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

package org.jetbrains.codeviewer.ui.editor

import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.fillMaxHeight
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.offset
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.foundation.text.selection.DisableSelection
import androidx.compose.foundation.text.selection.SelectionContainer
import androidx.compose.material.CircularProgressIndicator
import androidx.compose.material.LocalContentColor
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Surface
import androidx.compose.material.Text
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.alpha
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.text.AnnotatedString
import androidx.compose.ui.text.SpanStyle
import androidx.compose.ui.text.buildAnnotatedString
import androidx.compose.ui.text.withStyle
import androidx.compose.ui.unit.dp
import org.jetbrains.codeviewer.platform.VerticalScrollbar
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.loadableScoped
import org.jetbrains.codeviewer.util.withoutWidthConstraints
import kotlin.text.Regex.Companion.fromLiteral

@Composable
fun EditorView(model: Editor, settings: Settings) = key(model) {
    with (LocalDensity.current) {
        SelectionContainer {
            Surface(
                Modifier.fillMaxSize(),
                color = MaterialTheme.colors.background,
            ) {
                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.codeGuide)
                        )
                    }
                } else {
                    CircularProgressIndicator(
                        modifier = Modifier
                            .size(36.dp)
                            .padding(4.dp)
                    )
                }
            }
        }
    }
}

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

    Box(Modifier.fillMaxSize()) {
        val scrollState = rememberLazyListState()

        LazyColumn(
            modifier = Modifier.fillMaxSize(),
            state = scrollState
        ) {
            items(lines.size) { index ->
                Box(Modifier.height(settings.fontSize.toDp() * 1.6f)) {
                    Line(Modifier.align(Alignment.CenterStart), maxNum, lines[index], settings)
                }
            }
        }

        VerticalScrollbar(
            Modifier.align(Alignment.CenterEnd),
            scrollState
        )
    }
}

// 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) {
        DisableSelection {
            Box {
                LineNumber(maxNum, Modifier.alpha(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 = LocalContentColor.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 {
        buildAnnotatedString {
            withStyle(AppTheme.code.simple) {
                append(content.value.value)
            }
        }
    },
    fontSize = settings.fontSize,
    fontFamily = Fonts.jetbrainsMono(),
    maxLines = 1,
    modifier = modifier,
    softWrap = false
)

@Composable
private fun codeString(str: String) = buildAnnotatedString {
    withStyle(AppTheme.code.simple) {
        val strFormatted = str.replace("\t", "    ")
        append(strFormatted)
        addStyle(AppTheme.code.punctuation, strFormatted, ":")
        addStyle(AppTheme.code.punctuation, strFormatted, "=")
        addStyle(AppTheme.code.punctuation, strFormatted, "\"")
        addStyle(AppTheme.code.punctuation, strFormatted, "[")
        addStyle(AppTheme.code.punctuation, strFormatted, "]")
        addStyle(AppTheme.code.punctuation, strFormatted, "{")
        addStyle(AppTheme.code.punctuation, strFormatted, "}")
        addStyle(AppTheme.code.punctuation, strFormatted, "(")
        addStyle(AppTheme.code.punctuation, strFormatted, ")")
        addStyle(AppTheme.code.punctuation, strFormatted, ",")
        addStyle(AppTheme.code.keyword, strFormatted, "fun ")
        addStyle(AppTheme.code.keyword, strFormatted, "val ")
        addStyle(AppTheme.code.keyword, strFormatted, "var ")
        addStyle(AppTheme.code.keyword, strFormatted, "private ")
        addStyle(AppTheme.code.keyword, strFormatted, "internal ")
        addStyle(AppTheme.code.keyword, strFormatted, "for ")
        addStyle(AppTheme.code.keyword, strFormatted, "expect ")
        addStyle(AppTheme.code.keyword, strFormatted, "actual ")
        addStyle(AppTheme.code.keyword, strFormatted, "import ")
        addStyle(AppTheme.code.keyword, strFormatted, "package ")
        addStyle(AppTheme.code.value, strFormatted, "true")
        addStyle(AppTheme.code.value, strFormatted, "false")
        addStyle(AppTheme.code.value, strFormatted, Regex("[0-9]+"))
        addStyle(AppTheme.code.annotation, strFormatted, Regex("^@[a-zA-Z_]*"))
        addStyle(AppTheme.code.comment, strFormatted, Regex("^\\s*//.*"))
        
        // Keeps copied lines separated and fixes crash during selection:
        // https://partnerissuetracker.corp.google.com/issues/199919707
        append("\n")
    }
}

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

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