package io.oxygenhub.android.ui.dashboard

import androidx.compose.foundation.clickable

import androidx.compose.foundation.layout.Arrangement

import androidx.compose.foundation.layout.BoxWithConstraints

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.rememberScrollState

import androidx.compose.foundation.verticalScroll

import androidx.compose.material.icons.Icons

import androidx.compose.material.icons.automirrored.outlined.CallMerge

import androidx.compose.material.icons.outlined.EditNote

import androidx.compose.material.icons.outlined.Inbox

import androidx.compose.material.icons.outlined.MarkEmailUnread

import androidx.compose.material.icons.outlined.RadioButtonUnchecked

import androidx.compose.material.icons.outlined.Search

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

import androidx.compose.material3.HorizontalDivider

import androidx.compose.material3.Icon

import androidx.compose.material3.IconButton

import androidx.compose.material3.ListItem

import androidx.compose.material3.ListItemDefaults

import androidx.compose.material3.MaterialTheme

import androidx.compose.material3.Text

import androidx.compose.material3.TextButton

import androidx.compose.runtime.Composable

import androidx.compose.runtime.getValue

import androidx.compose.ui.Alignment

import androidx.compose.ui.Modifier

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.text.font.FontWeight

import androidx.compose.ui.text.style.TextOverflow

import androidx.compose.ui.unit.dp

import androidx.lifecycle.compose.collectAsStateWithLifecycle

import io.oxygenhub.android.api.Inbox

import io.oxygenhub.android.api.IssueBrief

import io.oxygenhub.android.api.ProposalBrief

import io.oxygenhub.android.api.Repository

import io.oxygenhub.android.ui.backdrop.Backdrop

import io.oxygenhub.android.ui.backdrop.skyScene

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

import io.oxygenhub.android.ui.common.AvatarImage

import io.oxygenhub.android.ui.common.Load

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

import io.oxygenhub.android.ui.common.Panel

import io.oxygenhub.android.ui.common.panelColors

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

import io.oxygenhub.android.ui.repos.RepositoryRow

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

import io.oxygenhub.android.ui.theme.Tones

@Composable

fun DashboardScreen(

    vm: DashboardViewModel,

    hub: String,

    inbox: Load<Inbox>,

    onRefreshInbox: () -> Unit,

    onOpenRepository: (Repository) -> Unit,

    onAllRepositories: () -> Unit,

    onInbox: () -> Unit,

    onOpenProposal: (ProposalBrief) -> Unit = {},

    onOpenIssue: (IssueBrief) -> Unit = {},

    onSearch: (() -> Unit)? = null,

    /** Projects, when the bar has no room for it (a phone, #14). */

    onProjects: (() -> Unit)? = null,

) {

    val state by vm.state.collectAsStateWithLifecycle()

    AppScreen(

        title = "Dashboard",

        subtitle = hub.substringAfter("://"),

        actions = {

            if (onProjects != null) {

                IconButton(onClick = onProjects) { Icon(Icons.Outlined.ViewKanban, contentDescription = "Projects") }

            }

            if (onSearch != null) {

                IconButton(onClick = onSearch) { Icon(Icons.Outlined.Search, contentDescription = "Search issues and proposals") }

            }

        },

    ) {

        LoadContent(state, onRefresh = { vm.refresh(); onRefreshInbox() }) { d ->

            // Your sky behind it, as on the hub's dashboard (#23): a finger draws it near and names a repository.

            Backdrop(key = d.sky, make = { still -> skyScene(d.sky, still) }, modifier = Modifier.fillMaxSize()) {

                DashboardContent(d, inbox, onOpenRepository, onAllRepositories, onInbox, onOpenProposal, onOpenIssue)

            }

        }

    }

}

@Composable

fun DashboardContent(

    d: Dashboard,

    inbox: Load<Inbox>,

    onOpenRepository: (Repository) -> Unit,

    onAllRepositories: () -> Unit,

    onInbox: () -> Unit,

    onOpenProposal: (ProposalBrief) -> Unit = {},

    onOpenIssue: (IssueBrief) -> Unit = {},

) {

    BoxWithConstraints {

        // Side by side once there is room (a tablet, or a foldable open).

        val wide = maxWidth >= 720.dp

        Column(

            Modifier

                .fillMaxWidth()

                .verticalScroll(rememberScrollState())

                .padding(16.dp),

        ) {

            Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(12.dp)) {

                AvatarImage(d.avatar, d.username, size = 48.dp)

                Text(d.greeting, style = MaterialTheme.typography.headlineMedium, fontWeight = FontWeight.Bold)

            }

            Spacer(Modifier.height(16.dp))

            if (wide) {

                Row(horizontalArrangement = Arrangement.spacedBy(16.dp)) {

                    Column(Modifier.weight(2f), verticalArrangement = Arrangement.spacedBy(16.dp)) {

                        Proposals(d, onOpenProposal)

                        Assigned(d, onOpenIssue)

                        Recent(d, onOpenRepository, onAllRepositories)

                    }

                    Column(Modifier.weight(1f)) { Unread(inbox, onInbox) }

                }

            } else {

                Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {

                    Unread(inbox, onInbox)

                    Proposals(d, onOpenProposal)

                    Assigned(d, onOpenIssue)

                    Recent(d, onOpenRepository, onAllRepositories)

                }

            }

        }

    }

}

/** Proposals waiting for the account's review, then its own: each opens where it can be landed. */

@Composable

private fun Proposals(d: Dashboard, onOpen: (ProposalBrief) -> Unit) {

    val p = d.proposals ?: return

    Column(verticalArrangement = Arrangement.spacedBy(16.dp)) {

        if (p.review.isNotEmpty()) ProposalCard("Waiting for your review", p.review, onOpen)

        if (p.authored.isNotEmpty()) ProposalCard("Your proposals", p.authored, onOpen)

    }

}

/** Open issues assigned to the account (#31), as the hub's dashboard lists them; each opens. */

@Composable

private fun Assigned(d: Dashboard, onOpen: (IssueBrief) -> Unit) {

    val list = d.assigned?.takeIf { it.isNotEmpty() } ?: return

    Panel(Modifier.fillMaxWidth(), colors = panelColors(alpha = 0.9f)) {

        Text(

            "Assigned to you · ${list.size}",

            style = MaterialTheme.typography.titleMedium,

            modifier = Modifier.padding(start = 16.dp, top = 16.dp, end = 16.dp, bottom = 4.dp),

        )

        list.forEachIndexed { i, b ->

            if (i > 0) HorizontalDivider()

            ListItem(

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

                colors = ListItemDefaults.colors(containerColor = Color.Transparent),

                leadingContent = { Icon(Icons.Outlined.RadioButtonUnchecked, contentDescription = "Open", tint = LocalStatusColors.current.ok) },

                headlineContent = { Text(b.title, maxLines = 2, overflow = TextOverflow.Ellipsis) },

                supportingContent = { Text("${b.repository} #${b.number} · ${relativeTime(b.updatedMs)}", maxLines = 1, overflow = TextOverflow.Ellipsis) },

            )

        }

    }

}

@Composable

private fun ProposalCard(title: String, list: List<ProposalBrief>, onOpen: (ProposalBrief) -> Unit) {

    Panel(Modifier.fillMaxWidth(), colors = panelColors(alpha = 0.9f)) {

        Text(

            "$title · ${list.size}",

            style = MaterialTheme.typography.titleMedium,

            modifier = Modifier.padding(start = 16.dp, top = 16.dp, end = 16.dp, bottom = 4.dp),

        )

        list.forEachIndexed { i, b ->

            if (i > 0) HorizontalDivider()

            ListItem(

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

                colors = ListItemDefaults.colors(containerColor = Color.Transparent),

                leadingContent = {

                    Icon(

                        if (b.state == "draft") Icons.Outlined.EditNote else Icons.AutoMirrored.Outlined.CallMerge,

                        contentDescription = b.state,

                        tint = if (b.state == "draft") MaterialTheme.colorScheme.onSurfaceVariant else LocalStatusColors.current.ok,

                    )

                },

                headlineContent = { Text(b.title, maxLines = 2, overflow = TextOverflow.Ellipsis) },

                supportingContent = {

                    val by = if (title.startsWith("Waiting")) " by ${b.author}" else ""

                    val conflicts = if (b.conflicted) " · conflicts" else ""

                    Text("${b.repository} #${b.number}$by · ${relativeTime(b.updatedMs)}$conflicts", maxLines = 1, overflow = TextOverflow.Ellipsis)

                },

            )

        }

    }

}

@Composable

private fun Unread(inbox: Load<Inbox>, onInbox: () -> Unit) {

    Panel(Modifier.fillMaxWidth().clickable(onClick = onInbox), colors = panelColors(alpha = 0.9f)) {

        ListItem(

            colors = ListItemDefaults.colors(containerColor = Color.Transparent),

            leadingContent = {

                Icon(if ((inbox.valueOrNull?.unread ?: 0) > 0) Icons.Outlined.MarkEmailUnread else Icons.Outlined.Inbox, contentDescription = null, tint = Tones.info)

            },

            headlineContent = {

                Text(

                    when (inbox) {

                        Load.Loading -> "Inbox"

                        is Load.Failed -> "Inbox unavailable"

                        is Load.Ready -> when (val n = inbox.value.unread) {

                            0L -> "Nothing unread"

                            1L -> "1 unread notification"

                            else -> "$n unread notifications"

                        }

                    },

                )

            },

            supportingContent = (inbox as? Load.Failed)?.let { f -> { Text(f.message) } },

        )

    }

}

@Composable

private fun Recent(d: Dashboard, onOpenRepository: (Repository) -> Unit, onAllRepositories: () -> Unit) {

    Panel(Modifier.fillMaxWidth(), colors = panelColors(alpha = 0.9f)) {

        Text(

            if (d.recentAreYours) "Your recent repositories" else "Recently updated on the hub",

            style = MaterialTheme.typography.titleMedium,

            modifier = Modifier.padding(start = 16.dp, top = 16.dp, end = 16.dp),

        )

        if (!d.recentAreYours) {

            Text(

                "You have no repositories of your own yet.",

                style = MaterialTheme.typography.bodySmall,

                color = MaterialTheme.colorScheme.onSurfaceVariant,

                modifier = Modifier.padding(horizontal = 16.dp),

            )

        }

        if (d.recent.isEmpty()) {

            Text("No repositories to show.", modifier = Modifier.padding(16.dp))

        }

        d.recent.forEachIndexed { i, repo ->

            if (i > 0) HorizontalDivider()

            RepositoryRow(repo, onClick = { onOpenRepository(repo) })

        }

        TextButton(onClick = onAllRepositories, modifier = Modifier.padding(8.dp)) { Text("All repositories") }

    }

}