package io.oxygenhub.android.ui.code

import androidx.compose.foundation.clickable

import androidx.compose.foundation.horizontalScroll

import androidx.compose.foundation.layout.Arrangement

import androidx.compose.foundation.layout.Box

import androidx.compose.foundation.layout.Row

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.rememberScrollState

import androidx.compose.material.icons.Icons

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

import androidx.compose.material.icons.outlined.AccountTree

import androidx.compose.material.icons.outlined.Folder

import androidx.compose.material.icons.outlined.History

import androidx.compose.material.icons.outlined.Link

import androidx.compose.material3.AssistChip

import androidx.compose.material3.DropdownMenu

import androidx.compose.material3.DropdownMenuItem

import androidx.compose.material3.HorizontalDivider

import androidx.compose.material3.Icon

import androidx.compose.material3.ListItem

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.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.unit.dp

import androidx.lifecycle.compose.collectAsStateWithLifecycle

import com.mikepenz.markdown.m3.Markdown

import io.oxygenhub.android.api.TreeEntry

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

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

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

import io.oxygenhub.android.ui.common.NoImages

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

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

/**

 * A repository's code (#3): where you are (the reference, then each folder

 * of the path, tappable), the folder's entries, and its README rendered.

 */

@Composable

fun CodeBrowser(

    vm: CodeViewModel,

    onOpenFile: (ref: String, path: String) -> Unit,

    onOpenHistory: (ref: String) -> Unit,

) {

    val state by vm.state.collectAsStateWithLifecycle()

    val ref by vm.ref.collectAsStateWithLifecycle()

    val path by vm.path.collectAsStateWithLifecycle()

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

        LazyColumn(Modifier.fillMaxWidth()) {

            item {

                Where(vm, ref, path, onOpenHistory)

                HorizontalDivider()

            }

            if (path.isNotEmpty()) {

                item {

                    ListItem(

                        modifier = Modifier.clickable { vm.up() },

                        leadingContent = { Icon(Icons.Outlined.Folder, contentDescription = null, tint = Tones.folder) },

                        headlineContent = { Text("..") },

                    )

                }

            }

            if (dir.entries.isEmpty()) {

                item { EmptyState(Icons.Outlined.Folder, "Nothing here", "This folder is empty at $ref.") }

            }

            items(dir.entries, key = { it.path }) { e ->

                Entry(e) { if (e.isDir) vm.open(e.path) else onOpenFile(ref, e.path) }

            }

            dir.readme?.let { readme ->

                item {

                    Panel(Modifier.fillMaxWidth().padding(12.dp)) {

                        Text(

                            readme.path.substringAfterLast('/'),

                            style = MaterialTheme.typography.titleSmall,

                            modifier = Modifier.padding(start = 16.dp, top = 12.dp, end = 16.dp),

                        )

                        Box(Modifier.padding(16.dp)) {

                            if (readme.path.lowercase().let { it.endsWith(".md") || it.endsWith(".markdown") }) {

                                Markdown(readme.text, imageTransformer = NoImages)

                            } else {

                                Text(readme.text, style = MaterialTheme.typography.bodyMedium)

                            }

                        }

                    }

                }

            }

        }

    }

}

/** The reference (a menu of bookmarks and tags) and the path, each folder a step back. */

@Composable

private fun Where(vm: CodeViewModel, ref: String, path: String, onOpenHistory: (String) -> Unit) {

    var picking by remember { mutableStateOf(false) }

    val refs by vm.refs.collectAsStateWithLifecycle()

    Row(

        Modifier.fillMaxWidth().horizontalScroll(rememberScrollState()).padding(horizontal = 12.dp, vertical = 6.dp),

        verticalAlignment = Alignment.CenterVertically,

        horizontalArrangement = Arrangement.spacedBy(4.dp),

    ) {

        Box {

            AssistChip(

                onClick = {

                    vm.loadRefs()

                    picking = true

                },

                label = { Text(ref) },

                leadingIcon = { Icon(Icons.Outlined.AccountTree, contentDescription = "Bookmark or tag") },

            )

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

                when (val r = refs) {

                    is Load.Ready -> {

                        r.value.first.forEach { b ->

                            DropdownMenuItem(text = { Text(b) }, onClick = {

                                picking = false

                                vm.setRef(b)

                            })

                        }

                        r.value.second.forEach { t ->

                            DropdownMenuItem(

                                text = { Text(t) },

                                leadingIcon = { Icon(Icons.Outlined.Link, contentDescription = "Tag") },

                                onClick = {

                                    picking = false

                                    vm.setRef(t)

                                },

                            )

                        }

                    }

                    is Load.Failed -> DropdownMenuItem(text = { Text(r.message) }, onClick = { picking = false })

                    Load.Loading -> DropdownMenuItem(text = { Text("Loading…") }, onClick = {})

                }

            }

        }

        TextButton(onClick = { vm.open("") }) { Text(vm.name) }

        val parts = path.split('/').filter { it.isNotEmpty() }

        parts.forEachIndexed { i, part ->

            Text("/", color = MaterialTheme.colorScheme.onSurfaceVariant)

            TextButton(onClick = { vm.open(parts.take(i + 1).joinToString("/")) }) { Text(part) }

        }

        TextButton(onClick = { onOpenHistory(ref) }) {

            Icon(Icons.Outlined.History, contentDescription = null, tint = Tones.info)

            Text(" History")

        }

    }

}

@Composable

private fun Entry(e: TreeEntry, onClick: () -> Unit) {

    ListItem(

        modifier = Modifier.clickable(onClick = onClick),

        leadingContent = {

            Icon(

                if (e.isDir) Icons.Outlined.Folder else Icons.AutoMirrored.Outlined.InsertDriveFile,

                contentDescription = if (e.isDir) "Folder" else "File",

                tint = if (e.isDir) Tones.folder else Tones.plain,

            )

        },

        headlineContent = { Text(e.name) },

        supportingContent = when {

            e.conflicted -> {

                { Text("conflicted", color = MaterialTheme.colorScheme.error) }

            }

            e.kind == "subrepo" -> {

                { Text("subrepo") }

            }

            else -> null

        },

        trailingContent = e.size?.takeIf { !e.isDir }?.let { { Text(bytes(it), style = MaterialTheme.typography.labelSmall) } },

    )

}

/** 1.2 KB, 3.4 MB. */

fun bytes(n: Long): String = when {

    n < 1024 -> "$n B"

    n < 1024 * 1024 -> "%.1f KB".format(n / 1024.0)

    else -> "%.1f MB".format(n / (1024.0 * 1024.0))

}