import APIClient
import SwiftUI
import WireProtocol

/// C2 · 项目 git 面板（web v0.6 `docs/plans/w6-project-git-panel.md` 的移动端对齐）。
///
/// 手机上不复制 web 的四列同步带 —— 那个布局在 720px 以下就会散架。语义完全一致，
/// 只把"带"改成竖排卡片：唯一的绿色仍然只有「已同步」可以拿到。
///
/// 安全：分支/上游/文件路径/提交主题/PR 标题**全是不可信服务器字节** ——
/// 一律 `Text(verbatim:)`（绝不 LocalizedStringKey/Markdown/链接探测）；PR 链接
/// 只在通过 `PrLink` 的 https+github.com 白名单后才可点。
struct GitPanelScreen: View {
    @State private var viewModel: GitPanelViewModel

    private enum Metrics {
        /// 提交信息输入框的行数区间（内容度量，非视觉 token）。
        static let commitEditorLines = 2...5
        /// 短 hash 展示长度（`git log --format=%h` 的常见宽度）。
        static let shortHashLength = 7
    }

    /// 整宽 DS 按钮的行内距（与 ProjectDetailScreen 的按钮行一致）。
    private static let buttonRowInsets = EdgeInsets(
        top: DS.Space.xs4, leading: DS.Space.lg16,
        bottom: DS.Space.xs4, trailing: DS.Space.lg16
    )

    init(viewModel: GitPanelViewModel) {
        _viewModel = State(initialValue: viewModel)
    }

    /// 生产入口：详情屏只需转手 endpoint/http/path。
    init(endpoint: HostEndpoint, http: any HTTPTransport, path: String) {
        self.init(viewModel: .forProject(endpoint: endpoint, http: http, path: path))
    }

    var body: some View {
        @Bindable var bindable = viewModel
        return List {
            stateSection
            feedbackSection
            changesSection
            commitSection(message: $bindable.commitMessage)
            pullRequestSection
            logSection
        }
        .listStyle(.insetGrouped)
        .navigationTitle(GitPanelCopy.title)
        .navigationBarTitleDisplayMode(.inline)
        .task {
            await viewModel.load()
            await viewModel.loadPullRequest() // gh 走外网，单独一条，不阻塞首屏
        }
        .refreshable {
            await viewModel.load()
            await viewModel.loadPullRequest()
        }
        .overlay {
            if !viewModel.isLoaded {
                ProgressView()
            }
        }
    }

    // MARK: - 同步状态

    @ViewBuilder private var stateSection: some View {
        Section(GitPanelCopy.stateSection) {
            if let band = viewModel.band {
                GitSyncBandView(band: band, branch: viewModel.branch)
                Button {
                    Task { await viewModel.fetchRemote() }
                } label: {
                    Label(GitPanelCopy.fetchButton, systemImage: "arrow.down.circle")
                }
                .buttonStyle(DSButtonStyle(kind: .secondary))
                .disabled(!viewModel.canFetch)
                .listRowInsets(Self.buttonRowInsets)
                .listRowBackground(Color.clear)
                .accessibilityHint(GitPanelCopy.fetchHint)
            }
            if let message = viewModel.stateErrorMessage {
                InlineMessage(text: message, tone: .error)
            }
        }
    }

    /// 写操作的成功/失败回执。服务器安全文案原样显示（`Text(verbatim:)`）。
    @ViewBuilder private var feedbackSection: some View {
        if viewModel.errorMessage != nil || viewModel.noticeMessage != nil {
            Section {
                if let message = viewModel.errorMessage {
                    InlineMessage(text: message, tone: .error)
                }
                if let message = viewModel.noticeMessage {
                    InlineMessage(text: message, tone: .success)
                }
            }
        }
    }

    // MARK: - 改动（stage / unstage）

    @ViewBuilder private var changesSection: some View {
        Section(GitPanelCopy.changesSection) {
            if let message = viewModel.changesErrorMessage {
                InlineMessage(text: message, tone: .error)
            }
            if viewModel.staged.isEmpty && viewModel.unstaged.isEmpty
                && viewModel.changesErrorMessage == nil {
                Text(GitPanelCopy.noChanges)
                    .font(DS.Typography.caption)
                    .foregroundStyle(DS.Palette.textSecondary)
            }
            ForEach(viewModel.staged) { file in
                changedFileRow(file, isStaged: true)
            }
            ForEach(viewModel.unstaged) { file in
                changedFileRow(file, isStaged: false)
            }
        }
    }

    private func changedFileRow(
        _ file: GitPanelViewModel.ChangedFile, isStaged: Bool
    ) -> some View {
        HStack(spacing: DS.Space.sm8) {
            VStack(alignment: .leading, spacing: DS.Space.xs2) {
                // 路径是服务器字节 → verbatim + 等宽中段截断。
                Text(verbatim: file.displayPath)
                    .font(DS.Typography.mono(.caption))
                    .foregroundStyle(DS.Palette.textPrimary)
                    .lineLimit(1)
                    .truncationMode(.middle)
                Text(GitChangeCopy.summary(file))
                    .dsMetaText()
            }
            Spacer(minLength: DS.Space.sm8)
            Button(isStaged ? GitPanelCopy.unstageButton : GitPanelCopy.stageButton) {
                Task { await viewModel.setStaged(file, staged: !isStaged) }
            }
            .font(DS.Typography.caption.weight(.semibold))
            .foregroundStyle(DS.Palette.accent)
            .frame(minWidth: DS.Layout.minHitTarget, minHeight: DS.Layout.minHitTarget)
            .disabled(viewModel.busy != nil)
        }
    }

    // MARK: - 提交 / 推送

    @ViewBuilder private func commitSection(message: Binding<String>) -> some View {
        Section(GitPanelCopy.commitSection) {
            TextField(GitPanelCopy.commitPlaceholder, text: message, axis: .vertical)
            .lineLimit(Metrics.commitEditorLines)
            .font(DS.Typography.body)
            .textInputAutocapitalization(.never)
            .autocorrectionDisabled()
            Button {
                Task { await viewModel.commit() }
            } label: {
                Label(GitPanelCopy.commitButton, systemImage: "checkmark.seal")
            }
            .buttonStyle(DSButtonStyle(kind: .primary))
            .disabled(!viewModel.canCommit)
            .listRowInsets(Self.buttonRowInsets)
            .listRowBackground(Color.clear)
            Button {
                Task { await viewModel.push() }
            } label: {
                Label(GitPanelCopy.pushButton, systemImage: "arrow.up.circle")
            }
            .buttonStyle(DSButtonStyle(kind: .secondary))
            .disabled(viewModel.busy != nil)
            .listRowInsets(Self.buttonRowInsets)
            .listRowBackground(Color.clear)
        }
    }

    // MARK: - PR / CI

    @ViewBuilder private var pullRequestSection: some View {
        if let pr = viewModel.pr {
            Section(GitPanelCopy.prSection) {
                PrStatusRow(status: pr)
            }
        }
    }

    // MARK: - 最近提交

    @ViewBuilder private var logSection: some View {
        Section(GitPanelCopy.logSection) {
            if let message = viewModel.logErrorMessage {
                InlineMessage(text: message, tone: .error)
            }
            if let log = viewModel.log {
                if log.commits.isEmpty {
                    Text(GitPanelCopy.noCommits)
                        .font(DS.Typography.caption)
                        .foregroundStyle(DS.Palette.textSecondary)
                }
                commitRows(log)
                if log.truncated {
                    Text(GitPanelCopy.truncatedLog)
                        .dsMetaText()
                }
            }
        }
    }

    @ViewBuilder private func commitRows(_ log: GitLogResult) -> some View {
        let boundary = GitLogBoundary.index(commits: log.commits, upstream: log.upstream)
        ForEach(Array(log.commits.enumerated()), id: \.element.hash) { index, commit in
            VStack(alignment: .leading, spacing: DS.Space.xs4) {
                commitRow(commit)
                // 未推送边界只画一次，且只在最后一个 unpushed 之后（w6/G4）。
                if index == boundary, let upstream = log.upstream {
                    UnpushedBoundary(upstream: upstream)
                }
            }
        }
    }

    private func commitRow(_ commit: CommitLogEntry) -> some View {
        HStack(alignment: .top, spacing: DS.Space.sm8) {
            Text(verbatim: String(commit.hash.prefix(Metrics.shortHashLength)))
                .font(DS.Typography.mono(.caption))
                .foregroundStyle(DS.Palette.textSecondary)
            VStack(alignment: .leading, spacing: DS.Space.xs2) {
                // 提交主题是服务器字节 → verbatim，两行上限。
                Text(verbatim: commit.subject)
                    .font(DS.Typography.callout)
                    .foregroundStyle(DS.Palette.textPrimary)
                    .lineLimit(2)
                Text(GitTimeFormat.relative(fromMs: Double(commit.at), nowMs: Date().timeIntervalSince1970 * 1_000))
                    .dsMetaText()
            }
            Spacer(minLength: 0)
            if commit.unpushed == true {
                Image(systemName: "arrow.up.circle")
                    .foregroundStyle(DS.Palette.statusWaiting)
                    .accessibilityLabel(GitChangeCopy.unpushedLabel)
            }
        }
    }
}

// MARK: - 文案（改动行摘要）

enum GitChangeCopy {
    static let unpushedLabel = "未推送"

    static func summary(_ file: GitPanelViewModel.ChangedFile) -> String {
        "\(statusLabel(file.status)) · +\(file.added) −\(file.removed)"
    }

    static func statusLabel(_ status: DiffFileStatus) -> String {
        switch status {
        case .modified: return "修改"
        case .added: return "新增"
        case .deleted: return "删除"
        case .renamed: return "重命名"
        case .binary: return "二进制"
        case .untracked: return "未跟踪"
        }
    }
}