Merge branch 'development' into test/transform-helper-functions

3 files changed, 291 insertions, 3 deletions

diff --git a/requirements.txt b/requirements.txt
index 0c81216..763b95a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -30,5 +30,6 @@ Werkzeug==3.0.3
 xmltodict==0.13.0
 s3fs 
 pandas
+pyarrow
+SQLAlchemy
 bs4
-pyarrow
\ No newline at end of file
diff --git a/src/load_lambda.py b/src/load_lambda.py
index c6a8e60..6e6bc80 100644
--- a/src/load_lambda.py
+++ b/src/load_lambda.py
@@ -1,2 +1,197 @@
-def lambda_handler():
-    pass
+import boto3
+from botocore.exceptions import ClientError
+import pandas as pd
+import pyarrow.parquet as pq
+from io import BytesIO
+import logging
+import json
+from src.extract_lambda import retrieve_secrets
+from sqlalchemy import create_engine
+
+
+logger = logging.getLogger(__name__)
+
+logging.basicConfig(
+    format="{asctime} - {levelname} - {message}",
+    style="{",
+    datefmt="%Y-%m-%d %H:%M",
+    level=logging.DEBUG,
+)
+
+logging.getLogger("botocore").setLevel(logging.INFO)
+
+
+def lambda_handler(event, context):
+    try:
+        uploaded_tables = upload_dfs_to_database()
+        if not uploaded_tables["uploaded"]:
+            return {
+                "statusCode": 200,
+                "body": json.dumps("No dataframes were uploaded."),
+            }
+        return {
+            "statusCode": 200,
+            "body": json.dumps(
+                f"""The following dataframes were uploaded successfully: 
+                {uploaded_tables["uploaded"]} ."""
+            ),
+        }
+    except Exception as e:
+        logger.error(f"Error: {e}", exc_info=True)
+        return {"statusCode": 500, "body": json.dumps("Internal server error.")}
+
+
+def retrieve_secrets():
+    secret_name = "bentley-RDS-credentials"
+    region_name = "eu-west-2"
+
+    # Create a Secrets Manager client
+    session = boto3.session.Session()
+    client = session.client(service_name="secretsmanager", region_name=region_name)
+
+    try:
+        get_secret_value_response = client.get_secret_value(SecretId=secret_name)
+    except ClientError as e:
+        logger.error(f"Failed to retrieve secret {secret_name}: {str(e)}")
+        raise e
+    except KeyError:
+        logger.error(f"Secret {secret_name} does not contain a SecretString")
+        raise ValueError(f"Secret {secret_name} does not contain a SecretString")
+
+    return get_secret_value_response["SecretString"]
+
+
+# connect to database, slightly different way of doing it, to allow manipulation through pandas
+
+
+def connect_to_db_and_return_engine():
+    try:
+        secrets = json.loads(retrieve_secrets())
+        host = secrets["host"]
+        port = secrets["port"]
+        user = secrets["user"]
+        password = secrets["password"]
+        database = secrets["database"]
+        conn_str = f"postgresql+pg8000://{user}:{password}@{host}:{port}/{database}"
+        # interface between python (pandas) and SQL
+        engine = create_engine(conn_str)
+        return engine
+    except Exception as e:
+        logger.error(f"Interface error: {e}")
+        raise RuntimeError("Failed to create database engine")
+
+
+# get transform bucket
+def get_transform_bucket(client=None):
+    if client is None:
+        client = boto3.client("s3")
+    try:
+        response = client.list_buckets()
+    except ClientError as e:
+        logger.error(f"Error listing S3 buckets: {e}")
+        raise RuntimeError("Error listing S3 buckets")
+
+    transform_bucket_filter = [
+        bucket["Name"]
+        for bucket in response["Buckets"]
+        if "transform" in bucket["Name"]
+    ]
+
+    if not transform_bucket_filter:
+        logger.error("No transform bucket found")
+        raise ValueError("No transform bucket found")
+
+    return transform_bucket_filter[0]
+
+
+# list and then retrieve parquet files from S3 bucket
+# convert parquet files into dataframes
+# return a dictionary of dataframes with name as key, and dataframe object as value
+
+
+def convert_parquet_files_to_dfs(bucket_name=None, client=None):
+    try:
+        if client is None:
+            client = boto3.client("s3")
+        if bucket_name is None:
+            bucket_name = get_transform_bucket()
+        files = client.list_objects_v2(Bucket=bucket_name)
+
+        dfs = {}
+        if "Contents" in files:
+            for file in files["Contents"]:
+                file_key = file["Key"]
+                try:
+                    file_obj = client.get_object(Bucket=bucket_name, Key=file_key)
+                    parquet_file = pq.ParquetFile(BytesIO(file_obj["Body"].read()))
+                    df = parquet_file.read().to_pandas()
+                    dfs[file_key] = df
+                except ClientError as e:
+                    logger.error(f"Unable to retrieve S3 object {file_key}: {e}")
+                except Exception as e:
+                    logger.error(f"Unable to process file {file_key}: {e}")
+        else:
+            logger.error(f"No files found in {bucket_name}.")
+            return {}
+    except ValueError as value_error:
+        logger.error(f"Unable to list objects: {value_error}")
+        raise
+    except ClientError as client_error:
+        logger.error(f"Unable to list objects: {client_error}")
+        raise
+
+    return dfs
+
+
+def upload_dfs_to_database():
+    upload_status = {"uploaded": [], "not_uploaded": []}
+    dict_of_dfs = convert_parquet_files_to_dfs()
+    db_engine = connect_to_db_and_return_engine()
+    immutable_df_dict = [
+        "dim_counterparty.parquet",
+        "dim_date.parquet",  # this needs to be mutable
+        "dim_location.parquet",
+        "dim_staff.parquet",
+        "dim_design.parquet",
+    ]
+    mutable_df_dict = [
+        "fact_sales_order",
+        "fact_purchase_order",
+        "fact_payment",
+        "dim_currency",
+    ]
+
+    for file_name, df in dict_of_dfs.items():
+        if file_name in immutable_df_dict:
+            table_name = file_name.split(".")[0]
+            try:
+                df.to_sql(
+                    table_name,
+                    con=db_engine,
+                    schema="project_team_2",
+                    if_exists="overwrite",
+                    index=False,
+                )
+                upload_status["uploaded"].append(table_name)
+            except Exception as e:
+                logger.error(f"Error uploading dataframe {file_name} to database: {e}")
+                raise
+        elif file_name.rsplit("_", 1)[0] in mutable_df_dict:
+            table_name = file_name.rsplit("_", 1)[0]
+            try:
+                df.to_sql(
+                    table_name,
+                    con=db_engine,
+                    schema="project_team_2",
+                    if_exists="overwrite",
+                    index=False,
+                )
+                upload_status["uploaded"].append(table_name)
+            except Exception as e:
+                logger.error(f"Error uploading dataframe {file_name} to database: {e}")
+                raise
+        else:
+            upload_status["not_uploaded"].append(file_name)
+            logger.error(f"{file_name} does not correspond with table in database")
+    db_engine.dispose()
+    return upload_status
diff --git a/tests/test_load_lambda.py b/tests/test_load_lambda.py
new file mode 100644
index 0000000..88c71e4
--- /dev/null
+++ b/tests/test_load_lambda.py
@@ -0,0 +1,92 @@
+import pandas as pd
+import pyarrow.parquet as pq
+from io import BytesIO
+from moto import mock_aws
+import boto3
+import os
+import pytest
+from src.load_lambda import (
+    lambda_handler,
+    connect_to_db_and_return_engine,
+    get_transform_bucket,
+    convert_parquet_files_to_dfs,
+    upload_dfs_to_database,
+)
+
+
+@pytest.fixture(scope="class")
+def aws_credentials():
+    os.environ["AWS_ACCESS_KEY_ID"] = "testing"
+    os.environ["AWS_SECRET_ACCESS_KEY"] = "testing"
+    os.environ["AWS_SECURIT_TOKEN"] = "testing"
+    os.environ["AWS_SESSION_TOKEN"] = "testing"
+    os.environ["AWS_DEFAULT_REGION"] = "eu-west-2"
+
+
+@pytest.fixture(scope="class")
+def mock_s3_client(aws_credentials):
+    with mock_aws():
+        yield boto3.client("s3")
+
+
+class TestLambdaHandler:
+    pass
+
+
+class TestRetrieveSecrets:
+    pass
+
+
+class TestConnectToDBAndReturnEngine:
+    pass
+
+
+class TestGetTransformBucket:
+    def test_raises_value_error_if_no_buckets(self, mock_s3_client):
+        with pytest.raises(ValueError, match="No transform bucket found"):
+            get_transform_bucket(mock_s3_client)
+
+    def test_raises_value_error_if_no_transform_bucket(self, mock_s3_client):
+        mock_s3_client.create_bucket(
+            Bucket="extract_bucket",
+            CreateBucketConfiguration={"LocationConstraint": "eu-west-2"},
+        )
+        with pytest.raises(ValueError, match="No transform bucket found"):
+            get_transform_bucket(mock_s3_client)
+
+    def test_returns_transform_bucket_if_one_bucket(self, mock_s3_client):
+        mock_s3_client.create_bucket(
+            Bucket="transform_bucket",
+            CreateBucketConfiguration={"LocationConstraint": "eu-west-2"},
+        )
+        result = get_transform_bucket(mock_s3_client)
+        assert result == "transform_bucket"
+
+    def test_only_returns_transform_bucket_if_several_buckets(self, mock_s3_client):
+        mock_s3_client.create_bucket(
+            Bucket="another_test_bucket",
+            CreateBucketConfiguration={"LocationConstraint": "eu-west-2"},
+        )
+        result = get_transform_bucket(mock_s3_client)
+        assert result == "transform_bucket"
+
+
+class TestConvertParquetToDfs:
+    def test_function_returns_empty_dictionary_if_no_files(self, mock_s3_client):
+        mock_s3_client.create_bucket(
+            Bucket="transform_bucket",
+            CreateBucketConfiguration={"LocationConstraint": "eu-west-2"},
+        )
+        result = convert_parquet_files_to_dfs(
+            bucket_name="transform_bucket", client=mock_s3_client
+        )
+        assert result == {}
+
+    # def test_function_returns_dictionary_with_table_with_file_key():
+    #     # need to mock parquet file and upload to mock bucket
+    #     result = convert_parquet_files_to_dfs(bucket_name="transform_bucket", client=mock_s3_client)
+    #     assert "dim_staff" in result
+
+
+class TestUploadDfsToDatabase:
+    pass