from django.shortcuts import render, redirect, get_object_or_404
from django.contrib.auth.decorators import login_required
from django.contrib.auth import authenticate, login, logout
from django.contrib import messages
from django.http import HttpResponse, JsonResponse
from django.db.models import Count, Q
from django.core.paginator import Paginator
from django.conf import settings
from openpyxl import load_workbook
from io import BytesIO
from datetime import date, timedelta

from .models import Asset, Category, AssetChangeLog
from .forms import AssetForm, AssetImportForm, CategoryForm
from .excel_utils import (
    export_assets_to_excel, generate_import_template,
    import_assets_from_excel, STATUS_MAP,
)


# ─── 认证 ────────────────────────────────────────

def login_view(request):
    if request.user.is_authenticated:
        return redirect('dashboard')

    if request.method == 'POST':
        username = request.POST.get('username', '')
        password = request.POST.get('password', '')
        user = authenticate(request, username=username, password=password)
        if user is not None:
            login(request, user)
            next_url = request.GET.get('next', '/')
            return redirect(next_url)
        else:
            messages.error(request, '用户名或密码错误')

    return render(request, 'assetapp/login.html')


def logout_view(request):
    logout(request)
    return redirect('login')


# ─── 仪表盘 ──────────────────────────────────────

@login_required
def dashboard(request):
    total_assets = Asset.objects.count()
    status_stats = Asset.objects.values('status').annotate(count=Count('id'))
    status_data = {item['status']: item['count'] for item in status_stats}

    category_stats = Asset.objects.values('category__name').annotate(
        count=Count('id')
    ).order_by('-count')

    # 即将过保（30天内）
    today = date.today()
    expiring_soon = Asset.objects.filter(
        warranty_expire__lte=today + timedelta(days=30),
        warranty_expire__gte=today,
        status='in_use',
    ).count()
    expired = Asset.objects.filter(
        warranty_expire__lt=today,
        status='in_use',
    ).count()

    # 最近变更
    recent_changes = AssetChangeLog.objects.select_related('operator')[:10]

    context = {
        'total_assets': total_assets,
        'status_data': status_data,
        'status_map': STATUS_MAP,
        'category_stats': category_stats,
        'expiring_soon': expiring_soon,
        'expired': expired,
        'recent_changes': recent_changes,
    }
    return render(request, 'assetapp/dashboard.html', context)


# ─── 资产列表 ─────────────────────────────────────

@login_required
def asset_list(request):
    queryset = Asset.objects.select_related('category')

    # 搜索（模糊搜索所有字段）
    search = request.GET.get('search', '').strip()
    if search:
        queryset = queryset.filter(
            Q(asset_number__icontains=search) |
            Q(name__icontains=search) |
            Q(serial_number__icontains=search) |
            Q(ip_address__icontains=search) |
            Q(bmc_address__icontains=search) |
            Q(brand__icontains=search) |
            Q(model__icontains=search) |
            Q(location__icontains=search) |
            Q(cabinet__icontains=search) |
            Q(cabinet_position__icontains=search) |
            Q(responsible_person__icontains=search) |
            Q(department__icontains=search) |
            Q(user__icontains=search) |
            Q(business_type__icontains=search) |
            Q(gpu_type__icontains=search) |
            Q(gpu_count__icontains=search)
        )

    # 筛选
    category_id = request.GET.get('category')
    if category_id:
        queryset = queryset.filter(category_id=category_id)

    status = request.GET.get('status')
    if status:
        queryset = queryset.filter(status=status)

    cabinet = request.GET.get('cabinet')
    if cabinet:
        queryset = queryset.filter(cabinet__icontains=cabinet)

    business_type = request.GET.get('business_type')
    if business_type:
        queryset = queryset.filter(business_type=business_type)

    # 排序
    sort = request.GET.get('sort', 'id')
    valid_sorts = ['id', '-id', 'asset_number', '-asset_number', 'name', '-name',
                   'created_at', '-created_at', 'updated_at', '-updated_at',
                   'purchase_date', '-purchase_date']
    if sort not in valid_sorts:
        sort = '-created_at'
    queryset = queryset.order_by(sort)

    # 分页
    paginator = Paginator(queryset, settings.ASSETS_PER_PAGE)
    page_number = request.GET.get('page', 1)
    page_obj = paginator.get_page(page_number)

    categories = Category.objects.all()
    cabinets = sorted(set(
        Asset.objects.values_list('cabinet', flat=True)
        .exclude(cabinet='')
        .exclude(cabinet=None)
    ))
    business_types = sorted(set(
        Asset.objects.values_list('business_type', flat=True)
        .exclude(business_type='')
        .exclude(business_type=None)
    ))

    context = {
        'page_obj': page_obj,
        'search': search,
        'categories': categories,
        'current_category': category_id,
        'current_status': status,
        'current_cabinet': cabinet,
        'current_business_type': business_type,
        'cabinets': cabinets,
        'business_types': business_types,
        'status_map': STATUS_MAP,
        'sort': sort,
    }
    return render(request, 'assetapp/asset_list.html', context)


# ─── 资产详情 ─────────────────────────────────────

@login_required
def asset_detail(request, pk):
    asset = get_object_or_404(Asset.objects.select_related('category', 'created_by'), pk=pk)
    change_logs = asset.change_logs.select_related('operator')[:20]
    context = {
        'asset': asset,
        'change_logs': change_logs,
        'status_map': STATUS_MAP,
    }
    return render(request, 'assetapp/asset_detail.html', context)


# ─── 资产创建 ─────────────────────────────────────

@login_required
def asset_create(request):
    if request.method == 'POST':
        form = AssetForm(request.POST)
        if form.is_valid():
            asset = form.save(commit=False)
            asset.created_by = request.user
            asset.save()

            AssetChangeLog.objects.create(
                asset=asset,
                asset_number=asset.asset_number,
                action='create',
                description='创建资产',
                operator=request.user,
            )

            messages.success(request, f'资产 {asset.asset_number} 创建成功！')
            return redirect('asset_detail', pk=asset.pk)
    else:
        form = AssetForm()

    context = {'form': form, 'action': 'create'}
    return render(request, 'assetapp/asset_form.html', context)


# ─── 资产编辑 ─────────────────────────────────────

@login_required
def asset_update(request, pk):
    asset = get_object_or_404(Asset, pk=pk)

    if request.method == 'POST':
        form = AssetForm(request.POST, instance=asset)
        if form.is_valid():
            # 记录变更
            changes = []
            for field in form.changed_data:
                old_val = str(form.initial.get(field, ''))
                new_val = str(form.cleaned_data.get(field, ''))
                changes.append(f'{field}: {old_val} → {new_val}')

                AssetChangeLog.objects.create(
                    asset=asset,
                    asset_number=asset.asset_number,
                    action='update',
                    field_name=field,
                    old_value=str(form.initial.get(field, '')),
                    new_value=str(form.cleaned_data.get(field, '')),
                    operator=request.user,
                )

            asset = form.save()

            if changes:
                messages.success(request, f'已更新 {len(changes)} 个字段')
            return redirect('asset_detail', pk=asset.pk)
    else:
        form = AssetForm(instance=asset)

    context = {'form': form, 'action': 'update', 'asset': asset}
    return render(request, 'assetapp/asset_form.html', context)


# ─── 资产删除 ─────────────────────────────────────

@login_required
def asset_delete(request, pk):
    asset = get_object_or_404(Asset, pk=pk)

    if request.method == 'POST':
        AssetChangeLog.objects.create(
            asset_number=asset.asset_number,
            action='delete',
            description=f'删除资产: {asset.name}',
            operator=request.user,
        )
        asset.delete()
        messages.success(request, f'资产 {asset.asset_number} 已删除')
        return redirect('asset_list')

    context = {'asset': asset}
    return render(request, 'assetapp/asset_confirm_delete.html', context)


# ─── Excel导出 ────────────────────────────────────

@login_required
def asset_export(request):
    queryset = Asset.objects.select_related('category')

    # 支持筛选导出
    category_id = request.GET.get('category')
    if category_id:
        queryset = queryset.filter(category_id=category_id)

    status = request.GET.get('status')
    if status:
        queryset = queryset.filter(status=status)

    wb = export_assets_to_excel(queryset)

    output = BytesIO()
    wb.save(output)
    output.seek(0)

    AssetChangeLog.objects.create(
        asset_number='-',
        action='export',
        description=f'导出 {queryset.count()} 条资产记录',
        operator=request.user,
    )

    today_str = date.today().strftime('%Y%m%d')
    response = HttpResponse(
        output.read(),
        content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
    )
    response['Content-Disposition'] = f'attachment; filename=硬件资产_{today_str}.xlsx'
    return response


# ─── Excel导入 ────────────────────────────────────

@login_required
def asset_import(request):
    if request.method == 'POST':
        form = AssetImportForm(request.POST, request.FILES)
        if form.is_valid():
            try:
                wb = load_workbook(request.FILES['excel_file'])
                ws = wb.active

                category_map = {c.name: c for c in Category.objects.all()}
                results = import_assets_from_excel(ws, category_map, operator=request.user)

                if results['success'] > 0:
                    messages.success(request, f"成功导入 {results['success']} 条资产")

                if results['skipped'] > 0:
                    messages.warning(request, f"跳过 {results['skipped']} 条（资产编号重复）")

                if results['errors']:
                    for error in results['errors'][:10]:
                        messages.error(request, error)
                    if len(results['errors']) > 10:
                        messages.error(request, f"...还有 {len(results['errors']) - 10} 条错误")

            except Exception as e:
                messages.error(request, f'导入失败: {str(e)}')

            return redirect('asset_list')
    else:
        form = AssetImportForm()

    return render(request, 'assetapp/asset_import.html', {'form': form})


# ─── 下载导入模板 ──────────────────────────────────

@login_required
def download_template(request):
    wb = generate_import_template()
    output = BytesIO()
    wb.save(output)
    output.seek(0)

    response = HttpResponse(
        output.read(),
        content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
    )
    response['Content-Disposition'] = 'attachment; filename=资产导入模板.xlsx'
    return response


# ─── 变更记录 ─────────────────────────────────────

@login_required
def change_log_list(request):
    logs = AssetChangeLog.objects.select_related('operator', 'asset')

    asset_number = request.GET.get('asset_number', '').strip()
    if asset_number:
        logs = logs.filter(asset_number__icontains=asset_number)

    action = request.GET.get('action')
    if action:
        logs = logs.filter(action=action)

    paginator = Paginator(logs, 30)
    page_number = request.GET.get('page', 1)
    page_obj = paginator.get_page(page_number)

    context = {
        'page_obj': page_obj,
        'asset_number': asset_number,
        'current_action': action,
    }
    return render(request, 'assetapp/changelog.html', context)


# ─── 分类管理 ─────────────────────────────────────

@login_required
def category_list(request):
    categories = Category.objects.annotate(asset_count=Count('assets')).order_by('name')
    return render(request, 'assetapp/category_list.html', {'categories': categories})


@login_required
def category_create(request):
    if request.method == 'POST':
        form = CategoryForm(request.POST)
        if form.is_valid():
            form.save()
            messages.success(request, f'分类 "{form.instance.name}" 创建成功')
            return redirect('category_list')
    else:
        form = CategoryForm()

    return render(request, 'assetapp/category_form.html', {'form': form, 'action': 'create'})


@login_required
def category_update(request, pk):
    category = get_object_or_404(Category, pk=pk)
    if request.method == 'POST':
        form = CategoryForm(request.POST, instance=category)
        if form.is_valid():
            form.save()
            messages.success(request, f'分类 "{category.name}" 已更新')
            return redirect('category_list')
    else:
        form = CategoryForm(instance=category)

    return render(request, 'assetapp/category_form.html', {'form': form, 'action': 'update', 'category': category})


@login_required
def category_delete(request, pk):
    category = get_object_or_404(Category, pk=pk)
    asset_count = category.assets.count()
    if asset_count > 0:
        messages.error(request, f'分类 "{category.name}" 下还有 {asset_count} 个资产，无法删除')
        return redirect('category_list')

    if request.method == 'POST':
        category.delete()
        messages.success(request, f'分类 "{category.name}" 已删除')
        return redirect('category_list')

    return render(request, 'assetapp/category_confirm_delete.html', {'category': category})