from __future__ import annotations

import json
import os
from collections.abc import Iterator
from dataclasses import dataclass
from typing import Any, cast

import boto3
import pytest
from moto import mock_aws
from sqlalchemy import Engine
from sqlmodel import Session

from infrastructure.address2uprn_queue_client import Address2UprnQueueClient
from infrastructure.s3.csv_s3_client import CsvS3Client
from orchestration.postcode_splitter_orchestrator import PostcodeSplitterOrchestrator
from orchestration.task_orchestrator import TaskOrchestrator
from repositories.tasks.subtask_postgres_repository import SubTaskPostgresRepository
from repositories.tasks.task_postgres_repository import TaskPostgresRepository
from repositories.unstandardised_address.unstandardised_address_list_csv_s3_repository import (
    UnstandardisedAddressListCsvS3Repository,
)

BUCKET = "splitter-bucket"
REGION = "us-east-1"


def _make_boto_client(service_name: str) -> Any:
    factory: Any = (
        boto3.client
    )  # pyright: ignore[reportUnknownMemberType, reportUnknownVariableType]
    return factory(service_name, region_name=REGION)


@pytest.fixture(autouse=True)
def _aws_creds() -> Iterator[None]:  # pyright: ignore[reportUnusedFunction]
    keys = (
        "AWS_ACCESS_KEY_ID",
        "AWS_SECRET_ACCESS_KEY",
        "AWS_SESSION_TOKEN",
        "AWS_DEFAULT_REGION",
    )
    prev: dict[str, Any] = {k: os.environ.get(k) for k in keys}
    os.environ["AWS_ACCESS_KEY_ID"] = "testing"
    os.environ["AWS_SECRET_ACCESS_KEY"] = "testing"
    os.environ["AWS_SESSION_TOKEN"] = "testing"
    os.environ["AWS_DEFAULT_REGION"] = REGION
    try:
        yield
    finally:
        for k, v in prev.items():
            if v is None:
                os.environ.pop(k, None)
            else:
                os.environ[k] = v


@dataclass
class Harness:
    splitter: PostcodeSplitterOrchestrator
    task_orchestrator: TaskOrchestrator
    subtasks: SubTaskPostgresRepository
    csv_client: CsvS3Client
    boto_sqs: Any
    queue_url: str
    repo: UnstandardisedAddressListCsvS3Repository


@pytest.fixture
def harness(db_engine: Engine) -> Iterator[Harness]:
    with mock_aws():
        # Infra: S3 + SQS
        boto_s3 = _make_boto_client("s3")
        boto_s3.create_bucket(Bucket=BUCKET)
        boto_sqs = _make_boto_client("sqs")
        queue: dict[str, Any] = boto_sqs.create_queue(QueueName="address2uprn-queue")
        queue_url = cast(str, queue["QueueUrl"])

        csv_client = CsvS3Client(boto_s3, BUCKET)
        repo = UnstandardisedAddressListCsvS3Repository(csv_client, BUCKET)
        queue_client = Address2UprnQueueClient(boto_sqs, queue_url)

        # DB: ephemeral PostgreSQL TaskOrchestrator
        with Session(db_engine) as session:
            task_repo = TaskPostgresRepository(session=session)
            subtask_repo = SubTaskPostgresRepository(session=session)
            task_orchestrator = TaskOrchestrator(
                task_repo=task_repo, subtask_repo=subtask_repo
            )

            splitter = PostcodeSplitterOrchestrator(
                task_orchestrator=task_orchestrator,
                unstandardised_address_repo=repo,
                queue_client=queue_client,
                max_batch_size=3,
            )

            yield Harness(
                splitter=splitter,
                task_orchestrator=task_orchestrator,
                subtasks=subtask_repo,
                csv_client=csv_client,
                boto_sqs=boto_sqs,
                queue_url=queue_url,
                repo=repo,
            )


def _upload_fixture_csv(csv_client: CsvS3Client) -> str:
    # Three postcode groups:
    #   AA1 1AA × 2 (within cap)
    #   BB2 2BB × 4 (oversize: > max_batch_size=3)
    #   CC3 3CC × 1 (final flush)
    # Expected batching with cap=3 and the algorithm in
    # ``iter_postcode_grouped_batches``:
    #   batch 1: [AA1 1AA × 2]           (flushed because oversize follows)
    #   batch 2: [BB2 2BB × 4]           (oversize own batch)
    #   batch 3: [CC3 3CC × 1]           (final flush)
    rows: list[dict[str, str]] = []
    rows.extend(
        {
            "Address 1": f"{i} High St",
            "Address 2": "",
            "Address 3": "",
            "postcode": "AA1 1AA",
            "Internal Reference": f"AA-{i}",
        }
        for i in range(1, 3)
    )
    rows.extend(
        {
            "Address 1": f"{i} Long Road",
            "Address 2": "",
            "Address 3": "",
            "postcode": "BB2 2BB",
            "Internal Reference": f"BB-{i}",
        }
        for i in range(1, 5)
    )
    rows.append(
        {
            "Address 1": "1 Final Way",
            "Address 2": "",
            "Address 3": "",
            "postcode": "CC3 3CC",
            "Internal Reference": "CC-1",
        }
    )
    return csv_client.save_rows(rows, "uploads/input.csv")


def _drain_queue(boto_sqs: Any, queue_url: str) -> list[dict[str, Any]]:
    bodies: list[dict[str, Any]] = []
    while True:
        received: dict[str, Any] = boto_sqs.receive_message(
            QueueUrl=queue_url, MaxNumberOfMessages=10, WaitTimeSeconds=0
        )
        messages = cast(list[dict[str, Any]], received.get("Messages", []))
        if not messages:
            break
        for message in messages:
            bodies.append(cast(dict[str, Any], json.loads(message["Body"])))
            boto_sqs.delete_message(
                QueueUrl=queue_url, ReceiptHandle=message["ReceiptHandle"]
            )
    return bodies


def test_split_and_dispatch_creates_three_children_for_fixture(
    harness: Harness,
) -> None:
    # arrange
    parent_task, parent_subtask = harness.task_orchestrator.create_task_with_subtask(
        task_source="manual:postcode-splitter-int"
    )
    input_uri = _upload_fixture_csv(harness.csv_client)

    # act
    child_ids = harness.splitter.split_and_dispatch(
        parent_task_id=parent_task.id,
        parent_subtask_id=parent_subtask.id,
        input_s3_uri=input_uri,
    )

    # assert
    assert len(child_ids) == 3
    # All child ids are unique and persisted as WAITING children of the
    # parent task.
    assert len(set(child_ids)) == 3
    for cid in child_ids:
        child = harness.subtasks.get(cid)
        assert child.task_id == parent_task.id


def test_split_and_dispatch_persists_child_inputs_with_task_id_and_s3_uri(
    harness: Harness,
) -> None:
    # arrange
    parent_task, parent_subtask = harness.task_orchestrator.create_task_with_subtask(
        task_source="manual:postcode-splitter-int"
    )
    input_uri = _upload_fixture_csv(harness.csv_client)

    # act
    child_ids = harness.splitter.split_and_dispatch(
        parent_task_id=parent_task.id,
        parent_subtask_id=parent_subtask.id,
        input_s3_uri=input_uri,
    )

    # assert
    for cid in child_ids:
        child = harness.subtasks.get(cid)
        assert child.inputs is not None
        assert child.inputs["task_id"] == str(parent_task.id)
        batch_uri = child.inputs["s3_uri"]
        assert isinstance(batch_uri, str)
        prefix = (
            f"s3://{BUCKET}/ara_postcode_splitter_batches/"
            f"{parent_task.id}/{parent_subtask.id}/"
        )
        assert batch_uri.startswith(prefix)
        assert batch_uri.endswith(".csv")


def test_split_and_dispatch_publishes_one_message_per_child_with_matching_ids(
    harness: Harness,
) -> None:
    # arrange
    parent_task, parent_subtask = harness.task_orchestrator.create_task_with_subtask(
        task_source="manual:postcode-splitter-int"
    )
    input_uri = _upload_fixture_csv(harness.csv_client)

    # act
    child_ids = harness.splitter.split_and_dispatch(
        parent_task_id=parent_task.id,
        parent_subtask_id=parent_subtask.id,
        input_s3_uri=input_uri,
    )

    # assert
    bodies = _drain_queue(harness.boto_sqs, harness.queue_url)
    assert len(bodies) == len(child_ids)

    # Match queue messages against persisted child inputs by child_subtask_id;
    # the message body's task_id/s3_uri must agree with the SubTask inputs.
    bodies_by_child = {body["sub_task_id"]: body for body in bodies}
    assert set(bodies_by_child.keys()) == {str(cid) for cid in child_ids}
    for cid in child_ids:
        child = harness.subtasks.get(cid)
        body = bodies_by_child[str(cid)]
        assert child.inputs is not None
        assert body == {
            "task_id": str(parent_task.id),
            "sub_task_id": str(cid),
            "s3_uri": child.inputs["s3_uri"],
        }


def test_split_and_dispatch_returns_child_ids_in_dispatch_order(
    harness: Harness,
) -> None:
    # arrange
    parent_task, parent_subtask = harness.task_orchestrator.create_task_with_subtask(
        task_source="manual:postcode-splitter-int"
    )
    input_uri = _upload_fixture_csv(harness.csv_client)

    # act
    child_ids = harness.splitter.split_and_dispatch(
        parent_task_id=parent_task.id,
        parent_subtask_id=parent_subtask.id,
        input_s3_uri=input_uri,
    )

    # assert
    # Re-load each child's saved batch and inspect the postcode_clean column
    # to confirm the dispatch order matches the postcode-batching algorithm:
    # AA-batch first, BB oversize batch second, CC final-flush third.
    postcodes_per_batch: list[set[str]] = []
    for cid in child_ids:
        child = harness.subtasks.get(cid)
        assert child.inputs is not None
        rows = harness.csv_client.read_rows(child.inputs["s3_uri"])
        postcodes_per_batch.append({row["postcode_clean"] for row in rows})

    assert postcodes_per_batch == [
        {"AA11AA"},
        {"BB22BB"},
        {"CC33CC"},
    ]