SwiftLint/Source/SwiftLintFramework/Rules/VariableNameRule.swift

//
//  VariableNameRule.swift
//  SwiftLint
//
//  Created by JP Simard on 2015-05-16.
//  Copyright (c) 2015 Realm. All rights reserved.
//

import SourceKittenFramework
import SwiftXPC

public struct VariableNameRule: ASTRule {
    public init() {}

    public let identifier = "variable_name"

    public func validateFile(file: File) -> [StyleViolation] {
        return validateFile(file, dictionary: file.structure.dictionary)
    }

    public func validateFile(file: File, dictionary: XPCDictionary) -> [StyleViolation] {
        let substructure = dictionary["key.substructure"] as? XPCArray ?? []
        return substructure.flatMap { subItem -> [StyleViolation] in
            var violations = [StyleViolation]()
            if let subDict = subItem as? XPCDictionary,
                let kindString = subDict["key.kind"] as? String,
                let kind = SwiftDeclarationKind(rawValue: kindString) {
                violations.appendContentsOf(
                    self.validateFile(file, dictionary: subDict) +
                    self.validateFile(file, kind: kind, dictionary: subDict)
                )
            }
            return violations
        }
    }

    public func validateFile(file: File,
        kind: SwiftDeclarationKind,
        dictionary: XPCDictionary) -> [StyleViolation] {
        let variableKinds: [SwiftDeclarationKind] = [
            .VarClass,
            .VarGlobal,
            .VarInstance,
            .VarLocal,
            .VarParameter,
            .VarStatic
        ]
        if !variableKinds.contains(kind) {
            return []
        }
        var violations = [StyleViolation]()
        if let name = dictionary["key.name"] as? String,
            let offset = (dictionary["key.offset"] as? Int64).flatMap({ Int($0) }) {
            let location = Location(file: file, offset: offset)
            let name = name.nameStrippingLeadingUnderscoreIfPrivate(dictionary)
            let nameCharacterSet = NSCharacterSet(charactersInString: name)
            if !NSCharacterSet.alphanumericCharacterSet().isSupersetOfSet(nameCharacterSet) {
                violations.append(StyleViolation(type: .NameFormat,
                    location: location,
                    severity: .Error,
                    reason: "Variable name should only contain alphanumeric characters: '\(name)'"))
            } else if name.substringToIndex(name.startIndex.successor()).isUppercase() {
                violations.append(StyleViolation(type: .NameFormat,
                    location: location,
                    severity: .Error,
                    reason: "Variable name should start with a lowercase character: '\(name)'"))
            } else if name.characters.count < 3 || name.characters.count > 40 {
                violations.append(StyleViolation(type: .NameFormat,
                    location: location,
                    severity: .Warning,
                    reason: "Variable name should be between 3 and 40 characters in length: " +
                    "'\(name)'"))
            }
        }
        return violations
    }

    public let example = RuleExample(
        ruleName: "Variable Name Rule",
        ruleDescription: "Variable name should only contain alphanumeric characters, " +
        "start with a a lowercase character and be between 3 and 40 characters in length.",
        nonTriggeringExamples: [
            "let myLet = 0",
            "var myVar = 0",
            "private let _myLet = 0"
        ],
        triggeringExamples: [
            "let MyLet = 0",
            "let _myLet = 0",
            "private let myLet_ = 0",
            "let my = 0"
        ],
        showExamples: false
    )
}