"""Trace / bus inventory from a LayoutGraph. Numbers only, no findings."""

from __future__ import annotations

import re
from collections import defaultdict

from pydantic import BaseModel

from backend.periscopex.models import DesignGraph, LayoutGraph, NetType
from backend.periscopex.si_check import net_length_mm, partner_net


_BUS_RE = re.compile(r"^(.*?)(\d+)$")


class PcbNetInventory(BaseModel):
    name: str
    length_mm: float = 0.0
    via_count: int = 0
    layers: list[str] = []
    width_min_mm: float | None = None
    width_max_mm: float | None = None
    pair: str | None = None
    bus: str | None = None
    net_type: str | None = None
    z0_ohm: float | None = None


class PcbInventoryReport(BaseModel):
    nets: list[PcbNetInventory] = []
    domains: list[str] = []
    group_count: int = 0


def _bus_name(net: str) -> str | None:
    m = _BUS_RE.match(net.split("/")[-1].replace(".", "_"))
    if not m:
        return None
    prefix, digits = m.group(1), m.group(2)
    if not prefix or len(digits) > 3:
        return None
    return prefix.rstrip("_") or None


def build_pcb_inventory(
    layout: LayoutGraph,
    graph: DesignGraph | None = None,
    *,
    domain_ids: list[str] | None = None,
    group_count: int = 0,
    z0_by_net: dict[str, float] | None = None,
) -> PcbInventoryReport:
    names: set[str] = set()
    layers: dict[str, set[str]] = defaultdict(set)
    widths: dict[str, list[float]] = defaultdict(list)
    vias: dict[str, int] = defaultdict(int)
    for s in layout.segments:
        if not s.net:
            continue
        names.add(s.net)
        if s.layer:
            layers[s.net].add(s.layer)
        if s.width > 0:
            widths[s.net].append(s.width)
    for v in layout.vias:
        if v.net:
            names.add(v.net)
            vias[v.net] += 1
    z0_by_net = z0_by_net or {}
    rows: list[PcbNetInventory] = []
    for name in sorted(names):
        w = widths.get(name) or []
        sch = graph.nets.get(name) if graph else None
        nt = sch.net_type.value if sch and isinstance(sch.net_type, NetType) else (
            str(sch.net_type) if sch and sch.net_type else None
        )
        partner = partner_net(name)
        if partner and partner not in names:
            partner = None
        rows.append(PcbNetInventory(
            name=name,
            length_mm=round(net_length_mm(layout, name), 3),
            via_count=vias.get(name, 0),
            layers=sorted(layers.get(name, ())),
            width_min_mm=min(w) if w else None,
            width_max_mm=max(w) if w else None,
            pair=partner,
            bus=_bus_name(name),
            net_type=nt,
            z0_ohm=z0_by_net.get(name),
        ))
    return PcbInventoryReport(
        nets=rows,
        domains=list(domain_ids or []),
        group_count=group_count,
    )