//
//  Configuration.swift
//  SwiftLint
//
//  Created by JP Simard on 8/23/15.
//  Copyright © 2015 Realm. All rights reserved.
//

import Foundation
import SourceKittenFramework

private let fileManager = FileManager.default

private enum ConfigurationKey: String {
    case disabledRules = "disabled_rules"
    case enabledRules = "enabled_rules" // deprecated in favor of OptInRules
    case excluded = "excluded"
    case included = "included"
    case optInRules = "opt_in_rules"
    case reporter = "reporter"
    case useNestedConfigs = "use_nested_configs" // deprecated
    case whitelistRules = "whitelist_rules"
    case warningThreshold = "warning_threshold"
}

public struct Configuration: Equatable {
    public static let fileName = ".swiftlint.yml"
    public let included: [String]             // included
    public let excluded: [String]             // excluded
    public let reporter: String               // reporter (xcode, json, csv, checkstyle)
    public var warningThreshold: Int?         // warning threshold
    public let rules: [Rule]
    public var rootPath: String?              // the root path to search for nested configurations
    public var configurationPath: String?     // if successfully loaded from a path

    public init?(disabledRules: [String] = [],
                 optInRules: [String] = [],
                 whitelistRules: [String] = [],
                 included: [String] = [],
                 excluded: [String] = [],
                 warningThreshold: Int? = nil,
                 reporter: String = XcodeReporter.identifier,
                 configuredRules: [Rule] = masterRuleList.configuredRules(with: [:])) {
        self.included = included
        self.excluded = excluded
        self.reporter = reporter

        // Validate that all rule identifiers map to a defined rule
        let validRuleIdentifiers = configuredRules.map {
            type(of: $0).description.identifier
        }

        let validDisabledRules = disabledRules.filter({ validRuleIdentifiers.contains($0) })
        let invalidRules = disabledRules.filter({ !validRuleIdentifiers.contains($0) })
        if !invalidRules.isEmpty {
            for invalidRule in invalidRules {
                queuedPrintError(
                    "configuration error: '\(invalidRule)' is not a valid rule identifier"
                )
            }
            let listOfValidRuleIdentifiers = validRuleIdentifiers.joined(separator: "\n")
            queuedPrintError("Valid rule identifiers:\n\(listOfValidRuleIdentifiers)")
        }

        // Validate that rule identifiers aren't listed multiple times
        if Set(validDisabledRules).count != validDisabledRules.count {
            let duplicateRules = validDisabledRules.reduce([String: Int]()) { accu, element in
                var accu = accu
                accu[element] = (accu[element] ?? 0) + 1
                return accu
            }.filter { $0.1 > 1 }
            queuedPrintError(duplicateRules.map { rule in
                "configuration error: '\(rule.0)' is listed \(rule.1) times"
            }.joined(separator: "\n"))
            return nil
        }

        // set the config threshold to the threshold provided in the config file
        self.warningThreshold = warningThreshold

        // white_list rules take precendence over all else.
        if !whitelistRules.isEmpty {
            if !disabledRules.isEmpty || !optInRules.isEmpty {
                queuedPrintError("'\(ConfigurationKey.disabledRules.rawValue)' or " +
                    "'\(ConfigurationKey.optInRules.rawValue)' cannot be used in combination " +
                    "with '\(ConfigurationKey.whitelistRules.rawValue)'")
                return nil
            }

            rules = configuredRules.filter { rule in
                return whitelistRules.contains(type(of: rule).description.identifier)
            }
        } else {
            rules = configuredRules.filter { rule in
                let id = type(of: rule).description.identifier
                if validDisabledRules.contains(id) { return false }
                return optInRules.contains(id) || !(rule is OptInRule)
            }
        }
    }

    public init?(dict: [String: Any]) {
        // Deprecation warning for "enabled_rules"
        if dict[ConfigurationKey.enabledRules.rawValue] != nil {
            queuedPrintError("'\(ConfigurationKey.enabledRules.rawValue)' has been renamed to " +
                "'\(ConfigurationKey.optInRules.rawValue)' and will be completely removed in a " +
                "future release.")
        }

        // Deprecation warning for "use_nested_configs"
        if dict[ConfigurationKey.useNestedConfigs.rawValue] != nil {
            queuedPrintError("Support for '\(ConfigurationKey.useNestedConfigs.rawValue)' has " +
                "been deprecated and its value is now ignored. Nested configuration files are " +
                "now always considered.")
        }

        func defaultStringArray(_ object: Any?) -> [String] {
            return [String].array(of: object) ?? []
        }

        // Use either new 'opt_in_rules' or deprecated 'enabled_rules' for now.
        let optInRules = defaultStringArray(
            dict[ConfigurationKey.optInRules.rawValue] ??
                dict[ConfigurationKey.enabledRules.rawValue]
        )

        // Log an error when supplying invalid keys in the configuration dictionary
        let validKeys = [
            ConfigurationKey.disabledRules,
            .enabledRules,
            .excluded,
            .included,
            .optInRules,
            .reporter,
            .useNestedConfigs,
            .warningThreshold,
            .whitelistRules
        ].map({ $0.rawValue }) + masterRuleList.list.keys

        let invalidKeys = Set(dict.keys).subtracting(validKeys)
        if !invalidKeys.isEmpty {
            queuedPrintError("Configuration contains invalid keys:\n\(invalidKeys)")
        }

        self.init(
            disabledRules: defaultStringArray(dict[ConfigurationKey.disabledRules.rawValue]),
            optInRules: optInRules,
            whitelistRules: defaultStringArray(dict[ConfigurationKey.whitelistRules.rawValue]),
            included: defaultStringArray(dict[ConfigurationKey.included.rawValue]),
            excluded: defaultStringArray(dict[ConfigurationKey.excluded.rawValue]),
            warningThreshold: dict[ConfigurationKey.warningThreshold.rawValue] as? Int,
            reporter: dict[ConfigurationKey.reporter.rawValue] as? String ??
                XcodeReporter.identifier,
            configuredRules: masterRuleList.configuredRules(with: dict)
        )
    }

    public init(path: String = Configuration.fileName, rootPath: String? = nil,
                optional: Bool = true, quiet: Bool = false) {
        let fullPath = path.bridge().absolutePathRepresentation()
        let fail = { (msg: String) in
            fatalError("Could not read configuration file at path '\(fullPath)': \(msg)")
        }
        if path.isEmpty || !FileManager.default.fileExists(atPath: fullPath) {
            if !optional { fail("File not found.") }
            self.init()!
            self.rootPath = rootPath
            return
        }
        do {
            let yamlContents = try String(contentsOfFile: fullPath, encoding: .utf8)
            let dict = try YamlParser.parse(yamlContents)
            if !quiet {
                queuedPrintError("Loading configuration from '\(path)'")
            }
            self.init(dict: dict)!
            configurationPath = fullPath
            self.rootPath = rootPath
            return
        } catch YamlParserError.yamlParsing(let message) {
            fail("Error parsing YAML: \(message)")
        } catch {
            fail("\(error)")
        }
        self.init()!
    }

    public func lintablePathsForPath(_ path: String,
                                     fileManager: FileManager = fileManager) -> [String] {
        // If path is a Swift file, skip filtering with excluded/included paths
        if path.bridge().isSwiftFile() {
            return [path]
        }
        let pathsForPath = included.isEmpty ? fileManager.filesToLintAtPath(path) : []
        let excludedPaths = excluded.flatMap {
            fileManager.filesToLintAtPath($0, rootDirectory: rootPath)
        }
        let includedPaths = included.flatMap {
            fileManager.filesToLintAtPath($0, rootDirectory: rootPath)
        }
        return (pathsForPath + includedPaths).filter({ !excludedPaths.contains($0) })
    }

    public func lintableFilesForPath(_ path: String) -> [File] {
        return lintablePathsForPath(path).flatMap { File(path: $0) }
    }

    public func configurationForFile(_ file: File) -> Configuration {
        if let containingDir = file.path?.bridge().deletingLastPathComponent {
            return configurationForPath(containingDir)
        }
        return self
    }
}

// MARK: - Nested Configurations Extension

extension Configuration {
    fileprivate func configurationForPath(_ path: String) -> Configuration {
        let pathNSString = path.bridge()
        let configurationSearchPath = pathNSString.appendingPathComponent(Configuration.fileName)

        // If a configuration exists and it isn't us, load and merge the configurations
        if configurationSearchPath != configurationPath &&
            FileManager.default.fileExists(atPath: configurationSearchPath) {
            return merge(Configuration(path: configurationSearchPath, rootPath: rootPath,
                optional: false, quiet: true))
        }

        // If we are not at the root path, continue down the tree
        if path != rootPath && path != "/" {
            return configurationForPath(pathNSString.deletingLastPathComponent)
        }

        // If nothing else, return self
        return self
    }

    // Currently merge simply overrides the current configuration with the new configuration.
    // This requires that all configuration files be fully specified. In the future this should be
    // improved to do a more intelligent merge allowing for partial nested configurations.
    internal func merge(_ configuration: Configuration) -> Configuration {
        return configuration
    }
}

// Mark - == Implementation

public func == (lhs: Configuration, rhs: Configuration) -> Bool {
    return (lhs.excluded == rhs.excluded) &&
           (lhs.included == rhs.included) &&
           (lhs.reporter == rhs.reporter) &&
           (lhs.configurationPath == rhs.configurationPath) &&
           (lhs.rootPath == lhs.rootPath) &&
           (lhs.rules == rhs.rules)
}