feat: add code highlighter

3 files changed, 357 insertions, 3 deletions

diff --git a/docs/src/wasmJsMain/kotlin/docs/component/CodeBlock.kt b/docs/src/wasmJsMain/kotlin/docs/component/CodeBlock.kt
index 982ce0c..26c4f21 100644
--- a/docs/src/wasmJsMain/kotlin/docs/component/CodeBlock.kt
+++ b/docs/src/wasmJsMain/kotlin/docs/component/CodeBlock.kt
@@ -24,17 +24,41 @@ import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.buildAnnotatedString
 import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.withStyle
 import androidx.compose.ui.unit.dp
+import docs.theme.CodeHighlightColors
 import docs.theme.DocsTheme
 
+enum class CodeLanguage {
+  KOTLIN,
+  GROOVY,
+  TOML,
+  PLAIN,
+}
+
 @Composable
 fun CodeBlock(
   code: String,
   modifier: Modifier = Modifier,
+  language: CodeLanguage = CodeLanguage.KOTLIN,
 ) {
+  val colors = DocsTheme.colors.codeHighlight
+  val highlightedCode = remember(code, language, colors) {
+    when (language) {
+      CodeLanguage.KOTLIN -> highlightKotlin(code, colors)
+      CodeLanguage.GROOVY -> highlightGroovy(code, colors)
+      CodeLanguage.TOML -> highlightToml(code, colors)
+      CodeLanguage.PLAIN -> AnnotatedString(code)
+    }
+  }
+
   Box(
     modifier = modifier
       .fillMaxWidth()
@@ -44,10 +68,306 @@ fun CodeBlock(
       .padding(16.dp),
   ) {
     Text(
-      text = code,
+      text = highlightedCode,
       style = DocsTheme.typography.code,
-      color = DocsTheme.colors.onSurface,
       fontFamily = FontFamily.Monospace,
     )
   }
 }
+
+private fun highlightKotlin(code: String, colors: CodeHighlightColors): AnnotatedString {
+  return buildAnnotatedString {
+    val keywords = setOf(
+      "fun", "val", "var", "class", "object", "interface", "enum", "sealed",
+      "if", "else", "when", "for", "while", "do", "return", "break", "continue",
+      "import", "package", "private", "public", "internal", "protected", "open",
+      "override", "abstract", "final", "companion", "data", "inline", "suspend",
+      "by", "in", "out", "is", "as", "try", "catch", "finally", "throw", "true",
+      "false", "null", "this", "super", "it", "get", "set", "const", "lateinit",
+      "expect", "actual",
+    )
+
+    var i = 0
+    while (i < code.length) {
+      when {
+        // Multi-line comment
+        code.startsWith("/*", i) -> {
+          val end = code.indexOf("*/", i + 2).let { if (it == -1) code.length else it + 2 }
+          withStyle(SpanStyle(color = colors.comment)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Single-line comment
+        code.startsWith("//", i) -> {
+          val end = code.indexOf('\n', i).let { if (it == -1) code.length else it }
+          withStyle(SpanStyle(color = colors.comment)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Triple-quoted string
+        code.startsWith("\"\"\"", i) -> {
+          val end = code.indexOf("\"\"\"", i + 3).let { if (it == -1) code.length else it + 3 }
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // String
+        code[i] == '"' -> {
+          val end = findStringEnd(code, i + 1, '"')
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Char
+        code[i] == '\'' -> {
+          val end = findStringEnd(code, i + 1, '\'')
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Annotation
+        code[i] == '@' -> {
+          val end = findIdentifierEnd(code, i + 1)
+          withStyle(SpanStyle(color = colors.annotation)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Number
+        code[i].isDigit() || (code[i] == '.' && i + 1 < code.length && code[i + 1].isDigit()) -> {
+          val end = findNumberEnd(code, i)
+          withStyle(SpanStyle(color = colors.number)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Identifier or keyword
+        code[i].isLetter() || code[i] == '_' -> {
+          val end = findIdentifierEnd(code, i)
+          val word = code.substring(i, end)
+          when {
+            word in keywords -> withStyle(SpanStyle(color = colors.keyword)) { append(word) }
+            word.first().isUpperCase() -> withStyle(SpanStyle(color = colors.type)) { append(word) }
+            else -> withStyle(SpanStyle(color = colors.plain)) { append(word) }
+          }
+          i = end
+        }
+        // Other characters
+        else -> {
+          withStyle(SpanStyle(color = colors.plain)) {
+            append(code[i])
+          }
+          i++
+        }
+      }
+    }
+  }
+}
+
+private fun highlightGroovy(code: String, colors: CodeHighlightColors): AnnotatedString {
+  return buildAnnotatedString {
+    val keywords = setOf(
+      "def", "class", "interface", "enum", "if", "else", "for", "while", "do",
+      "switch", "case", "default", "break", "continue", "return", "try", "catch",
+      "finally", "throw", "import", "package", "new", "true", "false", "null",
+      "this", "super", "static", "final", "public", "private", "protected",
+      "implementation", "api", "dependencies", "plugins", "id", "version",
+    )
+
+    var i = 0
+    while (i < code.length) {
+      when {
+        // Multi-line comment
+        code.startsWith("/*", i) -> {
+          val end = code.indexOf("*/", i + 2).let { if (it == -1) code.length else it + 2 }
+          withStyle(SpanStyle(color = colors.comment)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Single-line comment
+        code.startsWith("//", i) -> {
+          val end = code.indexOf('\n', i).let { if (it == -1) code.length else it }
+          withStyle(SpanStyle(color = colors.comment)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // String (double quote)
+        code[i] == '"' -> {
+          val end = findStringEnd(code, i + 1, '"')
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // String (single quote)
+        code[i] == '\'' -> {
+          val end = findStringEnd(code, i + 1, '\'')
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Number
+        code[i].isDigit() -> {
+          val end = findNumberEnd(code, i)
+          withStyle(SpanStyle(color = colors.number)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Identifier or keyword
+        code[i].isLetter() || code[i] == '_' -> {
+          val end = findIdentifierEnd(code, i)
+          val word = code.substring(i, end)
+          when {
+            word in keywords -> withStyle(SpanStyle(color = colors.keyword)) { append(word) }
+            word.first().isUpperCase() -> withStyle(SpanStyle(color = colors.type)) { append(word) }
+            else -> withStyle(SpanStyle(color = colors.plain)) { append(word) }
+          }
+          i = end
+        }
+        // Other characters
+        else -> {
+          withStyle(SpanStyle(color = colors.plain)) {
+            append(code[i])
+          }
+          i++
+        }
+      }
+    }
+  }
+}
+
+private fun highlightToml(code: String, colors: CodeHighlightColors): AnnotatedString {
+  return buildAnnotatedString {
+    var i = 0
+    while (i < code.length) {
+      when {
+        // Comment
+        code[i] == '#' -> {
+          val end = code.indexOf('\n', i).let { if (it == -1) code.length else it }
+          withStyle(SpanStyle(color = colors.comment)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Section header [section]
+        code[i] == '[' -> {
+          val end = code.indexOf(']', i).let { if (it == -1) code.length else it + 1 }
+          withStyle(SpanStyle(color = colors.keyword)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // String
+        code[i] == '"' -> {
+          val end = findStringEnd(code, i + 1, '"')
+          withStyle(SpanStyle(color = colors.string)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Number
+        code[i].isDigit() -> {
+          val end = findNumberEnd(code, i)
+          withStyle(SpanStyle(color = colors.number)) {
+            append(code.substring(i, end))
+          }
+          i = end
+        }
+        // Key (identifier before =)
+        code[i].isLetter() || code[i] == '_' || code[i] == '-' -> {
+          val end = findTomlKeyEnd(code, i)
+          val word = code.substring(i, end)
+          val isKey = code.substring(end).trimStart().startsWith("=")
+          if (isKey) {
+            withStyle(SpanStyle(color = colors.property)) { append(word) }
+          } else {
+            withStyle(SpanStyle(color = colors.plain)) { append(word) }
+          }
+          i = end
+        }
+        // Other characters
+        else -> {
+          withStyle(SpanStyle(color = colors.plain)) {
+            append(code[i])
+          }
+          i++
+        }
+      }
+    }
+  }
+}
+
+private fun findStringEnd(code: String, start: Int, quote: Char): Int {
+  var i = start
+  while (i < code.length) {
+    when {
+      code[i] == '\\' && i + 1 < code.length -> i += 2
+      code[i] == quote -> return i + 1
+      code[i] == '\n' -> return i
+      else -> i++
+    }
+  }
+  return code.length
+}
+
+private fun findIdentifierEnd(code: String, start: Int): Int {
+  var i = start
+  while (i < code.length && (code[i].isLetterOrDigit() || code[i] == '_')) {
+    i++
+  }
+  return i
+}
+
+private fun findTomlKeyEnd(code: String, start: Int): Int {
+  var i = start
+  while (i < code.length && (code[i].isLetterOrDigit() || code[i] == '_' || code[i] == '-')) {
+    i++
+  }
+  return i
+}
+
+private fun Char.isHexDigit(): Boolean =
+  this.isDigit() || this in 'a'..'f' || this in 'A'..'F'
+
+private fun findNumberEnd(code: String, start: Int): Int {
+  var i = start
+  var hasDecimal = false
+  var hasExponent = false
+
+  while (i < code.length) {
+    when {
+      code[i].isDigit() -> i++
+      code[i] == '.' && !hasDecimal && !hasExponent -> {
+        hasDecimal = true
+        i++
+      }
+      (code[i] == 'e' || code[i] == 'E') && !hasExponent -> {
+        hasExponent = true
+        i++
+        if (i < code.length && (code[i] == '+' || code[i] == '-')) i++
+      }
+      code[i] == 'f' || code[i] == 'F' || code[i] == 'L' || code[i] == 'd' || code[i] == 'D' -> {
+        i++
+        break
+      }
+      code[i] == 'x' || code[i] == 'X' -> {
+        i++
+        while (i < code.length && code[i].isHexDigit()) {
+          i++
+        }
+        break
+      }
+      else -> break
+    }
+  }
+  return i
+}
diff --git a/docs/src/wasmJsMain/kotlin/docs/screen/InstallationScreen.kt b/docs/src/wasmJsMain/kotlin/docs/screen/InstallationScreen.kt
index bd4c0f0..4c058cc 100644
--- a/docs/src/wasmJsMain/kotlin/docs/screen/InstallationScreen.kt
+++ b/docs/src/wasmJsMain/kotlin/docs/screen/InstallationScreen.kt
@@ -27,6 +27,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
 import docs.component.CodeBlock
+import docs.component.CodeLanguage
 import docs.config.BuildConfig
 import docs.theme.DocsTheme
 
@@ -80,7 +81,7 @@ fun InstallationScreen() {
       append("version.ref = \"colorpicker\" }")
     }
 
-    CodeBlock(code = versionCatalogCode)
+    CodeBlock(code = versionCatalogCode, language = CodeLanguage.TOML)
 
     Spacer(modifier = Modifier.height(32.dp))
 
diff --git a/docs/src/wasmJsMain/kotlin/docs/theme/DocsTheme.kt b/docs/src/wasmJsMain/kotlin/docs/theme/DocsTheme.kt
index 5ce6ea0..3fff946 100644
--- a/docs/src/wasmJsMain/kotlin/docs/theme/DocsTheme.kt
+++ b/docs/src/wasmJsMain/kotlin/docs/theme/DocsTheme.kt
@@ -25,6 +25,18 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.sp
 
 @Immutable
+data class CodeHighlightColors(
+  val keyword: Color,
+  val string: Color,
+  val number: Color,
+  val comment: Color,
+  val annotation: Color,
+  val type: Color,
+  val property: Color,
+  val plain: Color,
+)
+
+@Immutable
 data class DocsColors(
   val primary: Color,
   val onPrimary: Color,
@@ -38,6 +50,7 @@ data class DocsColors(
   val sidebarActive: Color,
   val divider: Color,
   val codeBackground: Color,
+  val codeHighlight: CodeHighlightColors,
   val success: Color,
   val warning: Color,
   val error: Color,
@@ -67,6 +80,16 @@ private fun darkColors(primary: Color) = DocsColors(
   sidebarActive = primary.copy(alpha = 0.15f),
   divider = Color(0xFF333333),
   codeBackground = Color(0xFF1A1A2E),
+  codeHighlight = CodeHighlightColors(
+    keyword = Color(0xFFCC7832),
+    string = Color(0xFF6A8759),
+    number = Color(0xFF6897BB),
+    comment = Color(0xFF808080),
+    annotation = Color(0xFFBBB529),
+    type = Color(0xFFA9B7C6),
+    property = Color(0xFF9876AA),
+    plain = Color(0xFFA9B7C6),
+  ),
   success = Color(0xFF4CAF50),
   warning = Color(0xFFFFC107),
   error = Color(0xFFEF5350),
@@ -85,6 +108,16 @@ private fun lightColors(primary: Color) = DocsColors(
   sidebarActive = primary.copy(alpha = 0.15f),
   divider = Color(0xFFE0E0E0),
   codeBackground = Color(0xFFF5F5F5),
+  codeHighlight = CodeHighlightColors(
+    keyword = Color(0xFF0000FF),
+    string = Color(0xFF067D17),
+    number = Color(0xFF1750EB),
+    comment = Color(0xFF8C8C8C),
+    annotation = Color(0xFFBBB529),
+    type = Color(0xFF000000),
+    property = Color(0xFF871094),
+    plain = Color(0xFF000000),
+  ),
   success = Color(0xFF4CAF50),
   warning = Color(0xFFFF9800),
   error = Color(0xFFF44336),