//
//  GMAlbumsViewController.m
//  GMPhotoPicker
//
//  Created by Guillermo Muntaner Perelló on 19/09/14.
//  Copyright (c) 2014 Guillermo Muntaner Perelló. All rights reserved.
//

#import "GMImagePickerController.h"
#import "GMAlbumsViewController.h"
#import "GMGridViewCell.h"
#import "GMGridViewController.h"
#import "GMAlbumsViewCell.h"

#include <Photos/Photos.h>

@interface GMAlbumsViewController() <PHPhotoLibraryChangeObserver>

@property (strong,nonatomic) NSArray *collectionsFetchResults;
@property (strong,nonatomic) NSArray *collectionsLocalizedTitles;
@property (strong,nonatomic) NSArray *collectionsFetchResultsAssets;
@property (strong,nonatomic) NSArray *collectionsFetchResultsTitles;
@property (nonatomic, weak) GMImagePickerController *picker;
@property (strong,nonatomic) PHCachingImageManager *imageManager;

@end


@implementation GMAlbumsViewController

- (id)init
{
  if (self = [super initWithStyle:UITableViewStylePlain]) {
    self.preferredContentSize = kPopoverContentSize;
  }
  
  return self;
}

static NSString *const AllPhotosReuseIdentifier = @"AllPhotosCell";
static NSString *const CollectionCellReuseIdentifier = @"CollectionCell";

- (void)viewDidLoad
{
  [super viewDidLoad];
  
  self.view.backgroundColor = [self.picker pickerBackgroundColor];
  
  // Navigation bar customization
  if (self.picker.customNavigationBarPrompt) {
    self.navigationItem.prompt = self.picker.customNavigationBarPrompt;
  }
  
  self.imageManager = [[PHCachingImageManager alloc] init];
  
  // Table view aspect
  self.tableView.rowHeight = kAlbumRowHeight;
  self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
  
  // Buttons
  NSDictionary *barButtonItemAttributes = @{NSFontAttributeName: [UIFont fontWithName:self.picker.pickerFontName size:self.picker.pickerFontHeaderSize]};
  
  NSString *cancelTitle = self.picker.customCancelButtonTitle ? self.picker.customCancelButtonTitle : NSLocalizedStringFromTableInBundle(@"picker.navigation.cancel-button",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"Cancel");
  self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:cancelTitle
                                                                           style:UIBarButtonItemStylePlain
                                                                          target:self.picker
                                                                          action:@selector(dismiss:)];
  if (self.picker.useCustomFontForNavigationBar) {
    [self.navigationItem.leftBarButtonItem setTitleTextAttributes:barButtonItemAttributes forState:UIControlStateNormal];
    [self.navigationItem.leftBarButtonItem setTitleTextAttributes:barButtonItemAttributes forState:UIControlStateSelected];
  }
  
  if (self.picker.allowsMultipleSelection) {
    NSString *doneTitle = self.picker.customDoneButtonTitle ? self.picker.customDoneButtonTitle : NSLocalizedStringFromTableInBundle(@"picker.navigation.done-button",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"Done");
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:doneTitle
                                                                              style:UIBarButtonItemStyleDone
                                                                             target:self.picker
                                                                             action:@selector(finishPickingAssets:)];
    if (self.picker.useCustomFontForNavigationBar) {
      [self.navigationItem.rightBarButtonItem setTitleTextAttributes:barButtonItemAttributes forState:UIControlStateNormal];
      [self.navigationItem.rightBarButtonItem setTitleTextAttributes:barButtonItemAttributes forState:UIControlStateSelected];
    }
    
    self.navigationItem.rightBarButtonItem.enabled = (self.picker.autoDisableDoneButton ? self.picker.selectedAssets.count > 0 : TRUE);
  }
  
  // Bottom toolbar
  self.toolbarItems = self.picker.toolbarItems;
  
  // Title
  if (!self.picker.title) {
    self.title = NSLocalizedStringFromTableInBundle(@"picker.navigation.title",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"Navigation bar default title");
  } else {
    self.title = self.picker.title;
  }
  
  // Fetch PHAssetCollections:
  PHFetchResult *topLevelUserCollections = [PHCollectionList fetchTopLevelUserCollectionsWithOptions:nil];
  PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
  self.collectionsFetchResults = @[topLevelUserCollections, smartAlbums];
  self.collectionsLocalizedTitles = @[NSLocalizedStringFromTableInBundle(@"picker.table.smart-albums-header",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"Smart Albums"),NSLocalizedStringFromTableInBundle(@"picker.table.user-albums-header",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"Albums")];
  
  [self updateFetchResults];
  
  // Register for changes
  [[PHPhotoLibrary sharedPhotoLibrary] registerChangeObserver:self];
  
  if ([self respondsToSelector:@selector(setEdgesForExtendedLayout:)])
  {
    self.edgesForExtendedLayout = UIRectEdgeNone;
  }
}

- (void)dealloc
{
  [[PHPhotoLibrary sharedPhotoLibrary] unregisterChangeObserver:self];
}

- (UIStatusBarStyle)preferredStatusBarStyle {
  return self.picker.pickerStatusBarStyle;
}

- (void)selectAllAlbumsCell {
  NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
  [self tableView:self.tableView didSelectRowAtIndexPath:indexPath];
}

-(void)updateFetchResults
{
  //What I do here is fetch both the albums list and the assets of each album.
  //This way I have acces to the number of items in each album, I can load the 3
  //thumbnails directly and I can pass the fetched result to the gridViewController.
  
  self.collectionsFetchResultsAssets=nil;
  self.collectionsFetchResultsTitles=nil;
  
  //Fetch PHAssetCollections:
  PHFetchResult *topLevelUserCollections = [self.collectionsFetchResults objectAtIndex:0];
  PHFetchResult *smartAlbums = [self.collectionsFetchResults objectAtIndex:1];
  
  //All album: Sorted by descending creation date.
  NSMutableArray *allFetchResultArray = [[NSMutableArray alloc] init];
  NSMutableArray *allFetchResultLabel = [[NSMutableArray alloc] init];
  {
    PHFetchOptions *options = [[PHFetchOptions alloc] init];
    options.predicate = [NSPredicate predicateWithFormat:@"mediaType in %@", self.picker.mediaTypes];
    options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
    PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsWithOptions:options];
    [allFetchResultArray addObject:assetsFetchResult];
    [allFetchResultLabel addObject:NSLocalizedStringFromTableInBundle(@"picker.table.all-photos-label",  @"GMImagePicker", [NSBundle bundleForClass:GMImagePickerController.class], @"All photos")];
  }
  
  //User albums:
  NSMutableArray *userFetchResultArray = [[NSMutableArray alloc] init];
  NSMutableArray *userFetchResultLabel = [[NSMutableArray alloc] init];
  for(PHCollection *collection in topLevelUserCollections)
  {
    if ([collection isKindOfClass:[PHAssetCollection class]])
    {
      PHFetchOptions *options = [[PHFetchOptions alloc] init];
      options.predicate = [NSPredicate predicateWithFormat:@"mediaType in %@", self.picker.mediaTypes];
      PHAssetCollection *assetCollection = (PHAssetCollection *)collection;
      
      //Albums collections are allways PHAssetCollectionType=1 & PHAssetCollectionSubtype=2
      
      PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:options];
      [userFetchResultArray addObject:assetsFetchResult];
      [userFetchResultLabel addObject:collection.localizedTitle];
    }
  }
  
  
  //Smart albums: Sorted by descending creation date.
  NSMutableArray *smartFetchResultArray = [[NSMutableArray alloc] init];
  NSMutableArray *smartFetchResultLabel = [[NSMutableArray alloc] init];
  for(PHCollection *collection in smartAlbums)
  {
    if ([collection isKindOfClass:[PHAssetCollection class]])
    {
      PHAssetCollection *assetCollection = (PHAssetCollection *)collection;
      
      //Smart collections are PHAssetCollectionType=2;
      if(self.picker.customSmartCollections && [self.picker.customSmartCollections containsObject:@(assetCollection.assetCollectionSubtype)])
      {
        PHFetchOptions *options = [[PHFetchOptions alloc] init];
        options.predicate = [NSPredicate predicateWithFormat:@"mediaType in %@", self.picker.mediaTypes];
        options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
        
        PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:options];
        if(assetsFetchResult.count>0)
        {
          [smartFetchResultArray addObject:assetsFetchResult];
          [smartFetchResultLabel addObject:collection.localizedTitle];
        }
      }
    }
  }
  
  self.collectionsFetchResultsAssets= @[allFetchResultArray,smartFetchResultArray,userFetchResultArray];
  self.collectionsFetchResultsTitles= @[allFetchResultLabel,smartFetchResultLabel,userFetchResultLabel];
}


#pragma mark - Accessors

- (GMImagePickerController *)picker
{
  return (GMImagePickerController *)self.navigationController.parentViewController;
}


#pragma mark - Rotation

- (BOOL)shouldAutorotate
{
  return YES;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations
{
  return UIInterfaceOrientationMaskAllButUpsideDown;
}


#pragma mark - UITableViewDataSource

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
  return (NSInteger)self.collectionsFetchResultsAssets.count;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
  PHFetchResult *fetchResult = self.collectionsFetchResultsAssets[(NSUInteger)section];
  return (NSInteger)fetchResult.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
  static NSString *CellIdentifier = @"Cell";
  
  GMAlbumsViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
  if (cell == nil) {
    cell = [[GMAlbumsViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
  }
  
  // Increment the cell's tag
  NSInteger currentTag = cell.tag + 1;
  cell.tag = currentTag;
  
  // Set the label
  cell.textLabel.font = [UIFont fontWithName:self.picker.pickerFontName size:self.picker.pickerFontHeaderSize];
  cell.textLabel.text = (self.collectionsFetchResultsTitles[(NSUInteger)indexPath.section])[(NSUInteger)indexPath.row];
  cell.textLabel.textColor = self.picker.pickerTextColor;
  
  // Retrieve the pre-fetched assets for this album:
  PHFetchResult *assetsFetchResult = (self.collectionsFetchResultsAssets[(NSUInteger)indexPath.section])[(NSUInteger)indexPath.row];
  
  // Display the number of assets
  if (self.picker.displayAlbumsNumberOfAssets) {
    cell.detailTextLabel.font = [UIFont fontWithName:self.picker.pickerFontName size:self.picker.pickerFontNormalSize];
    cell.detailTextLabel.text = [self tableCellSubtitle:assetsFetchResult];
    cell.detailTextLabel.textColor = self.picker.pickerTextColor;
  }
  
  // Set the 3 images (if exists):
  if ([assetsFetchResult count] > 0) {
    CGFloat scale = [UIScreen mainScreen].scale;
    
    //Compute the thumbnail pixel size:
    CGSize tableCellThumbnailSize1 = CGSizeMake(kAlbumThumbnailSize1.width*scale, kAlbumThumbnailSize1.height*scale);
    PHAsset *asset = assetsFetchResult[0];
    [cell setVideoLayout:(asset.mediaType==PHAssetMediaTypeVideo)];
    [self.imageManager requestImageForAsset:asset
                                 targetSize:tableCellThumbnailSize1
                                contentMode:PHImageContentModeAspectFill
                                    options:nil
                              resultHandler:^(UIImage *result, NSDictionary *info) {
                                if (cell.tag == currentTag) {
                                  cell.imageView1.image = result;
                                }
                              }];
    
    // Second & third images:
    // TODO: Only preload the 3pixels height visible frame!
    if ([assetsFetchResult count] > 1) {
      //Compute the thumbnail pixel size:
      CGSize tableCellThumbnailSize2 = CGSizeMake(kAlbumThumbnailSize2.width*scale, kAlbumThumbnailSize2.height*scale);
      PHAsset *asset = assetsFetchResult[1];
      [self.imageManager requestImageForAsset:asset
                                   targetSize:tableCellThumbnailSize2
                                  contentMode:PHImageContentModeAspectFill
                                      options:nil
                                resultHandler:^(UIImage *result, NSDictionary *info) {
                                  if (cell.tag == currentTag) {
                                    cell.imageView2.image = result;
                                  }
                                }];
    } else {
      cell.imageView2.image = nil;
    }
    
    if ([assetsFetchResult count] > 2) {
      CGSize tableCellThumbnailSize3 = CGSizeMake(kAlbumThumbnailSize3.width*scale, kAlbumThumbnailSize3.height*scale);
      PHAsset *asset = assetsFetchResult[2];
      [self.imageManager requestImageForAsset:asset
                                   targetSize:tableCellThumbnailSize3
                                  contentMode:PHImageContentModeAspectFill
                                      options:nil
                                resultHandler:^(UIImage *result, NSDictionary *info) {
                                  if (cell.tag == currentTag) {
                                    cell.imageView3.image = result;
                                  }
                                }];
    } else {
      cell.imageView3.image = nil;
    }
  } else {
    [cell setVideoLayout:NO];
    cell.imageView3.image = [UIImage imageNamed:@"GMEmptyFolder"];
    cell.imageView2.image = [UIImage imageNamed:@"GMEmptyFolder"];
    cell.imageView1.image = [UIImage imageNamed:@"GMEmptyFolder"];
  }
  
  return cell;
}

#pragma mark - UITableViewDelegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
  UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
  
  // Init the GMGridViewController
  GMGridViewController *gridViewController = [[GMGridViewController alloc] initWithPicker:[self picker]];
  // Set the title
  gridViewController.title = cell.textLabel.text;
  // Use the prefetched assets!
  gridViewController.assetsFetchResults = [[_collectionsFetchResultsAssets objectAtIndex:(NSUInteger)indexPath.section] objectAtIndex:(NSUInteger)indexPath.row];
  
  // Remove selection so it looks better on slide in
  [tableView deselectRowAtIndexPath:indexPath animated:true];
  
  // Push GMGridViewController
  [self.navigationController pushViewController:gridViewController animated:YES];
}

-(void)tableView:(UITableView *)tableView willDisplayHeaderView:(UIView *)view forSection:(NSInteger)section
{
  UITableViewHeaderFooterView *header = (UITableViewHeaderFooterView *)view;
  //    header.contentView.backgroundColor = [UIColor clearColor];
  //    header.backgroundView.backgroundColor = [UIColor clearColor];
  
  // Default is a bold font, but keep this styled as a normal font
  header.textLabel.font = [UIFont fontWithName:self.picker.pickerFontName size:self.picker.pickerFontNormalSize];
  header.textLabel.textColor = self.picker.pickerTextColor;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
  //Tip: Returning nil hides the section header!
  
  NSString *title = nil;
  if (section > 0) {
    // Only show title for non-empty sections:
    PHFetchResult *fetchResult = self.collectionsFetchResultsAssets[(NSUInteger)section];
    if (fetchResult.count > 0) {
      title = self.collectionsLocalizedTitles[(NSUInteger)(section - 1)];
    }
  }
  return title;
}


#pragma mark - PHPhotoLibraryChangeObserver

- (void)photoLibraryDidChange:(PHChange *)changeInstance
{
  // Call might come on any background queue. Re-dispatch to the main queue to handle it.
  dispatch_async(dispatch_get_main_queue(), ^{
    
    NSMutableArray *updatedCollectionsFetchResults = nil;
    
    for (PHFetchResult *collectionsFetchResult in self.collectionsFetchResults) {
      PHFetchResultChangeDetails *changeDetails = [changeInstance changeDetailsForFetchResult:collectionsFetchResult];
      if (changeDetails) {
        if (!updatedCollectionsFetchResults) {
          updatedCollectionsFetchResults = [self.collectionsFetchResults mutableCopy];
        }
        [updatedCollectionsFetchResults replaceObjectAtIndex:[self.collectionsFetchResults indexOfObject:collectionsFetchResult] withObject:[changeDetails fetchResultAfterChanges]];
      }
    }
    
    // This only affects to changes in albums level (add/remove/edit album)
    if (updatedCollectionsFetchResults) {
      self.collectionsFetchResults = updatedCollectionsFetchResults;
    }
    
    // However, we want to update if photos are added, so the counts of items & thumbnails are updated too.
    // Maybe some checks could be done here , but for now is OKey.
    [self updateFetchResults];
    [self.tableView reloadData];
    
  });
}

#pragma mark - Cell Subtitle

- (NSString *)tableCellSubtitle:(PHFetchResult*)assetsFetchResult
{
  // Just return the number of assets. Album app does this:
  return [NSString stringWithFormat:@"%ld", (long)[assetsFetchResult count]];
}

@end