import AppKit
import SwiftUI

private enum MediaLibraryFilter: String, CaseIterable, Identifiable {
    case all = "全部"
    case movies = "电影"
    case series = "剧集"
    case unmatched = "未识别"
    var id: String { rawValue }
}

struct MediaLibraryPage: View {
    @ObservedObject var model: AppModel
    @State private var sourceID: String?
    @State private var sourceName = "云盘根目录"
    @State private var items: [MediaLibraryItem] = []
    @State private var selectedID: String?
    @State private var filter: MediaLibraryFilter = .all
    @State private var searchText = ""
    @State private var isLoading = false
    @State private var errorText = ""
    @State private var showFolderPicker = false

    private var filteredItems: [MediaLibraryItem] {
        items.filter { item in
            let matchesSearch = searchText.isEmpty || item.title.localizedCaseInsensitiveContains(searchText) || item.originalTitle.localizedCaseInsensitiveContains(searchText)
            let matchesFilter: Bool
            switch filter {
            case .all: matchesFilter = true
            case .movies: matchesFilter = item.mediaKind == .movie
            case .series: matchesFilter = item.mediaKind == .tv
            case .unmatched: matchesFilter = !item.isMatched
            }
            return matchesSearch && matchesFilter
        }
    }

    private var featuredItem: MediaLibraryItem? {
        selectedID.flatMap { id in items.first { $0.id == id } }
            ?? items.first(where: { $0.backdropData != nil })
            ?? items.first
    }

    var body: some View {
        ZStack {
            Color(red: 0.055, green: 0.06, blue: 0.06).ignoresSafeArea()
            ScrollView {
                LazyVStack(alignment: .leading, spacing: 0) {
                    if let featuredItem { featuredHero(featuredItem) }
                    libraryControls
                    libraryContent
                }
            }
        }
        .preferredColorScheme(.dark)
        .sheet(isPresented: $showFolderPicker) {
            ScanFolderPickerSheet(model: model, title: "选择影视库目录", selectionLabel: "设为影视库") { id, name in
                model.mediaLibraryTarget = nil
                sourceID = id
                sourceName = name
                Task { await loadLibrary() }
            }
        }
        .task {
            syncTarget()
            await loadLibrary()
        }
        .onChange(of: model.mediaLibraryTarget?.id) { _, _ in
            syncTarget()
            Task { await loadLibrary() }
        }
    }

    private func featuredHero(_ item: MediaLibraryItem) -> some View {
        ZStack(alignment: .bottomLeading) {
            MediaArtwork(data: item.backdropData ?? item.posterData, icon: item.file.isDirectory ? "folder.fill" : "film.fill", contentMode: .fill)
                .frame(maxWidth: .infinity)
                .frame(height: 330)
                .clipped()
            LinearGradient(colors: [.clear, Color.black.opacity(0.28), Color.black.opacity(0.92)], startPoint: .top, endPoint: .bottom)
            LinearGradient(colors: [Color.black.opacity(0.76), .clear], startPoint: .leading, endPoint: .trailing)
            VStack(alignment: .leading, spacing: 12) {
                HStack(spacing: 8) {
                    if let kind = item.mediaKind {
                        Text(kind == .movie ? "电影" : "剧集")
                    } else {
                        Text(item.file.isDirectory ? "媒体文件夹" : "云盘视频")
                    }
                    if !item.year.isEmpty { Text(item.year) }
                }
                .font(.caption.weight(.semibold)).foregroundStyle(.white.opacity(0.72))
                Text(item.title).font(.system(size: 34, weight: .bold)).foregroundStyle(.white).lineLimit(2)
                if !item.overview.isEmpty {
                    Text(item.overview).font(.callout).foregroundStyle(.white.opacity(0.78)).lineLimit(3).frame(maxWidth: 620, alignment: .leading)
                }
                HStack(spacing: 10) {
                    Button { open(item) } label: {
                        Label(item.file.isDirectory ? "浏览内容" : "播放", systemImage: item.file.isDirectory ? "rectangle.grid.2x2" : "play.fill")
                    }
                    .buttonStyle(.borderedProminent).tint(.white).foregroundStyle(.black)
                    if !item.file.isDirectory {
                        Button { Task { await model.download(item.file) } } label: { Label("下载", systemImage: "arrow.down.circle") }
                            .buttonStyle(.bordered)
                    }
                }
            }
            .padding(.horizontal, 34).padding(.bottom, 30)
        }
        .frame(height: 330)
    }

    private var libraryControls: some View {
        VStack(spacing: 14) {
            HStack(spacing: 14) {
                VStack(alignment: .leading, spacing: 3) {
                    Text("影视库").font(.title2.weight(.bold))
                    Text(sourceName).font(.caption).foregroundStyle(.secondary).lineLimit(1)
                }
                Spacer()
                TextField("搜索影片、剧集", text: $searchText)
                    .textFieldStyle(.plain)
                    .padding(.horizontal, 12).frame(width: 230, height: 34)
                    .background(Color.white.opacity(0.09), in: RoundedRectangle(cornerRadius: 6))
                Button { showFolderPicker = true } label: { Image(systemName: "folder") }.buttonStyle(.bordered).help("选择影视库目录")
                Button { Task { await loadLibrary() } } label: {
                    if isLoading { ProgressView().controlSize(.small) } else { Image(systemName: "arrow.clockwise") }
                }
                .buttonStyle(.bordered).help("刷新影视库").disabled(isLoading)
            }
            HStack {
                Picker("分类", selection: $filter) {
                    ForEach(MediaLibraryFilter.allCases) { Text($0.rawValue).tag($0) }
                }
                .pickerStyle(.segmented).labelsHidden().frame(width: 360)
                Spacer()
                Text("\(filteredItems.count) 项").font(.caption.monospacedDigit()).foregroundStyle(.secondary)
            }
        }
        .padding(.horizontal, 28).padding(.vertical, 20)
    }

    @ViewBuilder private var libraryContent: some View {
        if isLoading && items.isEmpty {
            VStack(spacing: 14) {
                ProgressView().controlSize(.large)
                Text("正在构建影视库…").font(.callout.weight(.medium))
                Text("正在匹配媒体信息与海报").font(.caption).foregroundStyle(.secondary)
            }
            .frame(maxWidth: .infinity).padding(.vertical, 90)
        } else if !errorText.isEmpty && items.isEmpty {
            ContentUnavailableView("影视库加载失败", systemImage: "exclamationmark.triangle", description: Text(errorText))
                .frame(maxWidth: .infinity).padding(.vertical, 70)
        } else if filteredItems.isEmpty {
            ContentUnavailableView("没有匹配的媒体", systemImage: "film.stack", description: Text("调整搜索或分类筛选。"))
                .frame(maxWidth: .infinity).padding(.vertical, 70)
        } else {
            LazyVGrid(columns: [GridItem(.adaptive(minimum: 145, maximum: 190), spacing: 18)], alignment: .leading, spacing: 24) {
                ForEach(filteredItems) { item in
                    MediaPosterCard(item: item, isSelected: selectedID == item.id) {
                        withAnimation(.easeInOut(duration: 0.18)) { selectedID = item.id }
                    } onOpen: {
                        open(item)
                    }
                    .contextMenu {
                        Button { open(item) } label: { Label(item.file.isDirectory ? "浏览内容" : "播放", systemImage: item.file.isDirectory ? "folder" : "play.fill") }
                        if !item.file.isDirectory { Button { Task { await model.download(item.file) } } label: { Label("下载", systemImage: "arrow.down.circle") } }
                        Button { Task { await model.share(item.file) } } label: { Label("分享", systemImage: "square.and.arrow.up") }
                    }
                }
            }
            .padding(.horizontal, 28).padding(.bottom, 36)
        }
    }

    private func syncTarget() {
        if let target = model.mediaLibraryTarget, target.isDirectory {
            sourceID = target.id
            sourceName = target.name
        } else {
            sourceID = model.currentScanRootID
            sourceName = model.scanScopeLocationName
        }
    }

    @MainActor private func loadLibrary() async {
        guard !isLoading else { return }
        isLoading = true
        errorText = ""
        defer { isLoading = false }
        do {
            let loaded = try await model.loadMediaLibrary(parentID: sourceID)
            items = loaded
            if !loaded.contains(where: { $0.id == selectedID }) { selectedID = loaded.first?.id }
        } catch is CancellationError { }
        catch { errorText = error.localizedDescription }
    }

    private func open(_ item: MediaLibraryItem) {
        if item.file.isDirectory {
            sourceID = item.file.id
            sourceName = item.title
            model.mediaLibraryTarget = item.file
            Task { await loadLibrary() }
        } else {
            Task { await model.playWithExternalPlayer(item.file) }
        }
    }
}

private struct MediaPosterCard: View {
    let item: MediaLibraryItem
    let isSelected: Bool
    let onSelect: () -> Void
    let onOpen: () -> Void
    @State private var isHovered = false

    var body: some View {
        Button(action: onSelect) {
            VStack(alignment: .leading, spacing: 9) {
                ZStack(alignment: .bottomTrailing) {
                    MediaArtwork(data: item.posterData, icon: item.file.isDirectory ? "folder.fill" : "film.fill", contentMode: .fill)
                        .aspectRatio(2 / 3, contentMode: .fit)
                        .frame(maxWidth: .infinity)
                        .clipShape(RoundedRectangle(cornerRadius: 6, style: .continuous))
                    if item.file.isDirectory {
                        Image(systemName: "rectangle.grid.2x2.fill").font(.caption.weight(.bold)).padding(7).background(.black.opacity(0.68), in: Circle()).padding(8)
                    } else if isHovered {
                        Image(systemName: "play.fill").font(.title3).frame(width: 42, height: 42).background(.white, in: Circle()).foregroundStyle(.black).padding(10)
                    }
                }
                .overlay { RoundedRectangle(cornerRadius: 6).stroke(isSelected ? Color.orange : Color.white.opacity(isHovered ? 0.38 : 0.10), lineWidth: isSelected ? 2 : 1) }
                Text(item.title).font(.callout.weight(.semibold)).lineLimit(1)
                HStack(spacing: 6) {
                    Text(item.year.isEmpty ? (item.file.isDirectory ? "文件夹" : "视频") : item.year)
                    if let kind = item.mediaKind { Text("·"); Text(kind == .movie ? "电影" : "剧集") }
                }
                .font(.caption).foregroundStyle(.secondary).lineLimit(1)
            }
            .contentShape(Rectangle())
        }
        .buttonStyle(.plain)
        .onHover { isHovered = $0 }
        .simultaneousGesture(TapGesture(count: 2).onEnded(onOpen))
    }
}

private struct MediaArtwork: View {
    let data: Data?
    let icon: String
    let contentMode: ContentMode

    var body: some View {
        Group {
            if let data, let image = NSImage(data: data) {
                Image(nsImage: image).resizable().aspectRatio(contentMode: contentMode)
            } else {
                ZStack {
                    LinearGradient(colors: [Color(red: 0.19, green: 0.22, blue: 0.20), Color(red: 0.08, green: 0.09, blue: 0.09)], startPoint: .topLeading, endPoint: .bottomTrailing)
                    Image(systemName: icon).font(.system(size: 42, weight: .light)).foregroundStyle(.white.opacity(0.28))
                }
            }
        }
    }
}