import SwiftUI

/// 播放区 + 悬浮信息 + 进度/句面板。训练与全屏横屏共用。
struct PlayerSectionView: View {
    @ObservedObject var controller: PlayerController
    var showsContinuousToggle: Bool
    @Binding var continuousPlayback: Bool
    var showsSubtitle: Binding<Bool>? = .constant(true)
    var onFullscreen: () -> Void

    @State private var progressDragging = false
    @State private var dragPositionMs: Int64 = 0
    @State private var explanationSentence: SentenceBoundary?

    var body: some View {
        VStack(spacing: 0) {
            playerSurface
            if showsSubtitle?.wrappedValue == true {
                sentencePanel
            }
        }
        .padding(.horizontal, 16)
        .sheet(item: $explanationSentence) { sentence in
            SentenceExplanationSheet(
                courseTitle: controller.currentItem?.title ?? "口语训练课程",
                sentence: sentence
            )
        }
    }

    private var playerSurface: some View {
        ZStack {
            PlayerSurfaceView(controller: controller)
                .aspectRatio(16.0 / 9.0, contentMode: .fit)
                .frame(maxWidth: .infinity)
            VStack {
                HStack(spacing: 8) {
                    overlayPill(timeText)
                    Spacer()
                    Button(action: cycleSpeed) {
                        overlayPill(Theme.formatSpeed(controller.snapshot.speed))
                    }
                    .buttonStyle(.plain)
                }
                Spacer()
            }
            .padding(12)
            VStack {
                Spacer()
                HStack {
                    Spacer()
                    Button(action: onFullscreen) {
                        Image(systemName: "arrow.up.left.and.arrow.down.right")
                            .font(.system(size: 18, weight: .bold))
                            .foregroundColor(.white)
                            .frame(width: 44, height: 44)
                            .background(Theme.overlay)
                            .clipShape(Circle())
                    }
                    .buttonStyle(.plain)
                }
            }
            .padding(12)
        }
        .background(Color.black)
        .clipShape(RoundedRectangle(cornerRadius: 8))
        .overlay(
            RoundedRectangle(cornerRadius: 8)
                .stroke(Theme.border, lineWidth: 1)
        )
        .padding(.bottom, 10)
    }

    private var sentencePanel: some View {
        VStack(alignment: .leading, spacing: 6) {
            Text(controller.currentItem?.title ?? "未选择课程")
                .font(.system(size: 17, weight: .bold))
                .foregroundColor(.white)
                .lineLimit(1)
            if showsContinuousToggle {
                HStack(spacing: 0) {
                    Text("连续播放")
                        .font(.system(size: 13, weight: .bold))
                        .foregroundColor(Theme.textSubtle)
                    Spacer()
                    Toggle("", isOn: $continuousPlayback)
                        .labelsHidden()
                        .tint(Theme.accent)
                }
                .padding(.vertical, 2)
            }
            Text(sentenceMetaText)
                .font(.system(size: 13))
                .foregroundColor(Theme.textSubtle)
            HStack(alignment: .center, spacing: 8) {
                Text(sentenceTextText)
                .font(.system(size: 15))
                    .foregroundColor(.white)
                    .lineLimit(2)
                Spacer()
                Button {
                    guard let sentence = controller.currentSentence, !(sentence.text ?? "").isEmpty else {
                        return
                    }
                    controller.pause()
                    explanationSentence = sentence
                } label: {
                    Image(systemName: "lightbulb.circle.fill")
                        .font(.system(size: 23, weight: .semibold))
                        .foregroundColor(
                            controller.currentSentence?.text?.isEmpty == false
                                ? Theme.accentLight
                                : Theme.textSubtle
                        )
                        .frame(width: 32, height: 32)
                        .background(Theme.overlay)
                        .clipShape(Circle())
                        .accessibilityLabel("AI 讲解这句话")
                }
                .buttonStyle(.plain)
            }
            progressRow
            Text(statusText)
                .font(.system(size: 13))
                .foregroundColor(Theme.textSubtle)
        }
        .padding(.bottom, 10)
    }

    private var progressRow: some View {
        let duration = controller.snapshot.durationMs
        return HStack(spacing: 8) {
            Slider(
                value: progressBinding,
                in: 0...max(1, Double(duration)),
                onEditingChanged: { editing in
                    if editing {
                        progressDragging = true
                    } else {
                        progressDragging = false
                        controller.seek(to: dragPositionMs)
                    }
                }
            )
            .tint(Theme.accent)
        }
    }

    private var progressBinding: Binding<Double> {
        Binding(
            get: {
                if progressDragging {
                    return Double(dragPositionMs)
                }
                return Double(controller.snapshot.positionMs)
            },
            set: { newValue in
                dragPositionMs = Int64(newValue)
            }
        )
    }

    private var timeText: String {
        let snapshot = controller.snapshot
        return "\(Theme.formatTime(snapshot.positionMs)) / \(Theme.formatTime(snapshot.durationMs))"
    }

    private var sentenceMetaText: String {
        switch controller.boundaryState {
        case .loading(let isLocal):
            return isLocal ? "句子边界分析中" : "句子边界加载中"
        case .failed:
            return "暂无句子边界"
        case .idle, .loaded:
            guard let sentence = controller.currentSentence else {
                return "暂无句子边界"
            }
            let count = controller.currentItem?.sentences.count ?? 0
            let countText = count > 0 ? " / \(count)" : ""
            return "第 \(sentence.index + 1)\(countText) 句  \(Theme.formatTime(sentence.startMs))-\(Theme.formatTime(sentence.endMs))"
        }
    }

    private var sentenceTextText: String {
        switch controller.boundaryState {
        case .loading(let isLocal):
            if isLocal {
                return "正在匹配服务端句子边界"
            }
            return controller.currentItem?.title ?? "加载中"
        case .failed:
            return ""
        case .idle, .loaded:
            guard let sentence = controller.currentSentence else {
                return ""
            }
            if let text = sentence.text, !text.isEmpty {
                return text
            }
            return "当前句子"
        }
    }

    private var statusText: String {
        if let message = controller.cacheState.statusMessage {
            return message
        }
        if let message = controller.transientMessage {
            return message
        }
        return controller.playbackStatusText(controller.snapshot)
    }

    private func overlayPill(_ text: String) -> some View {
        Text(text)
            .font(.system(size: 13, weight: .bold))
            .foregroundColor(.white)
            .padding(.horizontal, 10)
            .padding(.vertical, 6)
            .background(Theme.overlay)
            .clipShape(RoundedRectangle(cornerRadius: 8))
    }

    private func cycleSpeed() {
        let current = controller.snapshot.speed
        let cycle: [Float] = [1.0, 1.25, 1.5, 1.75, 2.0]
        let next = cycle.first { $0 > current + 0.001 } ?? cycle.first ?? 1.0
        controller.setPlaybackSpeed(next)
    }
}

struct SentenceExplanationSheet: View {
    let courseTitle: String
    let sentence: SentenceBoundary

    @State private var explanation = ""
    @State private var errorMessage: String?

    var body: some View {
        NavigationView {
            ScrollView {
                VStack(alignment: .leading, spacing: 14) {
                    Text(sentence.text ?? "")
                        .font(.system(size: 18, weight: .bold))
                        .foregroundColor(Theme.textDark)
                    if let errorMessage {
                        Text(errorMessage)
                            .font(.system(size: 15))
                            .foregroundColor(Theme.danger)
                    } else if explanation.isEmpty {
                        Text("AI 正在讲解这句话…")
                            .font(.system(size: 15))
                            .foregroundColor(Theme.textSubtle)
                    } else {
                        Text(explanation)
                            .font(.system(size: 16))
                            .foregroundColor(Theme.textDark)
                            .lineSpacing(5)
                    }
                }
                .frame(maxWidth: .infinity, alignment: .leading)
                .padding(20)
            }
            .background(Color.white.ignoresSafeArea())
            .navigationTitle("句子讲解")
            .navigationBarTitleDisplayMode(.inline)
        }
        .task {
            guard explanation.isEmpty, errorMessage == nil else { return }
            do {
                explanation = try await SentenceBoundaryAPI.explain(
                    sentence,
                    courseTitle: courseTitle
                )
            } catch {
                errorMessage = "讲解失败：\(error.localizedDescription)"
            }
        }
    }
}