package xyz.pixelatedw.recipe

import android.content.Intent
import android.net.Uri
import android.os.Bundle
import android.util.Log
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.activity.result.contract.ActivityResultContracts
import androidx.activity.viewModels
import androidx.compose.foundation.Image
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.PaddingValues
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.verticalScroll
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.ParagraphStyle
import androidx.compose.ui.text.SpanStyle
import androidx.compose.ui.text.TextStyle
import androidx.compose.ui.text.buildAnnotatedString
import androidx.compose.ui.text.font.FontStyle
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.text.style.TextIndent
import androidx.compose.ui.text.withStyle
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.em
import androidx.compose.ui.unit.sp
import androidx.core.text.trimmedLength
import androidx.documentfile.provider.DocumentFile
import androidx.lifecycle.ViewModel
import io.github.wasabithumb.jtoml.JToml
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.update
import org.commonmark.node.BulletList
import org.commonmark.node.Document
import org.commonmark.node.Emphasis
import org.commonmark.node.HardLineBreak
import org.commonmark.node.Heading
import org.commonmark.node.ListItem
import org.commonmark.node.Node
import org.commonmark.node.OrderedList
import org.commonmark.node.Paragraph
import org.commonmark.node.SoftLineBreak
import org.commonmark.node.StrongEmphasis
import org.commonmark.node.ThematicBreak
import org.commonmark.parser.Parser
import xyz.pixelatedw.recipe.ui.theme.RecipeTheme
import java.io.BufferedReader
import java.io.InputStreamReader
import androidx.compose.material3.Typography
import androidx.navigation.compose.NavHost
import androidx.navigation.compose.composable
import androidx.navigation.compose.rememberNavController


class MainActivity : ComponentActivity() {
	private val recipeView: RecipesView by viewModels()

	override fun onCreate(savedInstanceState: Bundle?) {
		super.onCreate(savedInstanceState)

		findSourceDir()

        enableEdgeToEdge()
        setContent {
			RecipeTheme {
				Surface {
					Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
						RecipeList(innerPadding, recipeView)
					}
				}
			}
        }
    }

	private fun findSourceDir() {
		val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE).apply {
			addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
			addCategory(Intent.CATEGORY_DEFAULT)
		}

		val getContent = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
			if (result.resultCode == RESULT_OK) {
				result.data?.data?.let { uri ->
					getRecipes(uri)
				}
			}
		}

		getContent.launch(intent)
	}

	private fun getRecipes(uri: Uri?) {
		if (uri == null) {
			return
		}

		val dir = DocumentFile.fromTreeUri(this, uri)
		if (dir != null) {
			val fileList: Array<DocumentFile> = dir.listFiles()
			for (file in fileList) {
				if (file.isFile && file.name?.endsWith(".md") == true) {
					val recipe = parseRecipe(file)
					if (recipe != null) {
						this.recipeView.addRecipe(recipe)
					}
				}
			}
		}
	}

	private fun parseRecipe(file: DocumentFile): Recipe? {
		val lastModified = file.lastModified()

		val inputStream = this.contentResolver.openInputStream(file.uri)
		val reader = BufferedReader(InputStreamReader(inputStream))
		val text = reader.readText()
		val lines = text.lines()

		val sb = StringBuilder()
		var hasToml = false
		var frontMatterSize = 0
		// TODO This could use some improvements as it always assumes frontmatter is the very first thing in the file
		for (i in 0..lines.size) {
			val line = lines[i]
			frontMatterSize += line.trimmedLength() + 1

			if (line == "+++") {
				if (hasToml) {
					break
				}
				hasToml = true
				continue
			}

			sb.appendLine(line)
		}

		val toml = JToml.jToml()
		val doc = toml.readFromString(sb.toString())

		val tags = arrayListOf<String>()
		for (tomlElem in doc["tags"]!!.asArray()) {
			tags.add(tomlElem!!.asPrimitive().asString())
		}

		val content = text.substring(frontMatterSize..<text.length)

		val recipe = Recipe(
			title = doc["title"]!!.asPrimitive().asString(),
			tags = tags,
			lastModified = lastModified,
			content = content
		)

		return recipe
	}
}

class RecipesView : ViewModel() {
	private val _activeRecipe = MutableStateFlow<Recipe?>( null )
	val activeRecipe = _activeRecipe.asStateFlow()

	private val _recipes = MutableStateFlow<List<Recipe>>( arrayListOf() )
	val recipes = _recipes.asStateFlow()

	fun addRecipe(recipe: Recipe) {
		_recipes.update {
			it + recipe
		}
	}

	fun setActive(recipe: Recipe) {
		_activeRecipe.update { recipe }
	}
}

data class Recipe(
	val title: String,
	val tags: List<String>,
	val lastModified: Long,
	val content: String
)

@Composable
fun RecipeList(padding: PaddingValues, view: RecipesView) {
	val recipes = view.recipes.collectAsState()
	val active = view.activeRecipe.collectAsState()

	val navController = rememberNavController()

	NavHost(
		navController = navController,
		startDestination = "list"
	) {
		composable("list") {
			LazyColumn(modifier = Modifier.padding(padding)) {
				items(recipes.value) { recipe ->
					RecipePreview(recipe, onClick = {
						view.setActive(recipe)
						navController.navigate("info")
					})
				}
			}
		}
		composable("info") {
			Column(
				modifier = Modifier
					.verticalScroll(rememberScrollState())
					.padding(padding)
			) {
				Row(
					horizontalArrangement = Arrangement.Center,
					modifier = Modifier.fillMaxWidth()
				) {
					Text(
						text = active.value!!.title,
						style = MaterialTheme.typography.displayLarge,
						textAlign = TextAlign.Center
					)
				}

				val annotatedString =
					parseMarkdown(active.value!!.content, MaterialTheme.typography)
				Text(text = annotatedString)
			}
		}
	}
}

@Composable
fun RecipePreview(recipe: Recipe, onClick: () -> Unit) {
	Column(modifier = Modifier
		.padding(8.dp)
		.clickable(onClick = onClick)) {
		Row(horizontalArrangement = Arrangement.Center, modifier = Modifier.fillMaxWidth()) {
			Image(
				painter = painterResource(R.drawable.ic_launcher_background),
				contentDescription = "Recipe image",
				modifier = Modifier.size(256.dp)
			)
		}
		Row(horizontalArrangement = Arrangement.Center, modifier = Modifier.fillMaxWidth()) {
			Text(
				text = recipe.title,
				modifier = Modifier.fillMaxWidth(),
				style = TextStyle(
					textAlign = TextAlign.Center,
					fontSize = 7.em,
				)
			)
		}
		Row(horizontalArrangement = Arrangement.End, modifier = Modifier.fillMaxWidth()) {
			for (tag in recipe.tags) {
				Text(
					text = tag,
					modifier = Modifier.padding(start = 8.dp)
				)
			}
		}
	}
}

//@Preview(
//	showBackground = true,
//	name = "Light Mode"
//)
//@Preview(
//	uiMode = Configuration.UI_MODE_NIGHT_YES,
//	showBackground = true,
//	name = "Dark Mode"
//)
//@Composable
//fun RecipePreviewPreview() {
//	RecipeTheme {
//		Surface {
//			RecipePreview(Recipe("Test", listOf("test", "test2", "test3")), active)
//		}
//	}
//}

private fun parseMarkdown(
	markdown: String,
	typography: Typography,
): AnnotatedString {
	val parser = Parser.builder().build()
	val document = parser.parse(markdown)
	val annotatedString = buildAnnotatedString {
		visitMarkdownNode(document, typography)
	}
	return annotatedString.trim() as AnnotatedString
}

private fun AnnotatedString.Builder.visitMarkdownNode(
	node: Node,
	typography:  Typography,
) {
	val headingColor = androidx.compose.ui.graphics.Color.White
	when (node) {
		is Heading -> {
			val style = when (node.level) {
				in 1..3 -> typography.titleLarge
				4 -> typography.titleMedium
				5 -> typography.bodySmall
				else -> typography.bodySmall
			}
			withStyle(style.toParagraphStyle().merge(ParagraphStyle(textAlign = TextAlign.Center))) {
				withStyle(style.toSpanStyle().copy(color = headingColor)) {
					visitChildren(node, typography)
					appendLine()
				}
			}
		}
		is Paragraph -> {
			if (node.parents.any { it is BulletList || it is OrderedList }) {
				visitChildren(node, typography)
			} else {
				withStyle(typography.bodyLarge.toParagraphStyle()) {
					visitChildren(node, typography)
					appendLine()
				}
			}
		}
		is Emphasis -> {
			withStyle(SpanStyle(fontStyle = FontStyle.Italic)) {
				visitChildren(node, typography)
			}
		}
		is StrongEmphasis -> {
			withStyle(SpanStyle(fontWeight = FontWeight.Bold)) {
				visitChildren(node, typography)
			}
		}
		is org.commonmark.node.Text -> {
			append(node.literal)
			visitChildren(node, typography)
		}
		is SoftLineBreak -> {
			append(" ")
		}
		is HardLineBreak -> {
			appendLine()
		}
		is ThematicBreak -> {
			withStyle(ParagraphStyle(textAlign = TextAlign.Center)) {
				withStyle(SpanStyle(letterSpacing = 0.sp)) {
					appendLine("─".repeat(10))
				}
			}
		}
		is OrderedList -> {
			withStyle(ParagraphStyle(textIndent = TextIndent(firstLine = 10.sp, restLine = 20.sp))) {
				visitChildren(node, typography)
			}
		}
		is BulletList -> {
			withStyle(ParagraphStyle(textIndent = TextIndent(firstLine = 10.sp, restLine = 20.sp))) {
				visitChildren(node, typography)
			}
		}
		is ListItem -> {
			if (node.parents.any { it is BulletList }) {
				append("• ")
			} else if (node.parents.any { it is OrderedList }) {
				val startNumber = (node.parents.first { it is OrderedList } as OrderedList).markerStartNumber
				val index = startNumber + node.previousSiblings.filterIsInstance<ListItem>().size
				append("$index. ")
			}
			visitChildren(node, typography)
			appendLine()
		}
		is Document -> {
			visitChildren(node, typography)
		}
		else -> {
			Log.e("MarkdownText", "Traversing unhandled node: $node")
			visitChildren(node, typography)
		}
	}
}

private fun AnnotatedString.Builder.visitChildren(
	node: Node,
	typography: Typography,
) {
	var child = node.firstChild
	while (child != null) {
		visitMarkdownNode(child, typography)
		child = child.next
	}
}

private val Node.parents: List<Node> get() {
	val list = mutableListOf<Node>()
	var current = this
	while (true) {
		current = current.parent ?: return list
		list += current
	}
}

private val Node.previousSiblings: List<Node> get() {
	val list = mutableListOf<Node>()
	var current = this
	while (true) {
		current = current.previous ?: return list
		list += current
	}
}