//
//  Cap.swift
//  CapCollector
//
//  Created by Christoph on 19.11.18.
//  Copyright © 2018 CH. All rights reserved.
//

import Foundation
import UIKit
import CoreImage

import SwiftyDropbox

protocol CapsDelegate: class {
    
    func capHasUpdates(_ cap: Cap)
    
    func capsLoaded()
}

final class Cap {
    
    // MARK: - Static variables
    
    static let jpgQuality: CGFloat = 0.3
    
    private static let mosaicColumns = 40
    
    static let mosaicCellSize: CGFloat = 60
    
    private static let mosaicRowHeight = mosaicCellSize * 0.866
    
    private static let mosaicMargin = mosaicCellSize - mosaicRowHeight
    
    static var delegate: CapsDelegate?
    
    static var shouldSave = true {
        didSet {
            save()
        }
    }
    
    static var hasMatches = false {
        didSet {
            guard !hasMatches else { return }
            all.forEach { _, cap in
                cap.match = nil
            }
        }
    }
    
    static var nextUnusedId: Int {
        return (all.keys.max() ?? 0) + 1
    }
    
    /// The number of caps currently in the database
    static var totalCapCount: Int {
        return all.count
    }
    
    /// The total number of images for all caps
    static var imageCount: Int {
        return all.reduce(0) { sum, cap in
            return sum + cap.value.count
        }
    }
    
    /**
     Match all cap names against the given string and return matches.
     - note: Each space-separated part of the string is matched individually
     */
    static func caps(matching text: String) -> [Cap] {
        let cleaned = text.clean
        let found = all.compactMap { (_,cap) -> Cap? in
            // For each part of text, check if name contains it
            for textItem in cleaned.components(separatedBy: " ") {
                if textItem != "" && !cap.name.contains(textItem) { return nil }
            }
            return cap
        }
        return found
    }
    
    // MARK: - Variables
    
    /// The unique number of the cap
    let id: Int
    
    /// The tile position of the cap
    var tile: Int
    
    /// The name of the cap
    var name: String {
        didSet {
            cleanName = name.clean
            Cap.save()
            event("Updated name for cap \(id) to \(name)")
            Cap.delegate?.capHasUpdates(self)
        }
    }
    
    /// The name of the cap wothout special characters
    private(set) var cleanName: String
    
    /// The number of images existing for the cap
    private(set) var count: Int {
        didSet {
            Cap.save()
            event("Updated count for cap \(id) to \(count)")
            Cap.delegate?.capHasUpdates(self)
        }
    }
    
    /// The average color of the cap
    var color: UIColor?
    
    /// The similarity of the cap to the currently processed image
    var match: Float? = nil
    
    // MARK: - All caps
    
    /// A dictionary of all known caps
    static var all = [Int : Cap]()
    
    // MARK: - Tile information
    
    /// A dictionary of the caps for the tiles
    static var tiles = [Int : Cap]()
    
    /**
     Get the cap image for a tile.
     */
    static func tileImage(tile: Int) -> UIImage? {
        return tiles[tile]?.thumbnail
    }
    
    static func tileColor(tile: Int) -> UIColor? {
        return tiles[tile]?.averageColor
    }
    
    /**
     Switch two tiles.
     */
    static func switchTiles(_ lhs: Int, _ rhs: Int) {
        let l = tiles[lhs]!
        let r = tiles[rhs]!
        l.tile = rhs
        r.tile = lhs
        tiles[rhs] = l
        tiles[lhs] = r
    }
    
    // MARK: - Initialization

    /**
     Create a new cap with an image
     - parameter image: The main image of the cap
     - parameter name: The name of the cap
     */
    init?(image: UIImage, name: String) {
        self.id = Cap.nextUnusedId
        self.tile = id - 1
        self.name = name
        self.count = 0
        self.cleanName = name.clean
        guard save(mainImage: image) else {
            return nil
        }
        Cap.all[self.id] = self
        Cap.tiles[self.id] = self
        Cap.shouldCreateFolderForCap(self.id)
        Cap.save()
        Cap.delegate?.capHasUpdates(self)
        DispatchQueue.global(qos: .userInitiated).async {
            self.add(image: image) { _ in
                
            }
        }
    }
    
    /**
     Create a cap from a line in the cap list file
     */
    init?(line: String) {
        guard line != "" else {
            return nil
        }
        let parts = line.components(separatedBy: ";")
        guard parts.count == 4 || parts.count == 8 else {
            Cap.error("Cap names: Invalid line \(line)")
            return nil
        }
        
        guard let nr = Int(parts[0]) else {
            Cap.error("Invalid id in line \(line)")
            return nil
        }
        guard let count = Int(parts[2]) else {
            Cap.error("Invalid count in line \(line)")
            return nil
        }
        guard let tile = Int(parts[3]) else {
            Cap.error("Invalid tile in line \(line)")
            return nil
        }
        if parts.count == 8 {
            guard let r = Int(parts[4]), let g = Int(parts[5]), let b = Int(parts[6]), let a = Int(parts[7]) else {
                Cap.error("Invalid color in line \(line)")
                return nil
            }
            self.color = UIColor(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: CGFloat(a)/255)
        }
        
        self.id = nr
        self.name = parts[1]
        self.count = count
        self.cleanName = name.clean
        self.tile = tile
        Cap.tiles[tile] = self
        Cap.all[id] = self
    }
    
    // MARK: - Images
    
    /// The main image of the cap
    var image: UIImage? {
        guard let data = DiskManager.image(for: id) else {
            self.downloadImage { _ in
                Cap.delegate?.capHasUpdates(self)
            }
            return nil
        }
        return UIImage(data: data)
    }

    /// The main image of the cap
    var thumbnail: UIImage? {
        if let data = DiskManager.thumbnail(for: id) {
            return UIImage(data: data)
        }
        return makeThumbnail()
    }
    
    var averageColor: UIColor? {
        if let c = color {
            return c
        }
        return makeAverageColor()
    }
    
    @discardableResult
    func makeThumbnail() -> UIImage? {
        guard let img = image else {
            return nil
        }
        let len = GridViewController.len * 2
        let thumb = img.resize(to: CGSize.init(width: len, height: len))
        guard let data = thumb.pngData() else {
            error("Failed to get PNG data from thumbnail for cap \(id)")
            return nil
        }
        _ = DiskManager.save(thumbnailData: data, for: id)
        event("Created thumbnail for cap \(id)")
        return thumb
    }
    
    /**
     Download a specified image of the cap.
     - Note: If the downloaded image is the main image, it is automatically saved to disk
     - Note: If the main image is requested and already downloaded, it is returned directly
     - parameter number: The number of the image
     - parameter completion: The completion handler, called with the image if successful
     - parameter image: The image, if the download was successful, or nil on error
    */
    func downloadImage(_ number: Int = 0, completion: @escaping (_ image: UIImage?) -> Void) {
        let path = imageFolderPath + "/\(id)-\(number).jpg"
        DropboxController.client.files.download(path: path).response { data, dbError in
            if let error = dbError {
                self.error("Failed to download image data (\(number)) for cap \(self.id): \(error)")
                completion(nil)
                return
            }
            
            guard let d = data?.1 else {
                self.error("Failed to download image data (\(number)) for cap \(self.id)")
                completion(nil)
                return
            }
            guard let image = UIImage(data: d) else {
                self.error("Corrupted image data (\(number)) for cap \(self.id)")
                completion(nil)
                return
            }
            if number == 0 {
                guard self.save(mainImage: image) else {
                    completion(nil)
                    return
                }
            }
            self.event("Downloaded image data (\(number)) for cap \(self.id)")
            completion(image)
        }
    }
    
    func save(mainImage: UIImage) -> Bool {
        guard let data = mainImage.jpegData(compressionQuality: Cap.jpgQuality) else {
            error("Failed to convert main image to data for cap \(id)")
            return false
        }
        guard DiskManager.save(imageData: data, for: id) else {
            error("Failed to save main image for cap \(id)")
            return false
        }
        event("Saved main image for cap \(id) to disk")
        makeThumbnail()
        
        Cap.delegate?.capHasUpdates(self)
        return true
    }
    
    func add(image: UIImage, completion: @escaping (Bool) -> Void) {
        self.upload(image: image) { saved in
            guard saved else {
                completion(false)
                return
            }
            // Increment cap count
            self.count += 1
            completion(true)
        }
    }
    
    private var imageFolderPath: String {
        return String(format: "/Images/%04d", id)
    }
    
    private static func imageFolderPath(for cap: Int) -> String {
        return String(format: "/Images/%04d", cap)
    }
    
    private func imageFilePath(imageId: Int) -> String {
        return imageFolderPath + "/\(id)-\(imageId).jpg"
    }
    
    // MARK: - Image upload

    private func folderExists(completion: @escaping (_ exists: Bool?) -> Void) {
        let path = "/Images"
        DropboxController.client.files.listFolder(path: path).response { response, error in
            if let e = error {
                self.error("Failed to get image folder list: \(e)")
                completion(nil)
                return
            }
            guard let result = response else {
                self.error("Failed to get image folder list")
                completion(nil)
                return
            }
            
            let exists = result.entries.contains { $0.name == "\(self.id)" }
            completion(exists)
        }
    }
    
    private static func createFolder(forCap cap: Int, completion: @escaping (_ success: Bool) -> Void) {
        guard shouldCreateFolder(forCap: cap) else {
            completion(true)
            return
        }
        // Create folder for cap
        let path = imageFolderPath(for: cap)
        DropboxController.client.files.createFolderV2(path: path).response { _, error in
            if let err = error {
                self.event("Could not create folder for cap \(cap): \(err)")
                completion(false)
            } else {
                self.event("Created folder for cap \(cap)")
                didCreateFolder(forCap: cap)
                completion(true)
            }
        }
    }
    
    private func upload(image: UIImage, savedCallback: @escaping (Bool) -> Void) {
        upload(image: image, number: count, savedCallback: savedCallback)
    }
    
    private func upload(image: UIImage, number: Int, savedCallback: @escaping (Bool) -> Void) {
        // Convert to data
        guard let data = image.jpegData(compressionQuality: Cap.jpgQuality) else {
            error("Failed to convert image to data")
            return
        }
        let fileName = "\(id)-\(number).jpg"
        // Save image to upload folder
        guard let url = DiskManager.saveForUpload(imageData: data, name: fileName) else {
            error("Could not save image for cap \(id) to upload folder")
            savedCallback(false)
            return
        }
        event("Saved image \(number) for cap \(id) for upload")
        savedCallback(true)
        
        Cap.uploadCapImage(at: url, forCap: id) { success in
            
        }
    }
    
    private static func uploadCapImage(at url: URL, forCap cap: Int, completion: @escaping (Bool) -> Void) {
        createFolder(forCap: cap) { created in
            guard created else { return }
            uploadCapImage(at: url, forCapWithExistingFolder: cap, completion: completion)
        }
    }
    
    private static func uploadCapImage(at url: URL, forCapWithExistingFolder cap: Int, completion: @escaping (Bool) -> Void) {
        let path = imageFolderPath(for: cap) + "/" + url.lastPathComponent
        
        let data: Data
        do {
            data = try Data(contentsOf: url)
        } catch {
            self.error("Could not read data from url \(url.path): \(error)")
            completion(false)
            return
        }
        
        DropboxController.client.files.upload(path: path, input: data).response { response, error in
            if let err = error {
                self.error("Failed to upload file at url: \(url): \(err)")
                completion(false)
                return
            }
            Cap.event("Uploaded image \(path)")
            guard DiskManager.removeFromUpload(url: url) else {
                self.error("Could not delete uploaded image for cap \(cap) at url \(url)")
                completion(false)
                return
            }
            completion(true)
        }
    }
    
    static func uploadRemainingImages() {
        guard let list = DiskManager.pendingUploads else {
            return
        }
        guard list.count != 0 else {
            event("No pending uploads")
            return
        }
        event("\(list.count) image uploads pending")
        
        for url in list {
            let cap = Int(url.lastPathComponent.components(separatedBy: "-").first!)!
            uploadCapImage(at: url, forCap: cap) { didUpload in
                // Delete image from disk if uploaded
                guard didUpload else {
                    self.error("Could not upload image at url \(url)")
                    return
                }
                guard DiskManager.removeFromUpload(url: url) else {
                    self.error("Could not delete uploaded image at url \(url)")
                    return
                }
            }
        }
    }
    
    func setMainImage(to imageId: Int, image: UIImage) {
        guard imageId != 0 else {
            self.event("No need to switch main image with itself")
            return
        }
        let tempFile = imageFilePath(imageId: count)
        let oldFile = imageFilePath(imageId: 0)
        let newFile = imageFilePath(imageId: imageId)
        DropboxController.shared.move(file: oldFile, to: tempFile) { success in
            guard success else {
                self.error("Could not move \(oldFile) to \(tempFile)")
                return
            }
            DropboxController.shared.move(file: newFile, to: oldFile) { success in
                guard success else {
                    self.error("Could not move \(newFile) to \(oldFile)")
                    return
                }
                DropboxController.shared.move(file: tempFile, to: newFile) { success in
                    if !success {
                        self.error("Could not move \(tempFile) to \(newFile)")
                    }
                    guard self.save(mainImage: image) else {
                        return
                    }
                    self.event("Successfully set image \(imageId) to main image for cap \(self.id)")
                }
            }
        }
    }
    
    // MARK: - Counts
    
    func updateCount(completion: @escaping (Bool) -> Void) {
        getImageCount { response in
            guard let count = response else {
                self.error("Could not update count for cap \(self.id)")
                completion(false)
                return
            }
            self.count = count
            completion(true)
        }
    }
    
    private func getImageCount(completion: @escaping (Int?) -> Void) {
        let path = imageFolderPath
        DropboxController.client.files.listFolder(path: path).response { response, error in
            if let err = error {
                self.error("Error getting folder content of cap \(self.id): \(err)")
                completion(nil)
                return
            }
            guard let files = response?.entries else {
                self.error("No content for folder of cap \(self.id)")
                completion(nil)
                return
            }
            completion(files.count)
        }
    }
    
    // MARK: - Sorted caps
    
    static var unsortedCaps: Set<Cap> {
        return Set(all.values)
    }
    
    static func capList(sortedBy criteria: SortCriteria, ascending: Bool) -> [Cap] {
        if ascending {
            return sorted([Cap](all.values), ascendingBy: criteria)
        } else {
            return sorted([Cap](all.values), descendingBy: criteria)
        }
    }
    
    private static func sorted(_ list: [Cap], ascendingBy parameter: SortCriteria) -> [Cap] {
        switch parameter {
        case .id: return list.sorted { $0.id < $1.id }
        case .count: return list.sorted { $0.count < $1.count }
        case .name: return list.sorted { $0.name < $1.name }
        case .match: return list.sorted { $0.match ?? 0 < $1.match ?? 0 }
        }
    }
    
    private static func sorted(_ list: [Cap], descendingBy parameter: SortCriteria) -> [Cap] {
        switch parameter {
        case .id: return list.sorted { $0.id > $1.id }
        case .count: return list.sorted { $0.count > $1.count }
        case .name: return list.sorted { $0.name > $1.name }
        case .match: return list.sorted { $0.match ?? 0 > $1.match ?? 0 }
        }
    }
    
    // MARK: - Loading, Saving & Uploading cap list
    
    /**
     Either load the names from disk or download them from dropbox.
     - parameter completion: The handler that is called with true on success, false on failure
     */
    static func load() {
        NameFile.makeAvailable { content in
            guard let lines = content else {
                return
            }
            self.readNames(from: lines)
        }
    }
    
    /// Read all caps from the content of a file
    private static func readNames(from fileContent: String) {
        let parts = fileContent.components(separatedBy: "\n")
        for line in parts {
            _ = Cap(line: line)
        }
        event("Loaded \(totalCapCount) caps from file")
        delegate?.capsLoaded()
    }
    
    static func getCapStatistics() -> [Int] {
        let counts = all.values.map { $0.count }
        var c = [Int](repeating: 0, count: counts.max()! + 1)
        counts.forEach { c[$0] += 1 }
        return c
    }
    
    static func save() {
        guard shouldSave else { return }
        let content = namesAsString()
        NameFile.save(names: content)
    }
    
    static func saveAndUpload(completion: @escaping (Bool) -> Void) {
        let content = namesAsString()
        NameFile.saveAndUpload(names: content) { success in
            guard success else {
                completion(false)
                return
            }
            Persistence.lastUploadedCapCount = totalCapCount
            Persistence.lastUploadedImageCount = imageCount
            completion(true)
        }
    }
    
    private static func namesAsString() -> String {
        return capList(sortedBy: .id, ascending: true).reduce("") { $0 + $1.description }
    }
    
    // MARK: - Folders to upload
    
    static func shouldCreateFolderForCap(_ cap: Int) {
        let oldCaps = Persistence.folderNotCreated
        guard !oldCaps.contains(cap) else {
            return
        }
        let newCaps = oldCaps + [cap]
        Persistence.folderNotCreated = newCaps
    }
    
    static func shouldCreateFolder(forCap cap: Int) -> Bool {
        return Persistence.folderNotCreated.contains(cap)
    }
    
    static func didCreateFolder(forCap cap: Int) {
        let oldCaps = Persistence.folderNotCreated
        guard oldCaps.contains(cap) else {
            return
        }
        Persistence.folderNotCreated = oldCaps.filter { $0 != cap }
    }
    
    // MARK: - Average color
    
    @discardableResult
    func makeAverageColor() -> UIColor? {
        guard let url = DiskManager.imageUrlForCap(id) else {
            event("No main image for cap \(id), no average color calculated")
            return nil
        }
        
        guard let inputImage = CIImage(contentsOf: url) else {
            error("Failed to read CIImage for main image of cap \(id)")
            return nil
        }
        let extentVector = CIVector(x: inputImage.extent.origin.x, y: inputImage.extent.origin.y, z: inputImage.extent.size.width, w: inputImage.extent.size.height)
        
        guard let filter = CIFilter(name: "CIAreaAverage", parameters: [kCIInputImageKey: inputImage, kCIInputExtentKey: extentVector]) else {
            error("Failed to create filter to calculate average for cap \(id)")
            return nil
        }
        guard let outputImage = filter.outputImage else {
            error("Failed get filter output for image of cap \(id)")
            return nil
        }
        
        var bitmap = [UInt8](repeating: 0, count: 4)
        let context = CIContext(options: [.workingColorSpace: kCFNull])
        context.render(outputImage, toBitmap: &bitmap, rowBytes: 4, bounds: CGRect(x: 0, y: 0, width: 1, height: 1), format: .RGBA8, colorSpace: nil)
        
        color = UIColor(
            red: saturate(bitmap[0]),
            green: saturate(bitmap[1]),
            blue: saturate(bitmap[2]),
            alpha: CGFloat(bitmap[3]) / 255)
        
        event("Average color updated for cap \(id)")
        Cap.save()
        return color
    }
}

/// Map expected range 75-200 to 0-255
private func saturate(_ component: UInt8) -> CGFloat {
    return max(min(CGFloat(component) * 2 - 150, 255), 0) / 255
}

// MARK: - Protocol Hashable

extension Cap: Hashable {
    
    static func == (lhs: Cap, rhs: Cap) -> Bool {
        return lhs.id == rhs.id
    }
    
    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
    }
    
}

// MARK: - Protocol CustomStringConvertible

extension Cap: CustomStringConvertible {
    
    var description: String {
        guard let c = color else {
            return String(format: "%04d", id) + ";\(name);\(count);\(tile)\n"
        }
        
        var fRed: CGFloat = 0
        var fGreen: CGFloat = 0
        var fBlue: CGFloat = 0
        var fAlpha: CGFloat = 0
        guard c.getRed(&fRed, green: &fGreen, blue: &fBlue, alpha: &fAlpha) else {
            return String(format: "%04d", id) + ";\(name);\(count);\(tile)\n"
        }
        let r = Int(fRed * 255.0)
        let g = Int(fGreen * 255.0)
        let b = Int(fBlue * 255.0)
        let a = Int(fAlpha * 255.0)
        return String(format: "%04d", id) + ";\(name);\(count);\(tile);\(r);\(g);\(b);\(a)\n"
    }
}

// MARK: - Protocol Logger

extension Cap: Logger {
    
    static let logToken = "[CAP]"
}

// MARK: - String extension

extension String {
    var clean: String {
        return lowercased().replacingOccurrences(of: "[^a-z0-9 ]", with: "", options: .regularExpression)
    }
}

// MARK: - Int extension

private extension Int {
    
    var isEven: Bool {
        return self % 2 == 0
    }
}