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


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


def _serialize_seat(row) -> dict:
    return {
        "seat_record_id": row.seat_record_id,
        "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 _build_diff(before_map: dict, after_map: dict) -> list[dict]:
    keys = sorted(set(before_map.keys()) | set(after_map.keys()))
    result: list[dict] = []

    for key in keys:
        before = before_map.get(key)
        after = after_map.get(key)

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

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


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_map = {}
        baseline_group_map = {}
        baseline_seat_map = {}
        baseline_scheme_version_id = None
    else:
        baseline_scheme_version_id = baseline.scheme_version_id
        baseline_sector_map = {
            row.sector_record_id: _serialize_sector(row)
            for row in await list_scheme_version_sectors(baseline.scheme_version_id)
        }
        baseline_group_map = {
            row.group_record_id: _serialize_group(row)
            for row in await list_scheme_version_groups(baseline.scheme_version_id)
        }
        baseline_seat_map = {
            row.seat_record_id: _serialize_seat(row)
            for row in await list_scheme_version_seats(baseline.scheme_version_id)
        }

    draft_sector_map = {row.sector_record_id: _serialize_sector(row) for row in draft_sectors}
    draft_group_map = {row.group_record_id: _serialize_group(row) for row in draft_groups}
    draft_seat_map = {row.seat_record_id: _serialize_seat(row) for row in draft_seats}

    sector_diff = _build_diff(baseline_sector_map, draft_sector_map)
    group_diff = _build_diff(baseline_group_map, draft_group_map)
    seat_diff = _build_diff(baseline_seat_map, draft_seat_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,
    }