ktlint-ruleset-standard/src/main/kotlin/com/github/shyiko/ktlint/ruleset/standard/ModifierOrderRule.kt

package com.github.shyiko.ktlint.ruleset.standard

import com.github.shyiko.ktlint.core.Rule
import org.jetbrains.kotlin.com.intellij.lang.ASTNode
import org.jetbrains.kotlin.com.intellij.psi.tree.TokenSet
import org.jetbrains.kotlin.lexer.KtTokens.ABSTRACT_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.ACTUAL_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.ANNOTATION_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.COMPANION_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.CONST_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.DATA_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.ENUM_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.EXPECT_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.EXTERNAL_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.FINAL_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.INFIX_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.INLINE_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.INNER_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.INTERNAL_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.LATEINIT_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.OPEN_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.OPERATOR_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.OVERRIDE_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.PRIVATE_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.PROTECTED_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.PUBLIC_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.SEALED_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.SUSPEND_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.TAILREC_KEYWORD
import org.jetbrains.kotlin.lexer.KtTokens.VARARG_KEYWORD
import org.jetbrains.kotlin.psi.KtAnnotationEntry
import org.jetbrains.kotlin.psi.KtDeclarationModifierList
import org.jetbrains.kotlin.psi.stubs.elements.KtStubElementTypes.ANNOTATION_ENTRY
import java.util.Arrays

class ModifierOrderRule : Rule("modifier-order") {

    // subset of KtTokens.MODIFIER_KEYWORDS_ARRAY (+ annotations entries)
    private val order = arrayOf(
        ANNOTATION_ENTRY,
        PUBLIC_KEYWORD, PROTECTED_KEYWORD, PRIVATE_KEYWORD, INTERNAL_KEYWORD,
        EXPECT_KEYWORD, ACTUAL_KEYWORD,
        FINAL_KEYWORD, OPEN_KEYWORD, ABSTRACT_KEYWORD, SEALED_KEYWORD, CONST_KEYWORD,
        EXTERNAL_KEYWORD,
        OVERRIDE_KEYWORD,
        LATEINIT_KEYWORD,
        TAILREC_KEYWORD,
        VARARG_KEYWORD,
        SUSPEND_KEYWORD,
        INNER_KEYWORD,
        ENUM_KEYWORD, ANNOTATION_KEYWORD,
        COMPANION_KEYWORD,
        INLINE_KEYWORD,
        INFIX_KEYWORD,
        OPERATOR_KEYWORD,
        DATA_KEYWORD
        // NOINLINE_KEYWORD, CROSSINLINE_KEYWORD, OUT_KEYWORD, IN_KEYWORD, REIFIED_KEYWORD
        // HEADER_KEYWORD, IMPL_KEYWORD
    )
    private val tokenSet = TokenSet.create(*order)

    override fun visit(
        node: ASTNode,
        autoCorrect: Boolean,
        emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> Unit
    ) {
        if (node.psi is KtDeclarationModifierList) {
            val modifierArr = node.getChildren(tokenSet)
            val sorted = modifierArr.copyOf().apply { sortWith(compareBy { order.indexOf(it.elementType) }) }
            if (!Arrays.equals(modifierArr, sorted)) {
                // Since annotations can be fairly lengthy and/or span multiple lines we are
                // squashing them into a single placeholder text to guarantee a single line output
                emit(node.startOffset, "Incorrect modifier order (should be \"${
                    squashAnnotations(sorted).joinToString(" ")
                }\")", true)
                if (autoCorrect) {
                    modifierArr.forEachIndexed { i, n ->
                        node.replaceChild(n, sorted[i].clone() as ASTNode)
                    }
                }
            }
        }
    }

    private fun squashAnnotations(sorted: Array<ASTNode>): List<String> {
        val nonAnnotationModifiers = sorted.filter { it.psi !is KtAnnotationEntry }
        return if (nonAnnotationModifiers.size != sorted.size) {
            listOf("@Annotation...") + nonAnnotationModifiers.map { it.text }
        } else {
            nonAnnotationModifiers.map { it.text }
        }
    }
}