from __future__ import annotations

from app.repositories.scheme_groups import list_scheme_version_groups
from app.repositories.scheme_seats import list_scheme_version_seats
from app.repositories.scheme_sectors import list_scheme_version_sectors
from app.services.baseline_selector import select_baseline_scheme_version


def _sector_compare_value(row) -> dict:
    return {
        "element_id": row.element_id,
        "sector_id": row.sector_id,
        "name": row.name,
        "classes_raw": row.classes_raw,
    }


def _sector_response_value(row) -> dict:
    payload = _sector_compare_value(row)
    payload["sector_record_id"] = row.sector_record_id
    return payload


def _group_compare_value(row) -> dict:
    return {
        "element_id": row.element_id,
        "group_id": row.group_id,
        "name": row.name,
        "classes_raw": row.classes_raw,
    }


def _group_response_value(row) -> dict:
    payload = _group_compare_value(row)
    payload["group_record_id"] = row.group_record_id
    return payload


def _seat_compare_value(row) -> dict:
    return {
        "element_id": row.element_id,
        "seat_id": row.seat_id,
        "sector_id": row.sector_id,
        "group_id": row.group_id,
        "row_label": row.row_label,
        "seat_number": row.seat_number,
    }


def _seat_response_value(row) -> dict:
    payload = _seat_compare_value(row)
    payload["seat_record_id"] = row.seat_record_id
    return payload


def _build_diff(
    *,
    before_compare_map: dict,
    after_compare_map: dict,
    before_payload_map: dict,
    after_payload_map: dict,
) -> list[dict]:
    keys = sorted(set(before_payload_map.keys()) | set(after_payload_map.keys()))
    result: list[dict] = []

    for key in keys:
        before_compare = before_compare_map.get(key)
        after_compare = after_compare_map.get(key)
        before_payload = before_payload_map.get(key)
        after_payload = after_payload_map.get(key)

        if before_compare is None and after_compare is not None:
            status = "added"
        elif before_compare is not None and after_compare is None:
            status = "removed"
        elif before_compare != after_compare:
            status = "changed"
        else:
            status = "unchanged"

        result.append(
            {
                "key": key,
                "status": status,
                "before": before_payload,
                "after": after_payload,
            }
        )
    return result


def _sector_key(row) -> str:
    return row.sector_id if row.sector_id else (row.element_id if row.element_id else row.sector_record_id)

def _group_key(row) -> str:
    return row.group_id if row.group_id else (row.element_id if row.element_id else row.group_record_id)

def _seat_key(row) -> str:
    return row.seat_id if row.seat_id else (row.element_id if row.element_id else row.seat_record_id)

async def build_structure_diff(
    *,
    scheme_id: str,
    draft_scheme_version_id: str,
    baseline_override_scheme_version_id: str | None = None,
) -> dict:
    baseline, baseline_strategy = await select_baseline_scheme_version(
        scheme_id=scheme_id,
        draft_scheme_version_id=draft_scheme_version_id,
        override_scheme_version_id=baseline_override_scheme_version_id,
    )

    draft_sectors = await list_scheme_version_sectors(draft_scheme_version_id)
    draft_groups = await list_scheme_version_groups(draft_scheme_version_id)
    draft_seats = await list_scheme_version_seats(draft_scheme_version_id)

    if baseline is None:
        baseline_sector_compare_map = {}
        baseline_group_compare_map = {}
        baseline_seat_compare_map = {}
        baseline_sector_payload_map = {}
        baseline_group_payload_map = {}
        baseline_seat_payload_map = {}
        baseline_scheme_version_id = None
    else:
        baseline_scheme_version_id = baseline.scheme_version_id
        baseline_sectors = await list_scheme_version_sectors(baseline.scheme_version_id)
        baseline_groups = await list_scheme_version_groups(baseline.scheme_version_id)
        baseline_seats = await list_scheme_version_seats(baseline.scheme_version_id)
        baseline_sector_compare_map = {
            _sector_key(row): _sector_compare_value(row)
            for row in baseline_sectors
        }
        baseline_sector_payload_map = {
            _sector_key(row): _sector_response_value(row)
            for row in baseline_sectors
        }
        baseline_group_compare_map = {
            _group_key(row): _group_compare_value(row)
            for row in baseline_groups
        }
        baseline_group_payload_map = {
            _group_key(row): _group_response_value(row)
            for row in baseline_groups
        }
        baseline_seat_compare_map = {
            _seat_key(row): _seat_compare_value(row)
            for row in baseline_seats
        }
        baseline_seat_payload_map = {
            _seat_key(row): _seat_response_value(row)
            for row in baseline_seats
        }

    draft_sector_compare_map = {_sector_key(row): _sector_compare_value(row) for row in draft_sectors}
    draft_sector_payload_map = {_sector_key(row): _sector_response_value(row) for row in draft_sectors}
    draft_group_compare_map = {_group_key(row): _group_compare_value(row) for row in draft_groups}
    draft_group_payload_map = {_group_key(row): _group_response_value(row) for row in draft_groups}
    draft_seat_compare_map = {_seat_key(row): _seat_compare_value(row) for row in draft_seats}
    draft_seat_payload_map = {_seat_key(row): _seat_response_value(row) for row in draft_seats}

    sector_diff = _build_diff(
        before_compare_map=baseline_sector_compare_map,
        after_compare_map=draft_sector_compare_map,
        before_payload_map=baseline_sector_payload_map,
        after_payload_map=draft_sector_payload_map,
    )
    group_diff = _build_diff(
        before_compare_map=baseline_group_compare_map,
        after_compare_map=draft_group_compare_map,
        before_payload_map=baseline_group_payload_map,
        after_payload_map=draft_group_payload_map,
    )
    seat_diff = _build_diff(
        before_compare_map=baseline_seat_compare_map,
        after_compare_map=draft_seat_compare_map,
        before_payload_map=baseline_seat_payload_map,
        after_payload_map=draft_seat_payload_map,
    )

    return {
        "baseline_scheme_version_id": baseline_scheme_version_id,
        "baseline_strategy": baseline_strategy,
        "summary": {
            "sectors_added": sum(1 for item in sector_diff if item["status"] == "added"),
            "sectors_removed": sum(1 for item in sector_diff if item["status"] == "removed"),
            "sectors_changed": sum(1 for item in sector_diff if item["status"] == "changed"),
            "groups_added": sum(1 for item in group_diff if item["status"] == "added"),
            "groups_removed": sum(1 for item in group_diff if item["status"] == "removed"),
            "groups_changed": sum(1 for item in group_diff if item["status"] == "changed"),
            "seats_added": sum(1 for item in seat_diff if item["status"] == "added"),
            "seats_removed": sum(1 for item in seat_diff if item["status"] == "removed"),
            "seats_changed": sum(1 for item in seat_diff if item["status"] == "changed"),
        },
        "sectors": sector_diff,
        "groups": group_diff,
        "seats": seat_diff,
    }