Model/backend/postcode_splitter/main.py

import os
import sys
import json
import pandas as pd
import requests
import boto3
from uuid import UUID
from urllib.parse import unquote
from utils.s3 import read_csv_from_s3 as read_csv_from_s3_dict
from utils.logger import setup_logger
from tqdm import tqdm
from backend.app.db.functions.tasks.Tasks import SubTaskInterface

logger = setup_logger()


def parse_s3_uri(s3_uri: str) -> tuple[str, str]:
    """
    Parse S3 URI to extract bucket and key.

    Supports two formats:
    1. S3 URI format: s3://bucket/key
    """
    logger.info("Parsing S3 URI")

    try:
        # Check if it's an S3 URI format
        if s3_uri.startswith("s3://"):
            parts = s3_uri[5:].split("/", 1)
            if len(parts) < 2:
                raise ValueError("S3 URI must include both bucket and key")
            bucket = parts[0]
            key = parts[1]
            logger.info(f"Extracted bucket: {bucket}, key: {key}")
            return bucket, key

        # Otherwise, treat as AWS console URL
        logger.info("Parsing as AWS console URL")

        # Split base URL and query string
        if "?" not in s3_uri:
            raise ValueError("No query string found")

        base, query = s3_uri.split("?", 1)

        # Extract bucket from base URL
        if "/s3/object/" not in base:
            raise ValueError("No '/s3/object/' found in URL path")

        path_parts = base.split("/s3/object/")
        bucket = path_parts[1]
        logger.info(f"Extracted bucket: {bucket}")

        # Extract prefix from query parameters
        params = dict(item.split("=") for item in query.split("&") if "=" in item)
        key = unquote(params.get("prefix", ""))
        logger.info(f"Extracted key: {key}")

        return bucket, key
    except Exception as e:
        logger.error(f"Error parsing S3 URI: {type(e).__name__}: {e}")
        raise ValueError(f"Could not parse S3 URI") from e


def send_to_address2uprn_queue(task_id: str, rows: list) -> str:
    """
    Send a postcode group to the address2UPRN SQS queue.

    Args:
        task_id: The parent task ID
        rows: List of row dictionaries for this postcode group

    Returns:
        Message ID from SQS
    """
    sqs_client = boto3.client("sqs")
    queue_url = os.getenv("ADDRESS2UPRN_QUEUE_URL")

    if not queue_url:
        raise ValueError("ADDRESS2UPRN_QUEUE_URL environment variable not set")

    message_body = {
        "task_id": task_id,
        "rows": rows,
    }

    response = sqs_client.send_message(
        QueueUrl=queue_url,
        MessageBody=json.dumps(message_body),
    )

    logger.info(
        f"Sent message to address2UPRN queue. "
        f"Task: {task_id}, MessageId: {response['MessageId']}"
    )

    return response["MessageId"]


def handler(event, context, local=False):
    print(f"Function: {context.function_name}")
    print(f"Request ID: {context.aws_request_id}")

    # Example SQS message for testing (copy and paste into SQS):
    # {
    #   "task_id":"e31f2f21-175b-4a91-a3ec-a6baa325e917",
    #   "s3_uri":"s3://retrofit-data-dev/ara_raw_inputs/peabody/2025_11_11 - Peabody - Data Extracts for Domna_transformed.csv"
    # }

    # Handle both single event and batch events (SQS, etc.)
    records = event.get("Records", [event])
    results = []
    errors = []
    subtask_interface = SubTaskInterface()

    for record in records:
        task_id = None
        subtask_id = None
        try:
            # For local development
            if local is True:
                record = {}
                record["body"] = (
                    '{"task_id":"e31f2f21-175b-4a91-a3ec-a6baa325e917","s3_uri":"s3://retrofit-data-dev/ara_raw_inputs/peabody/2025_11_11 - Peabody - Data Extracts for Domna_transformed.csv"}'
                )
            # Parse body (inputs)
            if isinstance(record.get("body"), str):
                body = json.loads(record["body"])
            else:
                body = record.get("body", {})

            # Validate required fields
            task_id = body.get("task_id")
            s3_uri = body.get("s3_uri")

            if not task_id:
                errors.append({"error": "Missing required field: task_id"})
                continue

            if not s3_uri:
                errors.append({"error": "Missing required field: s3_uri"})
                continue

            # Convert task_id to UUID
            try:
                task_id = UUID(task_id) if isinstance(task_id, str) else task_id
            except ValueError as e:
                errors.append({"error": f"Invalid UUID format for task_id: {str(e)}"})
                continue

            # Create a new subtask for this postcode splitter invocation
            subtask_id = subtask_interface.create_subtask(
                task_id=task_id, inputs={"s3_uri": s3_uri}
            )
            logger.info(f"Created subtask {subtask_id} for task {task_id}")

            # Read CSV from S3
            logger.info(f"Processing S3 URI: {s3_uri}")
            bucket, key = parse_s3_uri(s3_uri)
            logger.info(f"S3 Bucket: {bucket}, Key: {key}")

            csv_data = read_csv_from_s3_dict(bucket, key)
            df = pd.DataFrame(csv_data)
            # just do 5 well we are testing, sqs connection
            if local:
                df = df.head(5)

            # TODO: DELETE ME, if you see this in the PR.
            # TODO: DELETE ME, if you see this in the PR.
            # TODO: DELETE ME, if you see this in the PR.
            df = df.head(1983)

            logger.info(f"CSV loaded: {len(df)} rows, {len(df.columns)} columns")

            # Sanitise postcodes
            df["postcode_clean"] = df["postcode"].str.upper().str.replace(" ", "")

            clean_df = df.dropna(subset=["postcode_clean"])

            postcode_to_addresses = {
                postcode: group.to_dict(orient="records")
                for postcode, group in clean_df.groupby("postcode_clean", sort=False)
            }

            logger.info(f"Total postcodes: {len(postcode_to_addresses)}")

            # Calculate total rows to send
            total_rows = sum(len(rows) for rows in postcode_to_addresses.values())
            logger.info(f"Total rows to send: {total_rows}")

            batch_size = 500

            # If all rows fit in one batch, just send them all at once
            if total_rows <= batch_size:
                all_rows = []
                for postcode, rows in postcode_to_addresses.items():
                    all_rows.extend(rows)
                try:
                    send_to_address2uprn_queue(
                        task_id=str(task_id),
                        rows=all_rows,
                    )
                    logger.info(
                        f"Sent all {len(all_rows)} rows in single batch to address2UPRN queue"
                    )
                except Exception as e:
                    logger.error(
                        f"Failed to send all rows to address2UPRN queue: {e}",
                        exc_info=True,
                    )
                    errors.append(
                        {
                            "error": "Failed to send to address2UPRN queue",
                            "details": str(e),
                        }
                    )
            else:
                # Multi-batch processing for large datasets
                batch_rows = []
                total_sent = 0

                for postcode, rows in postcode_to_addresses.items():
                    logger.info(f"Processing postcode {postcode} with {len(rows)} rows")
                    # If postcode itself is larger than batch_size, send it individually
                    if len(rows) > batch_size:
                        # First, send the current batch if it has data
                        if batch_rows:
                            try:
                                send_to_address2uprn_queue(
                                    task_id=str(task_id),
                                    rows=batch_rows,
                                )
                                logger.info(
                                    f"Sent batch of {len(batch_rows)} rows to address2UPRN queue"
                                )
                                batch_rows = []
                            except Exception as e:
                                logger.error(
                                    f"Failed to send batch to address2UPRN queue: {e}",
                                    exc_info=True,
                                )
                                errors.append(
                                    {
                                        "error": "Failed to send to address2UPRN queue",
                                        "details": str(e),
                                    }
                                )

                        # Send the large postcode on its own
                        try:
                            send_to_address2uprn_queue(
                                task_id=str(task_id),
                                rows=rows,
                            )
                            logger.info(
                                f"Sent large postcode {postcode} ({len(rows)} rows) to address2UPRN queue"
                            )
                        except Exception as e:
                            logger.error(
                                f"Failed to send large postcode to address2UPRN queue: {e}",
                                exc_info=True,
                            )
                            errors.append(
                                {
                                    "error": "Failed to send to address2UPRN queue",
                                    "details": str(e),
                                }
                            )
                        continue

                    # If adding this postcode's rows would exceed batch_size, send current batch
                    current_batch_size = len(batch_rows) + len(rows)
                    if batch_rows and current_batch_size > batch_size:
                        logger.info(
                            f"Batch threshold reached: current {len(batch_rows)} + next postcode {len(rows)} = {current_batch_size} > {batch_size}"
                        )
                        try:
                            send_to_address2uprn_queue(
                                task_id=str(task_id),
                                rows=batch_rows,
                            )
                            logger.info(
                                f"Sent batch of {len(batch_rows)} rows to address2UPRN queue (total sent: {total_sent})"
                            )
                            total_sent += len(batch_rows)
                            batch_rows = []
                        except Exception as e:
                            logger.error(
                                f"Failed to send batch to address2UPRN queue: {e}",
                                exc_info=True,
                            )
                            errors.append(
                                {
                                    "error": "Failed to send to address2UPRN queue",
                                    "details": str(e),
                                }
                            )

                    # Add current postcode's rows to batch
                    batch_rows.extend(rows)

                # Send remaining batch
                if batch_rows:
                    try:
                        send_to_address2uprn_queue(
                            task_id=str(task_id),
                            rows=batch_rows,
                        )
                        total_sent += len(batch_rows)
                        logger.info(
                            f"Sent final batch of {len(batch_rows)} rows to address2UPRN queue (total sent: {total_sent})"
                        )
                        batch_rows = []
                    except Exception as e:
                        logger.error(
                            f"Failed to send final batch to address2UPRN queue: {e}",
                            exc_info=True,
                        )
                        errors.append(
                            {
                                "error": "Failed to send to address2UPRN queue",
                                "details": str(e),
                            }
                        )

        except json.JSONDecodeError as e:
            logger.error(f"Invalid JSON in request body: {e}")
            errors.append({"error": "Invalid JSON in request body", "details": str(e)})
            # Mark subtask as failed if we have one
            if subtask_id:
                try:
                    subtask_interface.update_subtask_status(
                        subtask_id, "failed", outputs={"error": str(e)}
                    )
                except Exception as db_error:
                    logger.error(f"Failed to update subtask status: {db_error}")
        except Exception as e:
            logger.error(f"Unexpected error processing record: {e}", exc_info=True)
            errors.append({"error": "Unexpected error", "details": str(e)})
            # Mark subtask as failed if we have one
            if subtask_id:
                try:
                    subtask_interface.update_subtask_status(
                        subtask_id, "failed", outputs={"error": str(e)}
                    )
                except Exception as db_error:
                    logger.error(f"Failed to update subtask status: {db_error}")

    # Return error if all records failed
    if errors and not results:
        return {"statusCode": 500, "body": json.dumps({"errors": errors})}

    return {
        "statusCode": 200,
        "body": json.dumps(
            {"processed": results, "errors": errors if errors else None}
        ),
    }