/*
 Copyright 2015 OpenMarket Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "SegmentedViewController.h"

#import "VectorDesignValues.h"

@interface SegmentedViewController ()
{
    // list of displayed UIViewControllers
    NSArray* viewControllers;
    
    // displayed viewController
    NSLayoutConstraint *displayedVCTopConstraint;
    NSLayoutConstraint *displayedVCLeftConstraint;
    NSLayoutConstraint *displayedVCWidthConstraint;
    NSLayoutConstraint *displayedVCHeightConstraint;
    
    // list of NSString
    NSArray* sectionTitles;
    
    // list of section labels
    NSArray* sectionLabels;
    
    // the selected marker view
    UIView* selectedMarkerView;
    NSLayoutConstraint *leftMarkerViewConstraint;
}

@end

@implementation SegmentedViewController

#pragma mark - Class methods

+ (UINib *)nib
{
    return [UINib nibWithNibName:NSStringFromClass([SegmentedViewController class])
                          bundle:[NSBundle bundleForClass:[SegmentedViewController class]]];
}

+ (instancetype)segmentedViewController
{
    return [[[self class] alloc] initWithNibName:NSStringFromClass([SegmentedViewController class])
                                          bundle:[NSBundle bundleForClass:[SegmentedViewController class]]];
}

/**
 init the segmentedViewController with a list of UIViewControllers.
 @param titles the section tiles
 @param viewControllers the list of viewControllers to display.
 @param defaultSelected index of the default selected UIViewController in the list.
 */
- (void)initWithTitles:(NSArray*)titles viewControllers:(NSArray*)someViewControllers defaultSelected:(NSUInteger)index
{
    viewControllers = someViewControllers;
    sectionTitles = titles;
    _selectedIndex = index;
}

- (void)setSelectedIndex:(NSUInteger)selectedIndex
{
    if (_selectedIndex != selectedIndex)
    {
        _selectedIndex = selectedIndex;
        [self displaySelectedViewController];
    }
}

#pragma mark -

- (void)addConstraint:(UIView*)view constraint:(NSLayoutConstraint*)aConstraint
{
    // sanity check
    if (view && aConstraint)
    {
        if ([NSLayoutConstraint respondsToSelector:@selector(activateConstraints:)])
        {
            [NSLayoutConstraint activateConstraints:@[aConstraint]];
        }
        else
        {
            [view addConstraint:aConstraint];
        }
    }
}

- (void)removeConstraint:(UIView*)view constraint:(NSLayoutConstraint*)aConstraint
{
    // sanity check
    if (view && aConstraint)
    {
        if ([NSLayoutConstraint respondsToSelector:@selector(deactivateConstraints:)])
        {
            [NSLayoutConstraint deactivateConstraints:@[aConstraint]];
        }
        else
        {
            [view removeConstraint:aConstraint];
        }
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Check whether the view controller has been pushed via storyboard
    if (!self.viewControllerContainer)
    {
        // Instantiate view controller objects
        [[[self class] nib] instantiateWithOwner:self options:nil];
    }

    // Adjust Top
    [self removeConstraint:self.view constraint:self.selectionContainerTopConstraint];
    
    // it is not possible to define a constraint to the topLayoutGuide in the xib editor
    // so do it in the code ..
    self.selectionContainerTopConstraint = [NSLayoutConstraint constraintWithItem:self.topLayoutGuide
                                                                  attribute:NSLayoutAttributeBottom
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:self.selectionContainer
                                                                  attribute:NSLayoutAttributeTop
                                                                 multiplier:1.0f
                                                                   constant:0.0f];
    
    [self addConstraint:self.selectionContainer constraint:self.selectionContainerTopConstraint];
    
    [self createSegmentedViews];
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    if (_selectedViewController)
    {
        // Make iOS invoke child viewWillAppear and viewDidAppear
        [_selectedViewController beginAppearanceTransition:YES animated:animated];
        [_selectedViewController endAppearanceTransition];
    }
}

- (void)createSegmentedViews
{
    NSMutableArray* labels = [[NSMutableArray alloc] init];
    
    NSUInteger count = viewControllers.count;
    
    for(NSUInteger index = 0; index < count; index++)
    {
        // create programmatically each label
        UILabel *label = [[UILabel alloc] init];
        
        label.text = [sectionTitles objectAtIndex:index];
        label.font = [UIFont systemFontOfSize:17];
        label.textAlignment = NSTextAlignmentCenter;
        label.textColor = VECTOR_GREEN_COLOR;
        label.backgroundColor = [UIColor clearColor];
        
        // the constraint defines the label frame
        // so ignore any autolayout stuff
        [label setTranslatesAutoresizingMaskIntoConstraints:NO];
        
        // add the label before setting the constraints
        [self.selectionContainer addSubview:label];
    
        NSLayoutConstraint *leftConstraint;
        if (labels.count)
        {
            leftConstraint = [NSLayoutConstraint constraintWithItem:label
                                                          attribute:NSLayoutAttributeLeading
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:[labels objectAtIndex:(index-1)]
                                                          attribute:NSLayoutAttributeTrailing
                                                         multiplier:1.0
                                                           constant:0];
        }
        else
        {
            leftConstraint = [NSLayoutConstraint constraintWithItem:label
                                         attribute:NSLayoutAttributeLeading
                                         relatedBy:NSLayoutRelationEqual
                                            toItem:self.selectionContainer
                                         attribute:NSLayoutAttributeLeading
                                        multiplier:1.0
                                          constant:0];
        }
        
        NSLayoutConstraint *rightConstraint = [NSLayoutConstraint constraintWithItem:label
                                                                           attribute:NSLayoutAttributeWidth
                                                                           relatedBy:NSLayoutRelationEqual
                                                                              toItem:self.selectionContainer
                                                                           attribute:NSLayoutAttributeWidth
                                                                          multiplier:1.0 / count
                                                                            constant:0];
        
        NSLayoutConstraint *topConstraint = [NSLayoutConstraint constraintWithItem:label
                                                                         attribute:NSLayoutAttributeTop
                                                                         relatedBy:NSLayoutRelationEqual
                                                                            toItem:self.selectionContainer
                                                                         attribute:NSLayoutAttributeTop
                                                                        multiplier:1.0
                                                                          constant:0];
        
        
        
        NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:label
                                                                            attribute:NSLayoutAttributeHeight
                                                                            relatedBy:NSLayoutRelationEqual
                                                                               toItem:self.selectionContainer
                                                                            attribute:NSLayoutAttributeHeight
                                                                           multiplier:1.0
                                                                             constant:0];
        
        
        // set the constraints
        if ([NSLayoutConstraint respondsToSelector:@selector(activateConstraints:)])
        {
            [NSLayoutConstraint activateConstraints:@[leftConstraint, rightConstraint, topConstraint, heightConstraint]];
        }
        else
        {
            [self.selectionContainer addConstraint:leftConstraint];
            [self.selectionContainer addConstraint:rightConstraint];
            [self.selectionContainer addConstraint:topConstraint];
            [label addConstraint:heightConstraint];
        }
        
        UITapGestureRecognizer *labelTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onLabelTouch:)];
        [labelTapGesture setNumberOfTouchesRequired:1];
        [labelTapGesture setNumberOfTapsRequired:1];
        label.userInteractionEnabled = YES;
        [label addGestureRecognizer:labelTapGesture];
            
        [labels addObject:label];
    }
    
    sectionLabels = labels;
    
    [self addSelectedMarkerView];
    
    [self displaySelectedViewController];
}

- (void)addSelectedMarkerView
{
    // create the selected marker view
    selectedMarkerView = [[UIView alloc] init];
    selectedMarkerView.backgroundColor = VECTOR_GREEN_COLOR;
    [selectedMarkerView setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.selectionContainer addSubview:selectedMarkerView];
    
    leftMarkerViewConstraint = [NSLayoutConstraint constraintWithItem:selectedMarkerView
                                                            attribute:NSLayoutAttributeLeading
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:[sectionLabels objectAtIndex:_selectedIndex]
                                                            attribute:NSLayoutAttributeLeading
                                                           multiplier:1.0
                                                             constant:0];
    
    
    NSLayoutConstraint *widthConstraint = [NSLayoutConstraint constraintWithItem:selectedMarkerView
                                                                       attribute:NSLayoutAttributeWidth
                                                                       relatedBy:NSLayoutRelationEqual
                                                                          toItem:self.selectionContainer
                                                                       attribute:NSLayoutAttributeWidth
                                                                      multiplier:1.0 / sectionLabels.count
                                                                        constant:0];
    
    NSLayoutConstraint *bottomConstraint = [NSLayoutConstraint constraintWithItem:selectedMarkerView
                                                                        attribute:NSLayoutAttributeBottom
                                                                        relatedBy:NSLayoutRelationEqual
                                                                           toItem:self.selectionContainer
                                                                        attribute:NSLayoutAttributeBottom
                                                                       multiplier:1.0
                                                                         constant:0];
    
    
    
    NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:selectedMarkerView
                                                                        attribute:NSLayoutAttributeHeight
                                                                        relatedBy:NSLayoutRelationEqual
                                                                           toItem:nil
                                                                        attribute:NSLayoutAttributeNotAnAttribute
                                                                       multiplier:1.0
                                                                         constant:3];
    
    // set the constraints
    if ([NSLayoutConstraint respondsToSelector:@selector(activateConstraints:)])
    {
        [NSLayoutConstraint activateConstraints:@[leftMarkerViewConstraint, widthConstraint, bottomConstraint, heightConstraint]];
    }
    else
    {
        [self.selectionContainer addConstraint:leftMarkerViewConstraint];
        [self.selectionContainer addConstraint:bottomConstraint];
        [selectedMarkerView addConstraint:heightConstraint];
        [selectedMarkerView addConstraint:heightConstraint];
    }
}

- (void)displaySelectedViewController
{
    if (_selectedViewController)
    {
        NSUInteger index = [viewControllers indexOfObject:_selectedViewController];
        
        if (index != NSNotFound)
        {
            UILabel* label = [sectionLabels objectAtIndex:index];
            label.font = [UIFont systemFontOfSize:17];
        }
        
        [_selectedViewController.view removeFromSuperview];
        [_selectedViewController removeFromParentViewController];
        
        [self removeConstraint:_selectedViewController.view constraint:displayedVCWidthConstraint];
        [self removeConstraint:_selectedViewController.view constraint:displayedVCHeightConstraint];
        [self removeConstraint:self.viewControllerContainer constraint:displayedVCTopConstraint];
        [self removeConstraint:self.viewControllerContainer constraint:displayedVCLeftConstraint];
    }
    
    UILabel* label = [sectionLabels objectAtIndex:_selectedIndex];
    label.font = [UIFont boldSystemFontOfSize:17];

    // update the marker view position
    [self removeConstraint:selectedMarkerView constraint:leftMarkerViewConstraint];

    leftMarkerViewConstraint = [NSLayoutConstraint constraintWithItem:selectedMarkerView
                                                            attribute:NSLayoutAttributeLeading
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:[sectionLabels objectAtIndex:_selectedIndex]
                                                            attribute:NSLayoutAttributeLeading
                                                           multiplier:1.0
                                                             constant:0];

    [self addConstraint:selectedMarkerView constraint:leftMarkerViewConstraint];

    // Set the new selected view controller
    _selectedViewController = [viewControllers objectAtIndex:_selectedIndex];

    // Make iOS invoke child viewWillAppear
    [_selectedViewController beginAppearanceTransition:YES animated:YES];

    [self addChildViewController:_selectedViewController];
    
    [_selectedViewController.view setTranslatesAutoresizingMaskIntoConstraints:NO];
    [self.viewControllerContainer addSubview:_selectedViewController.view];
    
    
    displayedVCTopConstraint = [NSLayoutConstraint constraintWithItem:_selectedViewController.view
                                                            attribute:NSLayoutAttributeTop
                                                            relatedBy:NSLayoutRelationEqual
                                                               toItem:self.viewControllerContainer
                                                            attribute:NSLayoutAttributeTop
                                                           multiplier:1.0f
                                                             constant:0.0f];
    [self addConstraint:self.viewControllerContainer constraint:displayedVCTopConstraint];
    
    displayedVCLeftConstraint = [NSLayoutConstraint constraintWithItem:_selectedViewController.view
                                                             attribute:NSLayoutAttributeLeading
                                                             relatedBy:NSLayoutRelationEqual
                                                                toItem:self.viewControllerContainer
                                                             attribute:NSLayoutAttributeLeading
                                                            multiplier:1.0f
                                                              constant:0.0f];
    
    [self addConstraint:self.viewControllerContainer constraint:displayedVCLeftConstraint];
    
    displayedVCWidthConstraint = [NSLayoutConstraint constraintWithItem:_selectedViewController.view
                                                                        attribute:NSLayoutAttributeWidth
                                                                        relatedBy:NSLayoutRelationEqual
                                                                           toItem:self.viewControllerContainer
                                                                        attribute:NSLayoutAttributeWidth
                                                                       multiplier:1.0
                                                                         constant:0];
    [self addConstraint:_selectedViewController.view constraint:displayedVCWidthConstraint];
    
    displayedVCHeightConstraint = [NSLayoutConstraint constraintWithItem:_selectedViewController.view
                                                              attribute:NSLayoutAttributeHeight
                                                              relatedBy:NSLayoutRelationEqual
                                                                 toItem:self.viewControllerContainer
                                                              attribute:NSLayoutAttributeHeight
                                                             multiplier:1.0
                                                               constant:0];
    [self addConstraint:_selectedViewController.view constraint:displayedVCHeightConstraint];
    
    [_selectedViewController didMoveToParentViewController:self];
    [_selectedViewController endAppearanceTransition];
 
    // refresh the navbar background color
    // to display if the homeserver is reachable.
    [self onMatrixSessionChange];
}

#pragma mark - Search

- (void)showSearch:(BOOL)animated
{
    [super showSearch:animated];

    // Show the tabs header
    if (animated)
    {
        [UIView animateWithDuration:.3 delay:0 options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseIn
                         animations:^{

                             self.selectionContainerHeightConstraint.constant = 44;
                             [self.view layoutIfNeeded];
                         }
                         completion:^(BOOL finished){
                         }];
    }
    else
    {
        self.selectionContainerHeightConstraint.constant = 44;
        [self.view layoutIfNeeded];
    }
}

- (void)hideSearch:(BOOL)animated
{
    [super hideSearch:animated];

    // Hide the tabs header
    if (animated)
    {
        [UIView animateWithDuration:.3 delay:0 options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseIn
                         animations:^{

                             self.selectionContainerHeightConstraint.constant = 0;
                             [self.view layoutIfNeeded];
                         }
                         completion:^(BOOL finished) {
                             // Go back to the main tab
                             // Do it at the end of the animation when the tabs header of the SegmentedVC is hidden
                             // so that the user cannot see the selection bar of this header moving
                             self.selectedIndex = 0;
                             self.selectedViewController.view.hidden = NO;
                         }];
    }
    else
    {
        self.selectionContainerHeightConstraint.constant = 0;
        [self.view layoutIfNeeded];

        // Go back to the recents tab
        self.selectedIndex = 0;
        self.selectedViewController.view.hidden = NO;
    }
}

#pragma mark - touch event

- (void)onLabelTouch:(UIGestureRecognizer*)gestureRecognizer
{
    NSUInteger pos = [sectionLabels indexOfObject:gestureRecognizer.view];
    
    // check if there is an update before triggering anything
    if ((pos != NSNotFound) && (_selectedIndex != pos))
    {
        // update the selected index
        _selectedIndex = pos;
        
        [self displaySelectedViewController];
    }
}

@end