# Auto-generated transaction service
"""Cross-table transaction service for atomic operations.

This service provides methods for executing atomic transactions across multiple
DynamoDB tables using TransactWriteItems and TransactGetItems APIs.

Currently supports:
- TransactWrite: Atomic write operations (Put, Update, Delete, ConditionCheck)
- TransactGet: Atomic read operations (Get)

Future versions may support additional cross-table patterns.
"""
from __future__ import annotations

from decimal import Decimal
from typing import Any

import boto3
from botocore.exceptions import ClientError

from entities import {{ entity_imports }}


class TransactionService:
    """Service for cross-table transactional operations.

    This service handles atomic operations that span multiple DynamoDB tables.
    All operations are atomic - either all succeed or all fail together.

    Attributes:
        dynamodb: Boto3 DynamoDB resource for multi-table access
        client: Boto3 DynamoDB client for transaction operations
    """

    def __init__(self, dynamodb_resource: boto3.resource):
        """Initialize transaction service.

        Args:
            dynamodb_resource: Boto3 DynamoDB resource configured for your region
                              Example: boto3.resource('dynamodb', region_name='us-west-2')
        """
        self.dynamodb = dynamodb_resource
        self.client = dynamodb_resource.meta.client

    {% for pattern in cross_table_patterns %}
    def {{ pattern.name }}(self, {{ format_parameters(pattern.parameters) }}) -> {{ map_return_type(pattern.return_type) }}:
        """{{ pattern.description }}

        Args:
            {%- for param in pattern.parameters %}
            {{ param.name }}: {{ get_param_description(param) }}
            {%- endfor %}

        Returns:
            {{ map_return_type(pattern.return_type) }}: {{ get_return_description(pattern) }}

        Raises:
            ValueError: If entity validation fails or relationships are invalid
            ClientError: If transaction fails (e.g., condition check failure, item already exists)
        """
        # TODO: Implement Access Pattern #{{ pattern.pattern_id }}
        # Operation: {{ pattern.operation }} | Tables: {{ format_table_names(pattern) }}
        #
        # Cross-Table Transaction Example:
        {% if pattern.operation == 'TransactWrite' -%}
        # Step 1: Validate entity relationships (if needed)
        # Example: Ensure email_lookup.user_id matches user.user_id
        #
        # Step 2: Build keys for all entities
        {% for entity_inv in pattern.entities_involved -%}
        # {{ entity_inv.entity }}.build_pk_for_lookup(...)
        {% if entity_inv.get('condition') -%}
        # Condition: {{ entity_inv.condition }}
        {% endif -%}
        {% endfor -%}
        #
        # Step 3: Convert entities to DynamoDB items and add keys
        {% for param in pattern.parameters if param.type == 'entity' -%}
        # {{ param.name }}_item = {{ param.name }}.model_dump(exclude_none=True)
        # {{ param.name }}_item['{{ entity_to_table_config[param.entity_type].partition_key }}'] = {{ param.name }}.pk()
        {% if entity_to_table_config[param.entity_type].get('sort_key') -%}
        # {{ param.name }}_item['{{ entity_to_table_config[param.entity_type].sort_key }}'] = {{ param.name }}.sk()
        {% endif -%}
        {% endfor -%}
        #
        # Step 4: Execute transaction
        # response = self.client.transact_write_items(
        #     TransactItems=[
        {% for entity_inv in pattern.entities_involved -%}
        #         {
        #             '{{ entity_inv.action }}': {
        #                 'TableName': '{{ entity_inv.table }}',
        {% if entity_inv.action in ['Put'] -%}
        #                 'Item': <entity>_item,  # Item includes partition key from Step 3
        {% elif entity_inv.action in ['Update'] -%}
        #                 'Key': {'{{ entity_to_table_config[entity_inv.entity].partition_key }}': <pk_value>{% if entity_to_table_config[entity_inv.entity].get('sort_key') %}, '{{ entity_to_table_config[entity_inv.entity].sort_key }}': <sk_value>{% endif %}},
        #                 'UpdateExpression': 'SET #field = :val',
        #                 'ExpressionAttributeNames': {'#field': 'field_name'},
        #                 'ExpressionAttributeValues': {':val': value},
        {% elif entity_inv.action in ['Delete', 'ConditionCheck'] -%}
        #                 'Key': {'{{ entity_to_table_config[entity_inv.entity].partition_key }}': <pk_value>{% if entity_to_table_config[entity_inv.entity].get('sort_key') %}, '{{ entity_to_table_config[entity_inv.entity].sort_key }}': <sk_value>{% endif %}},
        {% endif -%}
        {% if entity_inv.get('condition') -%}
        #                 'ConditionExpression': '{{ entity_inv.condition }}'
        {% endif -%}
        #             }
        #         },
        {% endfor -%}
        #     ]
        # )
        #
        # Step 5: Handle errors
        # try:
        #     response = self.client.transact_write_items(...)
        #     return True  # or appropriate return value
        # except ClientError as e:
        #     if e.response['Error']['Code'] == 'TransactionCanceledException':
        #         # Handle condition check failures
        #         reasons = e.response['Error'].get('CancellationReasons', [])
        #         # Parse reasons to determine which condition failed
        #         raise ValueError(f"Transaction failed: {reasons}")
        #     raise
        {% elif pattern.operation == 'TransactGet' -%}
        # Step 1: Build keys for all entities
        {% for entity_inv in pattern.entities_involved -%}
        # {{ entity_inv.entity }}.build_pk_for_lookup(...)
        {% endfor -%}
        #
        # Step 2: Execute transaction
        # response = self.client.transact_get_items(
        #     TransactItems=[
        {% for entity_inv in pattern.entities_involved -%}
        #         {
        #             'Get': {
        #                 'TableName': '{{ entity_inv.table }}',
        #                 'Key': {'{{ entity_to_table_config[entity_inv.entity].partition_key }}': <pk_value>{% if entity_to_table_config[entity_inv.entity].get('sort_key') %}, '{{ entity_to_table_config[entity_inv.entity].sort_key }}': <sk_value>{% endif %}}
        #             }
        #         },
        {% endfor -%}
        #     ]
        # )
        #
        # Step 3: Parse and return results
        # items = response.get('Responses', [])
        # result = {}
        {% for entity_inv in pattern.entities_involved -%}
        # if items[{{ loop.index0 }}].get('Item'):
        #     result['{{ entity_inv.entity | lower }}'] = {{ entity_inv.entity }}(**items[{{ loop.index0 }}]['Item'])
        {% endfor -%}
        # return result
        {% endif -%}
        pass

    {% endfor -%}
