compose-jb/examples/codeviewer/common/src/commonMain/kotlin/org/jetbrains/codeviewer/ui/editor/EditorView.kt

package org.jetbrains.codeviewer.ui.editor

import androidx.compose.foundation.AmbientContentColor
import androidx.compose.foundation.Text
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.material.CircularProgressIndicator
import androidx.compose.material.Surface
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.key
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.drawOpacity
import androidx.compose.ui.platform.DensityAmbient
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.SpanStyle
import androidx.compose.ui.text.annotatedString
import androidx.compose.ui.text.withStyle
import androidx.compose.ui.unit.dp
import org.jetbrains.codeviewer.platform.SelectionContainer
import org.jetbrains.codeviewer.platform.VerticalScrollbar
import org.jetbrains.codeviewer.platform.WithoutSelection
import org.jetbrains.codeviewer.ui.common.AppTheme
import org.jetbrains.codeviewer.ui.common.Fonts
import org.jetbrains.codeviewer.ui.common.Settings
import org.jetbrains.codeviewer.util.LazyColumnFor
import org.jetbrains.codeviewer.util.loadable
import org.jetbrains.codeviewer.util.loadableScoped
import org.jetbrains.codeviewer.util.withoutWidthConstraints
import kotlin.text.Regex.Companion.fromLiteral

@Composable
fun EditorView(model: Editor, settings: Settings) = key(model) {
    with (DensityAmbient.current) {
        SelectionContainer {
            Surface(
                Modifier.fillMaxSize(),
                color = AppTheme.colors.backgroundDark,
            ) {
                val lines by loadableScoped(model.lines)

                if (lines != null) {
                    Box {
                        Lines(lines!!, settings)
                        Box(
                            Modifier
                                .offset(
                                    x = settings.fontSize.toDp() * 0.5f * settings.maxLineSymbols
                                )
                                .width(1.dp)
                                .fillMaxHeight()
                                .background(AppTheme.colors.backgroundLight)
                        )
                    }
                } else {
                    CircularProgressIndicator(
                        modifier = Modifier
                            .size(36.dp)
                            .padding(4.dp)
                    )
                }
            }
        }
    }
}

@Composable
private fun Lines(lines: Editor.Lines, settings: Settings) = with(DensityAmbient.current) {
    val maxNum = remember(lines.lineNumberDigitCount) {
        (1..lines.lineNumberDigitCount).joinToString(separator = "") { "9" }
    }

    Box(Modifier.fillMaxSize()) {
        val scrollState = rememberLazyListState()
        val lineHeight = settings.fontSize.toDp() * 1.6f

        LazyColumnFor(
            lines.size,
            modifier = Modifier.fillMaxSize(),
            state = scrollState,
            itemContent = { index ->
                val line: Editor.Line? by loadable { lines.get(index) }
                Box(Modifier.height(lineHeight)) {
                    if (line != null) {
                        Line(Modifier.align(Alignment.CenterStart), maxNum, line!!, settings)
                    }
                }
            }
        )

        VerticalScrollbar(
            Modifier.align(Alignment.CenterEnd),
            scrollState,
            lines.size,
            lineHeight
        )
    }
}

// Поддержка русского языка
// دعم اللغة العربية
// 中文支持
@Composable
private fun Line(modifier: Modifier, maxNum: String, line: Editor.Line, settings: Settings) {
    Row(modifier = modifier) {
        WithoutSelection {
            Box {
                LineNumber(maxNum, Modifier.drawOpacity(0f), settings)
                LineNumber(line.number.toString(), Modifier.align(Alignment.CenterEnd), settings)
            }
        }
        LineContent(
            line.content,
            modifier = Modifier
                .weight(1f)
                .withoutWidthConstraints()
                .padding(start = 28.dp, end = 12.dp),
            settings = settings
        )
    }
}

@Composable
private fun LineNumber(number: String, modifier: Modifier, settings: Settings) = Text(
    text = number,
    fontSize = settings.fontSize,
    fontFamily = Fonts.jetbrainsMono(),
    color = AmbientContentColor.current.copy(alpha = 0.30f),
    modifier = modifier.padding(start = 12.dp)
)

@Composable
private fun LineContent(content: Editor.Content, modifier: Modifier, settings: Settings) = Text(
    text = if (content.isCode) {
        codeString(content.value.value)
    } else {
        annotatedString {
            withStyle(AppTheme.code.simple) {
                append(content.value.value)
            }
        }
    },
    fontSize = settings.fontSize,
    fontFamily = Fonts.jetbrainsMono(),
    modifier = modifier,
    softWrap = false
)

private fun codeString(str: String) = annotatedString {
    withStyle(AppTheme.code.simple) {
        append(str.replace("\t", "    "))
        addStyle(AppTheme.code.punctuation, ":")
        addStyle(AppTheme.code.punctuation, "=")
        addStyle(AppTheme.code.punctuation, "\"")
        addStyle(AppTheme.code.punctuation, "[")
        addStyle(AppTheme.code.punctuation, "]")
        addStyle(AppTheme.code.punctuation, "{")
        addStyle(AppTheme.code.punctuation, "}")
        addStyle(AppTheme.code.punctuation, "(")
        addStyle(AppTheme.code.punctuation, ")")
        addStyle(AppTheme.code.punctuation, ",")
        addStyle(AppTheme.code.keyword, "fun ")
        addStyle(AppTheme.code.keyword, "val ")
        addStyle(AppTheme.code.keyword, "var ")
        addStyle(AppTheme.code.keyword, "private ")
        addStyle(AppTheme.code.keyword, "internal ")
        addStyle(AppTheme.code.keyword, "for ")
        addStyle(AppTheme.code.keyword, "expect ")
        addStyle(AppTheme.code.keyword, "actual ")
        addStyle(AppTheme.code.keyword, "import ")
        addStyle(AppTheme.code.keyword, "package ")
        addStyle(AppTheme.code.value, "true")
        addStyle(AppTheme.code.value, "false")
        addStyle(AppTheme.code.value, Regex("[0-9]*"))
        addStyle(AppTheme.code.annotation, Regex("^@[a-zA-Z_]*"))
        addStyle(AppTheme.code.comment, Regex("^\\s*//.*"))
    }
}

private fun AnnotatedString.Builder.addStyle(style: SpanStyle, regexp: String) {
    addStyle(style, fromLiteral(regexp))
}

private fun AnnotatedString.Builder.addStyle(style: SpanStyle, regexp: Regex) {
    for (result in regexp.findAll(toString())) {
        addStyle(style, result.range.first, result.range.last + 1)
    }
}