//
//  ViewController.swift
//  TagTunes
//
//  Created by Kim Wittenburg on 28.08.15.
//  Copyright © 2015 Kim Wittenburg. All rights reserved.
//

import SearchAPI
import AppKitPlus

class MainViewController: NSViewController, SearchDelegate, LookupQueueDelegate {
    
    // MARK: Types
    
    /// This struct contains *magic numbers* like references to storyboard
    /// identifiers.
    private struct Constants {

        /// The identifier of the segue that embeds the
        /// `OutlineContentViewController` in its parent view.
        static let OutlineContentViewControllerEmbedSegueIdentifier = "embedOutlineContentViewController"

        /// The identifier of the segue that embeds the `LookupViewController` in
        /// its parent view.
        static let LookupViewControllerEmbedSegueIdentifier = "embedLookupViewController"

        /// The space between the lookup panel and its superview when it's
        /// visible.
        static let LookupPanelExpandedBottomSpace: CGFloat = -4

        /// The space between the superview and the lookup panel, if it's not
        /// visible.
        static let LookupPanelCollapsedBottomSpace: CGFloat = -82

        /// The delay between the lookup controller completing and it being
        /// hidden.
        static let LookupPanelHideDelay: NSTimeInterval = 2
        
        /// This constant is used for KVO observations on a `Preferences`
        /// instance.
        static var PreferencesKVOContext = "PreferencesKVOContext"
    }

    // MARK: Properties
    
    /// The view controller that manages the display of the content.
    internal var contentViewController: ContentViewController!

    // MARK: View Life Cycle
    
    override func viewDidLoad() {
        super.viewDidLoad()

        Preferences.sharedPreferences.addObserver(self, forKeyPath: "useCensoredNames", options: [], context: &Constants.PreferencesKVOContext)
        Preferences.sharedPreferences.addObserver(self, forKeyPath: "caseSensitive", options: [], context: &Constants.PreferencesKVOContext)
    }
    
    override func prepareForSegue(segue: NSStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == Constants.OutlineContentViewControllerEmbedSegueIdentifier {
            contentViewController = segue.destinationController as? ContentViewController
        }
    }
    
    deinit {
        Preferences.sharedPreferences.removeObserver(self, forKeyPath: "useCensoredNames")
        Preferences.sharedPreferences.removeObserver(self, forKeyPath: "caseSensitiv")
    }
    
    
    // MARK: Notifications
    
    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        if context == &Constants.PreferencesKVOContext {
            contentViewController.updateAllItems()
        }
    }
    
    
    // MARK: Searching

    func searchController(searchController: SearchController, didSelectSearchResult searchResult: TagTunesItem) {
        contentViewController.addItem(searchResult)
    }

    // MARK: Lookup Panel

    func lookupQueue(lookupQueue: LookupQueue, willBeginLookupForTracks tracks: [TagTunesTrack]) {
    }

    func lookupQueue(lookupQueue: LookupQueue, completedLookupForTracks tracks: [TagTunesTrack]) {
        var newAlbumItems = [AlbumItem]()
        for track in tracks {
            if case .Found(let result) = track.lookupState {
                if let album = result.collection.map(contentViewController.itemForEntity) as? AlbumItem {
                    album.addAssociatedTrack(track, forChildEntity: result)
                } else if let collection = result.collection {
                    let album = AlbumItem(entity: collection)
                    album.addAssociatedTrack(track, forChildEntity: result)
                    contentViewController.addItem(album)
                    newAlbumItems.append(album)
                } else {
                    fatalError("Lookup returned a song without album.")
                }
            } else {
                NSApp.unsortedTracksController.addTracks([track]) // TODO: Show failure reason
            }
        }
        for album in newAlbumItems {
            album.beginLoadingChildren()
        }
    }

    func lookupQueueDidFinishLookup(lookupQueue: LookupQueue) {
    }

    // MARK: Saving

    @IBAction func save(sender: AnyObject?) {
        var items = [AnyObject]()
        for item in contentViewController.selectedItems {
            if let group = item as? TagTunesGroupItem {
                for child in group.children {
                    for track in child.associatedTracks {
                        saveQueue.addOperation(SaveOperation(track: track, entity: child))
                    }
                }
                items.append(group)
            } else if let entity = item as? TagTunesEntityItem {
                for track in entity.associatedTracks {
                    saveQueue.addOperation(SaveOperation(track: track, entity: entity))
                }
                items.append(entity)
            } else if let track = item as? TagTunesTrack {
                if let entity = track.entity {
                    saveQueue.addOperation(SaveOperation(track: track, entity: entity))
                    items.append(track)
                }
            }
        }
        contentViewController.removeItems(items)
    }

    // TODO: Use Operations for this
    /// Exports the artwork of the first selected item to a file. This methods
    /// presents a `NSSavePanel` so the user can specify where to save the
    /// artwork.
    @IBAction func exportArtwork(sender: AnyObject?) {
        let item: TagTunesItem
        let object = contentViewController.selectedItems.first
        if let track = object as? TagTunesTrack {
            if let theItem = track.entity {
                item = theItem
            } else {
                return
            }
        } else if let theItem = object as? TagTunesItem {
            item = theItem
        } else {
            return
        }
        var album: Album
        switch item {
        case let songItem as SongItem:
            album = songItem.album
        case let albumItem as AlbumItem:
            album = albumItem.album
        default: return
        }
        let savePanel = NSSavePanel()
        savePanel.allowedFileTypes = ["jpg"]
        savePanel.nameFieldStringValue = Preferences.sharedPreferences.useCensoredNames ? album.censoredName : album.name
        savePanel.beginSheetModalForWindow(view.window!) { response -> Void in
            if response == NSModalResponseOK {
                let bitmapRep = album.artwork.optimalArtworkImageForSize(CGFloat.max)?.representations[0] as? NSBitmapImageRep
                guard bitmapRep != nil else {
                    let alert = NSAlert()
                    alert.messageText = NSLocalizedString("The artwork could not be saved.", comment: "Error message informing the user that an artwork could not be saved to a file.")
                    alert.informativeText = NSLocalizedString("Please check your network connection. Also make sure that you have write permissions to the destination you selected.", comment: "Informative text for the 'The artwork could not be saved.' error.")
                    alert.addButtonWithTitle(NSLocalizedString("OK", comment: "Button title"))
                    alert.beginSheetModalForWindow(self.view.window!, completionHandler: nil)
                    return
                }
                let data = bitmapRep!.representationUsingType(.NSJPEGFileType, properties: [:])
                data?.writeToURL(savePanel.URL!, atomically: false)
            }
        }
    }
    
    
    // MARK: Other Actions
    
    /// Removes the selected items from the outline view.
    @IBAction internal func delete(sender: AnyObject?) {
        self.contentViewController.removeSelectedItems()
    }

    /// Shows the currently selected item in the iTunes store.
    @IBAction internal func showInITunesStore(sender: AnyObject?) {
        if let item = contentViewController.clickedItems.first as? TagTunesItem {
            NSWorkspace.sharedWorkspace().openURL(item.entity.viewURL)
        }
    }
        
}

// MARK: - User Interface Validations

extension MainViewController: NSUserInterfaceValidations {

    func validateUserInterfaceItem(anItem: NSValidatedUserInterfaceItem) -> Bool {
        if anItem.action() == #selector(MainViewController.save(_:)) {
            return canSave
        } else if anItem.action() == #selector(MainViewController.exportArtwork(_:)) {
            return canExportArtworks
        } else if anItem.action() == #selector(MainViewController.delete(_:)) {
            return canDelete
        } else if anItem.action() == #selector(MainViewController.showInITunesStore(_:)) {
            return canShowInITunesStore
        }
        return false
    }
    
    /// Returns whether it is currently valid to invoke `save(_:)`.
    private var canSave: Bool {
        return !contentViewController.selectedItems.isEmpty
    }
    
    /// Returns whether it is currently valid to invoke `exportArtworks(_:)`.
    private var canExportArtworks: Bool {
        return contentViewController.selectedItems.count == 1
    }
    
    /// Returns whether it is currently valid to invoke
    /// `delete(_:)`.
    private var canDelete: Bool {
        return !contentViewController.selectedItems.isEmpty
    }

    private var canShowInITunesStore: Bool {
        return contentViewController.clickedItems.count == 1 && contentViewController.clickedItems.first is TagTunesItem
    }
    
}