//
//  TravelAlbumAIRetouchTemplateViewModel.swift
//  suixinkan
//

import Foundation

/// AI 修图模板选择状态，负责实时加载、按工作流单选、校验和任务提交。
final class TravelAlbumAIRetouchTemplateViewModel {
    private(set) var refinedTemplates: [TravelAlbumAIRetouchTemplate] = []
    private(set) var atmosphereTemplates: [TravelAlbumAIRetouchTemplate] = []
    private(set) var coverTemplates: [TravelAlbumAIRetouchTemplate] = []
    private(set) var selectedRefinedTemplateId: Int?
    private(set) var selectedAtmosphereTemplateId: Int?
    private(set) var selectedCoverTemplateId: Int?
    private(set) var isLoading = false
    private(set) var isSubmitting = false
    private(set) var loadErrorMessage: String?

    let scenicId: Int
    let workflow: TravelAlbumAIRetouchWorkflow

    var onStateChange: (() -> Void)?
    var onShowMessage: ((String) -> Void)?
    var onSubmitted: (() -> Void)?

    /// 创建首次 AI 修图模板状态；素材 ID 会排序并去重，确保提交稳定。
    convenience init(albumId: Int, scenicId: Int, materialIds: [Int]) {
        self.init(
            scenicId: scenicId,
            workflow: .initial(albumId: albumId, materialIds: materialIds)
        )
    }

    /// 使用明确工作流创建模板选择状态。
    init(scenicId: Int, workflow: TravelAlbumAIRetouchWorkflow) {
        self.scenicId = scenicId
        switch workflow {
        case .initial(let albumId, let materialIds):
            self.workflow = .initial(
                albumId: albumId,
                materialIds: Array(Set(materialIds)).sorted()
            )
        case .reretouch:
            self.workflow = workflow
        }
    }

    /// 当前工作流需要展示的模板分组。
    var visibleCategories: [TravelAlbumAIRetouchTemplateCategory] {
        workflow.visibleCategories
    }

    /// 当前分组是否为选填。
    func isOptional(_ category: TravelAlbumAIRetouchTemplateCategory) -> Bool {
        workflow.isOptional(category)
    }

    /// 当前必选模板或业务参数缺失时用于底部提示的文案。
    var validationMessage: String? {
        guard !isLoading, loadErrorMessage == nil else { return nil }
        guard workflow.isValid else {
            if case .reretouch = workflow {
                return "当前图片缺少修图批次，请刷新后重试"
            }
            return "请选择要修图的照片"
        }
        for category in visibleCategories where !isOptional(category) {
            if templates(for: category).isEmpty || selectedTemplateId(for: category) == nil {
                return unavailableMessage(for: category)
            }
        }
        return nil
    }

    /// 是否满足提交条件。
    var canSubmit: Bool {
        !isLoading
            && !isSubmitting
            && loadErrorMessage == nil
            && workflow.isValid
            && validationMessage == nil
    }

    /// 实时拉取当前景区模板并按工作流设置默认选择。
    func loadTemplates(api: any TravelAlbumServing) async {
        guard scenicId > 0 else {
            loadErrorMessage = "请先选择景区"
            notifyStateChange()
            return
        }
        guard !isLoading else { return }
        isLoading = true
        loadErrorMessage = nil
        notifyStateChange()

        do {
            let response = try await api.aiRetouchTemplates(scenicId: scenicId)
            refinedTemplates = response.refinedTemplates
            atmosphereTemplates = response.atmosphereTemplates
            coverTemplates = response.coverTemplates
            selectedRefinedTemplateId = visibleCategories.contains(.refined) ? refinedTemplates.first?.id : nil
            selectedAtmosphereTemplateId = visibleCategories.contains(.atmosphere) && !isOptional(.atmosphere)
                ? atmosphereTemplates.first?.id
                : nil
            selectedCoverTemplateId = visibleCategories.contains(.cover) ? coverTemplates.first?.id : nil
            isLoading = false
            notifyStateChange()
        } catch is CancellationError {
            isLoading = false
            notifyStateChange()
        } catch {
            refinedTemplates = []
            atmosphereTemplates = []
            coverTemplates = []
            selectedRefinedTemplateId = nil
            selectedAtmosphereTemplateId = nil
            selectedCoverTemplateId = nil
            isLoading = false
            loadErrorMessage = error.localizedDescription.isEmpty ? "模板加载失败" : error.localizedDescription
            notifyStateChange()
        }
    }

    /// 返回指定分组的模板。
    func templates(for category: TravelAlbumAIRetouchTemplateCategory) -> [TravelAlbumAIRetouchTemplate] {
        switch category {
        case .refined: refinedTemplates
        case .atmosphere: atmosphereTemplates
        case .cover: coverTemplates
        }
    }

    /// 返回指定分组当前选中的模板 ID。
    func selectedTemplateId(for category: TravelAlbumAIRetouchTemplateCategory) -> Int? {
        switch category {
        case .refined: selectedRefinedTemplateId
        case .atmosphere: selectedAtmosphereTemplateId
        case .cover: selectedCoverTemplateId
        }
    }

    /// 选择模板；仅选填分组允许再次点击取消，必选分组保持单选。
    func toggleTemplate(id: Int, category: TravelAlbumAIRetouchTemplateCategory) {
        guard visibleCategories.contains(category),
              templates(for: category).contains(where: { $0.id == id })
        else { return }
        switch category {
        case .refined:
            selectedRefinedTemplateId = id
        case .atmosphere:
            selectedAtmosphereTemplateId = isOptional(category) && selectedAtmosphereTemplateId == id ? nil : id
        case .cover:
            selectedCoverTemplateId = id
        }
        notifyStateChange()
    }

    /// 按当前工作流提交首次修图或覆盖重修任务。
    func submit(api: any TravelAlbumServing) async {
        guard !isSubmitting else { return }
        guard canSubmit else {
            onShowMessage?(validationMessage ?? "当前无法提交AI修图")
            return
        }

        isSubmitting = true
        notifyStateChange()
        defer {
            isSubmitting = false
            notifyStateChange()
        }

        do {
            switch workflow {
            case .initial(let albumId, let materialIds):
                guard let refinedTemplateId = selectedRefinedTemplateId else {
                    onShowMessage?("请选择原图精修模板")
                    return
                }
                try await api.submitAIRetouch(
                    TravelAlbumAIRetouchRequest(
                        userEquityTravelId: albumId,
                        materialIds: materialIds,
                        refinedTemplateId: refinedTemplateId,
                        atmosphereTemplateId: selectedAtmosphereTemplateId,
                        coverTemplateId: selectedCoverTemplateId
                    )
                )
            case .reretouch(let materialId, let batchId, let type):
                try await api.submitAIReretouch(
                    TravelAlbumAIReretouchRequest(
                        id: materialId,
                        aiRetouchBatchId: batchId,
                        type: type,
                        refinedTemplateId: type == .atmosphere ? nil : selectedRefinedTemplateId,
                        atmosphereTemplateId: type == .refined ? nil : selectedAtmosphereTemplateId
                    )
                )
            }
            onSubmitted?()
        } catch is CancellationError {
            return
        } catch {
            onShowMessage?(error.localizedDescription.isEmpty ? "AI修图任务提交失败" : error.localizedDescription)
        }
    }

    private func unavailableMessage(for category: TravelAlbumAIRetouchTemplateCategory) -> String {
        switch category {
        case .refined: "暂无可用的原图精修模板"
        case .atmosphere: "暂无可用的氛围感修图模板"
        case .cover: "暂无可用的封面风格模板"
        }
    }

    private func notifyStateChange() {
        onStateChange?()
    }
}