import SwiftUI
import CoreModel
import CoreUI
import DesignSystem

public struct PlanSubmitScreen: View {
    private let viewModel: PlanSubmitViewModel
    private let type: PlanType
    private let periodKey: String

    @State private var content = ""
    @Environment(\.dismiss) private var dismiss

    public init(viewModel: PlanSubmitViewModel, type: PlanType, periodKey: String) {
        self.viewModel = viewModel
        self.type = type
        self.periodKey = periodKey
    }

    public var body: some View {
        contentView
            .navigationTitle("\(type.label) · \(periodKey)")
            .task { viewModel.load() }
            .onChange(of: viewModel.uiState) { _, newState in
                if case .success(let data) = newState, content.isEmpty, !data.content.isEmpty {
                    content = data.content
                }
            }
            .onChange(of: viewModel.saved) { _, saved in
                if saved { dismiss() }
            }
    }

    @ViewBuilder
    private var contentView: some View {
        switch viewModel.uiState {
        case .loading:
            LoadingView()
        case .error(let message):
            ErrorView(message: message) { viewModel.load() }
        case .success(let data):
            submitContent(data)
        }
    }

    private func submitContent(_ data: PlanSubmitData) -> some View {
        ScrollView {
            VStack(spacing: DS.Spacing.md) {
                if !data.canSubmit, let message = data.message {
                    Text(message)
                        .font(.caption)
                        .foregroundStyle(DS.Color.brandMuted)
                        .frame(maxWidth: .infinity, alignment: .leading)
                }

                VStack(alignment: .trailing, spacing: DS.Spacing.xs) {
                    TextEditor(text: $content)
                        .frame(minHeight: 120)
                        .scrollContentBackground(.hidden)
                        .padding(DS.Spacing.sm)
                        .background(data.canSubmit ? DS.Color.brandPaper : DS.Color.brandChip)
                        .clipShape(RoundedRectangle(cornerRadius: 12, style: .continuous))
                        .overlay(
                            RoundedRectangle(cornerRadius: 12, style: .continuous)
                                .stroke(DS.Color.disabled, lineWidth: 1)
                        )
                    Text("\(content.count)/1000")
                        .font(.caption)
                        .foregroundStyle(DS.Color.faintText)
                }

                HStack {
                    Text("＋ 添加图片（\(data.attachments.count)/4）")
                        .font(.subheadline)
                        .foregroundStyle(data.canSubmit ? DS.Color.brandGold : DS.Color.disabled)
                    Spacer()
                }
                .padding(DS.Spacing.sm)
                .frame(maxWidth: .infinity)
                .background(Color.white)
                .overlay(
                    RoundedRectangle(cornerRadius: 12, style: .continuous)
                        .stroke(data.canSubmit ? DS.Color.brandGold : DS.Color.disabled, lineWidth: 1)
                )

                Button(saveTitle(data)) {
                    viewModel.save(content: content)
                }
                .buttonStyle(.borderedProminent)
                .disabled(!(data.canSubmit && !content.isEmpty && !viewModel.saving))

                HistorySection(history: data.history)
            }
            .padding(DS.Spacing.md)
        }
        .background(DS.Color.brandPaper)
    }

    private func saveTitle(_ data: PlanSubmitData) -> String {
        if !data.canSubmit { return "不可提交" }
        if data.checked { return "保存修改" }
        return "保存计划"
    }
}

private struct HistorySection: View {
    let history: [MyPlanRecord]

    var body: some View {
        VStack(alignment: .leading, spacing: DS.Spacing.sm) {
            Text("历史计划")
                .font(.subheadline.bold())
                .foregroundStyle(DS.Color.brandDark)
            if history.isEmpty {
                EmptyStateView(title: "暂无历史计划", systemImage: "doc")
            } else {
                ForEach(history.indices, id: \.self) { index in
                    let item = history[index]
                    VStack(alignment: .leading, spacing: DS.Spacing.xs) {
                        Text("\(item.submittedTime) · \(item.status)")
                            .font(.caption)
                            .foregroundStyle(DS.Color.brandGold)
                        Text(item.content)
                            .font(.subheadline)
                            .foregroundStyle(DS.Color.brandBrown)
                    }
                    .padding(DS.Spacing.md)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .background(Color.white)
                    .clipShape(RoundedRectangle(cornerRadius: 12, style: .continuous))
                }
            }
        }
    }
}