changes

api/urls.py

@@ -53,5 +53,6 @@ urlpatterns = [
     re_path('generate-document/$',views.generate_document),
     re_path('model-fields/(?P<name>.+)/', importdata.model_fields),
     re_path('read-excel/', importdata.read_excel),
-    re_path('find-key/$', importdata.find_key)
+    re_path('find-key/$', importdata.find_key),
+    re_path('email-preview/$', views.preview_email_template)
 ]

app/payment.py

@@ -3,24 +3,22 @@ from rest_framework.decorators import api_view
 from rest_framework.response import Response
 from django.db import transaction
 from datetime import datetime
+from decimal import Decimal
+from django.db.models import F
+import threading
 
-
-decimal = 0
-#==========================================================================================
+# ==========================================================================================
 def getcode(code, Model):
-  try:
-    obj = Model.objects.latest('id')
-    val = 1 if obj == None else obj.id + 1
-  except Exception as e:
-    val = 1
-  length = len(str(val))
-  text = ''
-  for i in range(0, 6-length):
-    text += '0'
-  return '{}{}{}'.format(code, text, val)
+    try:
+        obj = Model.objects.latest('id')
+        val = 1 if obj is None else obj.id + 1
+    except Exception:
+        val = 1
+    length = len(str(val))
+    text = '0' * (6 - length)
+    return f"{code}{text}{val}"
 
-
-#==========================================================================================
+# ==========================================================================================
 def account_entry_api(code, amount, content, type, category, userid, ref=None, product=None, customer=None, date=None):
     try:
         user = User.objects.get(id=userid)
@@ -34,10 +32,9 @@ def account_entry_api(code, amount, content, type, category, userid, ref=None, p
             start_balance = account.balance or 0
             
             if entry_type.code == 'DR' and start_balance < amount:
-                return {'error': 'Số dư không đủ để thực hiện giao dịch.'}
+                return {'error': 'Số dư không đủ để thực hiện giao dịch.'}, None
 
             if entry_type.code == 'CR':
-                # account.balance = F('balance') + amount
                 account.balance += amount
             else:
                 account.balance -= amount
@@ -58,72 +55,413 @@ def account_entry_api(code, amount, content, type, category, userid, ref=None, p
                 account=account,
                 date=system_date,
                 ref=ref,
-                product=None if product==None else Product.objects.get(id=product),
-                customer=None if customer==None else Customer.objects.get(id=customer)
+                product=None if product is None else Product.objects.get(id=product),
+                customer=None if customer is None else Customer.objects.get(id=customer)
             )
 
         text = 'id,account__currency__code,ref,balance_before,balance_after,code,account,account__code,account__branch__name,account__type__name,date,amount,content,inputer,inputer__fullname,approver,approver__fullname,create_time,update_time,type,type__code,type__name'
         fields = text.split(',')
-        return Internal_Entry.objects.filter(id=entry.id).values(*fields).first()
+        response_data = Internal_Entry.objects.filter(id=entry.id).values(*fields).first()
+        return response_data, entry
 
     except User.DoesNotExist:
-        return {'error': f"Người dùng với ID {userid} không tồn tại."}
+        return {'error': f"Người dùng với ID {userid} không tồn tại."}, None
     except Internal_Account.DoesNotExist:
-        return {'error': f"Tài khoản nội bộ với mã '{code}' không tồn tại."}
+        return {'error': f"Tài khoản nội bộ với mã '{code}' không tồn tại."}, None
     except Entry_Type.DoesNotExist:
-        return {'error': f"Loại bút toán với mã '{type}' không tồn tại."}
+        return {'error': f"Loại bút toán với mã '{type}' không tồn tại."}, None
     except Entry_Category.DoesNotExist:
-        return {'error': f"Danh mục bút toán với ID '{category}' không tồn tại."}
+        return {'error': f"Danh mục bút toán với ID '{category}' không tồn tại."}, None
     except Exception as e:
-        return {'error': f"Đã xảy ra lỗi không mong muốn: {str(e)}"}
+        return {'error': f"Đã xảy ra lỗi không mong muốn: {str(e)}"}, None
 
-#==========================================================================================
+# ==========================================================================================
+# HÀM LẤY RULE TỪ BIZ_SETTING (detail là string)
+# ==========================================================================================
+def get_allocation_rule():
+    try:
+        rule_setting = Biz_Setting.objects.get(code='rule')
+        rule_value = (rule_setting.detail or 'principal-fee').strip()
+        
+        if rule_value.lower() in ['fee-principal', 'phạt trước', 'phat truoc']:
+            return 'fee-principal'
+        else:
+            return 'principal-fee'
+            
+    except Biz_Setting.DoesNotExist:
+        return 'principal-fee'
+
+# ==========================================================================================
+# HÀM PHÂN BỔ THÔNG THƯỜNG
+# ==========================================================================================
+def allocate_payment_to_schedules(entries):
+    if not entries:
+        return {"status": "no_entries", "message": "Không có bút toán"}
+
+    allocation_rule = get_allocation_rule()
+    updated_schedules = []
+    errors = []
+
+    # Lấy status "đã thanh toán" một lần
+    paid_payment_status = None
+    paid_txn_status = None
+    try:
+        paid_payment_status = Payment_Status.objects.get(id=2)
+    except Payment_Status.DoesNotExist:
+        errors.append("Không tìm thấy Payment_Status id=2 (đã thanh toán)")
+
+    try:
+        paid_txn_status = Transaction_Status.objects.get(id=2)
+    except Transaction_Status.DoesNotExist:
+        errors.append("Không tìm thấy Transaction_Status id=2 (đã thanh toán)")
+
+    for entry in entries:
+        if entry.type.code != 'CR' or entry.account.id == 5:
+            continue
+
+        amount = Decimal(str(entry.amount))
+        if amount <= 0:
+            continue
+
+        with transaction.atomic():
+            try:
+                booked = Product_Booked.objects.filter(product=entry.product).first()
+                if not booked or not booked.transaction:
+                    errors.append(f"Entry {entry.code}: Không tìm thấy Transaction")
+                    continue
+
+                txn = booked.transaction
+
+                txn_detail = None
+                try:
+                    current = Transaction_Current.objects.get(transaction=txn)
+                    txn_detail = current.detail
+                except (Transaction_Current.DoesNotExist, AttributeError):
+                    txn_detail = Transaction_Detail.objects.filter(
+                        transaction=txn
+                    ).order_by('-create_time').first()
+
+                if not txn_detail:
+                    errors.append(f"Entry {entry.code}: Không tìm thấy Transaction_Detail")
+                    continue
+
+                schedules = Payment_Schedule.objects.filter(
+                    txn_detail=txn_detail,
+                    status__id=1  # giả sử status=1 là chưa thanh toán
+                ).order_by('cycle', 'from_date')
+
+                if not schedules.exists():
+                    continue
+
+                remaining = amount
+                total_allocated = Decimal('0')
+
+                for sch in schedules:
+                    if remaining <= 0:
+                        break
+
+                    penalty_remain = Decimal(str(sch.penalty_remain or 0))
+                    amount_remain = Decimal(str(sch.amount_remain or 0))
+                    paid_amount = Decimal(str(sch.paid_amount or 0))
+                    penalty_paid = Decimal(str(sch.penalty_paid or 0))
+                    remain_amount = Decimal(str(sch.remain_amount or 0))
+
+                    to_penalty = Decimal('0')
+                    to_principal = Decimal('0')
+
+                    if allocation_rule == 'fee-principal':
+                        to_penalty = min(remaining, penalty_remain)
+                        remaining -= to_penalty
+                        penalty_paid += to_penalty
+                        penalty_remain -= to_penalty
+                        to_principal = min(remaining, amount_remain)
+                        remaining -= to_principal
+                        paid_amount += to_principal
+                        amount_remain -= to_principal
+                    else:
+                        to_principal = min(remaining, amount_remain)
+                        remaining -= to_principal
+                        paid_amount += to_principal
+                        amount_remain -= to_principal
+                        to_penalty = min(remaining, penalty_remain)
+                        remaining -= to_penalty
+                        penalty_paid += to_penalty
+                        penalty_remain -= to_penalty
+
+                    allocated_here = to_penalty + to_principal
+                    total_allocated += allocated_here
+
+                    sch.paid_amount = paid_amount
+                    sch.penalty_paid = penalty_paid
+                    sch.amount_remain = amount_remain
+                    sch.penalty_remain = penalty_remain
+                    sch.remain_amount = max(Decimal('0'), remain_amount - allocated_here)
+
+                    entry_list = sch.entry or []
+
+                    date_value = entry.date
+                    if hasattr(date_value, 'isoformat'):
+                        date_value = date_value.isoformat()
+                    else:
+                        date_value = str(date_value)
+
+                    entry_list.append({
+                        "code": entry.code,
+                        "amount": float(allocated_here),
+                        "date": date_value,
+                        "type": "CR",
+                        "principal": float(to_principal),
+                        "penalty": float(to_penalty),
+                        "rule": allocation_rule
+                    })
+                    sch.entry = entry_list
+
+                    if sch.amount_remain <= 0 and sch.penalty_remain <= 0 and paid_payment_status:
+                        sch.status = paid_payment_status
+
+                    sch.save(update_fields=[
+                        'paid_amount', 'penalty_paid', 'amount_remain',
+                        'penalty_remain', 'remain_amount', 'entry', 'status'
+                    ])
+
+                    updated_schedules.append(sch.id)
+
+                # Cập nhật Transaction_Detail
+                txn_detail.amount_received = F('amount_received') + total_allocated
+                txn_detail.amount_remaining = F('amount_remaining') - total_allocated
+                txn_detail.save()
+                txn_detail.refresh_from_db()
+
+                if txn_detail.amount_remaining <= 0 and paid_txn_status:
+                    txn_detail.status = paid_txn_status
+                    txn_detail.save(update_fields=['status'])
+
+                # Cập nhật Transaction
+                txn.amount_received = F('amount_received') + total_allocated
+                txn.amount_remain = F('amount_remain') - total_allocated
+                txn.save()
+                txn.refresh_from_db()
+
+                if txn.amount_remain <= 0 and paid_txn_status:
+                    txn.status = paid_txn_status
+                    txn.save(update_fields=['status'])
+
+            except Exception as exc:
+                errors.append(f"Entry {entry.code}: Lỗi phân bổ - {str(exc)}")
+
+    return {
+        "status": "success" if not errors else "partial_failure",
+        "updated_schedules": updated_schedules,
+        "errors": errors,
+        "rule_used": allocation_rule
+    }
+
+# ==========================================================================================
+# HÀM MIỄN LÃI
+# ==========================================================================================
+def allocate_penalty_reduction(entries):
+    if not entries:
+        return {"status": "no_entries", "message": "Không có bút toán"}
+
+    updated_schedules = []
+    errors = []
+
+    for entry in entries:
+        if entry.type.code != 'CR' or entry.account.id != 5:
+            continue  # Chỉ xử lý bút toán từ tài khoản miễn lãi
+
+        amount = Decimal(str(entry.amount))
+        if amount <= 0:
+            continue
+
+        with transaction.atomic():
+            try:
+                booked = Product_Booked.objects.filter(product=entry.product).first()
+                if not booked or not booked.transaction:
+                    errors.append(f"Entry {entry.code}: Không tìm thấy Transaction")
+                    continue
+
+                txn = booked.transaction
+
+                txn_detail = None
+                try:
+                    current = Transaction_Current.objects.get(transaction=txn)
+                    txn_detail = current.detail
+                except (Transaction_Current.DoesNotExist, AttributeError):
+                    txn_detail = Transaction_Detail.objects.filter(
+                        transaction=txn
+                    ).order_by('-create_time').first()
+
+                if not txn_detail:
+                    errors.append(f"Entry {entry.code}: Không tìm thấy Transaction_Detail")
+                    continue
+
+                # Lấy các lịch chưa thanh toán (status=1)
+                schedules = Payment_Schedule.objects.filter(
+                    txn_detail=txn_detail,
+                    status=1
+                ).order_by('cycle', 'from_date')
+
+                if not schedules.exists():
+                    continue
+
+                remaining_reduce = amount  # số tiền miễn lãi còn lại để phân bổ
+
+                for schedule in schedules:
+                    if remaining_reduce <= 0:
+                        break
+
+                    current_penalty_remain = Decimal(str(schedule.penalty_remain or 0))
+                    current_penalty_reduce = Decimal(str(schedule.penalty_reduce or 0))
+                    current_remain_amount = Decimal(str(schedule.remain_amount or 0))
+
+                    # Chỉ miễn tối đa bằng số phạt còn lại
+                    to_reduce = min(remaining_reduce, current_penalty_remain)
+                    remaining_reduce -= to_reduce
+
+                    # Cập nhật các trường
+                    schedule.penalty_reduce = current_penalty_reduce + to_reduce
+                    schedule.penalty_remain = current_penalty_remain - to_reduce
+
+                    # GIẢM TỔNG CÒN LẠI (remain_amount)
+                    schedule.remain_amount = max(Decimal('0'), current_remain_amount - to_reduce)
+
+                    # KHÔNG ĐỘNG ĐẾN amount_remain (nợ gốc còn lại)
+
+                    # Ghi trace bút toán miễn lãi
+                    entry_list = schedule.entry or []
+
+                    date_value = entry.date
+                    if hasattr(date_value, 'isoformat'):
+                        date_value = date_value.isoformat()
+                    else:
+                        date_value = str(date_value)
+
+                    entry_list.append({
+                        "code": entry.code,
+                        "amount": float(to_reduce),
+                        "date": date_value,
+                        "type": "REDUCTION",
+                        "note": "Miễn lãi phạt quá hạn"
+                    })
+                    schedule.entry = entry_list
+
+                    # Lưu lại
+                    schedule.save(update_fields=[
+                        'penalty_reduce', 'penalty_remain', 'remain_amount', 'entry'
+                    ])
+
+                    updated_schedules.append(schedule.id)
+
+            except Exception as exc:
+                errors.append(f"Entry {entry.code}: Lỗi miễn lãi - {str(exc)}")
+
+    return {
+        "status": "success" if not errors else "partial_failure",
+        "updated_schedules": updated_schedules,
+        "errors": errors,
+        "message": f"Đã miễn lãi cho {len(updated_schedules)} lịch thanh toán (chỉ giảm phạt + tổng còn lại)"
+    }
+
+# ==========================================================================================
+# BACKGROUND FUNCTION
+# ==========================================================================================
+def background_allocate(entries_created):
+    try:
+        # Debug type date
+        for e in entries_created:
+            print(f"Debug entry {e.code}: date type = {type(e.date)}, value = {e.date}")
+
+        normal_result = allocate_payment_to_schedules(entries_created)
+        reduction_result = allocate_penalty_reduction(entries_created)
+
+        print(f"[{datetime.now().strftime('%Y-%m-%d %H:%M:%S')}] Background allocation completed:")
+        print("Normal:", normal_result)
+        print("Reduction:", reduction_result)
+
+    except Exception as e:
+        print(f"[{datetime.now().strftime('%Y-%m-%d %H:%M:%S')}] Background allocation error: {str(e)}")
+
+# ==========================================================================================
+# API TẠO MỘT BÚT TOÁN
+# ==========================================================================================
 @api_view(['POST'])
 def account_entry(request):
-  print(request.data.get('date'))
-  ref = request.data.get('ref')
-  data = account_entry_api(
-      code=request.data['code'], 
-      amount=request.data['amount'], 
-      content=request.data['content'],
-      type=request.data['type'], 
-      category=request.data['category'], 
-      userid=request.data['user'], 
-      ref=ref,
-      product=request.data['product'], 
-      customer=request.data['customer'],
-      date=request.data.get('date')
-  )
+    print(request.data.get('date'))
+    ref = request.data.get('ref')
 
-  if 'error' in data:
-      return Response(data, status=400)
+    response_data, created_entry = account_entry_api(
+        code=request.data['code'],
+        amount=request.data['amount'],
+        content=request.data['content'],
+        type=request.data['type'],
+        category=request.data['category'],
+        userid=request.data['user'],
+        ref=ref,
+        product=request.data['product'],
+        customer=request.data['customer'],
+        date=request.data.get('date')
+    )
 
-  return Response(data)
+    if 'error' in response_data:
+        return Response(response_data, status=400)
 
+    if created_entry:
+        thread = threading.Thread(
+            target=background_allocate,
+            args=([created_entry],),
+            daemon=True
+        )
+        thread.start()
 
-#==========================================================================================
+    return Response({
+        **response_data,
+        "message": "Bút toán đã tạo thành công. Phân bổ thanh toán đang chạy ngầm..."
+    })
+
+# ==========================================================================================
+# API TẠO NHIỀU BÚT TOÁN
+# ==========================================================================================
 @api_view(['POST'])
 def account_multi_entry(request):
     try:
         result = []
-        data = request.data.get('data')
-        for obj in data:
-            row = account_entry_api(
-                code=obj['Tài khoản'], 
-                amount=obj['amount'], 
-                content=obj['content'],
-                type='CR', 
-                category=obj['category'], 
-                userid=request.data.get('user'), 
-                ref=obj['ref'],
-                product=obj['product'], 
-                customer=obj['customer'],
-                date=obj['date']
-            )
-            result.append(row)
+        entries_created = []
+        data_list = request.data.get('data', [])
 
-        return Response(result)
+        with transaction.atomic():
+            for obj in data_list:
+                response_data, created_entry = account_entry_api(
+                    code=obj['Tài khoản'],
+                    amount=obj['amount'],
+                    content=obj['content'],
+                    type='CR',
+                    category=obj['category'],
+                    userid=request.data.get('user'),
+                    ref=obj['ref'],
+                    product=obj['product'],
+                    customer=obj['customer'],
+                    date=obj['date']
+                )
+
+                result.append(response_data)
+
+                if created_entry:
+                    entries_created.append(created_entry)
+
+        if entries_created:
+            thread = threading.Thread(
+                target=background_allocate,
+                args=(entries_created,),
+                daemon=True
+            )
+            thread.start()
+
+        return Response({
+            "entries": result,
+            "message": "Bút toán đã tạo thành công. Phân bổ thanh toán đang chạy ngầm..."
+        })
 
     except Exception as e:
         print({'error': f"Đã xảy ra lỗi không mong muốn: {str(e)}"})
-        return Response(data, status=400)
+        return Response({'error': str(e)}, status=400)

app/views.py

@@ -27,6 +27,8 @@ from concurrent.futures import ThreadPoolExecutor
 import json
 import io
 import pandas as pd
+import numpy as np
+from num2words import num2words
 from django.db import transaction
 from django.apps import apps
 from django.core.exceptions import FieldDoesNotExist
@@ -1348,3 +1350,265 @@ def generate_document(request):
         count += 1
 
     return Response({"error": "Timeout chờ generate."}, status=status.HTTP_408_REQUEST_TIMEOUT)
+
+#=============================================================================
+# EMAIL TEMPLATE PREVIEW
+#=============================================================================
+class EmailTemplatePreview:
+    """
+    Class để preview nội dung email template với dữ liệu đã được map
+    Không gửi email, chỉ trả về nội dung đã render
+    """
+    
+    def __init__(self, template, context_pks: dict):
+        self.template = template
+        self.context_pks = context_pks
+        self.config = self.template.content  
+        self.data_context = {}
+        self.replacements = {}
+
+    def _get_model(self, model_string):
+        """Lấy model class từ string 'app.Model'"""
+        app_label, model_name = model_string.split(".")
+        return apps.get_model(app_label, model_name)
+
+    def _get_value_from_object(self, obj, field_path):
+        """Lấy giá trị từ object theo field path (hỗ trợ nested: 'user.profile.name')"""
+        if obj is None:
+            return None
+        value = obj
+        for part in field_path.replace("__", ".").split("."):
+            if value is None:
+                return None
+            value = getattr(value, part, None)
+        return value
+
+    def _resolve_lookup_value(self, lookup_from):
+        """Resolve giá trị lookup từ context_pks hoặc data_context"""
+        if lookup_from in self.context_pks:
+            return self.context_pks[lookup_from]
+
+        try:
+            alias, field_path = lookup_from.split(".", 1)
+            if alias not in self.data_context:
+                raise ValueError(f"Alias '{alias}' not found in data context.")
+            
+            source_object = self.data_context.get(alias)
+            return self._get_value_from_object(source_object, field_path)
+        except ValueError:
+            raise ValueError(f"Could not resolve '{lookup_from}'.")
+
+    def fetch_data(self):
+        """Fetch data từ database theo mappings config"""
+        mappings = self.config.get("mappings", [])
+        if not isinstance(mappings, list):
+            raise TypeError("Email template 'mappings' must be a list.")
+
+        # Process trigger object first
+        trigger_model_mapping = next((m for m in mappings if m.get("is_trigger_object", False)), None)
+        if trigger_model_mapping:
+            model_cls = self._get_model(trigger_model_mapping["model"])
+            lookup_field = trigger_model_mapping["lookup_field"]
+            lookup_value = self._resolve_lookup_value(trigger_model_mapping["lookup_value_from"])
+            alias = trigger_model_mapping["alias"]
+            if lookup_value is not None:
+                self.data_context[alias] = model_cls.objects.filter(**{lookup_field: lookup_value}).first()
+            else:
+                self.data_context[alias] = None
+
+        # Process other mappings
+        for mapping in mappings:
+            if mapping.get("is_trigger_object", False):
+                continue 
+
+            model_cls = self._get_model(mapping["model"])
+            lookup_field = mapping["lookup_field"]
+            lookup_value = self._resolve_lookup_value(mapping["lookup_value_from"])
+            alias = mapping["alias"]
+
+            if lookup_value is None:
+                self.data_context[alias] = None if mapping.get("type") == "object" else []
+                continue
+
+            queryset = model_cls.objects.filter(**{lookup_field: lookup_value})
+
+            if mapping.get("type") == "object":
+                self.data_context[alias] = queryset.first()
+            elif mapping.get("type") == "list":
+                self.data_context[alias] = list(queryset)
+
+    def _format_value(self, value, format_config):
+        """Format value theo config (currency, date, number_to_words, conditional)"""
+        if value is None:
+            return ""
+
+        format_type = format_config.get("type")
+        if not format_type:
+            return str(value)
+
+        try:
+            if format_type == "currency":
+                return "{:,}".format(np.int64(value)).replace(",", ".")
+            if format_type == "date":
+                date_format = format_config.get("format", "dd/mm/YYYY").replace("dd", "%d").replace("mm", "%m").replace("YYYY", "%Y")
+                return value.strftime(date_format)
+            if format_type == "number_to_words":
+                return num2words(value, lang=format_config.get("lang", "vi"))
+            if format_type == "conditional":
+                return format_config["true_value"] if value else format_config["false_value"]
+        except Exception as e:
+            print(f"Error formatting value '{value}' with config '{format_config}': {e}")
+            return "" 
+            
+        return str(value)
+
+    def prepare_replacements(self):
+        """Chuẩn bị dict replacements cho placeholders"""
+        # Add date placeholders
+        today = datetime.now()
+        self.replacements['[day]'] = str(today.day)
+        self.replacements['[month]'] = str(today.month)
+        self.replacements['[year]'] = str(today.year)
+        self.replacements['[date]'] = today.strftime("%d/%m/%Y")
+
+        # Process field mappings
+        mappings = self.config.get("mappings", [])
+        for mapping in mappings:
+            alias = mapping["alias"]
+            data = self.data_context.get(alias)
+            fields = mapping.get("fields", {})
+
+            if mapping.get("type") == "object":
+                if data is None:
+                    for placeholder in fields:
+                        self.replacements[placeholder] = ""
+                    continue
+                
+                for placeholder, config in fields.items():
+                    if isinstance(config, dict):
+                        value = self._get_value_from_object(data, config["source"])
+                        self.replacements[placeholder] = self._format_value(value, config.get("format", {}))
+                    else: 
+                        value = self._get_value_from_object(data, config)
+                        self.replacements[placeholder] = str(value) if value is not None else ""
+
+    def get_preview(self):
+        """
+        Main method để lấy preview email content - trả về nội dung y nguyên đã thay thế placeholders
+        
+        Returns:
+            dict: {
+                'subject': subject đã thay thế placeholders,
+                'content': body content đã thay thế placeholders (giữ nguyên format, căn lề),
+                'recipient_email': email người nhận,
+                'replacements': dict của tất cả replacements được áp dụng
+            }
+        """
+        try:
+            print(f"Generating preview for template: {self.template.name}")
+            
+            # Fetch data and prepare replacements
+            self.fetch_data()
+            self.prepare_replacements()
+
+            # Get templates from config
+            subject_template = self.config.get("subject", "")
+            body_template = self.config.get("content", "")
+            recipient_placeholder = self.config.get("recipient_placeholder", "[customer.email]")
+
+            # Apply replacements - giữ nguyên format, căn lề của template gốc
+            final_subject = subject_template
+            final_content = body_template
+            
+            for key, value in self.replacements.items():
+                final_subject = final_subject.replace(key, str(value))
+                final_content = final_content.replace(key, str(value))
+
+            recipient_email = self.replacements.get(recipient_placeholder, "")
+
+            result = {
+                'subject': final_subject,
+                'content': final_content,  # Nội dung y nguyên đã thay thế
+                'recipient_email': recipient_email,
+                'replacements': self.replacements.copy()
+            }
+
+            print(f"Preview generated successfully for '{self.template.name}'")
+            return result
+
+        except Exception as e:
+            print(f"Error generating preview for template '{self.template.name}': {e}")
+            import traceback
+            traceback.print_exc()
+            return None
+
+
+@api_view(['POST'])
+def preview_email_template(request):
+    """
+    API để preview email template - trả về nội dung đã thay thế placeholders
+    
+    POST /api/email/preview/
+    Body: {
+        "template_id": 1,
+        "context_pks": {
+            "contract_id": 456,
+            "customer_id": 789
+        }
+    }
+    
+    Response: {
+        "subject": "Thông báo hợp đồng #HD-001",
+        "content": "<div>Nội dung y nguyên đã thay thế...</div>",
+        "recipient_email": "customer@example.com",
+        "replacements": {
+            "[contract.code]": "HD-001",
+            "[customer.name]": "Nguyễn Văn A",
+            ...
+        }
+    }
+    """
+    try:
+        # Validate input
+        template_id = request.data.get('template_id')
+        if not template_id:
+            return Response(
+                {'error': 'template_id is required'}, 
+                status=status.HTTP_400_BAD_REQUEST
+            )
+        
+        context_pks = request.data.get('context_pks', {})
+        if not isinstance(context_pks, dict):
+            return Response(
+                {'error': 'context_pks must be a dictionary'}, 
+                status=status.HTTP_400_BAD_REQUEST
+            )
+        
+        # Get template
+        try:
+            template = Email_Template.objects.get(pk=template_id)
+        except Email_Template.DoesNotExist:
+            return Response(
+                {'error': f'Email_Template with id={template_id} does not exist'}, 
+                status=status.HTTP_404_NOT_FOUND
+            )
+        
+        # Generate preview
+        previewer = EmailTemplatePreview(template, context_pks)
+        preview = previewer.get_preview()
+        
+        if preview:
+            return Response(preview, status=status.HTTP_200_OK)
+        else:
+            return Response(
+                {'error': 'Failed to generate preview'}, 
+                status=status.HTTP_500_INTERNAL_SERVER_ERROR
+            )
+            
+    except Exception as e:
+        import traceback
+        traceback.print_exc()
+        return Response(
+            {'error': f'Unexpected error: {str(e)}'}, 
+            status=status.HTTP_500_INTERNAL_SERVER_ERROR
+        )