//
//  Copyright RevenueCat Inc. All Rights Reserved.
//
//  Licensed under the MIT License (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      https://opensource.org/licenses/MIT
//
//  Logger.swift
//
//  Created by Andrés Boedo on 11/13/20.
//

import Foundation

/// A function that can handle a log message including file and method information.
public typealias VerboseLogHandler = (_ level: LogLevel,
                                      _ message: String,
                                      _ file: String?,
                                      _ function: String?,
                                      _ line: UInt) -> Void

/// A function that can handle a log message.
public typealias LogHandler = (_ level: LogLevel,
                               _ message: String) -> Void

internal typealias InternalLogHandler = (_ level: LogLevel,
                                         _ message: String,
                                         _ category: String,
                                         _ file: String?,
                                         _ function: String?,
                                         _ line: UInt) -> Void

// MARK: - Logger

// This is a `struct` instead of `enum` so that
// we can use `Logger()` as a `LoggerType`.
// swiftlint:disable:next convenience_type
struct Logger {

    static var logLevel: LogLevel = Self.defaultLogLevel
    static var internalLogHandler: InternalLogHandler = Self.defaultLogHandler

    static let defaultLogHandler: InternalLogHandler = { level, message, category, file, functionName, line in
        RCDefaultLogHandler(
            Self.frameworkDescription,
            Logger.verbose,
            level,
            category,
            message,
            file,
            functionName,
            line
        )
    }

    static var verbose: Bool = false

    private static let defaultLogLevel: LogLevel = {
        #if DEBUG
        return .debug
        #else
        return .info
        #endif
    }()

    internal static let frameworkDescription = "Purchases"

}

extension Logger {

    static var verboseLogsEnabled: Bool { self.logLevel == .verbose }

}

// MARK: - LoggerType implementation

/// `Logger` can be used both with static or instance methods.
/// This allows us to use it directly (`Logger.info("...")`), or inject it:
/// ```swift
/// let logger: LoggerType
/// logger.info("...")
/// ```
extension Logger: LoggerType {

    func verbose(_ message: @autoclosure () -> LogMessage,
                 fileName: String? = #fileID,
                 functionName: String? = #function,
                 line: UInt = #line) {
        Self.verbose(message(), fileName: fileName, functionName: functionName, line: line)
    }

    func debug(_ message: @autoclosure () -> LogMessage,
               fileName: String? = #fileID,
               functionName: String? = #function,
               line: UInt = #line) {
        Self.debug(message(), fileName: fileName, functionName: functionName, line: line)
    }

    func info(_ message: @autoclosure () -> LogMessage,
              fileName: String? = #fileID,
              functionName: String? = #function,
              line: UInt = #line) {
        Self.info(message(), fileName: fileName, functionName: functionName, line: line)
    }

    func warn(_ message: @autoclosure () -> LogMessage,
              fileName: String? = #fileID,
              functionName: String? = #function,
              line: UInt = #line) {
        Self.warn(message(), fileName: fileName, functionName: functionName, line: line)
    }

    func error(_ message: @autoclosure () -> LogMessage,
               fileName: String = #fileID,
               functionName: String = #function,
               line: UInt = #line) {
        Self.error(message(), fileName: fileName, functionName: functionName, line: line)
    }

}

// MARK: - Static implementation

extension Logger {

    static func verbose(_ message: @autoclosure () -> LogMessage,
                        fileName: String? = #fileID,
                        functionName: String? = #function,
                        line: UInt = #line) {
        Self.log(level: .verbose, intent: .verbose, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func debug(_ message: @autoclosure () -> LogMessage,
                      fileName: String? = #fileID,
                      functionName: String? = #function,
                      line: UInt = #line) {
        Self.log(level: .debug, intent: .info, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func info(_ message: @autoclosure () -> LogMessage,
                     fileName: String? = #fileID,
                     functionName: String? = #function,
                     line: UInt = #line) {
        Self.log(level: .info, intent: .info, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func warn(_ message: @autoclosure () -> LogMessage,
                     fileName: String? = #fileID,
                     functionName: String? = #function,
                     line: UInt = #line) {
        Self.log(level: .warn, intent: .warning, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func error(_ message: @autoclosure () -> String,
                      fileName: String = #fileID,
                      functionName: String = #function,
                      line: UInt = #line) {
        Self.error(
            ErrorMessage(description: message()),
            fileName: fileName,
            functionName: functionName,
            line: line
        )
    }

    static func error(_ message: @autoclosure () -> LogMessage,
                      fileName: String = #fileID,
                      functionName: String = #function,
                      line: UInt = #line) {
        Self.log(level: .error, intent: .rcError, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

}

extension Logger {

    static func appleError(_ message: @autoclosure () -> String,
                           fileName: String = #fileID,
                           functionName: String = #function,
                           line: UInt = #line) {
        Self.appleError(
            ErrorMessage(description: message()),
            fileName: fileName,
            functionName: functionName,
            line: line
        )
    }

    static func appleError(_ message: @autoclosure () -> LogMessage,
                           fileName: String = #fileID,
                           functionName: String = #function,
                           line: UInt = #line) {
        Self.log(level: .error, intent: .appleError, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func appleWarning(_ message: @autoclosure () -> LogMessage,
                             fileName: String = #fileID,
                             functionName: String = #function,
                             line: UInt = #line) {
        Self.log(level: .warn, intent: .appleError, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func purchase(_ message: @autoclosure () -> LogMessage,
                         fileName: String = #fileID,
                         functionName: String = #function,
                         line: UInt = #line) {
        Self.log(level: .info, intent: .purchase, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func rcPurchaseSuccess(_ message: @autoclosure () -> LogMessage,
                                  fileName: String = #fileID,
                                  functionName: String = #function,
                                  line: UInt = #line) {
        Self.log(level: .info, intent: .rcPurchaseSuccess, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func rcPurchaseError(_ message: @autoclosure () -> LogMessage,
                                fileName: String = #fileID,
                                functionName: String = #function,
                                line: UInt = #line) {
        Self.log(level: .error, intent: .purchase, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func rcSuccess(_ message: @autoclosure () -> LogMessage,
                          fileName: String = #fileID,
                          functionName: String = #function,
                          line: UInt = #line) {
        Self.log(level: .debug, intent: .rcSuccess, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func user(_ message: @autoclosure () -> LogMessage,
                     fileName: String? = #fileID,
                     functionName: String? = #function,
                     line: UInt = #line) {
        Self.log(level: .debug, intent: .user, message: message(),
                 fileName: fileName, functionName: functionName, line: line)
    }

    static func log(level: LogLevel,
                    intent: LogIntent,
                    message: @autoclosure () -> LogMessage,
                    fileName: String? = #fileID,
                    functionName: String? = #function,
                    line: UInt = #line) {
        guard self.logLevel <= level else { return }

        let message = message()
        let content = [intent.prefix.notEmpty, message.description]
            .compactMap { $0 }
            .joined(separator: " ")

        Self.internalLogHandler(
            level,
            content,
            message.category,
            fileName,
            functionName,
            line
        )
    }

}

// MARK: - LogLevel comparable conformance

extension LogLevel: Comparable {

    // swiftlint:disable:next missing_docs
    public static func < (lhs: LogLevel, rhs: LogLevel) -> Bool {
        // Tests ensure that this can't happen
        guard let lhs = Self.order[lhs], let rhs = Self.order[rhs] else { return false }

        return lhs < rhs
    }

    private static let orderedLevels: [LogLevel] = [
        .verbose,
        .debug,
        .info,
        .warn,
        .error
    ]
    static let order: [LogLevel: Int] = Dictionary(uniqueKeysWithValues:
                                                    Self.orderedLevels
        .enumerated()
        .lazy
        .map { ($1, $0) }
    )

}

// MARK: -

private struct ErrorMessage: LogMessage {

    let description: String
    let category: String = "error"

}