//
//  MoleculeStackTemplate.swift
//  MVMCoreUI
//
//  Created by Scott Pfeil on 2/11/19.
//  Copyright © 2019 Verizon Wireless. All rights reserved.
//

import UIKit

open class MoleculeStackTemplate: ThreeLayerViewController, TemplateProtocol {

    var observer: NSKeyValueObservation?
    public var templateModel: TemplateModelProtocol?

    public func parseTemplateJSON() {
        guard let templateData = templateData() else {
            return
        }

        do {
            let decoder = JSONDecoder()
            let templateModel = try decoder.decode(StackPageTemplateModel.self, from: templateData)
            self.templateModel = templateModel
        } catch {
            MVMCoreUILoggingHandler.logDebugMessage(withDelegate: "error: \(error)")
        }
    }
    
    open override var loadObject: MVMCoreLoadObject? {
        didSet {
            if loadObject != oldValue {
                updateRequiredModules()
                observer?.invalidate()
                if let newObject = loadObject {
                    observer = newObject.observe(\MVMCoreLoadObject.pageJSON, options: [.old, .new]) { [weak self] (object, change) in
                        self?.updateRequiredModules()
                    }
                }
            }
        }
    }
    
    open override func spaceBetweenTopAndMiddle() -> CGFloat? {
        return 0
    }
    
    open override func viewForTop() -> UIView? {
        guard let headerModel = (templateModel as? StackPageTemplateModel)?.header,
            let molecule = MVMCoreUIMoleculeMappingObject.shared()?.createMolecule(headerModel, delegateObject() as? MVMCoreUIDelegateObject, true) else {
                return  nil
        }
        return molecule
    }
    
    open override func viewForMiddle() -> UIView? {

        guard let moleculeStackModel = (templateModel as? StackPageTemplateModel)?.moleculeStack else {
            return  nil
        }

        let stack = MoleculeStackView(frame: .zero)
        stack.useStackSpacingBeforeFirstItem = true
        stack.moleculesShouldSetHorizontalMargins = true
        stack.setWithModel(moleculeStackModel, delegateObject() as? MVMCoreUIDelegateObject, nil)
        return stack
    }
    
    override open func viewForBottom() -> UIView? {
        guard let footerModel = (templateModel as? StackPageTemplateModel)?.footer,
            let molecule = MVMCoreUIMoleculeMappingObject.shared()?.createMolecule(footerModel, delegateObject() as? MVMCoreUIDelegateObject, true) else {
            return  nil
        }
        return molecule
    }
    
    // MARK: - cache handling
    open override func pageTypesToListenFor() -> [Any]? {
        guard let pageType = self.pageType else {
            return super.pageTypesToListenFor()
        }
        return [pageType]
    }
    
    open override func modulesToListenFor() -> [Any]? {
        return loadObject?.requestParameters?.modules
    }
    
    /// Adds modules from requiredModules() to the MVMCoreViewControllerMapping.requiredModules map.
    open func updateRequiredModules() {
        if let requiredModules = requiredModules(), let pageType = pageType {
            MVMCoreViewControllerMappingObject.shared()?.addRequiredModules(toMapping: requiredModules, forPageType: pageType)
        }
    }
    
    /// Gets modules required by the loadObject.pageJSON.
    open func requiredModules() -> [Any]? {
        let modules: NSMutableArray = []
        let delegate = delegateObject() as? MVMCoreUIDelegateObject
        MVMCoreUIMoleculeMappingObject.addRequiredModules(forJSON: loadObject?.pageJSON?.optionalDictionaryForKey("header"), delegateObject: delegate, moduleList: modules, errorList: nil)
        MVMCoreUIMoleculeMappingObject.addRequiredModules(forJSON: loadObject?.pageJSON?.optionalDictionaryForKey("footer"), delegateObject: delegate, moduleList: modules, errorList: nil)
        MVMCoreUIMoleculeMappingObject.addRequiredModules(forJSON: loadObject?.pageJSON?.optionalDictionaryForKey("moleculeStack"), delegateObject: delegate, moduleList: modules, errorList: nil)
        return modules as? [Any]
    }
}