TeachMate/TeachMate/Views/CourseFormView.swift

//
//  CourseFormView.swift
//  TeachMate
//
//  Created by Hongli on 2025/3/18.
//

import SwiftUI
import SwiftData

// 课程表单视图
struct CourseFormView: View {
    @Environment(\.dismiss) private var dismiss
    @Environment(\.modelContext) private var modelContext
    @Environment(\.colorScheme) private var colorScheme
    @Query private var semesters: [Semester]
    
    enum FormMode {
        case add
        case edit(CourseModel)
    }
    
    let mode: FormMode
    let onSave: (CourseModel) -> Void
    
    @State private var name: String = ""
    @State private var selectedColor: String = "#FCF3CF" // 默认黄色
    @State private var selectedSemester: Semester?
    
    // 可选颜色
    private let colorOptions = [
        "#FCF3CF", // 黄色
        "#D6EAF8", // 蓝色
        "#FADBD8", // 红色
        "#D5F5E3", // 绿色
        "#E8DAEF"  // 紫色
    ]
    
    private var isFormValid: Bool {
        !name.isEmpty && selectedSemester != nil
    }
    
    var body: some View {
        NavigationStack {
            courseFormContent
                .navigationTitle(navigationTitle)
                .toolbarRole(.editor)
                .toolbar {
                    ToolbarItem(placement: .cancellationAction) {
                        Button("取消") {
                            dismiss()
                        }
                    }
                    
                    ToolbarItem(placement: .confirmationAction) {
                        Button("保存") {
                            saveCourse()
                            dismiss()
                        }
                        .disabled(!isFormValid)
                    }
                }
                .onAppear {
                    setupInitialValues()
                }
        }
    }
    
    // Main content view
    private var courseFormContent: some View {
        ZStack {
            // Background
            (colorScheme == .dark ? Color.black : Color.gray.opacity(0.1))
                .ignoresSafeArea()
            
            // Main content with horizontal layout
            HStack(spacing: 0) {
                // Left side - Form content
                formFieldsSection
            }
            .frame(minWidth: 600, idealWidth: 700, maxHeight: .infinity)
        }
    }
    
    // Form fields section
    private var formFieldsSection: some View {
        ScrollView(.vertical) {
            VStack(spacing: 24) {
                // 课程信息
                FormSection(title: "课程信息") {
                    courseInfoSection
                }
                
                // 颜色选择
                FormSection(title: "课程颜色") {
                    colorSelectionSection
                }
            }
            .padding()
            .frame(maxWidth: .infinity)
        }
        .frame(minWidth: 300, idealWidth: 350, maxWidth: .infinity)
    }
    
    // Course information section
    private var courseInfoSection: some View {
        VStack(alignment: .leading, spacing: 16) {
            // Course name input
            VStack(alignment: .leading, spacing: 8) {
                TextField("课程名称", text: $name)
                    .textFieldStyle(RoundedBorderTextFieldStyle())
                    .autocorrectionDisabled()
                    .frame(maxWidth: .infinity)
                
                Text("请输入课程的完整名称")
                    .font(.caption)
                    .foregroundStyle(.secondary)
            }
            
            Divider()
            
            // 学期选择
            HStack {
                Text("学期:")
                    .foregroundStyle(.secondary)
                
                Spacer()
                
                Picker("学期", selection: $selectedSemester) {
                    if semesters.isEmpty {
                        Text("请先创建学期").tag(nil as Semester?)
                    } else {
                        ForEach(semesters) { semester in
                            Text(semester.title).tag(semester as Semester?)
                        }
                    }
                }
                .pickerStyle(.menu)
            }
            
            Divider()
        }
        .frame(maxWidth: .infinity)
    }
    
    // Color selection section
    private var colorSelectionSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack {
                ForEach(colorOptions, id: \.self) { colorHex in
                    Circle()
                        .fill(Color(hex: colorHex) ?? .gray)
                        .frame(width: 30, height: 30)
                        .overlay(
                            Circle()
                                .stroke(selectedColor == colorHex ? Color.black : Color.clear, lineWidth: 2)
                        )
                        .onTapGesture {
                            selectedColor = colorHex
                        }
                        .padding(5)
                }
            }
            
            Text("选择一个颜色来标识课程")
                .font(.caption)
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity)
    }
        
    private var navigationTitle: String {
        switch mode {
        case .add:
            return "添加课程"
        case .edit:
            return "编辑课程"
        }
    }
    
    private func setupInitialValues() {
        switch mode {
        case .add:
            // 如果有当前学期，默认选择它
            selectedSemester = semesters.first(where: { $0.isCurrent }) ?? semesters.first
        case .edit(let course):
            name = course.name
            selectedColor = course.colorHex
            selectedSemester = course.semester
        }
    }
    
    private func saveCourse() {
        switch mode {
        case .add:
            guard let semester = selectedSemester else { return }
            
            let newCourse = CourseModel(
                name: name,
                colorHex: selectedColor
            )
            newCourse.semester = semester
            onSave(newCourse)
            
        case .edit(let course):
            course.name = name
            course.colorHex = selectedColor
            course.semester = selectedSemester
            onSave(course)
        }
    }
}
#Preview("添加课程") {
    CourseFormView(mode: .add, onSave: { _ in })
        .modelContainer(PreviewData.createContainer())
}

#Preview("编辑课程") {
    CourseFormView(mode: .edit(PreviewData.createSampleCourse()), onSave: { _ in })
        .modelContainer(PreviewData.createContainer())
}