import SwiftUI

// MARK: - 通用文本输入组件
struct TextInputView: View {
    @Binding var content: String
    @FocusState var isContentFieldFocused: Bool
    let placeholder: String
    let maxCharacters: Int
    
    var body: some View {
        VStack(spacing: 8) {
            ZStack {
                // 输入框主体
                TextEditor(text: $content)
                    .frame(minHeight: 120)
                    .padding(8)
                    .background(Color(.systemBackground))
                    .cornerRadius(8)
                    .overlay(
                        RoundedRectangle(cornerRadius: 8)
                            .stroke(isContentFieldFocused ? Color.blue : Color(.systemGray4), lineWidth: 1)
                    )
                    .focused($isContentFieldFocused)
                    .onChange(of: content) { newValue in
                        // 限制最大字符数
                        if newValue.count > maxCharacters {
                            content = String(newValue.prefix(maxCharacters))
                        }
                    }
                    .toolbar {
                        ToolbarItemGroup(placement: .keyboard) {
                            Spacer()
                            Button("完成") {
                                isContentFieldFocused = false
                            }
                            .foregroundColor(.blue)
                            .font(.system(size: 16, weight: .medium))
                        }
                    }
                
                // 占位符文本 - 左上角对齐
                if content.isEmpty && !isContentFieldFocused {
                    VStack {
                        HStack {
                            Text(placeholder)
                                .foregroundColor(.secondary)
                                .font(.body)
                            Spacer()
                        }
                        Spacer()
                    }
                    .padding(16)
                    .allowsHitTesting(false)
                    .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
                }
            }

            // 字符计数和限制提示 - 输入框底下
            HStack {
                Spacer() // Pushes content to the right

                VStack(alignment: .trailing, spacing: 4) {
                    // 字符限制提示
                    if content.count >= maxCharacters {
                        HStack(spacing: 4) {
                            Image(systemName: "exclamationmark.triangle")
                                .font(.caption)
                                .foregroundColor(.orange)
                            Text("已达到最大字符数")
                                .font(.caption)
                                .foregroundColor(.orange)
                        }
                    } else if content.count >= Int(Double(maxCharacters) * 0.93) {
                        HStack(spacing: 4) {
                            Image(systemName: "info.circle")
                                .font(.caption)
                                .foregroundColor(.blue)
                            Text("接近字符限制")
                                .font(.caption)
                                .foregroundColor(.blue)
                        }
                    }

                    // 字符计数
                    Text("\(content.count)/\(maxCharacters)")
                        .font(.caption)
                        .foregroundColor(getCharacterCountColor())
                }
            }
        }
    }
    
    private func getCharacterCountColor() -> Color {
        if content.count >= maxCharacters {
            return .orange
        } else if content.count >= Int(Double(maxCharacters) * 0.93) {
            return .blue
        } else {
            return .secondary
        }
    }
}

#Preview {
    TextInputView(
        content: .constant(""),
        placeholder: "输入任意文本内容...",
        maxCharacters: 150
    )
}