package io.oxygenhub.android.ui.projects

import androidx.compose.foundation.ExperimentalFoundationApi

import androidx.compose.foundation.combinedClickable

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.ExperimentalLayoutApi

import androidx.compose.foundation.layout.FlowRow

import androidx.compose.foundation.layout.fillMaxSize

import androidx.compose.foundation.layout.fillMaxWidth

import androidx.compose.foundation.layout.padding

import androidx.compose.foundation.lazy.LazyColumn

import androidx.compose.foundation.lazy.items

import androidx.compose.foundation.pager.HorizontalPager

import androidx.compose.foundation.pager.rememberPagerState

import androidx.compose.material.icons.Icons

import androidx.compose.material.icons.outlined.ViewKanban

import androidx.compose.material3.DropdownMenu

import androidx.compose.material3.DropdownMenuItem

import androidx.compose.material3.ElevatedCard

import androidx.compose.material3.HorizontalDivider

import androidx.compose.material3.ListItem

import androidx.compose.material3.MaterialTheme

import androidx.compose.material3.PrimaryScrollableTabRow

import androidx.compose.material3.SuggestionChip

import androidx.compose.material3.Tab

import androidx.compose.material3.Text

import androidx.compose.runtime.Composable

import androidx.compose.runtime.getValue

import androidx.compose.runtime.mutableStateOf

import androidx.compose.runtime.remember

import androidx.compose.runtime.rememberCoroutineScope

import androidx.compose.runtime.setValue

import androidx.compose.ui.Modifier

import androidx.compose.ui.unit.dp

import androidx.lifecycle.compose.collectAsStateWithLifecycle

import io.oxygenhub.android.api.Project

import io.oxygenhub.android.api.ProjectCard

import io.oxygenhub.android.ui.common.AppScreen

import io.oxygenhub.android.ui.common.EmptyState

import io.oxygenhub.android.ui.common.LoadContent

import io.oxygenhub.android.ui.common.relativeTime

import io.oxygenhub.android.ui.theme.LocalStatusColors

import kotlinx.coroutines.launch

/** The boards the account can see, each opening its columns. */

@Composable

fun ProjectsScreen(vm: ProjectsViewModel, onOpen: (Project) -> Unit) {

    val state by vm.state.collectAsStateWithLifecycle()

    AppScreen(title = "Projects") {

        LoadContent(state, onRefresh = vm::refresh) { projects ->

            if (projects.isEmpty()) {

                EmptyState(Icons.Outlined.ViewKanban, "No boards yet", "Project boards you and your organisations keep show here.")

            } else {

                LazyColumn {

                    items(projects, key = { "${it.owner}/${it.number}" }) { p ->

                        ListItem(

                            modifier = Modifier.clickable { onOpen(p) },

                            headlineContent = { Text(p.title) },

                            supportingContent = {

                                Text(

                                    listOfNotNull(

                                        "${p.owner} · #${p.number}",

                                        "closed".takeIf { p.closed },

                                        "private".takeIf { !p.public },

                                        relativeTime(p.updatedMs).takeIf { it.isNotEmpty() },

                                    ).joinToString(" · "),

                                )

                            },

                        )

                        HorizontalDivider()

                    }

                }

            }

        }

    }

}

/**

 * A board: its columns as tabs to swipe between, each column's cards; a

 * card opens its issue or proposal, and a long press moves it.

 */

@Composable

fun BoardScreen(vm: BoardViewModel, canWrite: Boolean, onBack: () -> Unit, onOpenCard: (ProjectCard) -> Unit) {

    val state by vm.state.collectAsStateWithLifecycle()

    val error by vm.error.collectAsStateWithLifecycle()

    AppScreen(

        title = (state as? io.oxygenhub.android.ui.common.Load.Ready)?.value?.project?.title ?: "Board",

        subtitle = "${vm.owner} · #${vm.number}",

        onBack = onBack,

    ) {

        LoadContent(state, onRefresh = vm::refresh) { board ->

            val pages = rememberPagerState { board.columns.size }

            val scope = rememberCoroutineScope()

            Column(Modifier.fillMaxSize()) {

                if (board.columns.isNotEmpty()) {

                    PrimaryScrollableTabRow(selectedTabIndex = pages.currentPage.coerceAtMost(board.columns.size - 1)) {

                        board.columns.forEachIndexed { i, c ->

                            Tab(selected = pages.currentPage == i, onClick = { scope.launch { pages.animateScrollToPage(i) } }, text = { Text("${c.name} ${c.cards.size}") })

                        }

                    }

                }

                error?.let { Text(it, color = MaterialTheme.colorScheme.error, modifier = Modifier.padding(12.dp)) }

                HorizontalPager(pages, Modifier.fillMaxSize()) { page ->

                    val column = board.columns[page]

                    if (column.cards.isEmpty()) {

                        EmptyState(Icons.Outlined.ViewKanban, "Nothing in ${column.name}", "Cards moved here show up here.")

                    } else {

                        LazyColumn(Modifier.fillMaxSize(), verticalArrangement = Arrangement.spacedBy(8.dp)) {

                            items(column.cards, key = { it.id }) { card ->

                                CardView(card, columns = board.columns.map { it.name }.filter { it != column.name }, canWrite, onOpen = { onOpenCard(card) }, onMove = { vm.move(card.id, it) })

                            }

                        }

                    }

                }

            }

        }

    }

}

@OptIn(ExperimentalFoundationApi::class, ExperimentalLayoutApi::class)

@Composable

private fun CardView(card: ProjectCard, columns: List<String>, canWrite: Boolean, onOpen: () -> Unit, onMove: (String) -> Unit) {

    var menu by remember { mutableStateOf(false) }

    val status = LocalStatusColors.current

    Box {

        ElevatedCard(

            Modifier.fillMaxWidth().padding(horizontal = 12.dp).combinedClickable(

                onClick = { if (card.kind != "note") onOpen() },

                onLongClick = { if (canWrite && columns.isNotEmpty()) menu = true },

            ),

        ) {

            Column(Modifier.padding(12.dp), verticalArrangement = Arrangement.spacedBy(4.dp)) {

                if (card.reference.isNotEmpty()) {

                    Text(

                        "${card.reference} · ${card.state}",

                        style = MaterialTheme.typography.labelSmall,

                        color = when (card.state) {

                            "open" -> status.ok

                            "landed", "closed" -> status.warn

                            else -> MaterialTheme.colorScheme.onSurfaceVariant

                        },

                    )

                }

                Text(card.title, style = MaterialTheme.typography.bodyMedium)

                if (card.labels.isNotEmpty() || card.assignees.isNotEmpty()) {

                    FlowRow(horizontalArrangement = Arrangement.spacedBy(4.dp)) {

                        card.labels.forEach { SuggestionChip(onClick = {}, label = { Text(it, style = MaterialTheme.typography.labelSmall) }) }

                        card.assignees.forEach { Text("@$it", style = MaterialTheme.typography.labelSmall, modifier = Modifier.padding(4.dp)) }

                    }

                }

            }

        }

        DropdownMenu(expanded = menu, onDismissRequest = { menu = false }) {

            columns.forEach { c ->

                DropdownMenuItem(text = { Text("Move to $c") }, onClick = {

                    menu = false

                    onMove(c)

                })

            }

        }

    }

}