//
//  IssueMergeSectionController.swift
//  Freetime
//
//  Created by Ryan Nystrom on 2/11/18.
//  Copyright © 2018 Ryan Nystrom. All rights reserved.
//

import Foundation
import IGListKit

final class IssueMergeSectionController: ListBindingSectionController<IssueMergeModel>,
ListBindingSectionControllerDataSource,
MergeButtonDelegate,
ListBindingSectionControllerSelectionDelegate {

    private let model: IssueDetailsModel
    private let client: GithubClient
    private let resultID: String?
    private var isMergeCapable = false
    private var loading = false

    init(
        model: IssueDetailsModel,
        client: GithubClient,
        mergeCapable: Bool,
        resultID: String?
        ) {
        self.model = model
        self.client = client
        self.isMergeCapable = mergeCapable
        self.resultID = resultID
        super.init()
        dataSource = self
        selectionDelegate = self
        let row = Styles.Sizes.rowSpacing
        inset = UIEdgeInsets(top: 3*row, left: 0, bottom: row, right: 0)
    }

    // MARK: Private API

    var preferredMergeTypeKey: String {
        return "com.freetime.IssueMergeSectionController.PreferredMergeType.\(model.repo).\(model.owner)"
    }

    var preferredMergeType: IssueMergeType {
        // repo must have at least one merge method
        guard let availableTypes = self.object?.availableTypes, availableTypes.count > 0 else {
            return .merge
        }

        // make sure serialized type exists in repo spec. repo settings can change after pref is set.
        guard let type = IssueMergeType(rawValue: UserDefaults.standard.integer(forKey: preferredMergeTypeKey)),
            availableTypes.contains(type) else {
                return availableTypes[0]
        }
        return type
    }

    func set(preferredMergeType: IssueMergeType) {
        UserDefaults.standard.set(preferredMergeType.rawValue, forKey: preferredMergeTypeKey)
    }

    func merge() {
        guard let id = resultID,
            let previous: IssueResult = client.cache.get(id: id)
            else { return }
        loading = true
        update(animated: true)

        client.merge(
            previous: previous,
            owner: model.owner,
            repo: model.repo,
            number: model.number,
            type: preferredMergeType,
            error: { [weak self] in
                self?.loading = false
                self?.update(animated: true)
        })
    }

    // MARK: ListBindingSectionControllerDataSource

    func sectionController(
        _ sectionController: ListBindingSectionController<ListDiffable>,
        viewModelsFor object: Any
        ) -> [ListDiffable] {
        guard let object = self.object else { return [] }

        var viewModels = [ListDiffable]()

        if object.contexts.count > 0 {
            let states = object.contexts.map { $0.state }
            let (state, stateDescription) = MergeHelper.combinedMergeStatus(for: states)

            viewModels.append(IssueMergeSummaryModel(title: stateDescription, state: state))
        }

        viewModels += object.contexts as [ListDiffable]

        let title: String
        let state: IssueMergeSummaryModel.State
        let buttonEnabled: Bool
        switch object.state {
        case .clean, .hasHooks, .unstable:
            title = NSLocalizedString("No conflicts with base branch", comment: "")
            state = .success
            buttonEnabled = true
        case .behind:
            title = NSLocalizedString("Head ref is out of date", comment: "")
            state = .warning
            buttonEnabled = false
        case .blocked:
            title = NSLocalizedString("Not authorized to merge", comment: "")
            state = .failure
            buttonEnabled = false
        case .unknown, .__unknown:
            title = NSLocalizedString("Merge status unknown", comment: "")
            state = .pending
            buttonEnabled = false
        case .dirty:
            title = NSLocalizedString("Merge conflicts found", comment: "")
            state = .warning
            buttonEnabled = false
        }
        viewModels.append(IssueMergeSummaryModel(
            title: title,
            state: state
        ))

        if isMergeCapable {
            viewModels.append(IssueMergeButtonModel(
                enabled: buttonEnabled,
                type: preferredMergeType,
                loading: loading
            ))
        }

        return viewModels
    }

    func sectionController(
        _ sectionController: ListBindingSectionController<ListDiffable>,
        sizeForViewModel viewModel: Any,
        at index: Int
        ) -> CGSize {
        guard let width = collectionContext?.insetContainerSize.width
            else { fatalError() }
        let height: CGFloat
        switch viewModel {
        case is IssueMergeButtonModel: height = Styles.Sizes.tableCellHeightLarge
        default: height = Styles.Sizes.tableCellHeight
        }
        return CGSize(width: width, height: height)
    }

    func sectionController(
        _ sectionController: ListBindingSectionController<ListDiffable>,
        cellForViewModel viewModel: Any,
        at index: Int
        ) -> UICollectionViewCell & ListBindable {
        let cellType: (UICollectionViewCell & ListBindable).Type
        switch viewModel {
        case is IssueMergeButtonModel: cellType = IssueMergeButtonCell.self
        case is IssueMergeSummaryModel: cellType = IssueMergeSummaryCell.self
        case is IssueMergeContextModel: cellType = IssueMergeContextCell.self
        default: fatalError()
        }
        guard let cell = collectionContext?.dequeueReusableCell(of: cellType, for: self, at: index) as? UICollectionViewCell & ListBindable
            else { fatalError() }

        if let cell = cell as? CardCollectionViewCell {
            cell.border = index == 0
                ? index == self.viewModels.count - 1 ? .full : .head
                : index == self.viewModels.count - 1 ? .tail : .neck
        }
        if let cell = cell as? IssueMergeButtonCell {
            cell.delegate = self
        }

        return cell
    }

    // MARK: MergeButtonDelegate

    func didSelect(button: MergeButton) {

        viewController?.view.endEditing(true)

        let alert = UIAlertController.configured(
            title: NSLocalizedString("Confirm merge", comment: ""),
            message: NSLocalizedString("Are you sure you want to merge this pull request?", comment: ""),
            preferredStyle: .alert
        )
        alert.addActions([
            AlertAction.cancel(),
            AlertAction(AlertActionBuilder {
                $0.title = NSLocalizedString("Merge", comment: "")
                $0.style = .default
            }).get { [weak self] _ in
                self?.merge()
            }
            ])
        viewController?.present(alert, animated: trueUnlessReduceMotionEnabled)
    }

    func didSelectOptions(button: MergeButton) {
        guard let types = self.object?.availableTypes, types.count > 0 else { return }

        viewController?.view.endEditing(true)

        let alert = UIAlertController.configured(
            title: NSLocalizedString("Change merge type", comment: ""),
            preferredStyle: .actionSheet
        )
        alert.popoverPresentationController?.sourceView = button.optionIconView

        for type in types {
            alert.add(action: AlertAction(AlertActionBuilder {
                $0.title = type.localized
                $0.style = .default
            }).get { [weak self] _ in
                self?.set(preferredMergeType: type)
                self?.update(animated: true)
            })
        }

        alert.add(action: AlertAction.cancel())
        viewController?.present(alert, animated: trueUnlessReduceMotionEnabled)
    }

    // MARK: ListBindingSectionControllerSelectionDelegate

    func sectionController(
        _ sectionController: ListBindingSectionController<ListDiffable>,
        didSelectItemAt index: Int,
        viewModel: Any
        ) {
        guard let viewModel = viewModel as? IssueMergeContextModel else { return }
        viewController?.presentSafari(url: viewModel.targetURL)
    }

}