amethyst/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/ThreadFeedView.kt

package com.vitorpamplona.amethyst.ui.screen

import androidx.compose.animation.Crossfade
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.itemsIndexed
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material.Divider
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.livedata.observeAsState
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.drawBehind
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import androidx.compose.runtime.collectAsState
import androidx.navigation.NavController
import coil.compose.AsyncImage
import coil.compose.rememberAsyncImagePainter
import com.google.accompanist.swiperefresh.SwipeRefresh
import com.google.accompanist.swiperefresh.rememberSwipeRefreshState
import com.vitorpamplona.amethyst.model.Note
import com.vitorpamplona.amethyst.ui.components.RichTextViewer
import com.vitorpamplona.amethyst.ui.note.BlankNote
import com.vitorpamplona.amethyst.ui.note.NoteCompose
import com.vitorpamplona.amethyst.ui.note.ReactionsRow
import com.vitorpamplona.amethyst.ui.note.UsernameDisplay
import com.vitorpamplona.amethyst.ui.note.timeAgoLong
import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel

@Composable
fun ThreadFeedView(noteId: String, viewModel: FeedViewModel, accountViewModel: AccountViewModel, navController: NavController) {
    val feedState by viewModel.feedContent.collectAsState()

    var isRefreshing by remember { mutableStateOf(false) }
    val swipeRefreshState = rememberSwipeRefreshState(isRefreshing)

    val listState = rememberLazyListState()

    LaunchedEffect(isRefreshing) {
        if (isRefreshing) {
            viewModel.refresh()
            isRefreshing = false
        }
    }

    SwipeRefresh(
        state = swipeRefreshState,
        onRefresh = {
            isRefreshing = true
        },
    ) {
        Column() {
            Crossfade(targetState = feedState) { state ->
                when (state) {
                    is FeedState.Empty -> {
                        FeedEmpty {
                            isRefreshing = true
                        }
                    }
                    is FeedState.FeedError -> {
                        FeedError(state.errorMessage) {
                            isRefreshing = true
                        }
                    }
                    is FeedState.Loaded -> {
                        var noteIdPositionInThread by remember { mutableStateOf(0) }
                        // only in the first transition
                        LaunchedEffect(noteIdPositionInThread) {
                            listState.animateScrollToItem(noteIdPositionInThread, 0)
                        }

                        val notePosition = state.feed.filter { it.idHex == noteId}.firstOrNull()
                        if (notePosition != null) {
                            noteIdPositionInThread = state.feed.indexOf(notePosition)
                        }

                        LazyColumn(
                            contentPadding = PaddingValues(
                                top = 10.dp,
                                bottom = 10.dp
                            ),
                            state = listState
                        ) {
                            itemsIndexed(state.feed, key = { _, item -> item.idHex }) { index, item ->
                                if (index == 0)
                                    NoteMaster(item, accountViewModel = accountViewModel, navController = navController)
                                else {
                                    Column() {
                                        Row() {
                                            NoteCompose(
                                                item,
                                                Modifier.drawReplyLevel(item.replyLevel(), MaterialTheme.colors.onSurface.copy(alpha = 0.32f)),
                                                isInnerNote = false,
                                                accountViewModel = accountViewModel,
                                                navController = navController,
                                            )
                                        }
                                    }
                                }
                            }
                        }
                    }
                    FeedState.Loading -> {
                        LoadingFeed()
                    }
                }
            }
        }
    }
}

// Creates a Zebra pattern where each bar is a reply level.
fun Modifier.drawReplyLevel(level: Int, color: Color): Modifier = this
    .drawBehind {
        val paddingDp = 2
        val strokeWidthDp = 2
        val levelWidthDp = strokeWidthDp + 1

        val padding = paddingDp.dp.toPx()
        val strokeWidth = strokeWidthDp.dp.toPx()
        val levelWidth = levelWidthDp.dp.toPx()

        repeat(level) {
            this.drawLine(
                color,
                Offset(padding + it * levelWidth, 0f),
                Offset(padding + it * levelWidth, size.height),
                strokeWidth = strokeWidth
            )
        }

        return@drawBehind
    }
    .padding(start = (2 + (level * 3)).dp)

@Composable
fun NoteMaster(baseNote: Note, accountViewModel: AccountViewModel, navController: NavController) {
    val noteState by baseNote.live.observeAsState()
    val note = noteState?.note

    if (note?.event == null) {
        BlankNote()
    } else {
        val authorState by note.author!!.live.observeAsState()
        val author = authorState?.user

        Column(
            Modifier
                .fillMaxWidth()
                .padding(top = 10.dp)) {
            Row(modifier = Modifier
                .padding(start = 12.dp, end = 12.dp)
                .clickable(onClick = {
                    author?.let {
                        navController.navigate("User/${it.pubkeyHex}")
                    }
                })
            ) {
                // Draws the boosted picture outside the boosted card.
                AsyncImage(
                    model = author?.profilePicture(),
                    placeholder = rememberAsyncImagePainter("https://robohash.org/${author?.pubkeyHex}.png"),
                    contentDescription = "Profile Image",
                    modifier = Modifier
                        .width(55.dp).height(55.dp)
                        .clip(shape = CircleShape)
                )

                Column(modifier = Modifier.padding(start = 10.dp)) {
                    Row(verticalAlignment = Alignment.CenterVertically) {
                        if (author != null)
                            UsernameDisplay(author)
                    }

                    Row(verticalAlignment = Alignment.CenterVertically) {
                        Text(
                            timeAgoLong(note.event?.createdAt),
                            color = MaterialTheme.colors.onSurface.copy(alpha = 0.32f)
                        )
                    }
                }
            }

            Row(modifier = Modifier.padding(horizontal = 12.dp)) {
                Column() {
                    val eventContent = note.event?.content
                    if (eventContent != null)
                        RichTextViewer(eventContent, note.event?.tags, navController)

                    ReactionsRow(note, accountViewModel)

                    Divider(
                        modifier = Modifier.padding(top = 10.dp),
                        thickness = 0.25.dp
                    )
                }
            }
        }
    }
}