined.Settings, "Settings") { vm.open(Screen.Settings) },
                        MenuItem(Icons.Outlined.Park, "Version") { showVersion = true },
                        MenuItem(Icons.Outlined.Block, "Exit", enabled = false) {}
                    )
                )
            }
        ) {
            SearchField(query, vm::setQuery, Modifier.weight(1f))
        }
    }

    VersionDialog(showVersion, { showVersion = false }, LocalUriHandler.current)

}

@OptIn(ExperimentalFoundationApi::class)
@Composable
private fun FolderRow(
    folder: MediaFolder,
    size: Dp,
    blurred: Boolean,
    marked: Boolean,
    onClick: () -> Unit,
    onLongPress: () -> Unit
) {
    val haptic = LocalHapticFeedback.current
    val faded = PageText.copy(alpha = FADE)

    Row(
        Modifier
            .fillMaxWidth()
            .combinedClickable(
                onClick = onClick,
                onLongClick = {
                    haptic.performHapticFeedback(HapticFeedbackType.LongPress)
                    onLongPress()
                }
            )
            .padding(start = EDGE - SEAM, end = EDGE, top = ROW_PAD, bottom = ROW_PAD),
        verticalAlignment = Alignment.CenterVertically
    ) {
        FolderCover(
            covers = folder.covers,
            size = size,
            blurred = blurred,
            marked = marked
        )
        Spacer(Modifier.width(ROW_GAP))
        Column(Modifier.weight(1f)) {
            Row(verticalAlignment = Alignment.CenterVertically) {
                Text(
                    folder.name,
                    color = PageText,
                    fontSize = 16.sp,
                    lineHeight = 20.sp,
                    maxLines = 1,
                    overflow = TextOverflow.Ellipsis,
                    modifier = Modifier.weight(1f, fill = false)
                )
                Spacer(Modifier.width(COUNT_GAP))
                Text(
                    folder.count.toString(),
                    color = faded,
                    fontSize = 14.sp,
                    lineHeight = 20.sp,
                    maxLines = 1
                )
            }
            TailText(if (folder.path == VarnishConfig.FAV_PATH) "" else folder.path, PageText.copy(alpha = PATH_FADE), 12.sp, 18.sp)
        }
    }
}

@Composable
private fun FolderCover(
    covers: List<MediaFile>,
    size: Dp,
    blurred: Boolean,
    marked: Boolean,
    modifier: Modifier = Modifier
) {
    val step = size * PEEK
    Box(modifier.width(size + step * (SHADES.size - 1)).height(size)) {
        for (i in SHADES.indices.reversed()) {
            val f = covers.getOrNull(i)
            key(f?.path ?: i) {
                CoverTile(
                    file = f,
                    size = size,
                    blurred = blurred,
                    marked = marked,
                    shade = SHADES[i],
                    front = i == 0,
                    modifier = Modifier.offset(x = step * i)
                )
            }
        }
    }
}

@Composable
private fun CoverTile(
    file: MediaFile?,
    size: Dp,
    blurred: Boolean,
    marked: Boolean,
    shade: Float,
    front: Boolean,
    modifier: Modifier = Modifier
) {
    val context = LocalContext.current
    Box(
        modifier
            .size(size)
            .background(if (marked) SEAM_MARK else PageBg, TILE_SHAPE)
            .padding(SEAM)
            .clip(RoundedCornerShape(BTN_RADIUS))
            .background(FieldBg),
        contentAlignment = Alignment.Center
    ) {
        if (file == null) {
            if (front) {
                Icon(
                    Icons.Outlined.Folder,
                    contentDescription = null,
                    tint = PageText.copy(alpha = 0.4f),
                    modifier = Modifier.size(size / 2)
                )
            }
        } else {
            val request = remember(file.path, file.modified, blurred) {
                thumbRequest(context, file, blurred)
            }
            AsyncImage(
                model = request,
                contentDescription = null,
                contentScale = ContentScale.Crop,
                modifier = Modifier.fillMaxSize()
            )
        }
        if (shade > 0f) {
            Box(Modifier.matchParentSize().background(PageBg.copy(alpha = shade)))
        }
    }
}

@Composable
private fun TailText(
    text: String,
    color: Color,
    fontSize: TextUnit,
    lineHeight: TextUnit,
    modifier: Modifier = Modifier
) {
    val measurer = rememberTextMeasurer()
    val style = LocalTextStyle.current.merge(
        TextStyle(color = color, fontSize = fontSize, lineHeight = lineHeight)
    )
    val h = with(LocalDensity.current) { lineHeight.toDp() }
    Spacer(
        modifier
            .fillMaxWidth()
            .height(h)
            .drawWithCache {
                val shown = tail(measurer, text, style, size.width.toInt())
                val res = measurer.measure(shown, style, softWrap = false, maxLines = 1)
                onDrawBehind { drawText(res) }
            }
    )
}

private const val ELLIPSIS = "\u2026"
private const val TAIL_EXTRA = 5

private fun tail(m: TextMeasurer, text: String, style: TextStyle, max: Int): String {
    fun fits(s: String) = m.measure(s, style, softWrap = false, maxLines = 1).size.width <= max
    if (max == Constraints.Infinity || fits(text)) return text
    var lo = 0
    var hi = text.length
    while (lo < hi) {
        val mid = (lo + hi) / 2
        if (fits(ELLIPSIS + text.substring(mid))) hi = mid else lo = mid + 1
    }
    return ELLIPSIS + text.substring((lo + TAIL_EXTRA).coerceAtMost(text.length))
}