import SwiftUI
import PhotosUI

/// 编辑资料:头像(PHPicker 选图上传)+ 昵称(改后 PATCH)。
struct ProfileEditView: View {
    @Environment(SessionStore.self) private var session
    @State private var nickname = ""
    @State private var avatarItem: PhotosPickerItem?
    @State private var saving = false
    @State private var uploading = false
    @State private var toast: String?
    private let service = UserService()

    var body: some View {
        Form {
            Section {
                HStack {
                    Spacer()
                    PhotosPicker(selection: $avatarItem, matching: .images) {
                        avatarThumb
                    }
                    Spacer()
                }
            }
            Section("昵称") {
                TextField("起个昵称", text: $nickname)
                    .onChange(of: nickname) { _, new in
                        nickname = String(new.prefix(16))
                    }
            }
            Section {
                Button {
                    Task { await saveNickname() }
                } label: {
                    Text(saving ? "保存中…" : "保存").frame(maxWidth: .infinity)
                }
                .disabled(saving || nickname.isEmpty)
            }
        }
        .navigationTitle("编辑资料")
        .navigationBarTitleDisplayMode(.inline)
        .onAppear { if nickname.isEmpty { nickname = session.user?.nickname ?? "" } }
        .onChange(of: avatarItem) { _, item in
            if let item { Task { await uploadAvatar(item) } }
        }
        .overlay(alignment: .bottom) { toastView }
    }

    private var avatarThumb: some View {
        AsyncImage(url: AppConfig.mediaURL(session.user?.avatarUrl)) { phase in
            if case .success(let image) = phase {
                image.resizable().aspectRatio(contentMode: .fill)
            } else {
                Image(systemName: "person.crop.circle.fill")
                    .resizable()
                    .foregroundStyle(AppColors.gray300)
            }
        }
        .frame(width: 88, height: 88)
        .clipShape(Circle())
        .overlay(alignment: .bottomTrailing) {
            Image(systemName: "camera.circle.fill")
                .font(.title3)
                .foregroundStyle(AppColors.brand)
                .background(Circle().fill(.white))
        }
        .opacity(uploading ? 0.5 : 1)
    }

    @ViewBuilder private var toastView: some View {
        if let toast {
            Text(toast)
                .font(.subheadline)
                .padding(.horizontal, 16).padding(.vertical, 10)
                .background(.black.opacity(0.8)).foregroundStyle(.white)
                .clipShape(Capsule()).padding(.bottom, 30)
                .task(id: toast) {
                    try? await Task.sleep(for: .seconds(2))
                    self.toast = nil
                }
        }
    }

    private func saveNickname() async {
        saving = true
        defer { saving = false }
        do {
            let updated = try await service.updateNickname(nickname)
            session.updateUser(updated)
            toast = "昵称已保存"
        } catch {
            toast = (error as? LocalizedError)?.errorDescription ?? "保存失败"
        }
    }

    private func uploadAvatar(_ item: PhotosPickerItem) async {
        uploading = true
        // 重置 avatarItem,使重选同一张图仍能再次触发(PhotosPickerItem 同图会生成新实例,但置 nil 更稳)
        defer { uploading = false; avatarItem = nil }
        guard let raw = try? await item.loadTransferable(type: Data.self),
              let jpeg = ImageDownsampler.jpeg(raw) else {
            toast = "图片读取失败"
            return
        }
        do {
            let updated = try await service.uploadAvatar(jpeg: jpeg)
            session.updateUser(updated)
            toast = "头像已更新"
        } catch {
            toast = (error as? LocalizedError)?.errorDescription ?? "上传失败"
        }
    }
}